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

Broughton, Sophie E.; O'Neill, Dan G.; Syme, Harriet M.; Geddes, Rebecca F.


Sophie E. Broughton

Dan G. O'Neill

Harriet M. Syme

Rebecca F. Geddes


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.

To describe clinical details of diagnoses associated with ionized hypercalcemia in cats and association with urolithiasis.

Cats (238) seen between 2009 and 2019 at a referral hospital with [iCa] above the normal reference interval.

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).

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.


Broughton, S. E., O'Neill, D. G., Syme, H. M., & Geddes, R. F. (in press). Ionized hypercalcemia in 238 cats from a referral hospital population (2009‐2019). Journal of Veterinary Internal Medicine,

Journal Article Type Article
Acceptance Date Dec 15, 2022
Online Publication Date Jan 16, 2023
Deposit Date Jan 19, 2023
Publicly Available Date Jan 19, 2023
Journal Journal of Veterinary Internal Medicine
Print ISSN 0891-6640
Electronic ISSN 1939-1676
Publisher Wiley Open Access
Peer Reviewed Peer Reviewed
Keywords General Veterinary
Additional Information Received: 2022-07-29; Accepted: 2022-12-15; Published: 2023-01-16


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