Does uric acid have a pathogenetic role in graft dysfunction and hypertension in renal transplant recipients?

Background. Uric acid (UA) may play a pathogenetic role in hypertension and kidney disease. We explored the prevalence of hyperuricemia and the relationship of UA to graft function and hypertension in prevalent renal transplant recipients (RTR). Methods. Baseline and follow-up data were collected on 90 RTR (mean age 51 yrs, 53% male, median transplant duration 7 years). Graft function was estimated using MDRD Study Equation 7. Results. At baseline, 70% RTR had hyperuricemia (UA > 7.0 mg/dl (0.42 mmol/L) in men and > 6.0 mg/dl (0.36 mmol/L) in women) compared to 80% after 2.2 years (P = 0.06). UA was not associated with blood pressure (BP) level but was higher in RTR with a history of hypertension compared to those without (8.6 +/- 1.8 vs. 7.3 +/- 2.2 mg/dl, [0.51 +/- 0.11 vs. 0.43 +/- 0.13 mmol/L], P = 0.003) and in RTR on >= 3 antihypertensive medications compared to those taking less (9.1 +/- 1.6 vs. 7.6 +/- 1.8 mg/dL, [0.54 +/- 0.1 vs. 0.45 +/- 0.11 mmol/L], P < 0.001). A history of hypertension was independently predictive of UA (beta 0.06, [95% Cl 0.02 to 0.10], P = 0.007) in addition to sex, cyclosporine dose, prednisolone dose, estimated glomerular filtration rate (eGFR(MDRD)) and beta-blocker therapy. UA was independently predictive of follow-up eGFR(MDRD) (beta -22.2 [95% CI -41.2 to -3.2], P = 0.02) but did not predict change in eGFRMDRD over time. UA was independently associated with requirement for antihypertensive therapy (beta 0.34, (95% Cl 1.05 to 1.90], P = 0.02). Conclusions. Hyperuricemia is common in RTR and is associated with need for antihypertensive therapy and level of graft function.