PURPOSE: We checked the levels of serum 25-hydroxyvitmain D (25OHD) in the patients with chronic kidney disease (CKD) to survey the status of vitamin D levels, to see the seasonal variations of 25OHD, and to evaluate the relationships among the levels of intact PTH, corrected calcium, and phosphorus. METHODS: We defined vitamin D insufficiency and vitamin D deficiency as serum 25-hydroxyvitamin D levels between 20 and 30 ng/mL and below 20 ng/mL, respectively. 185 patients in a single center were enlisted who categorized into 3 groups, CKD2-3, CKD4, and CKD5 by eGFR using MDRD7 equation. To see the seasonal differences of the levels of 25OHD, we collected laboratory data two times per each patient during summer division (April to September) and winter division (October to March). RESULTS: Prevalences of hypovitaminosis D were 42.8% (CKD2-3), 66.1% (CKD4), 92.8% (CKD5) in summer division and 48.7% (CKD2-3), 73.1% (CKD4), 92.8% (CKD5) in winter division. Seasonal difference of the levels of 25OHD was evident only in CKD stage 2-3 (p=0.018). Negative correlations were recognized between 25OHD and intact PTH (r=-0.2048, p<0.001), phosphorus (r=-0.1711, p=0.0011). CONCLUSION: Hypovitaminosis D is prevalent even in patients with early stages of CKD. The levels of 25OHD decreased significantly in winter division in patients with CKD stages 2-3. The levels of 25OHD were inversely correlated with those of intact PTH, phosphorus, respectively.
25-Hydroxyvitamin D 2 ; Calcium ; Humans ; Phosphorus ; Prevalence ; Renal Insufficiency, Chronic ; Seasons ; Vitamin D ; Vitamin D Deficiency

BACKGROUND: Determining the concentration profiles of serum 25-hydroxyvitamin D (25OHD) may aid in the clinical diagnosis and treatment of vitamin D deficiency. To date, the standardized liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay has been used for accurate and precise determination of 25-hydroxyvitamin D levels. Here, we evaluated the performance of the recently developed and introduced PerkinElmer Vitamin D kit and compared the measurements obtained by RIA and LC-MS/MS methods. METHODS: We evaluated the accuracy, precision, linearity, lower limit of quantification (LLOQ), recovery, and carry-over of the MSMS Vitamin D kit. Clinical specimens from 80 patients were used for the comparison between the MSMS Vitamin D kit (PerkinElmer, USA) and the RIA kit (DiaSorin, USA). RESULTS: The MSMS Vitamin D kit was found to produce intra-assay and inter-assay coefficients of variation (CVs) of less than 6% for precision and showed a bias of less than 5%. The MSMS Vitamin D kit displayed linearity within the range for total vitamin D levels of 4.5-150 ng/mL, and the lower limit of quantification for 25OHD was 0.38 ng/mL. The RIA measurements of 25OHD showed a correlation of y=0.9931x+0.2216 (r2=0.74) with the LC-MS/MS values. CONCLUSIONS: The LC-MS/MS assay of 25OHD3 and 25OHD2 showed excellent performance when using the MSMS Vitamin D kit and in terms of 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) derivatization. Further, the results obtained were well correlated with those obtained using the RIA method. Thus, assays using the MSMS Vitamin D kit are considered as more standardized, and they enable quicker and more accurate analysis and help reduce inter-laboratory variation than that by other existing methods.
25-Hydroxyvitamin D 2 ; Bias (Epidemiology) ; Calcifediol ; Humans ; Mass Spectrometry ; Tandem Mass Spectrometry ; Triazoles ; Vitamin D ; Vitamin D Deficiency ; Vitamins

OBJECTIVES: Dry eye disease (DED) is an increasingly important public health problem in Korea. Previous studies conducted in Korea have reported inconsistent results regarding the protective effects of vitamin D on DED, and these discrepancies may be related to the relatively simple questionnaire that has been used. Thus, we evaluated the association of serum vitamin D levels with DED using the ocular surface disease index (OSDI). METHODS: The present study evaluated data from participants in the Study Group for Environmental Eye Disease (2014-2015). This group included data from 752 participants, and data from 740 participants (253 men and 487 women) were analyzed in the present study. DED severity was evaluated using the OSDI. RESULTS: Higher serum vitamin D levels were associated with a non-significantly reduced risk of DED in the crude analysis (odds ratio [OR], 0.991; 95% confidence interval [CI], 0.971 to 1.011) and in the adjusted analysis (OR, 0.988; 95% CI, 0.966 to 1.010). In the crude analysis of no/mild DED vs. moderate/severe DED, men exhibited a decreased risk with increasing serum vitamin D levels (OR, 0.999; 95% CI, 0.950 to 1.051), while women exhibited an increased risk (OR, 1.003; 95% CI, 0.979 to 1.027). In these analyses, we found no significant associations. CONCLUSIONS: The findings of the present study support previous reports that serum vitamin D levels are not associated with DED.
25-Hydroxyvitamin D 2 ; Dry Eye Syndromes ; Eye Diseases* ; Female ; Humans ; Keratoconjunctivitis Sicca ; Korea ; Male ; Public Health ; Vitamin D* ; Vitamins*

No abstract available.
25-Hydroxyvitamin D 2/*blood ; Cholecalciferol/*blood ; Chromatography, High Pressure Liquid ; Humans ; *Radioimmunoassay ; Reagent Kits, Diagnostic ; *Tandem Mass Spectrometry

