Abstract
Rapid and simple laboratory diagnosis of cortisol excess due to Cushing's syndrome is highly desirable. To date chronic overproduction of cortisol and loss of diurnal cortisol variation are considered to be the most consistent metabolic abnormalities in Cushing's syndrome. Nevertheless free urinary cortisol (F) and plasma cortisol levels may yield false negative results. We there fore applied a recently developed RIA for 6βOHF. 6βOHF is the major unconjugated urinary metabolite of corticol. In the evaluation of 33 adolescents and young adults for Cushing's syndrome near normal 17OH corticosteroids (14mg/24h) and/or F (120μg/24h) were found in 6 patients. 6βOHF was at least 10 times above nl in all 33 patients (mean:8.11mg/24±2.01 (SE) mg/24h vs nl 0.40±0.1 mg/24h). The ratio of 6βOHF/F was also markedly elevated (mean 14,8±3.3; vs nl 6.7±1). The highest 6βOHF excretion was seen in patients with ectopic ACTH production and adrenal cancer (35 and 75mg/24hr respectively). 6βOHF proved to discriminate better than either 17OH corticosteroids or F; no false negative or positive cases were seen in the present series. Our data suggest that excess ACTH indirectly and corticol directly induce 6β-hydroxylase activity causing highly diagnostic increases in 6βOHF excretion. Measurement of urinary 6βOHF is therefore suggested as a new, clinically useful test in the evaluation of hypercortisolemic states.
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Saenger, P., Peterson, R. Usefulness of urinary 6β-hydroxycortisol (6βOHF) excretion in the diagnosis of Cusing's syndrome. Pediatr Res 18, 1213 (1984). https://doi.org/10.1203/00006450-198411000-00077
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DOI: https://doi.org/10.1203/00006450-198411000-00077