RESETTING OF PARATHYROID-HORMONE SECRETION AFTER VITAMIN-D-3 TREATMENT IN HYPOPARATHYROIDISM AND AFTER PARATHYROID ADENECTOMY IN PRIMARY HYPERPARATHYROIDISM
K. Mizunashi et al., RESETTING OF PARATHYROID-HORMONE SECRETION AFTER VITAMIN-D-3 TREATMENT IN HYPOPARATHYROIDISM AND AFTER PARATHYROID ADENECTOMY IN PRIMARY HYPERPARATHYROIDISM, Calcified tissue international, 57(1), 1995, pp. 30-34
The relationship between parathyroid hormone (PTH) secretion and extra
cellular calcium (Ca) level is reciprocal causality. The equilibrium o
perating point determines basal PTH secretion rate and basal extracell
ular Ca level. We studied how this equilibrium was achieved in the sub
jects with decreased PTH secretion or decreased parathyroid glands num
ber. Basal/maximum ratio of serum PTH, which reflects the basal secret
ory state of parathyroid glands, was increased in 9 hypoparathyroid pa
tients treated with vitamin D-3 (VD3) [7 patients with idiopathic hypo
parathyroidism (IHP), and two patients with postsurgical hypoparathyro
idism] and in seven of nine parathyroid adenectomized patients. There
was a negative correlation between the ratio and basal serum Ca level
in the patients with IHP after VD3 treatment (r = 0.7167, P < 0.05) an
d in the patients after parathyroid adenectomy (r = 0.7760, P < 0.05).
The regression curves in these two groups coincided regardless of the
difference in maximum PTH secretion rate, which suggested that the ba
sal secretory state of parathyroid glands was determined by extracellu
lar Ca level in a similar manner in these subjects. There was a sigmoi
dal relationship between basal/maximum ratio of serum PTH and basal se
rum Ca level, when the data were collected from 15 hypoparathyroid pat
ients before or after VD3 treatment, 9 parathyroid adenectomized patie
nts, and 10 normal subjects (r = 0.9057, P < 0.001). This sigmoidal cu
rve is thought to represent the fundamental relationship between the b
asal secretory state of parathyroid glands and extracellular Ca level.