Study of calcium homeostasis in feline hyperthyroidism

Abstract

Thirty cats with untreated hyperthyroidism were blood sampled and their calcium homeostatic mechanisms and renal function assessed. The results were compared with those obtained from 38 age-matched control cats. The hyperthyroid group of cats were found to have significantly lower blood ionised calcium and plasma creatinine concentrations and significantly higher plasma phosphate and parathyroid hormone concentrations. Hyperparathyroidism occurred in 77 per cent of hyperthyroid cats, with parathyroid hormone concentrations reaching up to 19 times the upper limit of the normal range. The aetiology, significance and reversibility of hyperparathyroidism in feline hyperthyroidism remains to be established but could have important implications for both bone strength and renal function.

Hypocalcemia and Primary Hypoparathyroidism

“…The importance of these findings is not known (Barber and Elliott, 1996). Hyperthyroid cats also had significantly increased serum PTH concentrations.…”

“…The physiology of this complication may be related to the hyperphosphatemia and secondary hyperparathyroidism documented in 18% and 77%, respectively, of untreated hyperthyroid cats (Barber and Elliott, 1996). The physiology of this complication may be related to the hyperphosphatemia and secondary hyperparathyroidism documented in 18% and 77%, respectively, of untreated hyperthyroid cats (Barber and Elliott, 1996).…”

Feline hyperthyroidism: diagnosis and treatment

“…Also, ionised calcium and parathormone concentrations were found to decrease and increase, respectively, in a significant number of cats in two studies. These findings indicate that hyperparathyroidism is common in hyperthyroidism, even though it may not be clinically significant (Archer and Taylor, 1996;Barber and Elliot, 1996). Azotaemia is present in about 10% of the cases; an expected finding since chronic kidney disease is also common in elderly cats (Broussard et al, 1995;Plantiga et al, 2005).…”

Investigation of the pathophysiological mechanism for altered calcium homeostasis in hyperthyroid cats

“…Abnormalities in calcium and phosphate homeostasis are common in hyperthyroid cats (Archer & Taylor , Barber & Elliott , Williams et al . ).…”

“…). Hyperthyroid cats have elevated plasma concentrations of phosphate and parathyroid hormone (PTH), and reduced plasma concentrations of ionized calcium and fibroblast growth factor‐23 (FGF‐23) (Archer & Taylor , Barber & Elliott , Williams et al . ).…”