BACKGROUND: Vitamin D has been recently shown to play important roles in the functioning of various systems. Most of the current analytical methods for measuring vitamin D levels are based on immunoassays. We simultaneously measured the levels of 25-hydroxyvitamin D3 [ 25(OH)D3 ] and 25-hydroxyvitamin D2 [ 25(OH)D2 ] in human serum by performing ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) after Diels-Alder derivatization with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) and evaluated the performance of our method. METHODS: After liquid-liquid extraction, samples were dried under N2 at 50degrees C for 1 hr followed by Diels-Alder derivatization with ethyl acetate containing 0.1 mg/mL PTAD. The samples were resuspended in 60 microL of methanol:10 mM ammonium formate solution (1:1, V/V). C18 UPLC column and positive ion multiple reaction monitoring transitions such as m/z 558.35-->298.1, 25(OH)D3; m/z 570.35-->298.1, 25(OH)D2; and m/z 564.35-->298.1, hexadeuterated-25(OH)D3 were used for UPLC-MS/MS. RESULTS: The within-run imprecision (CVs) for 25(OH)D3 and 25(OH)D2 were 3.5-4.0% and 3.8-4.2%, respectively, and the corresponding between-run CVs were 3.3-5.5% and 4.7-5.8%. The lower limit of quantification for 25(OH)D3 and 25(OH)D2 were 0.5 and 1.0 ng/mL, respectively. The curve for interassay calibration variability data obtained over concentrations of 0-120 ng/mL for 25(OH)D3 and 0-90 ng/mL for 25(OH)D2 was linear and reproducible [ 25(OH)D3, R2=0.993; 25(OH)D2, R2=0.998]. The total 25(OH)D levels in Koreans (average, 18.7 ng/mL) were lower than those in American Caucasians, and the percentage of people with total 25(OH)D levels under 10 ng/mL was 8.1%. CONCLUSIONS: Our method to measure 25(OH)D3 and 25(OH)D2 levels by performing UPLC-MS/MS after PTAD derivatization showed good performance as a sensitive and reproducible method for routine analysis of vitamin D status.
25-Hydroxyvitamin D 2 ; Acetates ; Calcifediol ; Calibration ; Formates ; Humans ; Immunoassay ; Liquid-Liquid Extraction ; Mass Spectrometry ; Quaternary Ammonium Compounds ; Tandem Mass Spectrometry ; Triazoles ; Vitamin D

PURPOSE: According to previous studies, vitamin D exhibits protective effects against breast cancer via the vitamin D receptor (VDR). There is growing evidence that breast cancer incidence is associated with various polymorphisms of the VDR gene. This study investigates the association of VDR poly(A) microsatellite variants with 25-hydroxyvitamin D (25(OH)D) serum levels and breast cancer risk. METHODS: Polymorphism analysis was performed on a total of 261 blood samples, which were collected from 134 women with breast cancer and 127 controls. Single strand conformation polymorphism was assessed by polymerase chain reaction in combination with sequencing to detect poly(A) lengths for each sample. The vitamin D levels of samples were determined by electrochemiluminescence. RESULTS: The poly(A) variant L allele frequency was significantly higher in cancer patients than in controls (odds ratio [OR], 1.73; 95% confidence interval [CI], 1.16-2.57; p=0.006). Thus, carriers of the L allele (LS and LL genotypes) have a higher risk for breast cancer (OR, 1.86; 95% CI, 1.13-3.05; p=0.013). A larger increase in the risk for breast cancer was found in individuals with the L carrier genotype and lowered 25(OH)D levels. CONCLUSION: The results primarily suggest that VDR gene polymorphism in the poly(A) microsatellite is associated with 25(OH)D levels and that it can affect the breast cancer risk in the female population from northern Iran.
25-Hydroxyvitamin D 2 ; Alleles ; Breast Neoplasms* ; Female ; Gene Frequency ; Genotype ; Humans ; Incidence ; Iran ; Microsatellite Repeats* ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Receptors, Calcitriol* ; Vitamin D

OBJECTIVES: Epidemiological studies have reported that vitamin D deficiency is associated with inflammatory disease. Smoking is a well-known risk factor for inflammation. However, few studies have investigated the interactive effect of vitamin D deficiency and smoking on inflammation. This study aims to investigate the interaction of vitamin D and smoking with inflammatory markers in the urban elderly. METHODS: We used data from the Korean Elderly Environmental Panel Study, which began in August 2008 and ended in August 2010, and included 560 Koreans > or =60 years old living in Seoul. Data was collected via questionnaires that included items about smoking status at the first visit. Vitamin D levels, high-sensitivity C-reactive protein (hs-CRP), and white blood cell (WBC) counts were repeatedly measured up to three times. RESULTS: The association of vitamin D and hs-CRP was significant after adjusting for known confounders (beta=-0.080, p=0.041). After separate analysis by smoking status, the association of vitamin D deficiency and hs-CRP in smokers was stronger than that in nonsmokers (smokers: beta=-0.375, p=0.013; non-smokers: beta=-0.060, p=0.150). Smoking status was an effect modifier that changed the association between vitamin D deficiency and hs-CRP (interaction estimate: beta=-0.254, p=0.032). Vitamin D was not significantly associated with WBC count (beta=0.003, p=0.805). CONCLUSIONS: Vitamin D deficiency was associated with hs-CRP in the urban elderly. Smoking status was an effect modifier of this association. Vitamin D deficiency was not significantly associated with WBC count.
25-Hydroxyvitamin D 2/blood ; Aged ; Biomarkers/blood ; Body Mass Index ; C-Reactive Protein/analysis ; Female ; Humans ; Inflammation ; Leukocyte Count ; Male ; Middle Aged ; *Smoking ; Urban Population ; Vitamin D/*blood ; Vitamin D Deficiency/diagnosis