Assay of 25-hydroxyvitamin D3 in human plasma by high-performance liquid chromatography

A method using preparative and analytical high-performance liquid chromatography (HPLC) is proposed for the assay of 25-hydroxyvitamin D3 (25-OH-D3) in human plasma. A constant volume (0.2--2.0 ml) of a plasma sample was saponified. The unsaponifiable matter was first applied to preparative HPLC using a column of the straight-phase type (Zorbax SIL) in order to separate a 25-OH-D3 fraction from lipophilic concomitants giving ultraviolet-absorbing noise. Then, the separated 25-OH-D3 fraction was applied to analytical HPLC using a column of the reversed-phase type (Zorbax ODS) in order to measure the content of 25-OH-D3 from the peak height. This is a revised method from Jones (1978): Clin. Chem., 24, 287--298). The results showed that the clean-up procedure by the first preparative HPLC was successfully performed because the peak corresponding to 25-OH-D3 on the chromatogram of the second analytical HPLC was not disturbed by any other interfering peaks. Moreover, recovery through the whole procedure was satisfacotry (about 100%) and the procedures of saponification and isolation of the unsaponifiable matter diminished the overload to the columns. These are the revised points of Jones' method. When two determinations were performed on 12 samples of plasma taken from normal adults in October, the values were 22.6 +/- 4.8 and 21.0 +/- 3.6 (mean +/- SD) ng/ml, respectively.     

Components of 25-hydroxyvitamin D in serum of young children in upper midwestern United States.

The relative importance of cholecalciferof (vitamin D3) and ergocalciferol (vitamin D2) in maintaining the vitamin D level in children (1/2 to 6 years old) living in the upper midwestern United States was determined by measurement of total 25-hydroxyvitamin D (25-OH-D), its components, and other indices of calcium homeostasis in serum. In 38 normal children, mean (range) serum total 25-OH-D was 32.8 (less than 5 to 53) ng/ml; in 25 of the 28 sera partitioned, the major component was 25-OH-D3. Significant seasonal variation in serum 25-OH-D3 (mean, range: 35.2, 17 to 51 ng/ml in summer and 15.9, less than 5 to 32 ng/ml in winter) was not accompanied by changes in mean serum 25-OH-D2, calcium, phosphorus, or alkaline phosphatase values. However, individual serum total 25-OH-D values correlated with serum phosphorus values (r = 0.37; P less than 0.05). The proportion of the total represented by 25-OH-D3 varied widely, with a a mean of 83% in summer and 67% in winter. Sources of D3, which include both dermal synthesis and intestinal absorption of D3 added to milk, appear to be more important than sources of D2 in maintaining vitamin D nutrition of young children throughout the year. However, sources of D2 offset the decrease in total 25-OH-D in winter months.     

25-Hydroxyvitamin D and 1,25-dihydroxyvitamin D of D2 and D3 origin in maternal and umbilical cord serum after vitamin D2 supplementation in human pregnancy

Serum concentrations of 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D [1,25-(OH)2D] of vitamin D2 and D3 origin were determined separately in 10 women before vitamin intake in early pregnancy, and repeated in maternal and cord serum obtained at delivery after 20 to 30 wk of vitamin D2 supplementation in a dose of 400 IU/day. Before supplementation 25-OHD2 and 1,25-(OH)D2D2 were present in just traceable or nondetectable concentrations, but the levels increased in all to a mean +/- 1 SD of 7.3 +/- 3.7 ng/ml and 37.2 +/- 18.1 pg/ml, respectively (p less than 0.0025), by the time of delivery. At delivery the total 25-OHD and 1,25-(OH)2D levels were always lower in the cord than in the maternal serum (30.7 +/- 14.2 versus 20.1 +/- 9.1 ng/ml, and 90.1 +/- 31.2 versus 37.3 +/- 11.6 pg/ml, p less than 0.0025). The paired concentrations of 25-OHD were closely related (r = 0.89, p less than 0.0005), while the association for 1,25-(OH)2D was not statistically significant (r = 0.53, p less than .01). The 25-OHD of D2 and D3 origin accounted for a similar proportion of the total 25-OHD in the maternal and cord serum (ratio of 25-OHD2 to 25-OHD3: 0.40 +/- 0.28 versus 0.45 +/- 0.29, p = NS), as did the respective 1,25-(OH)2D metabolites [ratio of 1,25-(OH)2D2 to 1,25-(OH)2D3: 0.73 +/- 0.35 versus 0.90 +/- 0.50, p = NS].(ABSTRACT TRUNCATED AT 250 WORDS)     

