Determinants of serum calcium in men and women. The Tromsø Study

Association of serum calcium and metabolically healthy obese in US adults: a cross-sectional study

OBJECTIVES

The relationship between serum calcium and occurrence of MHO (metabolically healthy obesity) and MUNO (metabolically unhealthy non-obesity) remains unclear, and distinguishing these two phenotypes is difficult within primary healthcare units. This study explores that relationship.

METHODS

This survey included 28590 adults from the National Health and Nutrition Examination Survey (NHANES) 2001-2018. Obesity phenotypes were categorized based on BMI and presence or absence of metabolic syndrome components. Weighted multivariate logistic regression analyses were used to assess the association between serum calcium levels and the obesity phenotype. Restricted cubic spline analysis characterized dose-response relationships, and stratified analyses explored these relationships across sociodemographic and lifestyle factors.

RESULTS

The overall prevalence of MHO and MUNO were 2.6% and 46.6%, respectively. After adjusting for covariates, serum calcium exhibited a negative association with MHO [OR (95%): 0.49 (0.36,0.67), p < 0.001], while exhibiting a positive association with MUNO [OR (95%): 1.48 (1.26,1.84), p < 0.001]. Additionally, we found a non-linear association between serum calcium levels and the incidences of MHO and MUNO. Stratified analyses demonstrated a strong negative correlation between serum calcium levels and MHO occurrence across various subgroups. There was no significant interaction between calcium and stratified variables except sex; the association between calcium and the occurrence of MHO was remarkable in female patients. Meanwhile, the predictive ability of serum calcium level for the occurrence of MUNO among all patients was consistent across various subgroups. There was a significant interaction between calcium level and stratified variables based on age, sex, race, and smoking status; the association was remarkable in older (≥ 40 years old), white, none or less smoking, and female patients.

CONCLUSIONS

A significant correlation was identified between serum calcium levels and MHO or MUNO. The findings suggest that serum calcium levels may serve as an indicator for more accurate assessment and diagnosis of MUNO and MHO, especially among individuals with abdominal obesity.

Analysis of influencing factors of serum total protein and serum calcium content in plasma donors

Background and objectives

The adverse effects of plasma donation on the body has lowered the odds of donation. The aim of this study was to investigate the prevalence of abnormal serum calcium and total serum protein related to plasma donation, identify the influencing factors, and come up with suggestions to make plasma donation safer.

Methods

Donors from 10 plasmapheresis centers in five provinces of China participated in this study. Serum samples were collected before donation. Serum calcium was measured by arsenazo III colorimetry, and the biuret method was used for total serum protein assay. An automatic biochemical analyzer was used to conduct serum calcium and total serum protein tests.

Results

The mean serum calcium was 2.3 ± 0.15 mmol/L and total serum protein was 67.75 ± 6.02 g/L. The proportions of plasma donors whose serum calcium and total serum protein were lower than normal were 20.55% (815/3,966) and 27.99% (1,111/3,969), respectively. There were significant differences in mean serum calcium and total serum protein of plasma donors with different plasma donation frequencies, gender, age, regions, and body mass index (BMI), (all p < 0.05). Logistic regression analysis revealed that donation frequencies, age, BMI and regions were significantly associated with a higher risk of low serum calcium level, and donation frequencies, gender, age and regions were significant determinants factors of odds of abnormal total serum protein.

Conclusions

Donation frequencies, gender, age, regions, and BMI showed different effects on serum calcium and total serum protein. More attention should be paid to the age, donation frequency and region of plasma donors to reduce the probability of low serum calcium and low total serum protein.

Age-dependent sex differences in cardiometabolic risk factors

Cardiometabolic diseases (CMDs) are a major cause of mortality worldwide, yet men and women present remarkable differences in disease prognosis, onset and manifestation. Here we characterize how sex differences in cardiometabolic risk factors vary with age by examining 45 phenotypes and 6 lifestyle factors in 146,021 participants of the Dutch population cohort Lifelines. We show that sex differences are present in 71% of the studied phenotypes. For 31% of these phenotypes, the phenotypic difference between sexes is dependent on age. CMD risk factors show various patterns of age-related sex differences, ranging from no difference for phenotypes such as body mass index (BMI) to strong age-modified sex differences for lipid levels. We also identify lifestyle factors that influence phenotypes in a sex- and age-dependent manner. These results highlight the importance of taking age into account when studying sex differences in CMDs.

