Functional analysis of ectopic parathyroid activity in cats.

The ability of ectopic parathyroid tissue to support calcium homeostasis was evaluated by measuring serum concentrations of calcium, phosphorus, albumin, magnesium, and parathyroid hormone before and for 12 weeks after bilateral thyroparathyroidectomy in 14 cats. During the immediate postoperative period, significant decrease was observed in serum calcium, magnesium, and parathyroid hormone (PTH) concentrations. Serum PTH concentration remained subnormal and did not significantly increase during the 12-week observation period. Despite persistent hypoparathyroidism, serum calcium and magnesium concentrations gradually increased. Ectopic parathyroid tissue is not capable of maintaining normal serum calcium concentration immediately after thyroparathyroidectomy. Serum calcium concentration gradually normalizes after thyroparathyroidectomy, apparently by means of a PTH-independent mechanism.

Adjustment of total serum calcium concentration for binding to albumin and protein in cats: 291 cases (1986-1987).

The relationships between total serum calcium and serum albumin and total serum calcium and serum protein concentrations were examined in 291 cats. There was a significant (P less than 0.001) linear relationship between serum calcium and serum albumin concentrations. Because of extreme variability among the calcium and albumin concentrations (R2 = 0.18), however, a dependable formula to adjust total serum calcium values for albumin or protein binding in the cat could not be constructed. An adjustment formula could not be based on the relationship between calcium and total protein concentrations because of the lack of a significant relationship (P = 0.21). The association between serum calcium and serum albumin or serum calcium and total protein concentrations is weaker in cats than in dogs or man.