Ionized hypercalcemia in 238 cats from a referral hospital population (2009‐2019)

Abstract

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.

Keywords

• AKI
• calcium
• cat
• idiopathic
• kidney stone