Importance of uric acid threshold in its correlation with metabolic syndrome

Abstract Background The relationship between Hyperuricemia and Cardiovascular risk has been established but whether or not a correlation between Serum Uric Acid (SUA) and Metabolic Syndrome (MS) exists is still a matter of debate. Indeed whether SUA level is part of MS diagnosis or just a pure marker of an unfavourable metabolic profile has not been demonstrated. Besides it’s unknown whether SUA’s addition to MS definition makes a difference in terms of prognosis. In our study we focused on evaluating in a group of hypertensive patients, the correlation between MS diagnosis and SUA defined with two different cut–off: 1) ≥6 mg/dL for women and ≥7 for men (classic cut–off); 2) >5.6 mg/dL for both sexes (recently proposed by the URRAH Project). Methods We enrolled 473 Hypertensive patients followed by the Hypertension Unit of San Gerardo Hospital (Monza, Italy), in which SUA was measured. Patients with Hyperuricemia were identified according to the two different thresholds. NCEP–ATP–III criteria were used for diagnosis of MS. Results MS was diagnosed in 33.6% while Hyperuricemia was found in 14.8% of subjects according to the traditional cut–off and 35.9% according to URRAH study’s cut–off. Hyperuricemia and MS coexist in 9.7% (traditional cut–off) and 17.3% (URRAH’s threshold) of the population. Hyperuricemia was more frequent in MS than in non–MS subjects (29 vs 7.6%, p–value<0.0001 for cut–off 6/7 mg/dL and 51.6 vs 28.0%, p–value<0.0001 for cut–off 5.6 mg/dL). Linear regression models showed that SUA is related to MS diagnosis (β = 1.597, p–value<0.0001). At logistic analysis Hyperuricemia was strongly related to MS when defined by the HURRAH‘s cut–off (OR = 0.303, p–value<0.0001). The same relation is weak, although significan, when Hyperuricemia was defined by the classic cut–off (OR = 0.182, p–value<0.0001). Conclusions Hyperuricemia is related with MS diagnosis especially when defined by the recently defined cut–off of 5.6 mg/dL.