Parathyroid glands and vitamin D
However, because 'vitamin D insufficiency' is defined biochemically as the degree of hypovitaminosis D resulting in an increase in PTH secretion , it may be. skin, liver, parathyroid gland, kidney, bone, and small intestine all play a role; increased PTH and Vitamin D leads to increase serum calcium. The relationship between vitamin D and parathyroid hormone: calcium homeostasis, bone turnover, and bone mineral density in postmenopausal women with.
Methods Participants A total of men and women were divided equally between 3 age groups years, years, and yearsidentified by a stratified, random selection process from the computerized population register of Reykjavik, the capital of Iceland, and invited to participate in our cross-sectional study on bone health. The recruitment period was from February to Januarywith an equal number of participants from each age group recruited monthly throughout the 2-year period to account for seasonal effects.
The participants answered a detailed questionnaire on health-related issues, height and weight were measured, and body mass index BMI was calculated as weight in kilograms divided by the square of height in meters. The Icelandic Medical Ethics Committee approved the study, and all participants provided a written consent form.
Dietary Assessment Vitamin D and calcium intake were assessed by using a self-administered, semi-quantitative food frequency questionnaire, which was developed by the Icelandic Nutrition Council. It has been described and used in several studies and validated for foods and nutrients, including both calcium and vitamin D, and repeated hour recalls were used as the reference method. Interassay variations were 6.
Interassay variation was 2. Serum cystatin C was measured by an immunoturbidimetric assay DakoCytomation, Copenhagen, Denmarkand serum ionized calcium was measured by an ion-specific electrode ABLRadiometer, Copenhagen, Denmark ; coefficient of variation was 1. Data Analysis We used analysis of variance ANOVA to compare the 3 age groups with respect to continuous variables, applying the Bonferroni method to control for multiple comparisons. Our main analysis by ANCOVA was to study the relationship between serum intact PTH levels and both calcium intake and serum hydroxyvitamin D levels, with and without the interaction between calcium intake and vitamin D status in the model.
We also tested for interaction between vitamin D status or calcium intake and the categorical variables smoking and sex, but these were not significant.
Vitamin D Status and Its Association with Parathyroid Hormone Concentration in Brazilians
For subsequent subgroup comparisons, we used Bonferroni adjustment for multiple comparisons. Data are presented as mean SDunless otherwise noted. Statistical analysis was performed by using SPSS version Received Aug 11; Accepted Nov There is a controversy regarding the definition of vitamin D insufficiency as it relates to bone health.
The objective of the study was to examine the evidence for a threshold value of serum hydroxyvitamin D 25OHD that defines vitamin D insufficiency as it relates to bone health. This was a cross-sectional analysis of baseline data in elderly Caucasian women, mean age 71 yr, combined with a literature review of 70 studies on the relationship of serum PTH to serum 25OHD.
Parathyroid Glands: Vitamin D and calcium levels
The study was conducted in independent-living women in the midwest United States. Serum hydroxyvitamin D 25OHD is considered to be the best indicator of overall vitamin D status of an individual. Very low levels of serum 25OHD can also cause osteomalacia. The definition of vitamin D insufficiency is less clear-cut.
Relationship between Vitamin D, Parathyroid Hormone, and Bone Health
This threshold has been used to define vitamin D insufficiency. This has led to an epidemic of vitamin D insufficiency, and it has been suggested that 1 billion people worldwide have vitamin D deficiency or insufficiency 3. A critical question, however, is what levels of serum PTH are harmful to bone because it was assumed that elevated serum PTH was related to bone loss 3. Independent of vitamin D metabolism, there is an age-related decrease in calcium absorption that probably contributes to secondary hyperparathyroidism 4.
We examined the relationship between serum PTH and serum 25OHD in our own data for evidence of a threshold or plateau and also examined the relationship between bone markers and serum 25OHD. This search retrieved studies that were conducted from January to June There were a total of 70 studies that showed a relationship between serum 25OHD and PTH 5— 5759— 6682 Seven of these studies were counted twice: Study subjects Information on our study subjects was derived from the baseline data of a 3-yr intervention trial [Sites Testing Osteoporosis Prevention or Intervention STOP IT ] in elderly women, described previously in detail They were healthy independent women living at home.