SHORT STATURE

 

Edward Lichten, M.D., P.C.
555 South Old Woodward Avenue #700

Birmingham, Michigan 48009

Telephone: 248.593.9999     Fax: 248.593.9037

Email: drlichten@yahoo.com  

Overview:

Wikipedia[1]

Short stature refers to a height of a human being which is below expected. Shortness is a vague term without a precise definition and with significant relativity to context. Because of the lack of preciseness, there is often disagreement about the degree of shortness that should be called short.

The American Association of Clinical Endocrinologists defines "short stature" as height more than 2 standard deviations below the mean for age and gender, which corresponds to the shortest 2.3% of individuals[1].

Human Growth Hormone (HGH) deficiency may occur at any time during infancy or childhood, with the most obvious sign being a noticeable slowing of growth. The deficiency may be genetic.

Increasing final height in children with short stature may be beneficial and could enhance health-related quality of life (HRQoL) outcomes barring troublesome side effects and excessive cost of treatments[2]. A full description of the algorithm and workup are noted by Nwosu from the University of Massachusetts [10].The Merck Manual notes that Constitutional Delay of Puberty [11] is the absence of pubertal development in boys over 1 years of age. “Diagnosis is by exclusion of growth hormone deficiency, hypothyroidism, and hypogonadism (whether primary or due to gonadotropin deficiency)”.

Merck Manual: high levels of LH and FSH, even with low normal testosterone indicate primary hypogonadism while lower than expected LH and FSH indicate secondary hypogonadism (indicate constitutional delay). Other testing include measuring the LH and FSH with 3 blood samples, 20 minutes apart and the hCG stimulation tests with subsequent serum measurements of testosterone at day 3-4.

TREATMENT:

For secondary hypogonadism, any underlying pituitary or hypothalamic disorder is treated. Overall, the goal is to provide androgen replacement starting with a low dose and progressively increasing the dose over 18 to 24 mo. Adolescents with androgen deficiency should be given long-acting injectable testosterone enanthate or cypionate 50 mg q 2 to 4 wk; the dose is increased up to 200 mg over 18 to 24 mo. A transdermal patch or gel may be used instead[12].

Advances in Medicine:

Mauras[13] reports that “aromatase blockade effectively blocks estrogen production in males with a reciprocal increase in testosterone.. anastrozole ..is under investigation in adolescent subjects with severe growth retardation.  This class of drugs.. offers promise as an adjunct treatment of growth delay in pubertal patients with GH deficiency, short stature, texostoxicosis, and other disorders of growth. ..represents off-label use of the product, and definitive data on their efficacy are not available.

 

Gafny [14] from the Children’s Medical Center of Israel showed that “chronic GH therapy (.1U/kg/day) caused a marked rise in both IGF-1 (473%) and insulin levels (96%) and a gradual decline of SHBG to 75% of the basal concentration. In GH treated constitutional short stature, serum IGF-1 peaked at 80% and insulin levels at 102% above the respective basal levels, while SHBG decreased to 83% after 5 days of treatment.

 

Editor: The use of anastrozole to lower estradiol and cause a reciprocal increase in testosterone is under a clinical study although no results have been posted[15].. Similarly, the question is raised by the SHBG androgen sensitivity test whether there is a differential diagnosis of 446, XY gonadal dysgenesis [16]. Stanozolol should lower SHBG by 75% in a 6 week period in normal individuals.

 

References:

[1-2] Wikipedia, short stature

[10] Nosu B. AFP 2008 Sep 1;78(5):597-605 [http://www.aafp.org/afp/2008/0901/p597.html]

[11] Merck Manual [http://www.merckmanuals.com/professional/pediatrics/endocrine_disorders_in_children/male_hypogonadism_in_children.html]

[13] Mauras N. Strategies for maximizing growth in puberty in children with short stature. 2011. PMID: 21981954 [http://www.ncbi.nlm.nih.gov/pubmed/21981954]

[14] Gafny M. 1994. PMID:792321 [http://www.ncbi.nlm.nih.gov/pubmed/7923821

[15] Mausa N. 2012. [http://clinicaltrials.gov/show/NCT01248416]

[16] Krause A. 2004. PMID:15146368 [http://www.ncbi.nlm.nih.gov/pubmed/15146368]

[KEYWORDS:] SHORT STATURE, DWARF, KLINEFELTERS

 


 

 

Article:

·          

American Family Physicians

Evaluation of Short and Tall Stature in Children

Am Fam Physician. 2008 Sep 1;78(5):597-604.

