Schöneshöfer M, Weber B, Nigam S
Clin Chem. 1983 Feb;29(2):385-9.
We identified non-metabolized, non-conjugated 20 alpha- and 20 beta-dihydrocortisol (20 alpha- and 20 beta-DHF) in urine from a patient with Cushing's disease, by use of three different liquid-chromatographic systems and by gas chromatography-mass spectrometry. We document that these 20-isomers of dihydrocortisol may strongly contribute to unspecific interferences with the immunological assessment of urinary free cortisol (F). The urinary excretion rates of 20 alpha- and 20 beta-DHF were quantified radioimmunologically with use of a cross-reacting cortisol antiserum after effective purification by liquid chromatography. The patient with Cushing's disease had mean peripheral cortisol concentrations of 1018 nmol/L. The urinary excretion rates (nmol/24 h) were 1455 for 20 alpha-DHF, 330 for 20 beta-DHF, and 18 for F. The corresponding reference values (median in nmol/24 h) were 174 for 20 alpha-DHF, 111 for 20 beta-DHF, and 68 for F (n = 22). We conclude that (a) specific estimation of urinary free F is not as highly sensitive for diagnosis of chronic hypercortisolemic states as is generally assumed; and (b) measurement of urinary free 20 alpha- and 20 beta-DHF or of the corresponding 20-DHF:F ratios may be more sensitive.
我们利用三种不同的液相色谱系统和气相色谱 - 质谱联用技术，在一位库欣病患者的尿液中鉴定出了未代谢、未结合的20α - 和20β - 二氢皮质醇（20α - 和20β - DHF）。我们证明，这些二氢皮质醇的20 - 异构体可能会对尿游离皮质醇（F）的免疫学评估产生强烈的非特异性干扰。在通过液相色谱有效纯化后，使用交叉反应的皮质醇抗血清通过放射免疫法对20α - 和20β - DHF的尿排泄率进行了定量。该库欣病患者的外周皮质醇平均浓度为1018 nmol/L。20α - DHF的尿排泄率（nmol/24 h）为1455，20β - DHF为330，F为18。相应的参考值（nmol/24 h的中位数）为：20α - DHF为174，20β - DHF为111，F为68（n = 22）。我们得出结论：（a）尿游离F的特异性测定对于慢性皮质醇增多症状态的诊断并不像通常认为的那样高度敏感；（b）测定尿游离20α - 和20β - DHF或相应的20 - DHF:F比值可能更敏感。
