Background Hyperhomocysteinemia, which is related with cardiovascular diseases and metabolic syndrome, is regarded as one of the important factors in endothelial cell damage processes. It is well known that gout is associated with metabolic syndrome, and cardiovascular diseases are major causes of mortality in gouty patients. However, there are few reports about the serum homocysteine levels in gouty patients, and their results reveal discrepancy.
Objectives In this study, we investigated whether or not serum homocysteine levels are elevated in the patients with chronic gout and which factors are associated with the elevated homocysteine levels.
Methods This cross-sectional study included 91 male patients with chronic gout and 97 age-matched healthy male controls. The averages of age were 51.19 ± 15.08 and 51.57 ± 17.01 years old, respectively. Serum homocysteine, uric acid (UA), blood urea nitrogen (BUN), creatinine (Cr) and other laboratory findings were tested for all participants. Serum homocysteine levels were measured by a competitive immunoassay using direct chemiluminescent (Siemens Centaur Immunoassay Systems, USA). The estimated glomurular filtration rate (eGFR) was uptained using modification of diet in renal disease (MDRD) formula, then the stages of chronic kidney disease (CKD) were classified according to eGFR levels as follows; stage 1, more than 90 mL/min/1.73m2: stage 2, 60-89 mL/min/1.73m2: stage 3, 30-59 mL/min/1.73m2: stage 4, 15-29 mL/min/1.73m2: stage 5, less than 15 mL/min/1.73m2.
Results The chronic gout group were not significantly different from the control group in serum uric acid levels (6.15 ± 2.23 mg/dL vs 5.82 ± 1.22 mg/dL, p = 0.224). However, the patients with chronic gout showed much higher serum homocysteine levels than healthy controls (13.96 ± 4.05 μmol/L vs 12.67 ± 3.52 μmol/L, p = 0.021). Serum homocysteine levels showed the positive correlations with serum BUN and Cr levels, and the negative correlation with eGFR (r = 0.429, p < 0.001; r = 0.435, p < 0.001; r = -0.413, p < 0.001, respectively) in the chronic gouty group. However, serum homocysteine levels are uncorrelated with serum uric acid levels or cholesterol profiles. The patients at stages 1 or 2 of CKD had significantly lower serum homocysteine levels than the patients at stage 3 of CKD (12.99 ± 4.81 μmol/L, 13.17 ± 2.97 μmol/L, and 17.45 ± 4.68 μmol/L, p < 0.001). Serum homocysteine levels were not different between the groups that are treated with allopurinol and with benzbromarone. In multiple linear analyses, serum homocysteine level was affected by eGFR (β = -0.385, p < 0.001), however, was not affected by the serum uric acid level.
Conclusions Serum homocysteine levels were higher in the male patients with chronic gout than in the healthy male controls. Hyperhomocysteinemia in gouty patients could be related not with serum uric acid levels, but with decreased renal function. Types of uric acid lowering agents did not affect the serum homocysteine levels.
Disclosure of Interest None Declared