25-hydroxy vitamin D levels in healthy premenopausal women: Association with bone turnover markers and bone mineral density
Introduction
Vitamin D deficiency is very common in elderly people [1] and is associated with an increased risk of falls and fragility fractures [2]. Its incidence is particularly high in southern European countries [3], [4]. Most of the epidemiogical studies have been performed in elderly persons, who are more likely to be affected by the advocated explanations for vitamin D deficiency, i.e. low dietary vitamin D intake and inadequate skin production of the vitamin [1].
The optimal serum concentration of 25-hydroxyvitamin D [25(OH)D] is generally defined as the concentration that maximally suppresses the serum parathyroid hormone (PTH). This is a useful criterion, but PTH may also fluctuate according to dietary calcium intake [5], [6] and renal function [7] which again are more likely to be inadequate in the elderly than in young individuals.
In few studies 25(OH)D levels were found to be correlated with bone mineral density (BMD) but most of these reports were from elderly patients [8], [9], [10], [11].
A negative correlation between 25(OH) D levels and bone turnover markers has been reported in a number of studies including mostly elderly individuals [4], [12], [13], [14], [15], [16].
The BONTURNO study [17] was designed to establish standard values for bone turnover markers, their relationship with BMD and their main determinants in young healthy premenopausal women. Here we describe the distribution and main determinants of 25(OH)D levels in this cohort of young women. We also determined whether there is an association between 25(OH)D levels and BMD or bone turnover markers in healthy young women.
Section snippets
Methods
The inclusion criteria of the women participating in the BONTURNO study, their baseline characteristics and the study procedures are described in detail elsewhere [17].
Briefly, healthy subjects with regular monthly cyclic menses were enrolled from 20 different sites uniformly distributed across Italy. Each centre was asked to recruit 5 healthy individuals for each 5 year age range from 20 to 49. Most volunteers were from the hospital staff or their relatives. Subjects with abnormal laboratory
Results
The main clinical characteristics of the entire study population and according to 25(OH)D levels lower or higher than 20 ng/ml, are listed in Table 1. The distribution frequencies for various 25(OH)D cut-off levels are listed in Table 2. 25(OH)D levels lower than 20 ng/ml were found in almost a third of the women and these women differ significantly from the other for a number of aspects such as sun exposure, physical activity and BMI (Table 1).
The 25(OH)D levels had to be logarithmically
Discussion
Vitamin D deficiency or insufficiency is very common among elderly subjects particularly from Southern European countries. In this study we found that vitamin D insufficiency, as defined by 25(OH)D levels lower than 20 ng/ml, is also common among otherwise healthy young women, accounting for a third of the cohort. The study population was made mostly by hospital staff, which might not be fully representative of the general population, even though we cannot predict in what direction they might
Conflict of interest
S.A. receives consultancy honoraria from MSD and Servier.
References (21)
- et al.
Serum vitamin D concentrations among elderly people in Europe
Lancet
(1995) - et al.
Relationship between serum parathyroid hormone, vitamin D sufficiency, age, and calcium intake
Bone
(2008) - et al.
Secondary hyperparathyroidism in elderly people: combined effect of renal insufficiency and vitamin D deficiency
Am. J. Clin. Nutr.
(1993) - et al.
Positive association between 25-hydroxy vitamin d levels and bone mineral density: a population-based study of younger and older adults
Am. J. Med.
(2004) Vitamin D deficiency
N. Engl. J. Med.
(2007)- et al.
Effect of vitamin D on falls: a meta-analysis
JAMA.
(2004) - et al.
A global study of vitamin D status and parathyroid function in postmenopausal women with osteoporosis: baseline data from the multiple outcomes of raloxifene evaluation clinical trial
J. Clin. Endocrinol. Metab.
(2001) - et al.
Relationship between serum parathyroid hormone levels, vitamin D sufficiency, and calcium intake
JAMA
(2005) - et al.
Vitamin D and bone mineral density
Osteoporos. Int.
(1998) - et al.
Relation between vitamin D insufficiency, bone density, and bone metabolism in healthy postmenopausal women
J. Bone Miner. Res.
(2001)
Cited by (79)
Effect of vitamin D metabolites on bone histomorphometry in healthy black and white women: An attempt to unravel the so-called vitamin D paradox in blacks
2023, Bone ReportsCitation Excerpt :However, 25(OH)D levels did not correlate to any bone histomorphometric variable in either black or white women. There is evidence that serum 25(OH)D levels are affected by age, menstrual status and BMI (Perez-Lopez et al., 2011; Adami et al., 2009; Holick, 2006; Rajakumar et al., 2011). Compared to white women, we found that serum 25(OH)D levels were significantly lower but 1,25(OH)2D levels significantly higher in black women matched for age, menstrual status and BMI, suggesting that the differences in 25(OH)D and 1,25(OH)2D levels might be independent of these factors.
Bone Mineral Density and Its Determinants: A Systematic Review of Risk Factors and Prevention Strategies
2023, Biomedical and Pharmacology Journal