Children and adolescents whose heights and growth velocities deviate from the normal percentiles on standard growth charts present a special challenge to physicians. Height that is less than the 3rd percentile or greater than the 97th percentile is deemed short or tall stature, respectively. A growth velocity outside the 25th to 75th percentile range may be considered abnormal. Serial height measurements over time documented on a growth chart are key in identifying abnormal growth. Short or tall stature is usually caused by variants of a normal growth pattern, although some patients may have serious underlying pathologies. A comprehensive history and physical examination can help differentiate abnormal growth patterns from normal variants and identify specific dysmorphic features of genetic syndromes. History and physical examination findings should guide laboratory testing.

Primary care physicians play an important role in identifying children with abnormal growth. In most cases, short or tall stature is caused by variants of a normal growth pattern; however, serious underlying pathology is present in some patients. A comprehensive history and physical examination should be performed in all children with abnormal growth, and laboratory studies should be based on these findings.1

SORT: KEY RECOMMENDATIONS FOR PRACTICE


Clinical recommendation

Evidence rating

References

Comments

A comprehensive history and physical examination should be completed in all children with abnormal growth.

C

1

The history and physical examination prevents unnecessary laboratory studies; children with dysmorphic features should be referred to a geneticist and an endocrinologist.

Accurate height and weight measurements in children should be plotted on a longitudinal growth chart.

C

5

Use of a growth chart is essential for monitoring a child's growth and overall health.

Ideally, accurate height and weight of children should be measured for more than six months to provide a better assessment of growth trends than with a shorter measurement period.

C

4

Midparental height should be calculated to determine the relationship of the child's current height to the parents' heights.

C

10

Children whose projected height differs from their genetic potential by more than 5 cm (2 in) should be further evaluated or referred to an endocrinologist.

Bone age radiography should be obtained to determine the relationship of the skeletal age to the chronologic age.

C

21

Children with bone age that is advanced or delayed by more than two standard deviations should be referred to an endocrinologist.


A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to http://www.aafp.org/afpsort.xml.

Normal Growth Pattern

A newborn's size is determined by the intra-uterine environment, which is influenced by maternal size, nutrition, general health, and social habits (e.g., smoking status). The average weight of a newborn is 7 lb, 3 oz (3.25 kg), and the average length is 50 cm (19.7 in).2 After birth, the growth rate becomes more dependent on the infant's genetic background.3

An important phenomenon, often called catch-up or catch-down growth, occurs in the first 18 months of life. In two thirds of children, the growth rate percentile shifts linearly until the child reaches his or her genetically determined growth channel or height percentile.3  Some children move up on the growth chart because they have tall parents, whereas others move down on the growth chart because they have short parents. By 18 to 24 months of age, most children's lengths have shifted to their genetically determined percentiles. Thereafter, growth typically proceeds along the same percentile until the onset of puberty (Table 1).

TABLE 1
Normal Growth Velocity at Various Life Stages


Life stage

Growth velocity per year

In utero

60 to 100 cm (24 to 40 in)

First year

23 to 27 cm (9 to 11 in)

Second year

10 to 14 cm (4 to 6 in)

Fourth year

6 to 7 cm (2 to 3 in)

Prepubertal nadir

5 to 5.5 cm (2 to 2.2 in)

Pubertal growth spurt

Girls: 8 to 12 cm (3 to 5 in)

 

Boys: 10 to 14 cm (4 to 6 in)

However, in children with certain conditions (e.g., growth hormone deficiency), normal birth weight and height may be followed by sustained growth deceleration starting at three to nine months of age. Beyond 24 months of age, children with constitutional delay of growth and puberty grow at a rate parallel to the 3rd percentile, whereas children with conditions such as growth hormone deficiency, Crohn's disease, and renal acidosis have a growth pattern that progressively falls further below the 3rd percentile or crosses percentiles.1

Approach to the Height Evaluation

MEASUREMENTS

Accurate serial height measurements documented over time on a growth chart are key in the evaluation of children and serve as the foundation for the diagnosis of growth abnormalities. The desired tool to measure height accurately is a wall-mounted, well-calibrated ruler with an attached horizontal measuring bar fixed at 90 degrees (e.g., a stadiometer). The child should stand erect, with the back of the head, back, buttocks area, and heels touching the vertical bar of the stadiometer; the horizontal measuring bar is lowered to the child's head to obtain the measurement. Children younger than three years should be measured on a firm horizontal platform that contains three essential components: an attached yardstick, a fixed headplate, and a movable footplate. One adult should hold the child's feet steady while another adult obtains the measurement.4 Inaccurate height measurement may result in failure to detect growth disorders or inappropriate referrals for normally growing children.4

GROWTH CHARTS

Plotting measurements on a growth chart (Figure 1) is essential for documenting and monitoring a child's longitudinal progression in size (i.e., the child's weight and height versus established normative data).5When properly plotted, a growth chart provides a snapshot of a child's growth pattern over time. The Centers for Disease Control and Prevention's growth charts are available athttp://www.cdc.gov/growthcharts.



