Open AccessChronic Kidney Disease in Cats and the Risk of Total Hypercalcemia
Author(s) -
van den Broek D.H.N.,
Chang Y.M.,
Elliott J.,
Jepson R.E.
Publication year - 2017
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/jvim.14643
Subject(s) - medicine , kidney disease , retrospective cohort study , hazard ratio , cohort , risk factor , logistic regression , proportional hazards model , confidence interval , gastroenterology
Background Chronic kidney disease ( CKD ) is a common comorbidity in cats with hypercalcemia, but whether CKD is a risk factor for hypercalcemia is unclear. Hypercalcemia often is diagnosed based on total calcium concentration ( tC a), which tends to underestimate the ionized calcium concentration ( iC a) in cats. Objectives Assessment of the performance of tC a for the diagnosis of ionized hypercalcemia, and exploration of factors influencing the relationship between iC a and tC a. Determination of risk factors for incident total hypercalcemia (ie, the development of hypercalcemia based on tC a during follow‐up). Animals Records of a cross‐section (n = 477) and observational cohort (n = 367) of client‐owned cats with and without azotemic CKD from first opinion practice. Methods Retrospective cross‐sectional and retrospective cohort study. The diagnostic accuracy of tC a as an index test for ionized hypercalcemia was evaluated, and risk factors for underestimation were explored by binary logistic and linear regression in a cross‐section of cats with and without azotemic CKD . Chronic kidney disease and clinicopathological variables were assessed as predictors of incident total hypercalcemia by both time‐invariant and time‐dependent Cox regression in a cohort of cats. Results Specificity of tC a for identification of ionized hypercalcemia was high (100%), but sensitivity was low. Underestimation was associated with lower venous bicarbonate concentrations. Cats with CKD had increased risk for incident total hypercalcemia (hazard ratio, 4.29; 95% confidence interval, 1.96–9.37; P < .001). Higher tC a predicted incident total hypercalcemia in both azotemic and nonazotemic cats ( P < .001). Conclusions and Clinical Importance Chronic kidney disease is a risk factor for incident total hypercalcemia, and most cats with increased tC a had concurrent ionized hypercalcemia. Higher baseline tC a predicts incident total hypercalcemia. Prospective studies assessing changes in iC a are warranted.