Cushing 17-hydroxycorticosteroid

Suppression tests For Cushing syndrome, give 1 mg at 11 pm. Draw blood for plasma cortisol determination the following day at 8 am. For greater accuracy, give 0.5 mg every 6 hours for 48 hours. Collect 24-hour urine to determine 17-hydroxycorticosteroid excretion. 

Interpretation Patients with Cushing s syndrome caused by an ACTH-secreting pituitary adenoma usually show (1) suppression of urinary free cortisol and 17-hydroxycorticosteroid excretion >50% of baseline by day 4 ... 

The blood of patients with Cushing s disease shows changes typical of hypercorticosteroidism and diabetes. The level of 17-hydroxycorticosteroids is increased in the urine. This is not pathognomonic of Cushing s disease, and such an increase must be differentiated from that attributable to stress or liver insufficiency. On the other hand, the levels of blood 17-corticosteroids are usually not markedly increased in Cushing s disease, and they barely exceed the normal values. 

A collective term for a group of corticosteroids having a hydroxyl group at the 11-position, which can be estimated fluo-metrically in plasma and urine. Since the main steroid measured is cortisol, with a minor contribution from corticosterone, the term for most clinical purposes is synonymous with cortisol. Increases in plasma and urine 11-hydroxycorticosteroid levels are found in Cushing s syndrome whereas decreased levels are found in Addison s disease. 

Decreased urinary excretion of 17-hydroxycorticosteroids occurs in Addison s disease while increases are found in Cushing s syndrome. 

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