Peripheral blood steroid levels in Cushing syndrome due to adrenocortical carcinoma or adenoma

Measurement of the peripheral vein levels of the steroids in the adrenal biosynthetic pathway affords a further possible definitive method of differentiating adrenocortical carcinoma from adrenal adenoma in the presence of Cushing syndrome. In patients with adrenal carcinoma the blood levels of 17-hydroxyprogesterone, testosterone, androstenedione, and dehydroepiandrosterone are far higher than those seen in association with adenoma. In addition, the adrenal cortical carcinoma appears to have a higher ratio of precursors to product in the early part of the biosynthetic path and a lower one in the distal portion than adrenal adenomas. In Cushing syndrome due to adrenal tumor the measurement of serum cortisol is preferably made after chromatographic separation from 11-deoxycortisol in view of the marked cross reactivity in the protein binding procedure.