title: Association between sex steroid hormones and hematocrit in a nationally representative sample of men.
abstract: Low or high hematocrit levels are associated with increased morbidity and mortality, mediated via anemia or thromboembolic events, respectively. It is therefore important to identify factors that influence hematocrit. Although androgens are known to stimulate hematopoietic cells, it is unknown whether circulating sex steroid hormones affect hematocrit. The association between serum sex steroid hormone concentrations and hematocrit in men aged ≥ 20 years was evaluated in a cross-sectional study of 1273 men in the Third National Health and Nutrition Examination Survey (1988-1991). Outcomes were low (<10th percentile), high (>90th percentile), and mean hematocrit. Men with low free testosterone levels had a lower hematocrit than men with normal free testosterone levels (P = .03), although no relationship was found between total testosterone level and hematocrit. The relationship between sex hormone-binding globulin (SHBG) and hematocrit was complex, with both low (P < .001) and high (P = .01) SHBG levels associated with lower hematocrit in men aged ≥ 20 years and only high (P = .01) SHBG levels in men aged ≥ 50 years. The odds ratio (OR) of high vs normal hematocrit increased as total estradiol (OR, 2.84; P trend = .04) and free estradiol (OR, 2.23; P trend = .09) levels increased. In this nationally representative study of men, sex steroid hormone levels, particularly low free testosterone and high SHBG levels, were associated with lower hematocrit, and high total and free estradiol levels were associated with high hematocrit. Thus, changes in sex hormone levels with aging may contribute to the increased prevalence of anemia and thromboembolic stroke in men as they age.
authors.affiliation: Sidney Kimmel Comprehensive Cancer Center and the Department of Epidemiology, Bloomberg School ofPublic Health, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Channing J
authors.initials: CJ
authors.lastname: Paller
authors.forename: Meredith S
authors.initials: MS
authors.lastname: Shiels
authors.forename: Sabine
authors.initials: S
authors.lastname: Rohrmann
authors.forename: Andy
authors.initials: A
authors.lastname: Menke
authors.forename: Nader
authors.initials: N
authors.lastname: Rifai
authors.forename: William G
authors.initials: WG
authors.lastname: Nelson
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Platz
authors.forename: Adrian S
authors.initials: AS
authors.lastname: Dobs
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000740:Anemia / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006400:Hematocrit; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D012738:Sex Hormone-Binding Globulin; D020521:Stroke / Q000453:epidemiology; D013739:Testosterone / Q000097:blood
chemical_list: D012739:Gonadal Steroid Hormones; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol