Serum 25-hydroxycalciferol Research Articles

ОЦЕНКА ОБЕСПЕЧЕННОСТИ ВИТАМИНОМ D ЮНЫХ СПОРТСМЕНОВ

Optimal vitamin D supplementation is necessary for the normal course of growth and develop-ment processes, bone formation, prevention of stress fractures, improvement of recovery after injuries and physical exertion in young athletes. There is a high prevalence of vitamin D deficien-cy in children and adolescents in Russia currently. The number of studies on the prevalence of vitamin D metabolic disorders in young athletes is insufficient. The purpose of this research was to assess the vitamin D availability in young athletes. Methods used: cross-sectional, single-center study included young athletes from 24 kinds of sports who underwent medical examination in March to July, 2022. Serum 25-hydroxycalciferol (25(OH)D3) was measured in all athletes using the chemiluminescence analysis. Results: 527 young athletes (254 (48.2%) boys/273 (51.8%) girls) aged 10 to 17 years and 11 months old (average 15.2 [14.2; 16.5] y/o) were examined. Vit-amin D deficiency (25(OH)D3 <20 ng/ml) was detected in 226 (42.9%) athletes, of which severe deficiency (25(OH)D3 <10 ng/ml) was in 5 (2%). Vitamin D insufficiency was diagnosed in 219 (41.6%), and the optimal level of 25(OH)D3 (>30 ng/ml) was detected only in 82 (15.5%). There were no statistically significant gender differences in the frequency of occurrence of vitamin D insufficiency (p=0.561) and deficiency (p=0.673). Conclusion: extremely low vitamin D availa-bility in young athletes was revealed. Conducting further research on the prevalence of vitamin D deficiency and ways to correct it in young athletes is necessary to start working on recommended optimizing and preventive and therapeutic approaches to correcting of the vitamin D levels in high-performance youth sports.

The relationship of serum 25-hydroxycalciferol levels with the severity of the new COVID-19 coronavirus infection in pregnant women

Introduction Novel coronavirus infection (NCI) COVID-19 in women during pregnancy has a different course – from asymptomatic to severe and extremely severe. Associations between the severity of NCI COVID-19 and the serum level of 25-hydroxycalciferol (25(OH)D), which is an active metabolite of vitamin D, are currently being studied. There are few data on the association of vitamin D deficiency with severe NCI in the general population, even less data reflecting the level of 25(OH)D in the blood serum of pregnant women suffering from NCI of varying degrees of severity. Purpose of research was to conduct clinical laboratory comparisons, including the level of the active metabolite of vitamin D 25-hydroxycalciferol in the blood serum of pregnant women with COVID-19 NCI of varying degrees of severity. Materials and methods. Under observation there were 29 pregnant women living in Chelyabinsk and Chelyabinsk region, who were admitted to the maternity obstetric service of the infectious hospital for patients with NCI COVID-19 during the 3rd–4th wave of the pandemic. Group 1 consisted of 16 pregnant women with severe NCI COVID-19. Group 2 included 13 pregnant women with mild NCI COVID-19. Serum 25(OH)D levels in these patients were determined by chemiluminescent immunoassay. Results. The patients with severe NCI COVID-19 are statistically more likely to be deficient in vitamin D, while adequate levels of the latter are not recorded. Discussion. Vitamin D deficiency may contribute to a more prominent systemic response with the development of a cytokine storm and cause a severe course of NCI COVID-19. Conclusions. The conducted research demonstrated the relationship of vitamin D deficiency with the severity of NCI COVID-19 in pregnant women. We suggest that vitamin D deficiency can be considered as a predictor of the severe course of NCI COVID-19.

Оцінка ризику розвитку соматотропної недостатності залежно від розподілу частот алелей і генотипів поліморфного локусу rs1544410 BsmI гена рецептора вітаміну D