Tissue distribution of 7-dehydrocholesterol, vitamin D3 and 25-hydroxyvitamin D3 in several species of fishes

A high-performance liquid chromatographic (HPLC) method for simultaneous determination of 7-dehydrocholesterol (7-DHC), vitamin D3 and 25-hydroxyvitamin D3 (25-OH-D3) in tissues of fishes was established, and using this method the tissue distribution of the sterols in lamprey (Entosphenus japonicus), great blue shark (Prionace glauca), skipjack (Katsuwonus pelamis) and albacore (Thunnus alalunga) was investigated. The results are summarized in the following: Although the alimentary canal, gall bladder and roe of lamprey and the alimentary canal of great blue shark contained comparatively high levels of 7-DHC (higher than 2,000 ng/wet tissue g), the other tissues of lamprey and great blue shark and all tissues of skipjack and albacore contained only low levels of 7-DHC (lower than 1,000 ng/g). There was no significant correlation between the levels of 7-DHC and vitamin D3. The contents of 7-DHC in the skin of skipjack and albacore were only 1/1,000 of those in the skin of rats. Although the contents of vitamin D3 in the liver of skipjack and albacore were extremely high (41,240 and 21,000 ng/g, respectively), those in the skin were very low (454 and 257 ng/g, respectively). 25-OH-D3 was detected in the viscera of skipjack, but the levels were not very high (lower than 150 ng/g). These levels were not significantly correlated with those of vitamin D3. The results suggest that large quantities of vitamin D3 in the liver of skipjack and albacore are supplied by other biosynthetic routes or by intake of vitamin D3 rather than by photochemical biosynthesis.     

Bone marrow and serum concentrations of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1 alpha,25-dihydroxyvitamin D in patients with leukemia and normal subjects

Concentrations of 25-hydroxyvitamin D (25-OH-D), 24,25-dihydroxyvitamin D [24,25(OH)2D], and 1 alpha,25-dihydroxyvitamin D [1,25(OH)2D] in bone marrow and serum of patients with leukemia and normal subjects were assayed. There were highly significant correlations between the bone marrow and serum concentrations of the respective vitamin D metabolites. Especially, the concentrations of 25-OH-D and 1,25(OH)2D in the bone marrow gave very similar values to those in serum. This is a big advantage in controlling the bone marrow levels of vitamin D metabolites in patients with leukemia, because doctors can calculate the bone marrow levels from the serum levels of the respective vitamin D metabolites without bone marrow aspiration. When 1 alpha-hydroxyvitamin D3 (1 alpha-OH-D3) was administered orally to eight patients with leukemia, clinical conditions were improved in seven patients: four complete remissions (CR), one partial response (PR), and two minor responses (MR) without severe hypercalcemia. The results suggest that the therapy with 1 alpha-OH-D3 is fairly effective for curing human leukemia although it is not dramatic.     

Effect of iron on serum 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D concentrations.

In 13 of 17 infants (aged 10.5 +/- 4.3; mean +/- SD mo) with iron-deficiency anemia, the serum 24,25-dihydroxyvitamin D concentration was below the normal range and in 9 of these 13 the serum 25-hydroxyvitamin D concentration was below the normal range despite the fact that these infants received 10 micrograms vitamin D/d from the age of 1 mo. The infants were treated with intramuscular iron dextran (Imferon). The iron-dextran treatment increased the hemoglobin and serum iron concentrations as well as 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D concentrations. It is known that iron deficiency impairs fat and vitamin A intestinal absorption. Therefore, it is suggested that absorption of vitamin D may also be impaired. This may contribute to the development of vitamin D deficiency. Iron supplementation may have improved the absorption of vitamin D in the small intestine and hence increased the vitamin D concentration in the plasma.     

