Plasma 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and parathyroid hormone in familial hypocalciuric hypercalcemia and primary hyperparathyroidism.

Abstract

INTRODUCTION:

Familial hypocalciuric hypercalcemia (FHH) is a lifelong, benign, inherited condition caused by inactivating mutations in the calcium-sensing receptor (CASR) gene. Both FHH and primary hyperparathyroidism (PHPT) are characterized by elevated P-calcium, normal or elevated plasma-parathyroid hormone (P-PTH), and typically normal renal function. In PHPT, vitamin D metabolism is typically characterized by low plasma levels of 25-hydroxyvitamin D (25OHD), and high plasma levels of 1,25-dihydroxyvitamin D (1,25(OH)(2)D). In FHH, the vitamin D metabolism is not very well known.

OBJECTIVE:

To compare and evaluate plasma 25OHD, 1,25(OH)(2)D, and PTH in FHH and PHPT.

DESIGN:

Cross-sectional study.

MATERIALS:

About 66 FHH patients with mutations in the CASR gene, 147 patients with surgically verified PHPT, and 46 controls matched to FHH patients according to age (+/-5 years), sex, and season. All patients had a P-creatinine <140 micromol/l.

METHODS:

We measured P-calcium, P-Ca(2)(+), P-albumin, P-creatinine, P-phosphate, P-magnesium, and P-PTH by standard laboratory methods. P-25OHD and P-1,25(OH)(2)D were measured by RIA or enzyme immunoassay. In FHH, all protein-coding exons in the CASR gene were sequenced and aligned to GenBank reference sequence NM_000388.2.

RESULTS:

PHPT patients had higher body mass index (2p<0.01), together with higher P-PTH (2p<0.01) and P-1,25(OH)(2)D (2p<0.01) compared with FHH patients. The groups had similar levels of P-Ca(2)(+) and of P-25OHD. The phenotypic expression of the CASR mutations (as determined by the degree of hypercalcemia) did not influence the levels of P-1,25(OH)(2)D.

CONCLUSION:

Even though P-calcium and P-25OHD were comparable, P-1,25(OH)(2)D and P-PTH differed between FHH and PHPT.

• Authors: Signe Engkjaer Christensen, Peter H Nissen, Peter Vestergaard, Lene Heickendorff, Lars Rejnmark, Kim Brixen, Leif Mosekilde
• Journal: European journal of endocrinology (Eur J Endocrinol) Vol. 159 Issue 6 Pg. 719-27 (Dec 2008) ISSN: 1479-683X [Electronic] England
• PMID: 18787045 (Publication Type: Comparative Study, Journal Article)

Chemical References

• CASR protein, human
• PTH protein, human
• Parathyroid Hormone
• Receptors, Calcium-Sensing
• Vitamin D
• 1,25-dihydroxyvitamin D
• 25-hydroxyvitamin D

Topics

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Cross-Sectional Studies
• Female
• Humans
• Hypercalcemia (blood, diagnosis, genetics)
• Hyperparathyroidism, Primary (blood, diagnosis, genetics)
• Male
• Middle Aged
• Parathyroid Hormone (blood)
• Receptors, Calcium-Sensing (genetics)
• Vitamin D (analogs & derivatives, blood)
• Young Adult