Low testosterone levels increase susceptibility to anemia, but may not be a sufficient causal factor for anemia in the elderly, reported Dr. Luigi Ferrucci of the National Institute on Aging, Bethesda, Md., and his colleagues.
The researchers evaluated data from the Italian InCHIANTI study, which enrolled 396 men and 509 women.
At baseline, 365 men did not have anemia, were a mean age of 74 years, and had a mean total testosterone level of 438 ng/dL.
Using the World Health Organization criteria, the investigators defined anemia as hemoglobin levels below 12 g/dL for women and 13 g/dL for men. Participants with “explained” anemia had one or more potential causes, and those with “unexplained” anemia had normal serum iron and no vitamin B12 or folate deficiencies.
Eleven men had explained anemia and a mean total testosterone of 355 ng/dL. Another 20 had unexplained anemia and a mean total testosterone of 332 ng/dL.
At baseline, 452 women did not have anemia, were a mean age of 64 years, and had a mean total testosterone of 64 ng/dL. Thirty-one had explained anemia and a mean total testosterone of 54 ng/dL; 26 had unexplained anemia and a mean total testosterone of 52 ng/dL (Arch. Intern. Med. 2006;166:1380–8).
Bioavailable testosterone level declined with age. Men in the lowest total and bioavailable testosterone level quartiles were 5.4 times and 13.1 times more likely, respectively, to be anemic than men in the highest quartiles. Women in the lowest bioavailable testosterone level quartile were 3.4 times more likely to have anemia than women in the highest quartile.
For a longitudinal analysis, 274 men and 337 women without anemia at baseline were reevaluated 3 years later; 23 men (8.4%) and 26 women (7.7%) had developed anemia.
Total testosterone levels were not significantly associated with anemia, but bioavailable testosterone was. Men and women in the lowest level quartiles were 4.7 and 4.4 times more likely, respectively, to develop anemia, compared with those in the higher level quartiles.