Parathyroid response to vitamin D insufficiency: relations to bone, body composition and to lifestyle characteristics.

Abstract

BACKGROUND:

Vitamin D insufficiency is very common and is known to cause secondary hyperparathyroidism (SHPT). However, in some subjects the PTH response to low vitamin D levels is blunted, which has been termed functional hypoparathyroidism (FHPT).

AIM:

We compared indices of calcium homeostasis, bone metabolism and body composition in subjects with differential PTH responses to low vitamin D levels.

DESIGN:

Cross-sectional study. In 405 recent postmenopausal women with vitamin D insufficiency, we compared levels of bone turnover markers, bone mineral density (BMD), body composition, and body weight between subjects with SHPT and FHPT.

RESULTS:

Plasma 25-hydroxyvitamin D (P-25OHD) levels were slightly higher (P < 0.05) in SHPT compared with FHPT. SHPT was associated with higher levels of osteocalcin and bone-specific alkaline phosphatase, whereas whole body BMD and hip- and lumbar spine-BMD were significantly reduced. Subjects with SHPT had a 7% (P < 0.01) higher body weight and a 23% higher fat mass (P < 0.01) than subjects with FHPT, whereas lean tissue mass did not differ between groups. In SHPT, fat mass was increased by 14% (P < 0.001) at the upper and lower extremities and by 33% (P < 0.001) at the trunk. In a regression model, significant predictors of fat mass was P-PTH (r(p) = 0.248, P < 0.01) and P-osteocalcin (r(p) = -0.115, P = 0.02), with no effects of P-25OHD or P-creatinine levels.

CONCLUSIONS:

Effects of vitamin D insufficiency on bone is associated with the PTH responses. The increased body weight and fat mass in SHPT compared with FHPT may imply that PTH excess contributes to fat accumulation.

• Authors: Lars Rejnmark, Peter Vestergaard, Christine Brot, Leif Mosekilde
• Journal: Clinical endocrinology (Clin Endocrinol (Oxf)) Vol. 69 Issue 1 Pg. 29-35 (Jul 2008) ISSN: 1365-2265 [Electronic] England
• PMID: 18208576 (Publication Type: Journal Article, Multicenter Study)

Chemical References

• Parathyroid Hormone
• Vitamin D

Topics

• Body Composition (physiology)
• Bone Density (physiology)
• Cohort Studies
• Cross-Sectional Studies
• Female
• Humans
• Life Style
• Menopause (blood, metabolism)
• Middle Aged
• Parathyroid Hormone (blood, metabolism)
• Vitamin D (blood)
• Vitamin D Deficiency (blood, metabolism)