Uric acid levels and metabolic shifts in hypertensive patients with moderate excretory dysfunction

BACKGROUND: Development of hyperuricemia — elevated level of uric acid — is often associated with arterial hypertension. Owing to the widespread prevalence of hyperuricemia in Russia, additional diagnostic markers and pathogenetic correlations between uric acid and other metabolic markers should be studied. In contrast to uric acid, homocysteine, citrulline, and homoarginine content in the blood depends on transmembrane transport and enzymatic reactions in kidney tissue.

AIM: To study the correlation between uric acid levels and metabolic dysfunction markers in hypertensive patients under moderate impairment of excretory function.

MATERIALS AND METHODS: The levels of uric acid, citrulline, homoarginine, total homocysteine, methionine, and other clinical and laboratory parameters were determined for 115 patients with arterial hypertension, with a median age and interquartile range of 64 [54–71] years and an estimated glomerular filtration rate of 45 ml/min/1.73 m².

RESULTS: In 57 (50%) patients, the uric acid level exceeded the threshold value of 360 μM, indicating an increased risk of cardiovascular complications. Reduced metabolic functions of the kidneys under decreased citrulline, total homocysteine, methionine, and homoarginine levels in the entire group of patients and separately in subgroups of men and women were observed significantly more often than an elevated uric acid level or decreased estimated glomerular filtration rate. The uric acid level was positively correlated with markers of carbohydrate-lipid metabolism: triglycerides (Rs=0.334, p=0.018), glucose (Rs=0.252, p=0.046), and body mass index (Rs=0.396, p=0.001). Similar to uric acid, the homoarginine level showed a positive relationship with body mass index (Rs=0.302, p=0.003). After adjusting for gender and estimated glomerular filtration rate, an association analysis regarding the role of body mass index was performed. It was found that the close correlation between uric acid level and body mass index was significant over others (r=0.421, p=0.0011). In predicting uric acid levels, the relative contribution of estimated glomerular filtration rate and body mass index was equivalent according to multiple regression analysis, that is, an increase in uric acid levels is associated with both renal dysfunction and accumulation of adipose tissue.

CONCLUSION: Renal metabolic insufficiency with hyperuricemia under the initial stages of hypertension is asymptomatic, thus, additional markers have been proposed for the evaluation of remodeling of tissue metabolism in the kidneys, including citrulline, homoarginine, and total homocysteine.