Effects of ergocalciferol supplementation on the concentration of vitamin D and its metabolites in human milk

The effect of maternal ergocalciferol (vitamin D2) supplementation on the concentrations of vitamin D, 25-hydroxyvitamin D (25-OH-D), 24R,25-dihydroxyvitamin D [24,25-(OH)2D], and 1 alpha,25-dihydroxyvitamin D [1,25-(OH)2D] in their milk was studied. Vitamin D2, D3, 25-OH-D2 and 25-OH-D3 were simultaneously determined by high performance liquid chromatography, and the determination of 24,25-(OH)2D and 1,25-(OH)2D was performed by competitive protein binding assay and radioreceptor assay, respectively, after separation of the D2 and D3 compounds. After healthy lactating mothers had received a daily oral dose of vitamin D2 (1,200 IU/d) for 4 wk, the concentrations of vitamin D2, D3 and the metabolites were determined in their plasma and milk. Although the plasma levels of 25-OH-D2 were significantly increased, the increase in milk was relatively small. On the other hand, the increase of vitamin D2 levels in milk was greater than that of 25-OH-D2 in milk after supplementation. The levels of 1,25-(OH)2D in milk was lower after 5 wk of lactation than after 1 wk of lactation, regardless of maternal vitamin D2 supplementation. When total antirachitic activities in milk were calculated, only a very slight increase was observed as a result of supplementation.     

Determination of 25-hydroxyvitamin D3 in sheep tissues by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method is described for the determination of 25-hydroxyvitamin D3 (25-OH-D3) in sheep tissue. The procedure involved saponification followed by chromatography on Sephadex LH-20 in order to remove extraneous material. Quantitation of 25-OH-D3 in tissue samples containing as little as 2 ng/g, was achieved by HPLC and ultraviolet detection at 254 nm in HPLC system.     

Lack of evidence for existence of vitamin D and 25-hydroxyvitamin D sulfates in human breast and cow's milk

The presence of water-soluble vitamin D and 25-OH-D sulfates in human breast and cow's milk was studied. We first confirmed that synthetic vitamin D2 and D3 sulfates could not be hydrolyzed by alkali but by acid. Breast or cow's milk was separated into milk whey containing water-soluble components and milk curd containing crude proteins and lipophilic components. The separated milk whey and curd were hydrolyzed by acid or alkali and each lipid extract was subjected to HPLC analysis. Neither peak due to vitamin D and 25-OH-D was observed in the chromatograms of acid- and alkali-hydrolyzed milk whey, whereas the peaks due to vitamin D3 and 25-OH-D3 were found in the chromatograms of both acid- and alkali-hydrolyzed milk curd and there was no significant difference between the respective peak heights. The eluates corresponding to the respective peaks observed on the latter's chromatograms were collected and subjected to UV, HPLC, GC-MS and GLC to identify the existence of vitamin D3 and 25-OH-D3, respectively. We concluded from these results that neither breast nor cow's milk contained water-soluble vitamin D and 25-OH-D sulfates, whereas they contained fat-soluble vitamin D3 and 25-OH-D3. The concentrations of vitamin D3 and 25-OH-D3 in breast milk were about 125 and 350 ng/liter, while those in cow's milk were about 420 and 270 ng/liter, respectively. The experiments on the transfer of 3H-D3 and 3H-25-OH-D3 perorally dosed to lactating rats into suckling pups through their milk also supported the above conclusion.     

Isolation and purification of in vivo-generated 25-hydroxyvitamin D2 by preparative high-performance liquid chromatography.