 

http://www.aafp.org/afp/2008/0901/afp20080901p597-f1.gif


Figure 1.

Plotted growth chart showing different patterns of growth. From top to bottom on the chart: growth pattern of a boy with constitutional tall stature who has tall parents; growth pattern of a boy with pathologic growth failure, showing cessation of statural growth before normal epiphyseal fusion; growth pattern of a boy with constitutional delay of growth and puberty, showing parallel growth along the 5th percentile and continued growth after the normal age of growth cessation.

Adapted from National Center for Health Statistics. National health and nutrition examination survey. Clinical growth charts. Hyattsville, Md.: U.S. Dept. of Health and Human Services, CDC.http://www.cdc.gov/nchs/about/major/nhanes/growthcharts/clinical_charts.htm. Accessed Nov. 21, 2007.

Children who are growing below the 3rd percentile or who cross percentiles after 24 months of age regardless of height should be evaluated. Although growth charts are designed to reflect continuous and steady growth in children, actual growth has been reported to occur in steps between stops and starts.6Growth velocity varies with the seasons, accelerating in the spring and summer.7 Conventionally, growth progression over an extended period (e.g., six to 12 months) is more informative than that over a shorter period.4

In children two to three years of age, spurious growth deceleration may seem to occur if standing height is plotted on a supine chart because standing height is always shorter than supine length. Therefore, supine length should always be plotted on a supine chart (used in patients from birth to three years of age), and standing height plotted on a height chart (used in patients two to 20 years of age).8

In children born prematurely, height and weight adjusted for gestational age should be plotted in the first two years of life. This adjustment is calculated by subtracting the number of weeks premature the child was born from the child's current age (with 40 weeks' gestation being a full-term birth). For example, the length of a three-month-old infant born at 34 weeks' gestation should be plotted at the 1.5-month point (12 weeks of age, minus six weeks prematurity).

An accurate weight measurement should also be graphed. Malnutrition (the most common cause of poor growth in children) can be diagnosed in a child two years or younger whose weight for length is less than the 5th percentile or in a child older than two years whose body mass index (BMI) for age is less than the 5th percentile. A BMI for age greater than the 95th percentile is consistent with overweight, and a BMI for age between the 85th and 95th percentiles indicates a risk of becoming overweight.

GENETIC POTENTIAL

Because adult stature is usually genetically determined,9  a child's adult height potential can be estimated by calculating the midparental height. The midparental height is a child's projected adult height based on the heights of the parents: in girls, the father's height minus 13 cm (5 in) is averaged with the mother's height; in boys, the mother's height plus 13 cm is averaged with the father's height (Table 2).

TABLE 2
Midparental Height Calculations


Midparental height formulas

Boys: [father's height in cm + (mother's height in cm + 13 cm)]/2

Girls: [(father's height in cm – 13 cm) + mother's height in cm]/2

Sample calculations

Midparental height calculations for a son and a daughter of parents with the following heights: father is 172.72 cm, mother is 157.48 cm

 

Son: [172.72 cm + (157.48 cm + 13 cm)]/2 = 171.6 cm

 

Daughter: [(172.72 cm – 13 cm) + 157.48 cm]/2 = 158.6 cm


note: For midparental height calculation in inches, 1 in = 2.5 cm.

A rough estimate of the child's projected height, without taking skeletal maturation or pubertal tempo into account, can be determined by extrapolating the child's growth along his or her own height percentile to the corresponding 20-year point. If the estimated final height is within 5 cm (2 in) of the mid-parental height, the child's current height is appropriate for the family. However, if the projected height differs from the midparental height by more than 5 cm, a variant growth pattern or a pathologic cause should be considered.10 It is important to measure the parents' heights in the office, rather than use their reported height, to avoid over- or underestimation of midparental height.

