Relationship between Vitamin D, Parathyroid Hormone, and Bone Health

Bone Metabolism Unit, Department of Medicine, Creighton University Medical Center, 601 North 30 Street, Suite 6718, Omaha, Nebraska 68131, USA.
The Journal of Clinical Endocrinology and Metabolism (Impact Factor: 6.21). 03/2011; 96(3):E436-46. DOI: 10.1210/jc.2010-1886
Source: PubMed


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 25-hydroxyvitamin D (25OHD) that defines vitamin D insufficiency as it relates to bone health.
This was a cross-sectional analysis of baseline data in 488 elderly Caucasian women, mean age 71 yr, combined with a literature review of 70 studies on the relationship of serum PTH to serum 25OHD.
The study was conducted in independent-living women in the midwest United States.
The relationship between serum 25OHD, serum PTH, and serum osteocalcin and 24-h urine N-telopeptides was evaluated.
Serum PTH was inversely correlated with serum 25OHD (r = -0.256, P < 0.0005), but no threshold as defined by suppression of serum PTH was found within the serum 25OHD range 6-60 ng/ml (15-150 nmol/liter). However, in contrast, there was a threshold for bone markers, serum osteocalcin and urine N-telopeptides, that increased only below a serum 25OHD of approximately 18 ng/ml (45 nmol/liter). Calcium absorption was not correlated with serum PTH and serum 25OHD, and no threshold was found. A literature review of 70 studies generally showed a threshold for serum PTH with increasing serum 25OHD, but there was no consistency in the threshold level of serum 25OHD that varied from 10 to 50 ng/ml (25-125 nmol/liter).
Vitamin D insufficiency should be defined as serum 25OHD less than 20 ng/ml (50 nmol/liter) as it relates to bone.

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Available from: Adarsh Sai, Mar 12, 2015
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    • "Another interesting observation relates to PTH as a functional marker of vitamin D status in adults, children and infants but not necessarily in neonates [44]–[47]. We found no correlation between 25(OH)D and iPTH in cord blood, which is in agreement with previous reports [44], [48], [49]. "
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    ABSTRACT: The optimal vitamin D intake for nursing women is controversial. Deterioration, at least in bone mass, is reported during lactation. This study evaluated whether vitamin D supplementation during lactation enhances the maternal and infant's vitamin D status, bone mass and body composition.
    Full-text · Article · Sep 2014 · PLoS ONE
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    • "The serum 25-(OH)D threshold is 5-10 ng/mL for normal calcium absorption.[19] The serum PTH level is inversely related to the serum 25-(OH)D level; with an increase in the serum 25-(OH)D level, there is a decrease in the serum PTH level that usually reaches a plateau.[16,20,21] The serum 25-(OH)D level at which the serum PTH levels plateaus varies from 12 to 50 ng/mL (with most values being <30 ng/mL).[16,20] "
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    ABSTRACT: After discontinuation of bisphosphonate therapy, an antiresorptive effect and antifracture protection persist for an undefined period. Patients are encouraged to continue calcium and vitamin D supplementation, during a bisphosphonate drug holiday. However, assessment of adequate calcium intake during the bisphosphonate drug holiday is difficult. Therefore, we measured the serum intact parathyroid hormone (PTH) level as a surrogate marker. A premenopausal woman discontinued bisphosphonate therapy, after 7.5 years of treatment. Two months later, blood calcium and phosphorus levels were normal, serum 25-hydroxyvitamin D level was 31.3 ng/mL, but serum PTH level had increased to 94.9 pg/mL. The elemental calcium supplement dose was increased to 600 mg/day, with no change in the cholecalciferol dose (400 IU). Her serum PTH levels decreased to 49.1 after 4 months and 32.9 pg/mL after 5 months. The serum PTH level may be helpful in assessing adequate calcium intake during a bisphosphonate drug holiday.
    Full-text · Article · Aug 2014
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    • "Using S-PTH as an outcome is difficult as the variation is large and also other factors have an effect on S-PTH. Sai et al. (96) concluded in a systematic review that ‘vitamin D insufficiency should be defined as serum 25(OH)D less than 50 nmol/l as it relates to bone’. "
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    ABSTRACT: The present literature review is part of the NNR5 project with the aim of reviewing and updating the scientific basis of the 4th edition of the Nordic Nutrition Recommendations (NNR) issued in 2004. The overall aim was to review recent scientific data on the requirements and health effects of vitamin D and to report it to the NNR5 Working Group, who is responsible for updating the current dietary reference values valid in the Nordic countries. The electronic databases MEDLINE and Swemed were searched. We formulated eight questions which were used for the search. The search terms related to vitamin D status and intake and different health outcomes as well as to the effect of different vitamin D sources on vitamin D status. The search was done in two batches, the first covering January 2000-March 2010 and the second March 2009-February 2011. In the first search, we focused only on systematic literature reviews (SLRs) and in the second on SLRs and randomized control trials (RCTs) published after March 2009. Furthermore, we used snowballing for SLRs and IRCTs published between February 2011 and May 2012. The abstracts as well as the selected full-text papers were evaluated in pairs. We found 1,706 studies in the two searches of which 28 studies were included in our review. We found 7 more by snowballing, thus 35 papers were included in total. Of these studies, 31 were SLRs and 4 were RCTs. The SLRs were generally of good or fair quality, whereas that of the included studies varied from good to poor. The heterogeneity of the studies included in the SLRs was large which made it difficult to interpret the results and provide single summary statements. One factor increasing the heterogeneity is the large variation in the assays used for assessing 25-hydroxyvitamin D concentration [25(OH)D], the marker of vitamin D status. The SLRs we have reviewed conclude that the evidence for a protective effect of vitamin D is only conclusive concerning bone health, total mortality and the risk of falling. Moreover, the effect was often only seen in persons with low basal 25(OH)D concentrations. In addition, most intervention studies leading to these conclusions report that intervention with vitamin D combined with calcium and not vitamin D alone gives these benefits. It was difficult to establish an optimal 25(OH)D concentration or vitamin D intake based on the SLRs, but there are evidence that a concentration of ≥50 nmol/l could be optimal. The dose-response studies relating vitamin D intake (fortification and supplementation) to S-25(OH)D suggested that an intake of 1-2.5 µg/day will increase the serum concentration by 1-2 nmol/l but this is dependent on the basal concentration with a response being greater when the basal concentration is low. Data show that a S-25(OH)D concentration of 50 nmol/l would reflect a sufficient vitamin D status. Results from this review support that the recommendation in NNR 2004 needs to be re-evaluated and increased for all age groups beyond 2 years of age. We refer to the total intake from food as well as supplements, given minimal sun exposure. Limited sunshine, however, does not reflect the situation for the majority of the Nordic population in the summertime. It should also be emphasized that there are large differences in results depending on assay methods and laboratories measuring 25(OH)D, adding to the uncertainty of determining an appropriate target concentration. Moreover, the dose-response of vitamin D on serum 25(OH)D-concentrations is not well established and is dependent on the basal concentrations, sunshine exposure and dietary intake. We advise that these uncertainties should be taken into account when setting the final Nordic recommendations.
    Full-text · Article · Oct 2013 · Food & Nutrition Research
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