In order to obtain a standard compound of 25-hydroxyvitamin D2 (25-OH-D2), a method for isolating in vivo-generated 25-OH-D2 from the blood of rats or rabbits was established by using several steps of preparative high-performance liquid chromatography (HPLC). When the unsaponifiable matter of the plasma obtained from rats or rabbits receiving a large dose of vitamin D2 was applied to the preparative HPLC using a Zorbax SIL column, a peak denoted as peak X was observed on the chromatogram. Since the peak X was thought to be due to 25-OH-D2 from the experiments of time course and dose-response, it was purified by subjecting it to successive preparative HPLC using several kinds of columns. From the results of ultraviolet (UV) absorption spectrum, gas chromatography-mass spectrometry (GC-MS) and mass chromatography, the purified peak X compound was confirmed to be 25-OH-D2. The proposed method for isolating in vivo-generated 25-OH-D2 is very convenient, because the time to perform each HPLC is very short though several steps of HPLC are used.     

Serum 25-hydroxyvitamin d concentrations and season-specific correlates in Japanese adults

Background

Several lines of evidence indicate an important role for vitamin D in the prevention of a range of diseases. Blood vitamin D levels show clear seasonal variation; however, data on the determinants of vitamin D status for each season are limited. We investigated the association between lifestyle and serum vitamin D concentration by season in Japanese workers.

Methods

Subjects were 312 men and 217 women aged 21 to 67 years who worked in municipal offices in Northern Kyushu, Japan and participated in a periodic checkup in July or November. Multiple linear regression analysis was used to examine the association between serum 25-hydroxivitamin D concentrations and lifestyle factors for each season.

Results

Mean serum 25-hydroxyvitamin D concentration was 27.4 ng/ml (68.4 nmol/L) and 21.4 ng/ml (53.4 nmol/L) for workers surveyed in July and November, respectively (P < 0.001); the prevalence of vitamin D deficiency (<20 ng/ml) was 9.3% and 46.7%, respectively (P < 0.001). In November, dietary vitamin D intake (in both sexes) and nonsmoking and physical activity (in men) were significantly associated with higher concentrations of serum 25-hydroxyvitamin D. In summer, fish/shellfish intake was associated with higher serum 25-hydroxyvitamin D concentrations in women.

Conclusions

Vitamin D deficiency is common in Japanese workers during seasons with limited sunlight. The lifestyle correlates of favorable vitamin D status in November were physical activity, dietary vitamin D intake, and nonsmoking.Key words: 25-hydroxyvitamin D, Japanese, lifestyle factors, vitamin D intakes     

Fortified malted milk drinks containing low-dose ergocalciferol and cholecalciferol do not differ in their capacity to raise serum 25-hydroxyvitamin D concentrations in healthy men and women not exposed to UV-B

Uncertainty remains regarding the efficacy of low intakes of ergocalciferol (vitamin D2 or D2) and cholecalciferol (vitamin D3 or D3) provided in food to increase serum 25-hydroxy-vitamin D (25-OH-D) metabolite concentrations when UV-B exposure is low. We recruited 40 healthy men and women into a double-blind, parallel design, randomized controlled trial. Participants received placebo or 1 of 4 experimental treatments (D2 or D3 at 5 or 10 μg/d) supplied as a malted milk drink for 4 wk during a period of minimal UV-B exposure in the UK. The primary outcome was a change in serum 25-OH-D2 and 25-OH-D3 concentrations measured by ultra-performance liquid chromatography tandem MS. The secondary outcomes were changes in concentrations of plasma parathyroid hormone and serum calcium (Ca(2+)). Baseline concentrations (geometric mean ± SD) of 25-OH-D2, 25-OH-D3, and total 25-OH-D were 3 ± 4, 32 ± 22, and 37 ± 22 nmol/L, respectively. Both D2- and D3-fortified drinks resulted in dose-dependent increases (P < 0.001) in their respective 25-OH metabolites that did not significantly differ in size. Increments from baseline compared with the placebo group following 5 and 10 μg/d of D2 were (mean ± SEM) 9.4 ± 2.5 and 17.8 ± 2.4 nmol/L for 25-OH-D2 and following 5 and 10 μg/d of D3 were 15.1 ± 4.7 and 22.9 ± 4.6 nmol/L for 25-OH-D3, respectively. There was no difference between D2 and D3 groups in the incremental AUC of their respective metabolites. These findings suggest that D2 and D3 are equipotent in increasing 25-OH-D in healthy men and women with negligible UV-B exposure.     

