DVM, PhD/ Professor School of Veterinary Medicine and Animal Science, University of Sao Paulo Sao Paulo, Sao Paulo, Brazil
Abstract: Background – Cats with hypercalcemia may have hypercalciuria, which may increase the risk to nephrolithiasis or renal mineralization.
Objective – To compare the urinary fractional excretion of calcium (uFECa) of cats with hypercalcemia or normocalcemia.
Animals – Thirty-two cats were prospectively recruited from the Veterinary Teaching Hospital of the University of Sao Paulo (2016 – 2019) based on the levels of blood ionized calcium (iCa).
Methods – Case-control study. Cats with iCa ≥ 1.4 mmol/L at three timepoints of evaluation were allocated into the hypercalcemic group (n= 13), and those with normal iCa levels (1.1 mmol/L ≤ iCa < 1.4 mmol/L) were assigned to the normocalcemic group (n= 19). uFECa was then assessed. After normality test (Shapiro-Wilk), Mann–Whitney and Spearman correlation were applied, considering P ≤ 0.05.
Results – Median iCa levels were (min – max) 1.46 (1.41 – 1.53) mmol/L and 1.34 (1.17 – 1.39) mmol/L in cats with hypercalcemia and normocalcemia, respectively (P< 0.0001). Hypercalcemic cats showed 0.42% (0.09 – 2.46) and normocalcemic cats had 0.20% (0.03 – 1.11) of uFECa (P= 0.06). No correlation was found between iCa and uFECa. Based on ultrasonographic results, nephrolithiasis was found in 14/19 (73.7%) of normocalcemic cats and 7/13 (53.8%) of hypercalcemic cats, and there were no differences in uFECa comparing cats with kidney stones with hypercalcemia or normocalcemia.
Conclusions and clinical importance – There were no differences in uFECa in cats with hypercalcemia or normocalcemia; further studies with larger sample sizes and prospective design are necessary to confirm this finding.