Growth hormone deficiency (GHD) is a disease caused by a significant disturbance in the growth hormone (GH) /growth factor system, it occures as a result of various hereditary or acquired causes and is characterized, first of all, by a significant delay in the child's growth and physical development. GHD can be isolated or combined with deficiency of other adenohypophysis hormones. The presence of a relationship between the GH /growth factor system and vitamin D (vit D) determines the involvement of genetic changes in the vit D receptor (VDR) in the pathogenesis of GHD. Purpose - to assess the risk of developing GHD based on the investigation of the distribution of allele frequencies and genotypes of the polymorphic locus rs1544410 BsmI of the VDR gene. Materials and methods. The determination of VDR BsmI gene (rs1544410) polymorphism was performed using the polymerase chain reaction method, followed by analysis of the length of restriction fragments upon their detection by agarose gel electrophoresis in 22 prepubertal children with GHD. The serum 25-hydroxycalciferol (25(OH)D) level was determined by immunochemiluminescent method on microparticles (Abbott, USA). Results. G/A allele was most often found in children with isolated GHD and multiple pituitary insufficiency (MPH) (43.8% and 83.3%, respectively). In the presence of G/A and G/G genotypes, the risk of GHD is reliably high: OR=3.60 (95% CI 1.40-9.23); OR=10.69 (95% CI 2.34-48.85) respectively; with the A/A genotype variant the risk of GHD is reliably low OR=0.11 (95% CI 0.04-0.33). Carrying the G allele of the polymorphic locus rs1544410 Bsm I of the VDR gene is associated with the risk of developing GHD OR=5.58 (95% CI 4.51-6.90; p<0.001). A significantly difference in the peak GH release was established in patients carrying the G/G and A/A, G/G and G/A alleles. 83.33% of children with MPH and 68.49% with isolated GHD had hypovitaminosis D. Vit D deficiency was recorded in carriers of all three types of alleles. Conclusions. In the presence of G/A and G/G genotypes, the risk of GHD increases, in the presence of the A/A genotype, it decreases. The G allele carrier of the polymorphic locus rs1544410 Bsm I of the VDR gene is associated with the risk of developing GHD OR=5.58 (95% CI 4.51-6.90; p<0.001), despite the ideal distribution of genotypes. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of all participating institutions. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

Фактори ризику гастроінтестинальної харчової алергії в дітей раннього віку

Purpose - to study risk factors of gastrointestinal food allergy (GIFA) in young children. Materials and methods. 68 young children with GIFA and 22 children of the same age with an unencumbered individual allergy history were examined. A study of children perinatal, family and individual allergy history was conducted, and a survey was conducted on the state of parents’ health. The vitamin D supply of children was determined by quantifying of serum 25-hydroxycalciferol (25(OH)D) concentration by using an immunochemical analyzer. Results. Anamnestic risk factors that showed a significant association with the development of GIFA in young children and reliably differed from the control group were: complicated obstetric history, medical treatment of mothers during pregnancy, early artificial feeding, burdensome family allergy history and gastrointestinal diseases presence in parents. Insufficient supply of vitamin D was in 79.4% of patients with GIFA compared with 13.6% of children in the control group. The average serum 25(OH)D value in children with GIFA was 34.18±1.7 ng/ml, which is significantly lower than in the control group (40.2±2.3 ng/ml; p<0,05), which may be an additional factor in the development and severity of the disease. Conclusions. Risk factors of gastrointestinal food allergy have been identified, which will improve the prevention, early diagnosis and treatment of gastrointestinal allergic disease. The research was carried out in accordance with the principles of the Helsinki declaration. The study protocol was approved by the Local ethics committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the author. Key words: gastrointestinal food allergy, risk factor, vitamin D, young children.

Association between Vitamin D Deficiency and Psoriasis: A Case-Control Study

The immunomodulatory effect of vitamin D is well known, and some previous studies have found a potential association between vitamin D deficiency and psoriasis. If this is the case, correction of vitamin D levels could provide a simple, cost-effective treatment method for psoriasis patients. The aim of this case-control study was to confirm whether there was such an association. We also investigated several potential risk factors of psoriasis. We recruited 68 consecutive psoriasis outpatients at three hospitals in Saudi Arabia, as well as 68 control patients with dermatological conditions, and compared serum 25-hydroxycalciferol levels. However, we found no significant differences in vitamin D levels between the two groups. This finding supports similar negative findings of some previous studies, but further studies are needed to resolve this matter.

Vitamin D status and cardiometabolic risk factors across latitudinal gradient in Iranian adults: National food and nutrition surveillance.

