Abstract
Rapid and simple laboratory diagnosis of cortisol excess due to Cushing's syndrome is highly desirable. To date chronic over-production of cortisol and loss of diurnal cortisol variation are considered to be the most consistent metabolic abnormalities in Cushing's syndrome. Nonetheless free urinary cortisol (F) and plasma cortisol levels may yield false negative results. We therefore applied a recently developed RIA for 6βOHF. 6βOHF is the major unconjugated urinary metabolite of cortisol. In the evaluation of 33 adolescents and young adults for Cushing's syndrome near normal 17OH corticosteroids (<14mg/24h) and/or F (<120μg/24 h) were found in 6 patients. 6βOHF was at least 10 times abovenl in all 33 patients (mean: 8.11mg/24±2.01(SE)mg/24h vs nl 0.4±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/24 hr respectively). The data show that 6βOHF is a rapid and reliable test for hypercortisolemia due to Cushing's syndrome. 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 further that excess ACTH indirectly and cortisol 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 in adolescence.
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Saenger, P., Peterson, R. USEFULNESS OF URINARY 6β-HYDROXYCORTISOL (6βOHF) EXCRETION IN THE DIAGNOSIS OF CUSHING'S SYNDROME. Pediatr Res 18 (Suppl 4), 99 (1984). https://doi.org/10.1203/00006450-198404001-00036
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DOI: https://doi.org/10.1203/00006450-198404001-00036