Disease relevance of 25-HYDROXYVITAMIN D2

• The tetany group had significantly lower serum 25OHD levels and higher 1,25(OH)2D levels, and had increased 1,25(OH)2D/25OHD as an index of the renal 25OHD-1-hydroxylase activity than those in the nontetany group [1].
• Vitamin D deficiency, defined as a serum 25OHD level below 39 nmol/liter was present in 73.6% [2].
• Over a 2-yr period of evaluation of 118 consecutive, free living patients with osteopenia or osteoporosis, we identified 18 subjects with depressed serum 25-hydroxyvitamin D (250HD; < or = 14 ng/mL) [3].
• The vitamin D metabolites, 25-hydroxyvitamin D (250HD) and 1,25-dihydroxyvitamin D [1,25-(OH)2D], were measured in samples of plasma from normal and X-linked hypophosphatemic (Hyp) mice, which are a model for this common form a human vitamin D-resistant rickets [4].
• In elderly men, winter levels of 25OHD were lowest whereas those of PTH, bone resorption markers and PINP were highest [5].

Psychiatry related information on 25-HYDROXYVITAMIN D2

• The major determinants of 25OHD were month of blood sampling, fat percentage, physical activity, and serum albumin [6].

High impact information on 25-HYDROXYVITAMIN D2

• An in vitro study of the liver 25-hydroxylation of vitamin D2 and the kidney 1- and 24-hydroxylations of 25-hydroxyvitamin D2 was undertaken in order to determine whether the discrimination against vitamin D2 seen in chicks in vivo is the result of a block of one or more of the steps in the activation of the vitamin D2 molecule [7].
• Serum bone biochemistry, 25OHD, and parathyroid hormone levels were measured [8].
• Multivariate analysis revealed 25OHD as an independent variable for AFPT, CRT, and postural sway [8].
• Two hundred and twenty-nine consecutive subjects, 202 women and 27 men, referred for evaluation of osteoporosis or low bone mineral density (BMD) had serum measurements of immunoreactive PTH (iPTH) and 25-hydroxyvitamin D (25OHD) performed [9].
• Despite persistent primary hyperparathyroidism, normalization of serum 25OHD levels in these 5 subjects increased their BMD at an annual rate of 6.3% and 8.2% in spine and hip, respectively [9].

Chemical compound and disease context of 25-HYDROXYVITAMIN D2

• Bone resorption was evaluated by 24-hour excretion of deoxypyridinoline and of C-terminal telopeptide of collagen type I. In young men (< 55 yrs) PTH level decreased with age (r = -0.18, P < 0.005) whereas 25-hydroxyvitamin D (25OHD) concentration was stable [5].

Biological context of 25-HYDROXYVITAMIN D2

• Seasonal variations of serum 25OHD were noted only in the control population; in this group the 25OHD levels also correlated with sunlight exposure (r = 0.48; P less than 0.01), as assessed by an outdoor score [10].
• Women with low 25OHD had a reduced vertebral bone density (VBD), assessed by quantitative computed tomography, compared to age-matched controls (P less than 0.001) [10].
• To provide further data on vitamin D metabolism in pregnancy, the concentrations of 25-hydroxyvitamin D (25OHD; n = 72), 24,25-dihydroxyvitamin D [24,25-(OH)2D; n = 70], and 1,25-(OH)2D (n = 59) were measured in amniotic fluid by competitive protein-binding radioassays [11].
• In multiple regression analysis 50-60% of the variation of total and free 1,25-(OH)2D could be explained by serum 25OHD, PTH(1-84), and especially IGF-I, suggesting a possible role of decreasing GH and IGF-I concentrations in the mineral homeostasis of the elderly [12].
• At term, the mean (+/- SE) concentrations of 25OHD and 24,25-(OH)2D in amniotic fluid (810 +/- 76 and 37.5 +/- 5.4 pg/ml, respectively) were significantly lower (P less than 0.01) than those at 16-18 weeks gestation (1707 +/- 2.67 and 149 +/- 3 pg/ml, respectively) [11].