Changes in the concentrations of vitamin D and its metabolites in the plasma of healthy subjects orally given physiological doses of vitamin D2 by multivitamin or vitamin D preparations

Changes in the concentrations of vitamin D and its metabolites in plasma of healthy subjects orally given physiological doses of vitamin D2 by multivitamin or vitamin D liquid preparations were determined and the bioavailability of vitamin D was studied. Separative assay on the D2 and D3 compounds of vitamin D, 25-hydroxyvitamin D (25-OH-D), 24R,25-dihydroxyvitamin D [24,25(OH)2D], and 1 alpha,25-dihydroxyvitamin D [1,25(OH)2D] was performed in plasma of eight healthy male volunteers. When the concentrations of vitamin D and its metabolites in plasma of volunteers were assayed after daily oral administration of 400 IU of vitamin D2 in a form of multivitamin tablet for 1 week, the variations of vitamin D3 and its metabolites in plasma levels were very small. In contrast, the concentrations of 25-OH-D2 and 1,25(OH)2D2 slightly increased after the administration, while neither vitamin D2 nor 24,25(OH)2D2 was detected. A single dose of 4,000 IU of vitamin D2 was orally given to the volunteers in a form of a vitamin D liquid preparation and the hourly variations were observed during 24 h. These concentrations of vitamin D2, 25-OH-D2, and 1,25(OH)2D2 were slightly higher than those of the repeated doses. The result suggests that even the high dose of 4,000 IU has little effect on the plasma levels of vitamin D2 and its metabolites by a single dose, indicating a low risk for hypervitaminosis D.     

宜昌夷陵地区11656例0~6岁婴幼儿25-羟维生素D水平检测分析

目的为了研究宜昌市夷陵区0~6岁儿童维生素D营养状况及其与年龄、性别、季节之间的关系,以便为夷陵区儿童合理补充维生素D提供科学依据。方法对2017年1月至2018年7月来夷陵区妇幼保健院体检的0~6岁11656例儿童,采用荧光免疫层析方法进行末梢血25-(OH)D 3水平检测。结果该区11656例儿童末梢血25-(OH)D 3水平为(29.35±7.59)ng/mL,其中维生素D缺乏组566例(4.86%),维生素D不足组6579例(56.44%),维生素D充足组4511例(38.70%)。1岁以内婴儿组维生素D水平明显高于幼儿组和学龄前组,3岁以后儿童维生素D水平明显下降,各年龄组间差异有统计学意义(χ2=145.846,P<0.05)。不同季节儿童维生素D水平春季最高,冬季最低(χ2=504.007,P<0.05)。不同性别间儿童维生素D水平差异并无统计学意义(t=0.841,P>0.05)。结论我区0~6岁儿童维生素D水平大部分处于不足的状态,应增加该区儿童维生素D的摄入量,尤其加强学龄前组儿童维生素D的补充及冬季户外活动。     

Effects of sun exposure and dietary vitamin D intake on serum 25-hydroxyvitamin D status in hemodialysis patients

BACKGROUND/OBJECTIVES

Vitamin D deficiency is common in hemodialysis patients. The aim of this study was to identify whether or not sun exposure and dietary vitamin D intake have effects on serum 25-hydroxyvitamin D (25(OH)D) status in hemodialysis (HD) patients. The objective was to identify the main determinants of serum vitamin D status in the study subjects.

SUBJECTS/METHODS

A cross-sectional study of 47 HD patients (19 males and 28 females) was performed. We assessed serum 25(OH)D and 1,25(OH)₂D levels between August and September 2012 and analyzed the prevalence of vitamin D deficiency in HD patients. To evaluate the determinants of serum 25(OH)D levels, we surveyed dietary vitamin D intake, degree of sun exposure, and outdoor activities. To compare biological variables, serum 25(OH)D was stratified as below 15 ng/ml or above 15 ng/ml.

