Circulating androgens and SHBG during the normal menstrual cycle in two ethnic populations.

The objective of this study was to study possible ethnic differences in steroid hormones and sex hormone-binding globulin (SHBG) during the menstrual cycle. Serum levels of the ovarian steroids estradiol (E2) and progesterone (P) and of follicle-stimulating hormone (FSH), luteinizing hormone (LH), SHBG, dehydroepiandrosterone (DHEA) and testosterone (T-ria) were all measured by immunoassay during the menstrual cycle in 15 Swedish and 11 West Asian regularly menstruating women. Testosterone (T-ms) was also measured by LC-MS/MS and so were 4-androstene-3,17-dione (A-4) and 17-alpha-hydroxyprogesterone (17-OHP). There were no ethnic differences in levels of ovarian steroids, gonadotrophins, A-4, 17-OHP and T-ms. DHEA were significantly higher and SHBG significantly lower in West Asian than in Swedish women. Surprisingly, T-ria was significantly higher in West Asian than in Swedish women and higher than T-ms (47% in Swedish and 107% in West Asian women). The difference (T-ria - T-ms) showed strong positive correlations to DHEA in the total and in West Asian but not in Swedish women, indicating an influence of DHEA/DHEAS metabolites on the T-ria results. In conclusion, ethnic differences in cross reacting steroids may cause erroneous results in one ethnic group by a steroid immunoassay having reasonable specificity in another. The reasons for the lower SHBG and the higher DHEA levels in West Asian women are not known. The results raise the question about establishing different reference values for certain analytes in different ethnic groups.

Predisposing factors and consequences of elevated biomarker levels in long-distance runners aged >or=55 years.

Cardiac biomarkers play an important role in the diagnosis of cardiovascular disease. Elevated levels can be seen in the context of strenuous exercise. We studied this phenomenon in senior endurance runners. We included 185 participants (61.1 +/- 5 years; 29% women) at a 30-km cross-country race who were self-reportedly in excellent health. Before and after the race, the creatinine, N-terminal pro-brain natriuretic peptide (NT-proBNP), and troponin T were analyzed, and participation in the number of previous races and the race duration were recorded. NT-proBNP increased from 53 ng/L (interquartile range 31 to 89) to 121 ng/L (interquartile range 79 to 184) and troponin T from undetectable to 0.01 microg/L (interquartile range 0.01 to 0.04). The independent predictors of a large NT-proBNP increase were (1) greater levels present at baseline, (2) a greater increase in creatinine (both p <0.001), (3) older age (p = 0.01), and (4) a longer race duration (p <0.05). Troponin T elevation was independently predicted by (1) older age (p = 0.01), (2) a greater increase in creatinine, and (3) participation in fewer previous races (both p <0.05). Of the 15 runners with an elevated (>194 ng/L) baseline NT-proBNP level (8.1% of 185), 4 were found to have serious cardiovascular disease (2.2% of whole sample). Of these 4 patients, 1 died from sudden cardiac death within months after the race. In conclusion, biomarker elevation occurs commonly in senior runners. A high baseline NT-proBNP is predictive of a large release during exercise, suggesting that the factors that control the at rest levels also determine its release with exertion. Troponin T elevation was seen in less-experienced participants. A small group of very ill runners were identified by NT-proBNP analysis.