Changes of the levels of serum calcium and parathyroid hormone in hyperthyroid patients

Serum calcium,inorganic phosphate and parathyroid hormone （PTH）were measured in 24 pat-ients with hyperthyroidism before and after antithyroid treatment.The Ievels of serum calciumwere 2.47±0.05 mmol/l（M±SE） before the treatment and 2.30±0.04 mmol/l after the treatm-ent（t=2.83,P＜0.01）.Of 24 patients,12.5%（3/24） had hypercalcemia before the treatment.Thelevels of serum inorganic phosphate were 1.11±0.05 mmol/l before the treatment and 1.08±0.04mmol/l after the treatment （t=0.82,P＞0.05）.The levels of serum PTH were 51.88±7.15 pg/ml before the treatment and 75.17 pg/ml after the treatment （t=4.44,P＜0.01）.There is a si-gnificant correlation between the changes of serum calcium and serum PTH following the treatm-ent.Our results suggest that hyperthyroid patients tend to have higher levels of serum calciumand thereby secretion of PTH from parathyroid is suppressed in some degree by relatively highserum calcium.