Effect of Calcitonin and Parathyroid Hormone Deficiency on Calcium and Phosphorus Metabolism in Sheep

Abstract

The experiment was to study the effects of thyroidectomy (TX) and thyroparathyroidectomy (TPTX) on serum concentrations and urinary excretions of calcium and phosphorus in sheep. There were no obvious changes in serum calcium and phosphorus concentrations after TXed operation. Serum calcium and hydroxyproline concentrations decreased 2nd day after TPTX and recovered 1 week after.Since there was a close relationship between serum calcium concentrations and serum hydroxyproline, it could be considered that a deficiency of parathyroid hormone reduced serum calcium concentrations through the decrease of bone resorption in sheep. The recovery of serum calcium and hydroxyproline concentrations might be dependent on an adaptation against the long term deficiency of parathyroid hormone, that is, the activation of vitamine D3 induced by low serum phosphorus concentrations.Serum phosphorus concentrations continued to decrease after TPTXed surgery.A deficiency of parathyroid hormone might result in the lowering of serum phosphorus concentrations.Urinary calcium excretion in TXed sheep had a trend to be higher than in intact sheep.TPTXed animals excreted more calcium via urine than TXed sheep.Urinary phosphorus excretion were much lower in TXed sheep when compared to intact and TPTXed sheep.These results indicated that a calcitonin deficiency brought about the promotion of urinary calcium excretion and the reduction of urinary phosphorus excretion and a parathyroid hormone deficiency enhanced urinary calcium loss in sheep.Jpn. J. Zootech. Sci., 54 (4): [232][233][234][235][236][237][238] 1983 It is well known that parathyroid hormone (PTH) and calcitonin (CT) play important roles in calcium and phosphorus metabolism in various animals. The decrease of calcium concentration in blood has been shown by thyroparathyroidectomy (TPTX) in rats1), goats2) and sheep3). KALU et al.4) indicated that the lowering of calcium concentration in blood plasma in TPTXed rats was resulted from the decrease of bone resorption and the increase of calcium excretion in urine. While PAYNE and SANSON5)reported that serum calcium and phosphorus concentrations lowered after TPTX though TPTX enhanced to release minerals from the bone and scarcely increased urinary calcium excretion in goats.It has been reported that CT has a hypocalcemic effect in rats6) and pigs7). It was also shown that the deficiency of CT induced by thyroidectomy (TX) increased serum calcium concentration in rats and pigs8). KALU9) suggested that a physiological role of CT was an inhibition of postprandial hypercalcemia which might be induced by the elevation of calcium absorption from the digestive tract. However, NELSON10) Jpn. J. Zootech. Sci., 54 (4): 232-238 232 1983

Hypocalcæmia and serum levels of inorganic phosphorus, magnesium parathyroid and calcitonin hormones in the last month of pregnancy in Awassi fat-tail ewes

“…Popoff (1982) and Matsui et al (1983) found a relationship between hyperparathyroidism and HCE in sheep. Similarly during parturient paresis (milk fever) in the cow, parathyroid hormone (PTH) concentration is higher (Horst et al, 1978;Allen and Sansom, 1986;Bar et al, 1988) and calcitonin (CT) concentration is lower (Mayer et al, 1975;Allen and Sansom, 1986) than normal values.…”