Bone Abstracts

Background: Sun exposure may be limited in Arctic populations and Greenland Inuit have adapted to the Arctic environment. The influence of chronic low vitamin D level on PTH to uphold a normal serum calcium remains to be elucidated.

Objective: To describe the association between PTH and factors known to influence PTH-, including vitamin D (25OHD) and calcium, in Arctic populations.

Methods: Inuit and non-Inuit in the capital city Nuuk in West Greenland and in the major town and in remote settlements in East Greenland were surveyed. Supplement use and life-style factors were determined by questionnaires, dietary habits by a food frequency questionnaire, and PTH, calcium and 25OHD were measured in serum.

Results: One percent of the population of Greenland was invited and 95% participated with 434 Inuit and 101 non-Inuit. Serum 25OHD was below 50(20) nmol/l in 23.0(0.2)% Inuit and 70.9(13.9)% of non-Inuit. Median serum PTH was 2.3(1.5) u/l in Inuit and 2.8(4.6) u/l in non-Inuit with plasma 25OHD below 50(20) nmol/l. Inuit and non-Inuit had different levels of serum calcium (P=0.023), PTH (P<0.001) and 25OHD (P<0.001). Factors important to PTH in multivariate regression analysis were 25OHD (P=0.007) and ethnicity (P<0.001).

Conclusions: Greenland Inuit had a lower PTH for the same level of vitamin D in serum compared with non-Inuit. This suggests that Arctic Inuit may have adapted to a low 25OHD status.