Anatomical context of 25-HYDROXYVITAMIN D2

• Similarly, the concentrations of 25OHD in pooled amniotic fluid samples, as determined by high pressure liquid chromatography and UV absorbance detection at 254 nm, were 664 +/- 188 pg/ml at term and 1240 +/- 294 pg/ml at midgestation [11].
• 1,25-Dihydroxyvitamin D2 has been prepared from 25-hydroxyvitamin D2 using rachitic chick kidney mitochondria [13].
• 25OHD levels correlated with participants' age (r=-0.15), weight (r=-0.11), body mass index (r=-0.13), fat mass (r=-0.14), percentage body fat (r=-0.16), physical activity (r=0.10) and the month of blood sampling (all P<0.0001) [14].
• We assessed the medical history, vitamin D intake from milk and supplements, and serum 25OHD levels in 231 women and 41 men who attended a Thyroid Clinic between January and March, 1999 [15].
• Individual quantitation of vitamin D2, vitamin D3, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3 in human milk [16].

Associations of 25-HYDROXYVITAMIN D2 with other chemical compounds

• Vitamin D3 supplementation raises serum 25OHD levels in postmenopausal black women, decreases secondary hyperparathyroidism, and reduces bone turnover [17].
• In 51 patients with serum 25OHD levels less than 15 ng/mL, gland weight, PTH, AP, and adjusted calcium were each significantly higher than in 97 patients with 25OHD levels of 15 ng/mL or more, but 1,25-dihydroxyvitamin D levels were similarly increased in both groups [18].
• Assay for plasma 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 by "high-performance" liquid chromatography [19].
• METHODS: We developed an HPLC method that selectively measures 25-hydroxyvitamin D2 [25(OH)D2] and D3 [25(OH)D3] and compared this assay with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, a competitive protein-binding assay (CPBA) on the Nichols Advantage platform, and an RIA from Diasorin [20].
• 3. Four of the samples contained more than 10 ng/ml of 25-hydroxyergocalciferol and the results are consistent with the reported 100% cross-reactivity of the competitive binding protein method for 25-hydroxyergocalciferol and 25-hydroxycholecalciferol [21].

Gene context of 25-HYDROXYVITAMIN D2

• In multivariate analyses that also corrected for balance and health status, PTH remained a significant predictor of falls independent of 25OHD [2].
• At 12 weeks of age (40-42 weeks postconceptual age), DBP, 25-hydroxyvitamin D (25OHD), calcium, phosphorus, copper, and albumin were all significantly increased (by paired t test) [22].
• The mean 25OHD level in the March sample (39.9 nmol/L, SD 19.7) was significantly lower than the mean 25OHD level in the September sample (44.9 nmol/L, SD 16.9) (P = .001) [23].
• Baseline patient characteristics including: age, basal serum 25-hydroxyvitamin D (25OHD), basal serum PTH, basal serum calcium and post treatment serum calcium, were similar in groups N and F. Mild hypercalcaemia occurred in only two (3.9%) patients [24].
• In the entire group, serum ionized calcium (Ca2+), bone gla protein (BGP), 25-hydroxyvitamin D (25OHD), and 1,25-dihydroxyvitamin D (1,25(OH)2D) were all lower than in age-matched controls, and carboxy-terminal parathyroid hormone (CPTH) was higher [25].

Analytical, diagnostic and therapeutic context of 25-HYDROXYVITAMIN D2

• Serum PTH was measured by means of 2 immunoradiometric assays, the Allegro intact PTH assay (Nichols Institute Diagnostics) and the new CAP assay (Scantibodies Laboratory, Inc.). We found a high prevalence (167 of 280; 59.6%) of low 25OHD (< or =30 nmol/L) in these otherwise healthy individuals [26].
• BMD at the lumbar spine was correlated with body mass index (BMI) (r = 0.278, p = 0.0003), age (r = -0.194, p = 0.0134) and serum 25OHD (r = 0.188, p = 0.0167) [27].
• METHODS: Cross-sectional study of 378 healthy, middle-aged and older community-dwelling men in Auckland, New Zealand. RESULTS: The mean 25OHD (SD) level was 85 (31) nmol/l. We found significant seasonal variation in 25OHD levels (peak in autumn 103 nmol/l, nadir in spring 59 nmol/l) [6].
• Our results showed a baseline mean 25OHD level in the active group of 9.6 (range < 5.5-12.7) ng/ml and in the control group of 10.0 (range < 5.5-12.9) ng/ml (P < 0.4) [28].
• A dose-response relationship in serum 25OHD levels was observed for sunbathing frequency before and after adjusting for age (P< 0.05) [29].

References