BODY PROPORTIONS

The evaluation of upper-to-lower body segment ratios in children growing below the 3rd percentile for height helps differentiate skeletal dysplasia leading to disproportionate limb shortening from conditions that primarily affect the spine, such as scoliosis.11 The upper-to-lower body segment ratio can be determined by measuring the distance from the symphysis pubis to the floor (i.e., lower body segment) in a patient standing erect against a wall. The lower body segment is subtracted from the child's height to obtain the upper body segment value. The ratio is then derived by dividing the upper body segment value by the lower segment value. A more accurate way of determining the upper-to-lower body segment ratio is to measure the upper body segment (sitting height). The sitting height is subtracted from the patient's standing height to obtain the lower body segment value. Body proportions vary during childhood. The average upper-to-lower body segment ratio is 1.7 at birth and decreases to 1.0 at 10 years of age with leg growth.

Measuring the arm span is also crucial in the evaluation of body proportions.12,13 The arm span is the distance between the tips of the left and right middle fingers when a child is standing against a flat wall with arms outstretched as far as possible, creating a 90 degree angle with the torso. In girls and boys, the arm span is shorter than height before puberty and greater than height after midpuberty. Arm span exceeds height by 5.3 cm (2.1 in) in the average adult man and by 1.2 cm (0.5 in) in the average adult woman.4 Scoliosis and related conditions can lead to shortened vertebral growth and an arm span disproportionate to height.

Short Stature

Growth disturbances manifest as abnormal absolute height or growth velocity. Short stature is defined as height that is two standard deviations below the mean height for age and sex (less than the 3rd percentile) or more than two standard deviations below the midparental height.4 A growth velocity disorder is defined as an abnormally slow growth rate, which may manifest as height deceleration across two major percentile lines on the growth chart. In some cases, short stature or slow growth is the initial sign of a serious underlying disease in an otherwise healthy-appearing child.14

EVALUATION OF SHORT STATURE IN CHILDREN

Figure 2 presents an algorithm for the evaluation of children with short stature.

History. A comprehensive history starting in the pre-and perinatal periods should be obtained (

Evaluation of Children with Short Stature

http://www.aafp.org/afp/2008/0901/afp20080901p597-f2.gif


Figure 2.

Algorithm for the evaluation of children with short stature.

Table 3). Emphases of the history include maternal health and habits during pregnancy, the duration of gestation, birth weight and length, and onset and duration of catch-up or catch-down growth. The child's growth pattern and general nutrition should also be evaluated along with a detailed review of systems.

TABLE 3
Emphases of the History in the Evaluation of Abnormal Growth in Children


Type of history

Emphases

Comments

Maternal pregnancy history

Medication use, infections, nutrition

Infections, placental insufficiency, poor nutrition, and medication adverse effects can impair fetal growth and development

Perinatal and birth history

Duration of gestation, perinatal information, growth (weight and length)

Perinatal history may point to specific pathologies, such as hypopituitarism or hypothyroidism; birth measurements reflect intrauterine conditions; duration of gestation determines pre- or postmaturity

Growth pattern in the first three years

Establish pattern of growth

Many children have catch-up or catch-down growth between 18 and 24 months of age; growth rate percentile shifts linearly (up or down, depending on parents' heights) until the child reaches his or her genetically determined growth channel or height percentile

Growth pattern after three years of age

Prepubertal and pubertal growth velocity

Most children with normal growth usually do not cross percentiles after two years of age; peak height velocities typically occur at Tanner stage III in girls and Tanner stage IV in boys

Nutritional history

Source and quantity of nutrition

Malnutrition is the most common cause of poor growth worldwide; thus, a detailed history of quality and quantity of nutrition is critical in the evaluation of abnormal growth; a 24-hour food recall or three-day food diary is important in the evaluation

Family history

Father's height and age during pubertal growth spurt; mother's height and age at menarche; heights of siblings, grandparents, uncles, and aunts; medical conditions of family members

The heights of parents determine the heights of their children; most children also follow their parents' pubertal tempos; certain genetic disorders can lead to short or tall stature

Review of systems

Energy level; sleep patterns; headaches; visual changes; vomiting; abdominal pain; diarrhea and constipation; status and progress of sexual maturation; medical conditions, such as polyuria, polydipsia, oliguria

A thorough systemic review evaluates the functional capacity of various body systems

Social history

Home and school situations; stressors; social habits, such as tobacco use

Psychosocial dwarfism can be caused by severe stress from a poor home or school environment

