Three indices of circulating parathyroid hormone (PTH) activity were compared between two groups: the first a group of 23 patients from three large kindreds with autosomal dominant hypercalcemia without hypercalciuria [familial hypocalciuric hypercalcemia (FHH)] and the second a group of 64 patients with typical primary hyperparathyroidism (1HPT) manifesting comparable hypercalcemia.
An activating mutation of the receptor for parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP) was recently found in a patient with Jansens's metaphyseal chondrodysplasia, a rare form of short-limbed dwarfism associated with hypercalcemia and normal or low serum concentrations of the two hormones.
The present study was undertaken to clarify the pharmacokinetics of 22-oxa-1,25-dihydroxyvitamin D3 (22-oxa-1,25-(OH)2D3, OCT), a vitamin D3 analogue with little calcemic activity, and its effect on the transcription of parathyroid hormone-related peptide (PTHRP) gene in nude mice bearing a human carcinoma (FA-6) associated with humoral hypercalcemia.
From these results, we speculate that although the VDR gene polymorphism may affect the serum PTH level, it is not a risk factor for hypercalcemia in sarcoidosis.
Hyperparathyroidism is associated with hypercalcemia and the excess of parathyroid hormone secretion; however, the alterations in molecular pattern of functional genes during parathyroid tumorigenesis have not been unraveled.
We report a case of a 51-year-old male with a history of human immunodeficiency virus (HIV) infection, well-controlled on antiretroviral treatment, who presented with polyarthritis and hypercalcemia due to an elevated parathyroid-hormone-related peptide.
Common features of this autosomal recessive condition included hypercalcemia with hypercalciuria, suppressed PTH and a high 25-OH-D<sub>3</sub>:24,25-(OH)<sub>2</sub>D<sub>3</sub> ratio.
Three of five relatives had mild hypercalcemia [s-Ca, 10.7-11.2 mg/dl (2.67-2.80 mmol/liter)] and detectable serum PTH [24.5-29.0 pg/ml (2.6-3.1 pmol/liter)].
The extensive chromatographic characterization of four parathyroid hormone (PTH)-like proteins in a human bronchial carcinoid tumour associated with humoral hypercalcaemia and severe osteitis fibrosa is described.
We conclude that partial duplication of 2p can be associated with hypercalcaemia and hypercalciuria and hypothesise that the underlying mechanism is an increased extra-renal, parathyroid hormone-independent 25-hydroxyvitamin D 1α-hydroxylase activity, leading to raised amounts of 1,25-dihydroxyvitamin D. The increased enzymatic activity could possibly be caused by calcineurin B subunit-related macrophage stimulation.
Thus, PTH-dependent hypercalcemia can occur in the setting of either inherited, generalized resistance to Ca(o)2+ (i.e., FHH and NSHPT) or acquired tissue selective resistance of pathological parathyroid glands to Ca(o)2+ (e.g., PHPT).
The differential diagnosis of hypercalcemia is subdivided into three broad categories: hyperproteinemia, PTH-mediated hypercalcemia, and non-PTH-mediated hypercalcemia.
Cloning of the CaR has increased understanding of the normal control of mineral ion homeostasis and has clarified the pathophysiology of PTH-dependent hypercalcemia.
Parathyroid hormone-related peptide (PTHrP)-mediated hypercalcemia was confirmed in 11 of the 16 patients in whom elevated-serum level or positive immunohistochemistry of PTHrP was observed.