Objective: Studies in patients with ankylosing spondylitis (AS) describe slightly elevated serum testosterone levels, but these studies were not properly controlled for possible confounders.
Methods: In a case-control study serum levels of sex steroids, luteinizing hormone, and sex hormone binding globulin (SHGB) were measured in patients with AS and in age and sex matched controls. The body mass index, smoking status, use of alcohol, and fat intake were recorded.
Results: Testosterone levels measured in serum extracts did not differ in 50 male patients with AS compared to controls (mean +/- SD 16 +/- 4 vs 15 +/- 5 nmol/l, respectively; p = 0.54). In unextracted serum, however, male patients showed elevated testosterone (p < 0.001) and dehydroepiandrosterone sulfate levels (p = 0.003), even after controlling for confounders (p < 0.001). One of 10 female patients had an elevated testosterone level in unextracted serum. The 17 male users and one of the 2 female users of phenylbutazone had the highest testosterone levels in unextracted serum, and all showed a significant decline after extraction. Serum levels of other sex steroids, luteinizing hormone, and SHGB did not differ significantly between patients and controls.
Conclusion: Serum testosterone levels are not elevated in male patients with AS. Spuriously elevated testosterone levels in unextracted serum might be related to the use of phenylbutazone in our patient sample.