Physical and Dental Examination. A thorough physical examination helps differentiate abnormal growth patterns from normal variants and identifies specific dysmorphic features of genetic syndromes. Growth hormone deficiency from hypopituitarism may cause micropenis, midface hypoplasia, and midline defects. Cushing syndrome can cause obesity, moon facies, violaceous striae, and cessation of linear growth. Chronic renal failure can cause pallor, ashen skin discoloration, and edema. Severe hypothyroidism can cause increased BMI from profound growth arrest with continued weight gain, sallow complexion, and delayed relaxation of the deep tendon reflexes. Girls with classic Turner syndrome present with short stature, a webbed neck, shield-shaped chest, and a low posterior hairline; whereas those with mosaic Turner syndrome may have no stigmata. Depending on the age of the child, rickets may cause craniotabes, bulbous wrists, and bowing of the extremities. Children with fetal alcohol syndrome present with short stature, low birth weight, poor weight gain, microcephaly, epicanthal folds, smooth philtrum, a flat nasal bridge, and a thin upper lip. Children with multiple dysmorphic features should be referred to subspecialists, including a geneticist and an endocrinologist.

Comparing a child's dental age with established norms provides an indirect assessment of skeletal age.15Some conditions may cause delayed tooth eruption, leading to delayed dental age. The eruption of primary and secondary teeth may be delayed for up to 1.3 years in children with growth hormone deficiency,16 up to 1.5 years in children with constitutional delay of growth and puberty,17 and more than two years in children with severe hypothyroidism.18

Laboratory Studies. A complete diagnostic evaluation should be performed, and certain patients should be referred to a pediatric endocrinologist (Table 4). The aim of the diagnostic evaluation is to confirm or rule out specific conditions based on history and physical examination findings.19 This approach prevents unnecessary laboratory studies because many disorders can cause short stature.

General screening tests (Table 5) assess the major organ systems, such as the liver, kidneys, and gastrointestinal tract, whereas specific concerns require more focused testing (Table 6). In addition to screening tests, thyroid function tests and karyotyping should be performed in all girls with short stature, even in the absence of clinical stigmata of Turner syndrome. In general, most children with short stature will have constitutional delay of growth and puberty or familial short stature, and few will need referral to a subspecialist.

TABLE 4
Abnormal Growth Findings Suggesting the Need for Referral


Height: growth less than the 3rd percentile or greater than the 95th percentile for height

Growth velocity: decreased or accelerated growth velocity for age (see Table 1 for normal growth velocities)

Genetic potential: projected height varies from midparental height by more than 5 cm (2 in)

Multiple syndromic or dysmorphic features: abnormal facies, midline defects, body disproportions

Bone age: advanced or delayed by more than two standard deviations


note: Patients with these findings should be referred to a pediatric endocrinologist.

TABLE 5
General Screening Tests in the Evaluation of Abnormal Growth in Children


Test

Function

Complete blood count with differential

Evaluates for anemia, blood dyscrasia, and infections

Basic metabolic panel

Rules out renal disease and electrolyte abnormalities that could occur with Bartter syndrome, other renal or metabolic disorders, and diabetes insipidus

Liver function testing

Assesses metabolic or infectious disorders associated with liver dysfunction

Urinalysis and urine pH level

Assesses kidney function and rules out renal tubular acidosis

Erythrocyte sedimentation rate

Evaluates for chronic inflammatory states

TABLE 6
Focused Diagnostic Tests in the Evaluation of Abnormal Growth in Children


Suspected cause

Diagnostic tests

Ancillary tests

Short stature

Celiac disease

Celiac antibody panel: antiendomysial, antigliadin, and tissue transglutaminase antibodies

Endoscopy

Cushing disease

Midnight serum cortisol, salivary cortisol, 24-hour urinary free cortisol estimations

Dexamethasone suppression test

Cystic fibrosis

Sweat chloride test

GH deficiency

IGF-I, IGF-binding protein 3

GH stimulation test

Hypothyroidism

Free thyroxine, TSH

Inflammatory disorders

Sedimentation rate, C-reactive protein

Endoscopy

Iron deficiency

Ferritin

Iron, TIBC

Turner syndrome

Karyotype

Echocardiography, renal ultrasonography

Vitamin D deficiency

25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone, ALK-P

Wrist radiography

Tall stature

Beckwith-Wiedemann syndrome

Insulin, glucose

Renal ultrasonography

GH excess

GH, IGF-I, IGF-binding protein 3

Pituitary MRI

Homocystinuria

Homocysteine, methionine

Infant of a mother with diabetes

Insulin, glucose

Klinefelter syndrome

LH, FSH, testosterone

Karyotype

Marfan syndrome

Clinical diagnosis using Ghent nosology*

Fibrillin-1 gene mutation, genetic consultation

Precocious puberty

   
 

Central

LH, FSH, estradiol, testosterone, bone age

GnRH analog stimulation test

 

Peripheral

17α-hydroxyprogesterone, HCG, DHEAS, estradiol, testosterone, bone age

Cosyntropin (Cortrosyn) stimulation test


ALK-P = alkaline phosphatase; DHEAS = dehydroepiandrosterone sulphate; FSH = follicle-stimulating hormone; GH = growth hormone; GnRH = gonadotropin-releasing hormone; HCG = human chorionic gonadotropin; IGF = insulin-like growth factor; LH = luteinizing hormone; MRI = magnetic resonance imaging; TIBC = total iron-binding capacity; TSH = thyroid-stimulating hormone.

