Abstract
RATIONALE: Urine contains free and conjugated steroids. Total
and free steroids were comprehensively quantified; UPLC-MS/MS based on
Li adduction allowed for detecting thirteen 3-OH-containing steroids,
two of which were detected in human urine for the first time.
METHODS: Free urinary steroids were isolated by solid-phase
extraction (SPE) with 80% acetonitrile. The total steroids were
prepared by enzymatic treatment of urine with a cocktail of sulfatase
and glucronidase, protein precipitation, and separation with the above
SPE. The free and total steroids were separately analyzed by UPLC-MS/MS
with and without introduction of Li + solution. The
steroids were quantified by two standard curves created using product
ion transitions derived from MH + and [M+Li]
+. RESULTS: Two groups of human urine, male
and female urine, were analyzed. The absolute amount of each steroid was
determined based on creatinine levels. The differences between the male
and female groups are clearly attributable to sex steroids. 7-OH P5 and
7-OH DHEA were, for the first time, quantified in the total steroids of
female urine, and the latter was identified in both female and male
urine. CONCLUSIONS: By combining UPLC-MS/MS based on lithium
ion incorporation with conventional UPLC-MS/MS, a total of 29 steroids
were identified in human urine containing two newly found steroids.