The relationship of uric acid with objective nutritional and metabolic risk indexes in hemodialysis patients

OBJECTIVE: Malnutrition is a common problem in hemodialysis patients and is associated with mortality. An increased risk of mortality has been observed in hemodialysis patients with both high and low uric acid levels. Geriatric Nutritional Risk Index (GNRI), Prognostic Nutritional Index (PNI) and Controlling Nutritional Status (CONUT) Score are nutritional indices used to determine malnutrition status. Visceral Adiposity Index (VAI) is a metabolic index used in the evaluation of visceral adiposity. These indices are more objective than other methods in evaluating the nutritional and metabolic status of the patient and have been found to be associated with mortality in hemodialysis patients. This study aimed to determine the importance of uric acid as a marker in the evaluation of optimal nutritional and metabolic status by investigating the relationship between uric acid values and GNRI, PNI, CONUT score and VAI in hemodialysis patients. METHOD: In this cross-sectional study, data obtained from 120 hemodialysis patients were analyzed retrospectively. GNRI was calculated using body weight, height and serum albumin levels. PNI was calculated using serum albumin level and total lymphocyte count. CONUT score was calculated using serum albumin, total lymphocyte count and total cholesterol. VAI was calculated using gender-specific formulas using waist circumference, body mass index, triglyceride and HDL-cholesterol levels. RESULTS: The median age of patients in the study group was 68 years (IQR 47–74). The mean serum uric acid value of the patients was calculated as 6.62 ± 1.19 mg/dl, mean GNRI as 103.3 ± 11.7, mean PNI as 46.15 ± 4.13. The median CONUT score value was 2 (IQR 1–3). The median VAI value was 2.54 (IQR 1.66–4.49). Positive correlations were found between serum uric acid value and GNRI (r = 0.305, p < 0.001), PNI (r = 0.266, p = 0.003) and VAI (r = 0.210, p = 0.022). When hemodialysis patients were divided into two groups according to the serum median uric acid level of 6.55 mg/dl, GNRI (p = 0.014), PNI (p = 0.015) and VAI (p = 0.041) values were significantly higher in the group with high uric acid levels. No relationship was found between serum uric acid value and CONUT score. CONCLUSION: In this study, serum uric acid levels in hemodialysis patients were found to be associated with both subjective nutritional risk indices; GNRI and PNI, and with the metabolic risk index; VAI. Our findings show that hypouricemia is a leading marker of undernutrition in hemodialysis patients. Our findings also suggest that the presence of hyperuricemia in hemodialysis patients may be an indicator of good nutrition, as well as hyperuricemia may also reflect the patient's metabolic risk status and an indicator of visceral fat accumulation resulting from excessive or unbalanced nutrition. In hemodialysis patients, uric acid is an important marker that reflects the nutritional and metabolic status of the patient when evaluated together with easy-to-measure, inexpensive and objective indices such as GNRI, PNI and VAI. KEYWORDS: Hemodialysis, Uric Acid, Geriatric Nutritional Risk Index, Prognostic Nutritional Index, CONUT Score, Visceral Adiposity Index