*—The clinical criteria for the diagnosis of Marfan syndrome, which requires a combination of findings in different organ systems.

Bone Age. A bone age assessment provides an estimate of a child's skeletal maturation by assessing the ossification of the epiphyseal centers.20 Bone age helps estimate the child's growth potential based on established norms and more accurately predicts adult height.21 The most widely used method for predicting adult height based on skeletal maturation involves comparing a frontal radiograph of the left hand and wrist with standards from the Greulich-Pyle atlas.22,23 An inaccurate bone age estimation and difficulty in predicting pubertal tempo may lead to an incorrect final height prediction.20 Generally, bone age is considered delayed if it is two standard deviations below the chronologic age.

The pattern of skeletal maturity helps differentiate various types of short stature.21 In patients with familial short stature, bone age is normal for chronologic age4; in patients with constitutional delay of growth and puberty, bone age corresponds with height age and is typically delayed by two standard deviations24; and in patients with pathologic short stature, bone age is severely delayed (usually more than two standard deviations), and the delay worsens over time.19

Tall Stature

Tall stature is defined as a height that is two standard deviations above the mean for age and sex (greater than the 95th percentile).9 Excessive growth, defined as an abnormally rapid growth velocity, could manifest as height acceleration across two major percentile lines on the growth chart. It is important to distinguish tall patients who are otherwise healthy from those who have underlying pathology. Most children whose height is greater than the 95th percentile are part of a normal distribution curve, and few have a defined abnormality.9 However, tall stature or height acceleration may be the initial manifestation of serious underlying diseases, such as congenital adrenal hyperplasia.25

EVALUATION OF TALL STATURE IN CHILDREN

Figure 3 presents an algorithm for the evaluation of children with tall stature.



 

Evaluation of Children with Tall Stature

http://www.aafp.org/afp/2008/0901/afp20080901p597-f3.gif


Figure 3.

Algorithm for the evaluation of children with tall stature.

History. A comprehensive history should be obtained for the evaluation of tall stature. The areas of emphasis are the same as for short stature. In infants with macrosomia, a history of maternal gestational diabetes and family history of dysmorphology should be explored.

Physical Examination. As with short stature, a thorough physical examination differentiates abnormal growth patterns from nonpathologic variants. Accurate height measurements over time plotted on a growth chart is the best tool for assessing abnormal growth velocity.

Assessment of genetic potential helps differentiate familial from pathologic tall stature. In familial tall stature, a child's height is consistent with the midparental height. In pathologic tall stature, such as that caused by growth hormone excess, the child's projected height greatly exceeds the midparental height.24

The evaluation of body proportions is essential in the differential diagnosis of tall stature or growth acceleration. Children with constitutional tall stature have a normal upper-to-lower body segment ratio and arm span, whereas most children with Klinefelter syndrome have an increased arm span and eunuchoid proportions (i.e., disproportionately long limbs with an arm span exceeding the height by 5 cm).26

Patients may demonstrate clinical signs that point to a particular etiology. For example, soft tissue overgrowth from growth hormone excess may cause coarse facial features, mandibular prominence, and enlargement of hands and feet.27 Patients with Klinefelter syndrome have small, firm testes.26 Slit lamp examination may reveal an inferior subluxation of the lens in patients with homocystinuria and superior subluxation in patients with Marfan syndrome.1

Assessment of sexual maturity helps detect tall stature caused by precocious puberty. Conventionally, precocious puberty is defined as the onset of breast development before eight years of age in girls or the onset of testicular enlargement (3 mL or more) before nine years of age in boys.28 A controversial study suggests that normal puberty could start as early as six years of age in black girls and seven years of age in white girls.29 Obesity is the most common cause of tall stature in children. Children who are obese usually have slightly advanced pubertal status for age, modest overgrowth, and minimally advanced skeletal maturation.1,27

Advanced skeletal maturation occurs with precocious puberty and some overgrowth syndromes such as Sotos syndrome, Marshall-Smith syndrome, and Beckwith-Wiedemann syndrome.9 Sotos syndrome is a rare genetic disorder that is associated with excessive physical growth, large head size, and advanced bone age. Marshall-Smith syndrome is characterized by unusually quick physical growth, advanced bone age, and abnormal facies. Beckwith-Wiedemann syndrome is associated with pre-and postnatal overgrowth, advanced bone age, macroglossia, omphalocele, and hypoglycemia.