This study aimed to evaluate the vitamin D status in an adult population across latitudinal gradient and to investigate its possible associations with certain cardiometabolic risk factors. A total of 1406 healthy subjects aged 19-60 years were randomly selected from six regions of Iran across latitudinal gradient from 29° N to 37.5° N. Anthropometric and biochemical assessments were performed. The combination of high body mass index (>25 kg/m2), low high-density lipoprotein cholesterol (< 40 mg/dl in males and < 50 mg/dl in females) and high triglycerides (> 150 mg/dl) was defined as cardiometabolic risk factors. The mean concentration of serum 25-hydroxycalciferol (25(OH)D) was 26.8±17.7 nmol/l. There were no significant differences in the mean serum 25(OH)D levels among different latitudes. Undesirable vitamin D status (deficiency and insufficiency) was found in 90.7% of the subjects. After adjustment for age and gender, the association between weight status and serum 25(OH)D was significant ( p< 0.04, odds ratio:1.49; confidence interval: 1.01-2.19). The prevalence of cardiometabolic risk factors among the subjects with serum 25(OH)D less than 27.5 nmol/l was significantly higher than those with serum calcidiol concentrations above 27.5 nmol/l (13.3% vs. 10.0%, p = 0.033). Undesirable vitamin D status is highly prevalent among Iranian adults of both sexes irrespective of latitude and even in sunny regions. The occurrence of cardiometabolic risk factors was significantly higher in those subjects with circulating calcidiol concentrations below 27.5 nmol/l.

Harmonization of serum 25-hydroxycalciferol assay results from high-performance liquid chromatography, enzyme immunoassay, radioimmunoassay, and immunochemiluminescence systems: A multicenter study.

Remarkable disagreement among different systems of 25-hydroxy vitamin D 25(OH)D assay makes decision making for both clinical and community interventions very difficult. This study aimed to harmonize the results obtained from different 25(OH)D assay systems. A total of 275 serum samples were analyzed for 25(OH)D using DIAsource-enzyme immunoassay (EIA), DIAsource-radioimmunoassay (RIA), Roche-electrochemiluminescence (ECL), Diasorin-chemiluminescent immunoassay (CLIA), and high-performance liquid chromatography (HPLC), as the reference method. Serum intact parathyroid hormone (iPTH) was also measured in all samples. Between-system agreement and harmonization were evaluated using Bland-Altman analysis, receiver operating characteristic (ROC), and regression analysis. Mean serum 25(OH)D concentrations and frequency distribution of vitamin D status showed a significant difference among the studied systems (P<.001 for both). Serum 25(OH)D assay results from all systems correlated with those from HPLC. As compared with HPLC, ECL showed a positive bias (+3.8nmol/L), whereas CLIA had a negative bias (-11.9nmol/L). Both EIA and RIA showed a more or less similar positive bias (8.0 and 8.1nmol/L, respectively). Using serum iPTH-based 25(OH)D cutoff points, only ECL results became comparable to and without significant difference with HPLC. However, when system-specific cutoffs were defined based on HPLC results using regression equations, mean 25(OH)D and frequency distribution of vitamin D status were more harmonized compared with the other methods. Our findings showed that with adjustment of circulating 25(OH)D based on HPLC, frequency distribution of vitamin D status, as judged by different methods, can be well harmonized with no statistically significant inter-system difference.

Decreased Serum 25-Hydroxycalciferol Levels in Pre-diabetic Adults.

To determine the serum 25-hydroxycalciferol levels [25(OH)D] in adults with pre-diabetes and normoglycaemia to examine a possible association of vitamin D deficiency with pre-diabetes. Case control study. Armed Forces Institute of Pathology, Rawalpindi, from November 2012 to July 2013. Atotal of 272 adults including 136 pre-diabetics and 136 normoglycaemics of either gender aged 20 years and above were consecutively inducted. Patients with diabetes mellitus, pregnancy, rickets and osteomalacia, ischemic heart disease, chronic kidney disease and chronic liver disease were excluded. Fasting Plasma Glucose (FPG) was estimated with hexokinase method on Modular p800 Roche chemistry analyzer while serum 25(OH)D was measured on Diasorin Liaison immunoassay analyzer using the chemiluminescent technique. Mean 25(OH)D levels in pre-diabetic and normoglycaemic groups were compared using Mann-Whitney U test. Spearman's correlation coefficient 'rs' was determined between serum 25(OH)D and FPG. Odds ratio for vitamin D deficiency was also calculated. Mean serum 25(OH)D level was low in pre-diabetics (23.2 nmol/L) as compared to normoglycaemics (29 nmol/L; p=0.001). Serum 25(OH)D level had inverse correlation with FPG (rs= -0.448, p=0.000). There was also significant association of vitamin D deficiency with pre-diabetes compared with normoglycaemia (OR: 2.21, p= 0.016; 95% CI: 1.15-4.27). Vitamin D deficiency with pre-diabetes suggested that vitamin D may have an important role in pathogenesis of pre-diabetes.

