Cause:Idiopathic or associated with other pituitary lesions; genetic, autosomal recessive

Pathophys:Growth hormone is responsible for growth stimulation and lipid mobilization/protein sparing. In pygmies and some genetic dwarfs (Nejm 1971;284:809), defect is in end-organ responsiveness from growth hormone receptor deficiency (Nejm 1990;323:1367). Insulin-like growth factor mediates these effects and alone is responsible for most prenatal growth (Nejm 1996;335:1363)

Dwarfism is associated with other pituitary defects 50% of the time

Sx:Dwarfism in children: height impairment is often greater than weight impairment, ie, "pudgy" kids; 50% are <3 d percentile at 1 yr

Si:

in children, short stature, decreased growth velocity, delayed bone age

in adults, osteoporosis, hyperlipidemia, diminished muscle strength and vitality

Hypoglycemia often, esp if ACTH deficiency too

r/o growth hormone receptor insensitivity due to mutation, partial or complete (Laron dwarfism) (Nejm 1995;333:1093)

Lab:

Chem:Hypoglycemia, esp if there are combined HGH and ACTH deficiencies present (Nejm 1968;278:57)

HGH (IGF-1) levels low for age, or fails to elevate w stimulation tests (insulin, clonidine, arginine, L-dopa, glucagon) (Nejm 1988;319:201)

Xray:Bone age is younger than chronologic age