@article { , title = {Ionized hypercalcemia in 238 cats from a referral hospital population (2009‐2019)}, abstract = {Background Ionized calcium concentration ([iCa]) is more sensitive for detecting calcium disturbances than serum total calcium concentration but literature on ionized hypercalcemia in cats is limited. Urolithiasis is a possible adverse consequence of hypercalcemia. Hypothesis/Objectives To describe clinical details of diagnoses associated with ionized hypercalcemia in cats and association with urolithiasis. Animals Cats (238) seen between 2009 and 2019 at a referral hospital with [iCa] above the normal reference interval. Methods Observational cross-sectional study. Signalment, serum biochemical and imaging findings were reviewed for cats with ionized hypercalcemia considered to be clinically relevant (>1.41 mmol/L). Data were summarized by cause of hypercalcemia (i.e., diagnosis). Results Diagnoses for the 238 cats with [iCa] >1.41 mmol/L included: acute kidney injury (AKI; 13\%), malignancy-associated (10.1\%), idiopathic hypercalcemia (IHC; 10.1\%), chronic kidney disease/renal diet-associated (8.4\%), iatrogenic (5.5\%), primary hyperparathyroidism (2.1\%), vitamin D toxicity (2.1\%) and granulomatous disease (1.7\%). In 112 cases (47.1\%), no cause for ionized hypercalcemia could be determined (n = 95), hypercalcemia was transient (n = 12), or the cat was juvenile (<1 year; n = 5). Urolithiasis was identified in 83.3\% of AKI, 72.7\% of iatrogenic, 61.1\% of CKD/renal diet-associated and 50\% of IHC cases that were imaged (<50\% for other diagnoses). Diagnoses with a high proportion of concurrent total hypercalcemia included primary hyperparathyroidism (100\%), vitamin D toxicity (100\%), malignancy-associated (71.4\%), granulomatous disease (66.7\%) and IHC (65.2\%). Conclusions and Clinical Importance Ionized hypercalcemia was most commonly associated with kidney diseases, neoplasia or IHC. The proportion of urolithiasis cases varied by diagnosis.}, doi = {10.1111/jvim.16627}, eissn = {1939-1676}, issn = {0891-6640}, journal = {Journal of Veterinary Internal Medicine}, publicationstatus = {Published}, publisher = {Wiley Open Access}, keyword = {General Veterinary}, author = {Broughton, Sophie E. and O'Neill, Dan G. and Syme, Harriet M. and Geddes, Rebecca F.} }