As an adult ages, it is normal for the pituitary to produce diminishing amounts of GH and many other<unk> s, particularly the sex steroids. Physicians therefore distinguish between the natural reduction in GH levels which comes with age, and the much lower levels of "true" deficiency. Such deficiency almost always has an identifiable cause, with adult-onset<unk>  without a definable cause ("idiopathic<unk> ") extremely rare. GH does function in adulthood to maintain muscle and bone mass and strength, and has poorly understood effects on cognition and mood.
Growth hormone deficiency
Prader–Willi syndrome
Isolated growth hormone deficiency
Turner syndrome
Thyroid dysgenesis
Noonan syndrome
Congenital hypothyroidism
Small for gestational age