Laboratory Studies. The choice of laboratory studies for the evaluation of tall stature or accelerated growth velocity should be dictated by history and physical examination findings. As with short stature, general screening studies evaluate the functional capacity of organ systems, and focused diagnostic testing evaluates specific concerns.


The Authors

BENJAMIN U. NWOSU, MD, is an assistant professor of pediatrics at the University of Massachusetts Medical School, Worcester. He received his medical degree from the College of Medicine at the University of Nigeria, Enugu State. Dr. Nwosu completed a pediatrics residency at Howard University Hospital, Washington, DC, and a pediatric endocrinology and diabetes fellowship at the National Institutes of Health, Bethesda, Md.

MARY M. LEE, MD, is a professor of pediatrics and cell biology at the University of Massachusetts Medical School and is chief of the university's Pediatric Endocrine Division. She received her medical degree from the State University of New York School of Medicine, Buffalo. Dr. Lee completed a pediatrics residency at Children's Hospital of Buffalo and a pediatric endocrinology and diabetes fellowship at Children's Hospital of Philadelphia (Pa.).

Address correspondence to Benjamin U. Nwosu, MD, 55 Lake Ave. N., Worcester, MA 01655 (e-mail:nwosub@ummhc.org). Reprints are not available from the authors.

Author disclosure: Dr. Nwosu received a research grant from Genentech, Inc., and is on the speakers' bureaus for Pfizer, Inc., and Insmed, Inc.

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2. Needlman RD. Growth and development. In: Behrman RE, et al. Nelson Textbook of Pediatrics. 17th ed. Philadelphia, Pa.: Saunders; 2003.

3. Aceto TJ, Dempsher DP, Garibaldi L, et al. Endocrine and metabolic dysfunction in the growing child and aged. In: Becker KL, et al. Principles and Practice of Endocrinology and Metabolism. 3rd ed. Philadelphia, Pa.: Lippincott Williams & Wilkins; 2001:1784–1808.

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5. National Center for Health Statistics. National health and nutrition examination survey. Clinical growth charts. Hyattsville, Md.: U.S. Dept. of Health and Human Services, Centers for Disease Control and Prevention.http://www.cdc.gov/nchs/about/major/nhanes/growthcharts/clinical_charts.htm. Accessed November 21, 2007.

6. Lampl  M, Veldhuis  JD, Johnson  ML.  Saltation and stasis: a model of human growth.  Science.  1992;258(5083):801–803.

7. Wehr  TA.  Effect of seasonal changes in daylength on human neuroendocrine function.  Horm Res.  1998;49(3–4):118–124.

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MERCK MANUAL

Diagnosis

·         Measurement of testosterone, LH, FSH

·         Karyotyping (for primary hypogonadism)

Diagnosis is often suspected based on developmental abnormalities or delayed puberty but requires confirmation by testing, including measurement of testosterone, LH, and FSH. LH and FSH levels are more sensitive than testosterone levels, especially for detecting primary hypogonadism.

LH and FSH levels also help determine whether hypogonadism is primary or secondary:

·         High levels, even with low-normal testosterone levels, indicate primary hypogonadism.

·         Levels that are low or lower than expected for the testosterone level indicate secondary hypogonadism.

In boys with short stature, delayed pubertal development, low testosterone, and low FSH and LH levels may indicate constitutional delay. Elevated serum FSH levels with normal serum testosterone and LH levels typically indicate impaired spermatogenesis but not impaired testosterone production. In primary hypogonadism, it is important to determine the karyotype to investigate for Klinefelter's syndrome.

Measurement of testosterone, FSH, and LH for diagnosis of hypogonadism requires an understanding of how the levels vary. Before puberty, serum testosterone levels are < 20 ng/dL (< 0.7 nmol/L) and in adulthood, levels are > 300 to 1200 mg/dL. Serum testosterone secretion is primarily circadian. In the 2nd half of puberty, levels are higher at night than during the latter part of the day. A single sample obtained in the morning can establish that circulating testosterone levels are normal. Because 98% of testosterone is bound to carrier proteins in serum (testosterone-binding globulin), alterations in these protein levels alter total testosterone levels. Measurement of total serum testosterone (protein bound and free) is usually the most accurate indicator of testosterone secretion.