Relationships between serum 25-hydroxycalciferol, vitamin D intake and disease activity in patients with rheumatoid arthritis –TOMORROW study

Objectives. The effect of serum 25-hydroxycalciferol [25(OH)D] on rheumatoid arthritis (RA) activity remains controversial. This study was undertaken with an aim to clarify the relationship between serum 25(OH)D and RA activity, and to determine the effects of dietary vitamin D intake and age on serum 25(OH)D level.Methods. A total of 208 outpatients with RA were matched according to age and sex with 205 individuals without RA (controls) from the TOMORROW study (UMIN000003876). We excluded 27 patients with RA and 19 control subjects who had been prescribed vitamin D medication or were taking vitamin D supplements. Vitamin D intake was assessed in the remaining 181 patients and 186 controls using the brief-type dietary history questionnaire. Serum 25(OH)D levels were measured using a radioimmunoassay.Results. Serum 25(OH)D levels were significantly lower in patients with RA than in the controls (p < 0.001). There was a significant and positive correlation between age and 25(OH)D in the patients (r = 0.283, p < 0.001), as with vitamin D intake and 25(OH)D, even after adjusting for age (r = 0.313, p < 0.001). Disease activity and 25(OH)D did not significantly correlate.Conclusions. Patients with RA were observed to have serum 25(OH)D levels which correlated with vitamin D intake and age but not disease activity.

The Association of Vitamin D Deficiency and Insufficiency with Diabetic Nephropathy: Implications for Health Disparities

To evaluate the association between vitamin D deficiency and insufficiency with diabetic nephropathy across racial/ethnic groups. Cross-sectional analysis of the 2001 to 2006 National Health and Nutrition Examination Survey. A nationally representative sample of 1216 adults (> or =20 years old) with diagnosed diabetes provides population estimates for >12.6 million individuals. Nephropathy was defined as urinary albumin-to-creatinine ratio > or =30 mg/g in a random spot urine sample. Serum 25-hydroxycalciferol vitamin D levels were characterized as <20 ng/mL vitamin D deficiency, 20 to 29 ng/mL vitamin D insufficiency, and > or =30 ng/mL normal vitamin D. Overall, 30.7% of adults with diabetes have nephropathy, 48.9% have vitamin D deficiency and 36.6% have vitamin D insufficiency. Minorities are more likely to have nephropathy (non-Hispanic whites, 27.8%; non-Hispanic blacks, 36.2%; Hispanics 38.5%; P = .02) and vitamin D deficiency (non-Hispanic whites, 39.5%; non-Hispanic blacks, 80.4%; Hispanic, 59.0%; P < .01). Higher proportions of individuals with nephropathy have vitamin D deficiency than individuals without nephropathy (53.2% vs 47.0%; P = .03). Logistic regressions demonstrate vitamin D deficiency and insufficiency are associated with the presence of nephropathy after adjustment for race/ethnicity, age, sex, hypertension, high cholesterol, smoking status, and use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (odds ratio, 1.85; 95% CI, 1.06-3.23 for vitamin D deficiency; and odds ratio, 1.79; 95% CI, 1.12-2.85 for vitamin D insufficiency). There is a high prevalence of vitamin D deficiency and insufficiency in individuals with diabetes; minorities have the highest prevalences. Thus, evaluating vitamin D levels in people with diabetes may be warranted. There is an independent association between vitamin D deficiency and vitamin D insufficiency with the presence of nephropathy, even after adjustment for race/ethnicity and other variables. Further studies of this relationship may lead to new interventions that decrease health disparities in the progression of diabetic nephropathy.

Vitamin D and enterocyte brush border membrane calcium transport and fluidity in the rat

