Hypovitaminosis of vitamin D in patients with gout (data from a pilot study)

The relationship between serum levels of vitamin D and uric acid (UA) in the blood may be bidirectional, yet remains unexplored in patients with gout. The aim of this study was to identify the association between serum levels of UA and vitamin D deficiency in patients with gout. Materials and Methods. This single-center observational study included 79 patients with a confirmed diagnosis of gout (72 [91.1 %] men and 7 [8.9 %] women) who were not receiving urate-lowering therapy (ULT). All patients underwent evaluation of uric acid (UA), vitamin D, parathyroid hormone, C-reactive protein (СRP), creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and serum calcium levels, alongside calculating the estimated glomerular filtration rate (eGFR). The levels of vitamin D and the frequency of vitamin D deficiency were compared across groups with different levels of UA in blood (quartiles): <426 µmol/L, 427 to 479 µmol/L, 480 to 540 µmol/L, and ≥ 540 µmol/L. Results. The mean level of vitamin D was below the normal reference values, at 22 (17–27) ng/mL (Median). Among the patients, 63 (80 %) exhibited vitamin D levels indicative of deficiency (< 30 ng/mL). A moderate correlation was found between vitamin D levels and serum calcium (ρ = 0.343, p = 0.002), while weak correlations were also noted between vitamin D levels and CRP (ρ = –0.204, p = 0.071) as well as parathyroid hormone (ρ = –0.216, p = 0.056). The levels of uric acid were categorized into quartiles: < 426 µmol/L, 427 to 479 µmol/L, 480 to 540 µmol/L, and ≥ 540 µmol/L. The analysis of vitamin D levels among different quartiles of UA revealed no significant relationship (p = 0.672). Conclusions. Vitamin D deficiency is prevalent in the majority of patients with gout (80 %); however, the severity of hyperuricemia is not associated with serum vitamin D levels. Further investigations are required to identify the causes of the high frequency of vitamin D deficiency in patients with gout.