Clinical meaning
The HPA axis regulates cortisol secretion through CRH (hypothalamus) stimulating ACTH (anterior pituitary) stimulating cortisol (adrenal cortex) with negative feedback. Chronic stress dysregulates the axis causing sustained cortisol elevation, immune suppression, metabolic derangements, and psychiatric effects. Exogenous glucocorticoid use >2-3 weeks suppresses the HPA axis requiring gradual taper to prevent adrenal crisis.
Diagnosis & workup
Diagnostics & workup: - Plasma metanephrines for pheochromocytoma screening - IGF-1 for growth hormone excess or deficiency screening - 24-hour urine free cortisol for Cushing confirmation - Free T4 and Free T3 for thyroid hormone assessment - Pituitary MRI for sellar/suprasellar mass evaluation - Fasting glucose and 2-hour OGTT for diabetes diagnosis - TSH (most sensitive for primary thyroid dysfunction)
Risk factors: - Eating disorders with hypothalamic amenorrhea - Pregnancy altering hormonal milieu (gestational DM, thyroiditis) - MEN syndrome family history - Obesity (BMI >30) with insulin resistance - Sleep deprivation disrupting cortisol and growth hormone secretion - Age-related hormonal decline (menopause, andropause) - Family history of endocrine disorders (autoimmune thyroid, T2DM)