growth%20hormone%20deficiency%20(pediatric)
GROWTH HORMONE DEFICIENCY (PEDIATRIC)
Growth hormone deficiency is a congenital or an acquired growth hormone axis disruption in the higher brain, hypothalamus or pituitary which results in short stature.
It may occur at any age.
Short stature is often the only feature present in patients with growth hormone deficiency and other causes of subnormal growth rate.
Etiology may be congenital conditions (eg defective pituitary development that leads to pituitary aplasia, empty sella, encephalocele, midline defects) or acquired conditions (eg tumors of the hypothalamic-pituitary region, cranial irradiation, infiltrative disease).

Principles of Therapy

Growth Hormone (GH) Replacement Therapy

  • GH replacement therapy is best accomplished under the direct supervision of a pediatric endocrinologist
  • Goals of pharmacotherapy
    • To restore normal GH levels & to reduce morbidity
    • To enable short children to achieve normal height w/ early improvement of the psychosocial problems related to short stature

Pharmacotherapy

Somatropin or Growth Hormone (GH)

  • Synthetic polypeptide human GH of recombinant DNA (rDNA) origin
  • Indicated for children w/ growth hormone deficiency (GHD), Turner syndrome, Prader-Willi syndrome, Noonan syndrome, short children small for gestational age, children w/ short stature homeobox-containing gene (SHOX) deficiency, & children w/ impared growth due to chronic kidney disease
  • May also be used for children w/ idiopathic short stature (ISS) shorter than -2.25 SD score whose epiphyses are not closed, & w/ expected adult height below the normal range (<63 in for males, <59 in for females)
  • Treatment should be started as soon as diagnosis of GHD is confirmed
  • GH trial therapy also recommended for children w/ otherwise unexplained short stature who pass GH stimulation tests, but who meet most of the following criteria:
    • Height >2.25 SD below the mean for age or >2 SD below the midparental height percentile
    • Growth velocity <25th percentile for bone age
    • Bone age >2 SD below the mean for age
    • Low serum IGF-1 & IGFBP-3
    • Other clinical features suggestive of GHD
  • Effects:
    • Induce normal statural growth
    • Correction of hypoglycemia
  • Target for treatment:
    • Satisfactory response is defined as an increase of height velocity of at least 2-3 cm/year above pre-treatment velocity
    • Growth rate <1 inch/year
    • Achieve normal adult height
    • Attainment of bone age of 14 years (girls) & 16 years (boys)
  • Further studies are needed to prove the relationship between GH therapy during childhood & increased incidence of stroke in adolescents; preventive measures against stroke is advised for those w/ known risk factors

Gonadotropin-Releasing Hormone (GnRH) Agonist

  • Studies found GnRH to be effective when given concurrently w/ recombinant GH
  • May delay epiphyseal fusion & prolong growth during puberty
  • Increases height & velocity in some GHD pediatric patients

Recombinant IGF-1/Mecasermin

  • Alternative treatment for patients w/ GH receptor abnormalities, STAT5b gene defects, & those w/ severe GHD unresponsive to therapy due to development of antibodies against GH
  • Further studies are needed to prove its efficacy in GHD
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