Primary hyperparathyroidism: evaluated by ⁴⁷Calcium kinetics, calcium balance and serum bone‐Gla‐protein

Abstract

Combined 47Calcium kinetic and calcium balance studies with correction for dermal calcium loss were performed in thirteen patients with primary hyperparathyroidism (PHP), in whom serum bone-Gla-protein (S-BGP) was measured, and in ten matched controls. Dietary calcium was normal in PHP but both net (7.9 +/- 1.4 mmol Ca day-1 in PHP v. 3.5 +/- 0.9 mmol Ca day-1 in normals (mean +/- SE] and true (11.1 +/- 1.6 v. 6.8 +/- 0.9 mmol Ca day-1) intestinal absorbed calcium were enhanced (P less than 0.05). The renal calcium excretion (10.9 +/- 0.8 v. 5.1 +/- 0.4 mmol Ca day-1, P less than 0.001) and the dermal calcium loss (2.5 +/- 0.3 v. 1.5 +/- 0.1 mmol Ca day-1, P less than 0.02) were increased in PHP. Both patients and controls were in a negative calcium balance (P less than 0.01 and P less than 0.001, respectively) without any difference between the groups (P greater than 0.10). Mineralization (12.0 +/- 1.7 v. 4.8 +/- 0.8 mmol Ca day-1, P less than 0.02) and resorption rates (17.6 +/- 2.5 v. 7.9 +/- 0.6 mmol Ca day-1, P less than 0.02) were increased in PHP and S-BGP correlated positively to both variables (r = 0.64, P less than 0.05 and r = 0.62, P less than 0.05, respectively). Serum immunoreactive parathyroid hormone correlated positively to serum calcium (r = 0.69, P less than 0.01) but not to the calcium kinetic data.

Plasma 1,25‐dihydroxyvitamin D levels in primary hyperparathyroidism depend on sex, body mass index, plasma phosphate and renal function

“…In accordance with previous studies 34,46–48 we found a positive correlation between plasma 1,25(OH) 2 D and the 24‐h renal calcium excretion, probably reflecting an increased vitamin D‐mediated active intestinal calcium absorption and a loss of bone mineral 49 . However, we did not find any association between plasma 1,25(OH) 2 D and the risk of renal stones.…”

THERAPY OF ENDOCRINE DISEASE: Hungry bone syndrome: still a challenge in the post-operative management of primary hyperparathyroidism: a systematic review of the literature

“…The remodelling space is the total amount of bone that at any time has been resorbed by osteoclasts but not yet reformed by osteoblasts during the coupled remodelling process because of the delay between resorption and formation. This space depends on the activation frequency of new remodelling sites, which is considerably increased in PHPT, leading to mineral depletion of bone and significantly contributing to the hypercalcaemia of PHPT (10,11,12,13,14).…”

Renal tubular reabsorption of calcium and sodium in primary hyperparathyroidism

“…An average value of Km was determined according to the procedure described in a previous paper (12). By substituting this value for Km (=0.1787) in [1] we get: S-UfCa-uCa/GFR = TmCa/GFR -0.1787 • In (S-UfCa • GFR/uCa) [2].…”

“…By inserting corresponding values of S-UfCa and uCa/GFR into [2], TmCa/GFR could be calculated for each of the normal controls. The average value of TmCa/GFR (=2.1416) for the 9 controls was then substituted in equa¬ tion [2]:…”

“…The hypercalcemia in primary hyperparathyroidism can be accounted for by the enhancing effect of PTH on flux of cal¬ cium from gut and bone and an increased capacity for renal tubular reabsorption of calcium (1), the latter apparently playing the major role (1,2).…”