Prior studies of vitamin D repletion showed a threefold increase in the maximum rate (Vmax) for calcium uptake by brush border membrane vesicles, but did not differentiate saturable and nonsaturable uptake components. We studied the calcium uptake and fluidity response of intestinal brush border vesicles to vitamin D by treatment with 1α,25-dihydroxy-24,24-difluorocholecalciferol (24,24-F-1,25-(OH) 2 D 3). Treatment responses were measured by effects on (1) saturable and nonsaturable initial uptake rates of calcium by rat proximal small intestinal brush border membrane vesicles; (2) transmucosal calcium transport by everted duodenal sac; and (3) fluorescence anisotropy. Treatment of vitamin D-depleted weanlings increased the Vmax by 50% ( P < .05) in vesicles from the proximal 12 cm of small intestine from rats injected with disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP), but there was no response in rats not injected with EHDP or in vesicles from the proximal 30 cm of small intestine. Vitamin D-depleted weanlings were D-deficient based on serum 25-hydroxycalciferol (25-OH-D) concentration, but to produce 1α,25-dihydroxycalciferol [1,25-(OH) 2D] depletion, EHDP injection was required. Treatment of vitamin D-replete adult rats caused a 20% ( P < .05) increase in Vmax. Treatment did not affect the calcium concentration at half-Vmax ( K T ), the rate constant for nonsaturable uptake ( K D ), or vesicle fluidity measured as fluorescence anisotropy. Contrasting with these minimal effects of treatment on brush border Vmax, treatment increased transmucosal calcium transport by everted duodenal sac almost threefold in vitamin D-depleted weanlings administered EHDP. Thus, vitamin D actions on enterocyte calcium transport (1) at the brush border increase saturable but not nonsaturable uptake, and (2) produce the major transport response distal to the brush border. Despite previously described changes in membrane lipid, brush border fluidity is unaffected by vitamin D treatment.

Serum 25-hydroxycalciferol concentrations in normal subjects and in haemodialysed patients with chronic renal failure.

The serum 25-OHD3 concentrations were measured in 16 normal subjects and in 12 haemodialysed patients with chronic renal failure. The mean values found in the two groups were 27.8 +/- 17.8 ng/ml and 23.9 +/- 12 ng/ml, respectively. The difference between the two values is not significant.

A simplified assay for serum 25-hydroxycalciferol

The measurement of serum 25-hydroxycalciferol (25-OH D) has proved to be a reliable index of the vitamin D nutritional status in man providing the renal 25-hydroxycalciferol-1 alpha-hydroxylase is functional. Since it is known that 25 OHD binds to alpha-globulins for its transport to the kidney, we have developed a competitive binding assay using an alpha-globulin enriched fraction (Cohn's fraction IV) as the ligand protein. A detection limit of 0.1 ng 25-OHD/tube was achieved and the non specific binding amounted to less than 3% of the initial binding. The intra- and inter-assay variations were 8.9 and 8.4% respectively. The reference values (nmol/1 +/- 2 s.d.) obtained from samples of 40 children were 50.5 +/- 21.5 with extremes of 34.8 and 95.2. The method thus proved to be a reliable and sensitive tool to assess serum 25-OHD levels.

The Relevance of 25‐Hydroxycalciferol Measurements in Sera of Patients with Renal Failure*

Iliac crest biopsies and serum specimens were obtained from 36 non-dialyzed uraemic patients. The mean serum 25-hydroxycalciferol concentration of the patients was lower than that of normal subjects and a significant correlation was found between 25-hydroxycalciferol values and the severity of osteomalacia. Parathyroid osteopathy was significantly correlated with serum immunoreactive parathyroid hormone but not with serum 25-hydroxycalciferol values. While normal serum 25-hydroxycalciferol concentrations in uraemic patients do not exclude the presence of osteomalacia, a low concentration is virtually diagnostic of this disorder.

THE RELEVANCE OF 25‐HYDROXYCALCIFEROL MEASUREMENTS IN THE TREATMENT OF HYPOPARATHYROIDISM*

In twenty-one patients with chronic hypoparathyroidism a close correlation was observed between the prescribed dose of ergocalciferol and mean serum 25-hydroxycalciferol levels. In the 75 serum specimens examined, a significant correlation was found between 25-hydroxycalciferol levels and calcium concentrations. The measurement of serum 25-hydroxycalciferol levels is of potential clinical value in the prediction of hyper- or hypocalcaemic episodes and in monitoring patient compliance.

Vitamin D and Osteoporosis

In elderly people with marginal exposure to the sunlight, males showed higher serum 25-hydroxycalciferol than females, whereas in those with ample or poor sunlight exposure, serum 25-hydroxycalciferol was higher or very low, respectively, exhibiting no sex difference in the vitamin D metabolite levels. The male predominance in serum 25-hydroxycalciferol levels seen among some aged population would be explained, at least in part, by the result of animal experiment suggesting the stimulatory effect of testosterone on vitamin D biosynthesis induced by ultaviolet irradiation. Testosterone was, furthermore, shown to have hypocalcemic action, probably through suppression of bone resortopton in vitamin D depleted but not in replete rats. Clinical implication of these two-fold effects of testosterone observed in rats was discussed in relevance to male predominance in serum 25-hydroxycalciferol level and bone mineral content in the aged population.