For LH and FSH levels, 3 blood samples should be taken at 20-min intervals. This approach maximizes the likelihood of detecting LH pulsations, which occur at 90- to 120-min intervals. Serum LH and FSH levels are usually < 5 mIU/mL before puberty and fluctuate between 5 and 20 mIU/mL during the 2nd half of puberty and into adulthood.

The human chorionic gonadotropin (hCG) stimulation test is done to assess the presence and secretory ability of testicular tissue; hCG 100 IU/kg is given to children. hCG stimulates Leydig cells, as does LH, with which it shares a structural subunit, and stimulates testicular production of testosterone. Testosterone levels should double after 3 to 4 days.

The GnRH stimulation test is done in boys to distinguish between hypothalamic dysfunction and pituitary dysfunction as the cause of hypogonadotropic hypogonadism. GnRH 2.5 μg/kg or leuprolide-acetate 500 μg is rapidly injected IV. The injection directly stimulates the pituitary to secrete LH and FSH, which are measured every 20 to 30 min for 2 h. Throughout childhood and into early puberty, response to GnRH is predominantly an increase in FSH with little or no increase in LH. During puberty, LH and FSH respond more or less equally (by doubling or tripling). An inadequate to absent increase in FSH and LH may indicate hypopituitarism.

Treatment

·         Surgery as needed

·         Hormone replacement

Cryptorchidism is corrected early to obviate concerns about cancer developing in later adulthood and to prevent testicular torsion (see Congenital Renal and Genitourinary Anomalies: Cryptorchidism).

For secondary hypogonadism, any underlying pituitary or hypothalamic disorder is treated. Overall, the goal is to provide androgen replacement starting with a low dose and progressively increasing the dose over 18 to 24 mo.

Adolescents with androgen deficiency should be given long-acting injectable testosterone enanthate or cypionate 50 mg q 2 to 4 wk; the dose is increased up to 200 mg over 18 to 24 mo. A transdermal patch or gel may be used instead.

Treatment of Kallmann syndrome with hCG can correct cryptorchidism and establish fertility. Pulsatile GnRH therapy given subcutaneously by a portable pump leads to endogenous sex hormone secretion, progressive virilization, and even fertility.

In isolated LH deficiency, testosterone, via conversion to estrogen by aromatase, induces normal epiphyseal closure.


 

 

KRAUSE A. APPLICATION OF THE SHBG ANDROGEN SENSITIVITY TEST

Exp Clin Endocrinol Diabetes. 2004 May;112(5):236-40.

Applicability of the SHBG androgen sensitivity test in the differential diagnosis of 46,XY gonadal dysgenesis, true hermaphroditism, and androgen insensitivity syndrome.

Krause A, Sinnecker GH, Hiort O, Thamm B, Hoepffner W.

Source

Children's Hospital of the University of Leipzig, Leipzig, Germany.

Abstract

The sex hormone-binding globulin (SHBG) androgen sensitivity test has been used as a simple method to assess androgen receptor function in vivo. After a short term oral administration of the anabolic-androgenic steroid stanozolol the mean nadir serum concentration of SHBG is used as a measure of androgen response. We performed this test in order to evaluate its applicability in 16 patients with intersexual genital status: eleven with 46,XY gonadal dysgenesis and three with true hermaphroditism (group I), and in two patients with androgen insensitivity syndrome (AIS, group II). Ten healthy adult volunteers served as controls. In the two patients with AIS (group II) we found a diminished decrease of serum SHBG to 80.1 % and 80.7 %, respectively, indicating slight residual androgen responsiveness. In eleven patients of group I who were not on hormone replacement therapy, a mean nadir level of 51.7 +/- 8.7 % was found. In the controls the mean nadir serumSHBG level was significantly higher (62.7 +/- 5.2 %), probably due to interference of endogenous androgens and contraceptive medication with the stanozolol-induced SHBG decrease. In three gonadectomised patients who were on hormone replacement therapy the initial SHBG concentration was increased (513.5 +/- 239.1 nmol/l); the mean nadir SHBG concentration of 45.6 +/- 9.8 % of the initial level indicates an increased sensitivity of the test in patients in whom the counteracting ovarian androgens are absent. Our findings confirm that under standard test conditions the SHBG androgen sensitivity test is a simple diagnostic tool for the detection of androgen receptor malfunction.