By how many fold is 24-hour urine free cortisol typically increased in primary hypercortisolism?

• A. Fourfold
• B. Twofold
• C. Tenfold
• D. Normal

Answer: (A)

In primary hypercortisolism, the adrenal glands produce cortisol autonomously, so a large amount is cleared and excreted daily as free cortisol in urine. The 24-hour urine free cortisol test reflects this excess and is typically markedly elevated—about four times the upper limit of normal. This level is a common, characteristic part of the picture in Cushing’s syndrome, indicating substantial but not necessarily extreme overproduction. A twofold rise is milder than what’s usually seen, a tenfold rise can occur but is less typical, and a normal result would argue against hypercortisolism.