Feline chronic renal failure: calcium homeostasis in 80 cases diagnosed between 1992 and 1995

Eighty cats with chronic renal failure (CRF) were evaluated in a prospective study to investigate the prevalence and aetiopathogenesis of renal secondary hyperparathyroidism (RHPTH), using routine plasma biochemistry and assays of parathyroid hormone (PTH), blood ionised calcium and 1,25 dihydroxycholecalciferol (1,25[OH](2)D-3). Hyperparathyroidism was a frequent sequela of CRF, affecting 84 per cent of cats with CRF, the severity and prevalence of RHPTH increasing with the degree of renal dysfunction, compared with an age-matched control population, plasma concentrations of phosphate and PTH were significantly higher and 1,25(OH)(2)D-3 concentrations were significantly lower in the two groups of cats presenting with clinical signs of CRF. Significant ionised hypocalcaemia was present only in cats with end-stage renal failure, However, a number of cats were hyperparathyroid in the absence of abnormalities in the parameters of calcium homeostasis measured in this study, There was a significant correlation between plasma phosphate and PTH concentrations.