RESULTS

Mean 25(OH)D and 1,25(OH)₂D levels were 13.5 ± 5.8 ng/ml and 20.6 ± 11.8 pg/ml, respectively. The proportions of serum 25(OH)D deficiency (< 15 ng/ml), insufficiency (15-< 30 ng/ml), and sufficiency (≥ 30 ng/ml) in subjects were 72.4%, 23.4%, and 4.3%, respectively. Prevalence of vitamin D deficiency in female patients was 78.6%, whereas that in males was 63.2% (P = 0.046). Vitamin D intake and sun exposure time were not significantly different between the two stratified serum 25(OH)D levels. Dietary intake of vitamin D did not contribute to increased serum 25(OH)D levels in HD patients. The main effective factors affecting serum 25(OH)D status were found to be the sun exposure and active outdoor exercise.

CONCLUSIONS

Hypovitaminosis D is common in HD patients and is higher in females than in males. Sun exposure is the most important determinant of serum 25(OH)D status in HD patients.     

Serum 25-hydroxyvitamin D3 levels are elevated in South Indian patients with ischemic heart disease

Several lines of evidence point to a possible relationship between vitamin D and cardiovascular disease. Animal experiments and observational studies in humans suggest vitamin D to be arteriotoxic and an association of high intake of vitamin D with increased incidence of ischemic heart disease (IHD). The major source of vitamin D in adults is vitamin D synthesized in the skin through exposure to the sun. In tropical environment there is a possibility of high level of solar exposure and enhanced serum levels of vitamin D in the population. We explored the relation between serum level of 25-hydroxyvitamin D₃ and IHD in a case-control study involving 143 patients with either angiographic evidence of coronary artery disease or patients with acute myocardial infarction and 70 controls, all men in the age group of 45–65 years. Fasting blood samples were collected, serum separated and serum levels of 25-hydroxyvitamin D₃ was measured by protein binding radioligand assay. Serum levels of cholesterol, triglyceride, calcium, magnesium and inorganic phosphate were also determined. Prevalences of diabetes, hypertension and smoking history were noted. Statistical comparisons of variables between cases and controls were done using ²-tests. Multivariate logistic regression analysis was done to examine the association of IHD with serum levels of 25-hydroxyvitamin D₃ controlling for selected variables. Serum levels of 25-hydroxyvitamin D₃, calcium, inorganic phosphate, total cholesterol, low density lipoprotein and triglycerides were elevated in a higher proportion of patients, compared to controls. Serum levels of 25-OH-D₃ above 222.5 nmol/l (89 ng/ml) was observed in 59.4% of cases compared to 22.1% in controls (p < 0.001; unadjusted odds ratio (OR): 5.17; 95% confidence interval (CI): 2.62–10.21). When controlled for age and selected variables using the multivariate logistic regression, the adjusted OR relating elevated serum 25-hydroxyvitamin D₃ levels ( 222.5 nmol/l, 89 ng/ml) and IHD is 3.18 (95% CI: 1.31–7.73). Given the evidences for the arteriotoxicity of vitamin D, further investigations are warranted to probe whether the elevated serum levels of 25-hydroxyvitamin D₃ observed in patients with IHD in a tropical environment has any pathogenic significance.     

Dahl salt-sensitive rats excrete 25-hydroxyvitamin D into urine

The plasma 25-hydroxyvitamin D concentration of Dahl salt-sensitive rats (S) is markedly decreased in response to high sodium chloride (salt) intake. We tested the hypothesis that urinary excretion is a mechanism for the decrease. Female S rats excreted 0.26 +/- 0.04 nmol 25-hydroxyvitamin D/24 h at wk 2 of high salt (80 g/kg) intake, five times that of female salt-resistant (R) rats at wk 2 of high salt intake and nine times that of S rats at wk 2 of low salt (3 g/kg) intake. The 25-hydroxyvitamin D binding activity in 24-h urine of S rats was 79 +/- 11 pmol/h at wk 2 of high salt intake, two times that in urine of S rats at wk 2 of low salt intake and > 35 times that in urine of R rats at wk 2 of low or high salt intake. We conclude that markedly decreased plasma 25-hydroxyvitamin D concentrations of S rats during high salt intake result in part from excretion of protein-bound 25-hydroxyvitamin D. Low plasma 25-hydroxyvitamin D concentrations in humans may also result in part from salt sensitivity, which is prevalent in > 50% of the United States hypertensive population.     

