Factors associated with elevated or blunted PTH response in vitamin D insufficient adults

Abstract

Objectives. The purpose of this study was to examine factors associated with high or low parathyroid hormone (PTH) levels in relationship to vitamin D insufficiency.Design. This was a cross-sectional study consisting of 516 healthy men and women, aged 30-85, all Caucasians with vitamin D insufficiency [serum 25(OH)D < 45 nmol L )1 ]. The group was divided into quartiles by PTH levels and the highest and lowest quartiles were compared with regard to various factors likely to affect calcium metabolism. We used stepwise multivariable logistic regression to determine the independent association between PTH levels and other variables for men and women separately.Results. We found that men in the lowest PTH quartile were significantly younger, had less energy intake, lower body mass index (BMI) and better kidney function compared with the highest PTH quartile. They had also higher ionized calcium, insulin-like growth factor (IGF1) and testosterone and were more likely to smoke. Women within the lowest PTH quartile were younger, had lower BMI and magnesium values and higher IGF1 levels and were more likely to smoke. Stepwise multivariate regression showed that IGF1, testosterone and BMI were significantly associated with PTH in men (R 2 = 0.472) but smoking, BMI and kidney function in women (R 2 = 0.362). Conclusions.Our results indicate that during vitamin D insufficiency, factors other than calcium and vitamin D may modify PTH response. These factors may be different between sexes and we have identified novel factors, IGF1 and testosterone in men which may be compensatory in nature and confirmed previous factors such as smoking, BMI and kidney function in women.

Association of air particulate pollution with bone loss over time and bone fracture risk: analysis of data from two independent studies

“…19 PTH levels are also significantly lower in smokers 37,38 and return to non-smoking levels after smoking cessation. 38 Such PTH alteration may represent an adaptive response to smoking-induced calcium mobilization from bone.…”

Severe vitamin D deficiency is common in critically ill patients at a high northern latitude

“…5 Serum levels of 25(OH)D have been shown to be inversely associated with all-cause, cardiovascular, cancer and respiratory disease, however the role of vitamin D in acute critical illness is less well-studied and understood. [12][13][14][15] No national vitamin D fortification programme exists in Iceland. 6,7 Two recent studies from countries at southern latitudes showed that low levels of vitamin D are common in intensive care patients and low levels were associated with prolonged hospital stay and increased mortality.…”

The American Diabetes Association's 57th Annual Advanced Postgraduate Course

“…Sufficiency is considered by U.S. groups to require levels >30 ng/ml (12), although Binkley pointed out that the European recommendation is for levels >20 ng/ml. Based on the relationship between vitamin D and PTH as a marker of bone health, it may be that the optimal 25-OH D varies by system, with optimal levels for bone and skeletal muscle 38–40, while periodontal and cancer prevention requirements may be lower (13). The Institute of Medicine Food and Nutrition Board is currently reviewing dietary reference intakes for vitamin D, and Binkley suggested that they probably will recommend 800–1,000 IU/day, which Binkley termed “conservative,” noting that to achieve levels >30 ng/ml for 97.5% of individuals a daily intake of 2,600 IU is required (14).…”