Hyposomatotropism (Growth Hormone Deficiency) Clinical Presentation

Updated: Jan 24, 2019
  • Author: Sunil Kumar Sinha, MD; Chief Editor: Robert P Hoffman, MD  more...
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Presentation

History

Congenital hyposomatotropism

Infants with congenital growth hormone (GH) deficiency (GHD) are typically born with a length and weight between the 5th and 10th percentile for their gestational age. A family history of short stature or parental consanguinity may suggest a genetic etiology.

One study compared fetal and neonatal growth curves in detecting growth restriction. [37]  Newborns with congenital hypopituitarism (defined as deficiencies of all anterior pituitary hormones) often present with midline craniofacial abnormalities (eg, single central maxillary incisor, cleft lip or palate, optic hypoplasia), hypoglycemia, blindness, micropenis, and hyperbilirubinemia. [38]

Hypoglycemia can be profound and clinically resembles congenital hyperinsulinism in patients with GHD or, especially, hypopituitarism. Hypoglycemia results from the lack of counterregulatory hormones important for glucose homeostasis; these include GH, corticotropin, and thyroid-stimulating hormone. Although not usually considered a source for hypoglycemia, thyroid hormone may stimulate gluconeogenesis and increase insulin clearance. This mechanism could account for the hyperinsulinemic hypoglycemia observed in a small number of patients with congenital hypothyroidism. [39, 40, 41, 42]

The combination of microcephalus, cryptorchidism, and hypoplasia of the scrotum can occur with coexistent GHD and gonadotropin deficiencies. [43] Testosterone bioactivity plays an essential role in the differentiation and development of the male genitalia. During the first trimester, GH modulates fetal testosterone production, perhaps by regulating placental chorionic gonadotropins. During the second and third trimesters, testosterone production appears to be independent of GH and relies on fetal pituitary gonadotropins.

Liver disease has been associated with neonatal hypopituitarism. [44] Hypothyroidism is a well-recognized cause of neonatal jaundice, typically an indirect hyperbilirubinemia. The current theory regarding conjugated hyperbilirubinemia is based on the relationship of GH to bile acid synthesis. GH stimulates the synthesis of bile acids, which are major determinants for the induction of canalicular bile secretion. Cholestasis associated with congenital hypopituitarism resolves with hormone replacement.

Neonatal hypoglycemia, persistent cholestatic jaundice, or hypogonadism in a male patient should immediately suggest the possibility of GHD. Neonatal hypopituitarism is potentially fatal if left untreated.

Acquired hyposomatotropism

Acquired GHD can have multiple sources. By the age of 6-12 months, infants with GHD clearly demonstrate an abnormally low growth velocity. Skeletal proportions remain normal, but skeletal age is delayed, often to less than 60% of the infant's chronologic age [45, 46, 47] . Delay in dental eruption may precede this finding. Characteristic facies in patients with GHD result from retarded growth of the facial bones. Closure of the fontanelles is often delayed and results in frontal bossing and hydrocephalus. The nasal bridge may be markedly underdeveloped, and the orbits may be shallow; these alterations result in disproportionate cephalofacial relationships.

The weight-to-height ratio tends to be increased, just as the ratio of fat to lean muscle is elevated because of the absence of the effect of GH on the peripheral tissues. Decreased development of lean muscle results in poor muscular tone during infancy and early childhood; this sometimes leads to gross motor delays. Hair growth is sparse, and nails are thin and grow slowly. Laryngeal hypoplasia results in continuation of the prepubescent voice in boys with GHD.

Puberty may be delayed by 3-7 years despite normal gonadotropin release. This is likely related to the delay in skeletal age. For reasons that remain incompletely understood, skeletal development must be of a certain age (at least 9 yr for girls and 10 yr for boys) for puberty to ensue. Despite this delay, sexual function and fertility are normal in people with GHD. Although micropenis may occur during infancy in the congenital form of GHD, the penis is normal for the person's body size during adulthood.

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Physical Examination

Findings in patients with congenital hyposomatotropism are summarized below:

  • Normal length at birth

  • Midline defects

  • Cleft lip

  • Cleft palate

  • Blindness

  • Single central maxillary incisor

  • Hypogonadotropic hypogonadism

  • Jaundice

  • Icterus

  • Hepatosplenomegaly

  • Hypoglycemia

  • Shaking

  • Irritability

  • Lethargy

  • Hypotonia

  • Diaphoresis

  • Tachycardia

  • Pallor

  • Seizures

Findings in patients with acquired hyposomatotropism are summarized below:

  • Short stature

  • Frontal bossing

  • Flattened nasal bridge 

  • Forehead prominence

  • Delayed dental eruption and exfoliation

  • Delayed bone age

  • Increased weight-to-height ratio

  • Poor muscle tone (motor delay may result)

  • Laryngeal hypoplasia

  • Poor hair and nail growth

  • Delayed puberty

  • Normal genitalia

  • Normal skeletal proportions

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