Serum 25-hydroxycalciferol in myocardial infarction

Oral intake of calciferol (vitamin D) was higher in patients with myocardial infarction than in controls. Having established an assay for 25-hydroxycalciferol (25-OH-D), the principal circulating form of the vitamin, we measured this compound in control subjects and patients with myocardial infarction. In controls, 25-OH-D varied with the season: levels were high in summer and low in winter. Furthermore, levels were low in control subjects above 60 years of age. In patients with myocardial infarction, normal and low values for 25-OH-D were found. It is concluded that in this region patients with myocardial infarction do not consume greater amounts of vitamin D.

Elevation of serum 25-hydroxycalciferol levels in androgen-treated and ultraviolet-irradiated rats.

Administration of 4-8 mg testosterone propionate significantly raised 25-hydroxycalciferol levels in the ultraviolet irradiated rats compared to the ultraviolet irradiated controls, but failed to influence serum 25-hydroxycalciferol levels in the non-irradiated animals. Estradiol benzoate and progesterone did not influence serum 25-hydroxycalciferol levels regardless of the ultraviolet irradiation. These findings implicate that testosterone enhances vitamin D biosynthesis induced by ultraviolet irradiation in rats, in accordance with the clinical observation that males often show higher levels of serum 25-hydroxycalciferol than females.

Radioimmunoassay of the binding protein for vitamin D and its metabolites in human serum: concentrations in normal subjects and patients with disorders of mineral homeostasis.

A radioimmunoassay for the binding protein for vitamin D and its metabolites (DBP) has been developed. Suitable rabbit anti-DBP antiserum was elicited after primary and one booster injection. Anti-DBP antisera, as well as antigroup-specific component antisera, produced a single, monospecific line of percipitation when reacted against purified DBP and human serum. DBP was iodinated with 125I and 125I-DBP was purified by gel filtration on Sephadex G-200. Binding of 125I-DBP by 20 nl of rabbit anti-DBP antisera was approximately 50% and was sharply competed for by 0.4-4.0 ng of DBP standard. Displacement of 125I-DBP by human serum dilutions or standard DBP gave identical curves, and only weak competition was observed with old and new world primate sera. Apo- and holo-DBP possessed indistinguishable immunoreactivity. The assay detects DBP in 1-10 nl of human serum with reasonable accuracy and with reasonable intra- and interassay precision. The mean serum concentration (+/- SEM) for a group of 40 normal adults was 525 +/- 24 mug/ml and no sex difference was observed. Higher levels were found in sera from pregnant women and women receiving oral contraceptives, and decreased concentrations were observed in premature cord and hypoproteinemic sera. No significant correlation between serum DBP levels and serum 25-hydroxycalciferol levels was found, and the DBP content of sera from vitamin D-deprived and vitamin D-treated subjects was indistinguishable from that of normal adults. DBP accounts for 6- of the alpha globulin in normal human serum. Considering the normal serum content of the parent vitamin and its metabolites to be approximately 0.1-0.2 mum, these immunoassay data confirm previous saturation analyses of human serum antiricketic sterol-binding capacity and suggest that greater than 95% of DBP circulates as the apoprotein under normal conditions.

Serum 25-Hydroxycalciferol Levels and Bone Mass in Children on Chronic Anticonvulsant Therapy

Abstract Fifty-six children with epilepsy receiving chronic therapy with phenobarbital or diphenylhydantoin or both and 51 controls were studied to determine the effects of anticonvulsant therapy on mineral, vitamin D and bone metabolism. Combination therapy was associated with the greatest decreases in serum calcium (9.72 ± 0.06 vs. 10.40 ± 0.05 mg per 100 ml in controls; p < 0.001), serum 25-hydroxycalciferol (13.1 ± 1.0 vs. 23.6 ± 0.9 ng per milliliter in controls; p < 0.001), and bone mass by photon absorptiometry (90.5 ± 1.6 vs. 100.7 ± 1.0 per cent in controls; p < 0.001). Serum bone and liver alkaline phosphatase isoenzyme activity was increased in both treatment groups. Serum calcium concentration correlated with serum 25-hydroxycholecalciferol levels in both the single and combined drug groups. Serum 25-hydroxycholecalciferol correlated with vitamin D intake in all groups, but mean levels of the metabolite were lower for any given level of vitamin D intake in treated patients. Thus, vitamin D sup...