Association between plasma 25-hydroxyvitamin D levels and fracture risk: the EPIC-Oxford study

The importance of vitamin D for bone health is well established, but few data exist on the relation between plasma levels of 25-hydroxyvitamin D and risk of fracture. The authors examined this association within the EPIC-Oxford (European Prospective Investigation into Cancer and Nutrition-Oxford cohort) study of men and women in the United Kingdom (1993-1999). Five years after recruitment, participants completed a follow-up questionnaire where fracture incidence was self-reported. Plasma 25-hydroxyvitamin D concentration was measured in 730 incident fracture cases and 1,445 matched controls. There was a clear association between plasma 25-hydroxyvitamin D concentration and month of blood draw, the highest values being during the summer months. Among women, there were significant relations between 25-hydroxyvitamin D levels and age, body mass index, marital status, use of hormone therapy, physical activity, diet group, dietary intake of vitamin D, and alcohol. Similar relations were seen among men, although often they were nonsignificant because of smaller numbers. There was no evidence of an association between plasma 25-hydroxyvitamin D and fracture risk for men or women; the relative risks associated with a doubling of plasma 25-hydroxyvitamin D were 1.15 (95% confidence interval: 0.82, 1.61) and 0.95 (95% confidence interval: 0.80, 1.13), respectively. These results were not affected by adjustment for potential confounders and were consistent across a number of subgroups.     

Concentrations of vitamin D-binding protein and vitamin D metabolites in plasma of patients with liver cirrhosis

Plasma levels of vitamin D-binding protein (DBP) and vitamin D metabolites in patients with decompensated and compensated liver cirrhosis were assayed. Plasma levels of DBP in the decompensated group were significantly lower than those in the compensated group, but both were lower than the normal range. The plasma levels of 25-hydroxyvitamin D (25-OH-D) and 1 alpha,25-dihydroxyvitamin D [1,25(OH)2D] in the compensated group were within the respective normal ranges, whereas both values in the decompensated group were significantly lower than those in the compensated group. Most of 25-OH-D (higher than 96%) was confirmed to be circulated as a bound form with DBP in the plasma of not only the compensated but also the decompensated group. When vitamin D2 was given to the decompensated group, a significant increase of 1,25(OH)2D levels in the plasma could not be observed while 25-OH-D levels were increased. On the other hand, the administration of 1 alpha-hydroxyvitamin D3 (1 alpha-OH-D3) to the decompensated group caused a significant increase in the plasma levels of 1,25(OH)2D. Therefore, we suggest that the administration of 1 alpha-OH-D3 is useful for the treatment of bone disease induced by liver cirrhosis.     

血清25-羟维生素D水平与2型糖尿病的关系

目的 研究血清维生素D水平在2型糖尿病发病过程中的作用。方法采用随机分层抽样,共589例志愿者纳入本研究。根据空腹血糖及口服葡萄糖耐量试验结果将志愿者区分为糖尿病人群及非糖尿病人群。共计249例检测了血清25-羟维生素D水平,应用二元Logistic回归分析糖尿病与相关因素的关系,应用Cox—Staurt趋势检验分析各年龄段血清25-羟维生素D水平,按血清25（OH）D四分位值分层,分别计算糖尿病患病优势比OR值及95％置信区间。结果所有年龄段均存在不同程度的25-羟维生素D缺乏,调节年龄、HOMA．IR、BMI后,血清25．羟维生素D水平与糖尿病发病呈剂量依赖的负相关（r=-0．9271,P〈0．01）,当血清25-羟维生素D水平达到94．6nmol／L以上时,糖尿病发病显著降低[OR=0．52,95％CI（0．23—0．78）,P〈0．01]。结论血清25-羟维生素D水平与2型糖尿病发病呈明显负相关,血清25-羟维生素D水平降低增加糖尿病发病风险。