Serum vitamin D metabolites do not differ between cats with chronic kidney disease and healthy cats.

ObjectiveThe aim of the present study was to characterize comprehensive vitamin D metabolite profiles in cats with chronic kidney disease (CKD) compared with healthy cats.MethodsA total of 33 healthy cats and 66 cats with CKD (six International Renal Interest Society [IRIS] stage 1, 36 IRIS stage 2, 18 IRIS stage 3, six IRIS stage 4) were prospectively enrolled. Serum vitamin D metabolites, including 25-hydroxyvitamin D3 (25[OH]D3), 3-epi-25-hydroxyvitamin D3 (3-epi-25[OH]D3), 1,25-dihydroxyvitamin D3 (1,25[OH]2D3; calcitriol) and 24,25-dihydroxyvitamin D3 (24,25[OH]2D3), were analyzed via liquid chromatography-tandem mass spectrophotometry. Vitamin D metabolites, clinicopathologic parameters, age, body weight and body condition score were compared between groups using a Mann-Whitney U-test or t-test as appropriate. Correlations between vitamin D metabolites and clinicopathologic parameters, age and weight were assessed using Spearman's rank test.ResultsThere was no significant difference in any vitamin D metabolite between groups. Median 25(OH)D3 concentrations in cats with CKD and healthy cats were 28.9 ng/ml (range 12.2-68.8) and 26.3 ng/ml (range 11.5-55.9), respectively. Median 3-epi-25(OH)D3 concentrations in cats with CKD and healthy cats were 9.1 ng/ml (range 2.2-30.4) and 7.2 ng/ml (range 1.9-22.9), respectively. Median calcitriol concentrations in cats with CKD and healthy cats were 141.3 pg/ml (range 38.6-367.8) and 127.9 pg/ml (range 71.5-235.8), respectively. Median 24,25(OH)2D3 concentrations in cats with CKD and healthy cats were 9.8 ng/ml (range 2.5-32.5) and 8.8 ng/ml (range 1.2-38.4), respectively. There was no correlation between any vitamin D metabolite and age or serum creatinine concentration, and no correlation between 25(OH)D and hematocrit, blood pressure or urine protein:creatinine ratio.Conclusions and relevanceVitamin D metabolites were not significantly different in cats with CKD, which could have implications for recommendations regarding calcitriol supplementation.