8 A.M. cortisol & 24-hour urine free cortisol
● cortisol ↑ in hypercortisolism (Cushing syndrome)
● cortisol ↓ in hypoadrenalism (primary or secondary)
● T4 ↓ & TSH ↑ in primary hypothyroidism (this may cause thyrotroph hyperplasia in pituitary gland)
● T4 ↓ & TSH nl or ↓ in secondary hypothyroidism (as in hypopituitarism)
● ↑ or ↑↑ with prolactinoma
● slight ↑ with pituitary stalk effect (usually < 90 ng/ml)
Gonadotropins (FSH, LH) and sex steroids (♀: estradiol, ♂: testosterone)
● ↓ in hypogonadotrophic hypogonadism (from mass effect causing compression of the pituitary gland)
● ↑ with gonadotropin-secreting adenoma
Insulin-like growth factor 1 (IGF- 1) AKA somatomedin C
● ↑ in acromegaly
● ↓ in hypopituitarism (one of the most sensitive markers)
IGF-1 is the primary test for excess growth hormone (GH); direct measurement of GH is unreliable