Association of famine exposure and the serum calcium level in healthy Chinese adults

OBJECTIVE

Famine exposure and higher serum calcium levels are related with increased risk of many disorders, including Alzheimer's disease, atherosclerosis, diabetes, and osteoporosis. Whether famine exposure has any effect on serum calcium level is unclear. Besides, the normal reference range of serum calcium is variable among different populations. Our aims are 1) determining the reference interval of calcium in Chinese adults; 2) exploring its relationship with famine exposure.

METHODS

Data in this study was from a cross-sectional study of the epidemiologic investigation carried out during March-August 2010 in Jiading district, Shanghai, China. Nine thousand and two hundred eleven participants with estimated glomerular filtration rate (eGFR) ≥60ml/min/1.73m² were involved to calculate reference interval of total calcium from 10569 participants aged 40 years or older. The analysis of famine exposure was conducted in 9315 participants with complete serum biochemical data and birth year information.

RESULTS

After rejecting outliers, the 95% reference interval of total serum calcium was 2.122~2.518 mmol/L. The equation of albumin-adjusted calcium was: Total calcium + 0.019* (49-Albumin), with a 95% reference interval of 2.151~2.500 mmol/L. Compared to the age-balanced control group, there was an increased risk of being at the upper quartile of total serum calcium (OR=1.350, 95%CI=1.199-1.521) and albumin-adjusted calcium (OR=1.381, 95%CI=1.234-1.544) in subjects experienced famine exposure in childhood. Females were more vulnerable to this impact (OR= 1.621, 95%CI= 1.396-1.883 for total serum calcium; OR=1.722, 95%CI= 1.497-1.980 for albumin-adjusted calcium).

CONCLUSIONS

Famine exposure is an important environmental factor associated with the changes in circulating calcium concentrations, the newly established serum calcium normal range and albumin-adjusted calcium equation, together with the history of childhood famine exposure, might be useful in identifying subjects with abnormal calcium homeostasis and related diseases, especially in females.

Serum electrolyte/metabolite abnormalities among patients with acute myocardial infarction: comparison between patients with and without diabetes mellitus

Background: Diabetes mellitus (DM) in a setting of acute myocardial infarction (AMI) is associated with significant metabolic changes and worse outcomes.Objective: To evaluate the prevalence and the prognostic significance of electrolyte/metabolite disturbances among AMI patients with vs. without DM.Methods: Patients admitted to a tertiary medical center with AMI throughout 2002-2012 were screened. Exclusion criteria were: dialysis, mechanical ventilation, and in-hospital coronary artery bypass graft (CABG) surgery. All the results of the following analyses were obtained: Glucose, Uric Acid, (UA) Calcium, Magnesium, Albumin, Potassium, and Sodium. The primary outcome was in-hospital all-cause mortality.Results: A total of 14,364 AMI patient admissions was evaluated, mean age 68.1 ± 14.4 years, 65.5% males, and 41.2% with DM. Following an adjustment to potential confounders, DM patients had increased risk for significant hyperglycemia, hyperuricemia, hypercalcemia, hypomagnesemia, hyperkalemia, and hyponatremia as well as significantly decreased risk for hypoglycemia, hypermagnesemia, and hypokalemia compared with nondiabetics. Overall, 681 (4.7%) patients died throughout the index admission. Deceased had an increased incidence of electrolyte/metabolite abnormalities versus hospital survivors. The prognostic significance of the different categories of the investigated variables is very similar among diabetics and nondiabetics, except increased and decreased uric acid levels [<4.5 (men); <4.0 (women) and ≥9.0 (men); ≥9.4 (women)] which are associated with worse outcomes among diabetics while hyperglycemia (Glucose ≥213 mg/dL) and increased Potassium levels (Potassium ≥4.4mEq/L) which comprise significantly worse prognosis among nondiabetics.Conclusions: Patients with DM admitted with AMI are at greater risk for electrolyte/metabolite abnormalities which are associated with increased risk for in-hospital mortality. The latter association is similar among patients with and without DM except for hyperglycemia and increased potassium levels (stronger among nondiabetics).

Nutritional Biomarkers and Associated Factors in Community-Dwelling Older Adults: Findings from the SHIELD Study

Aging is associated with intrinsic and extrinsic changes which affect the nutrient intake and nutritional status of an older individual. Suboptimal nutritional status is linked with adverse health outcomes. There are limited data in this area for community-dwelling older adults who are not at risk of malnutrition. The objective of this study was to describe the nutritional biomarkers in 400 community-dwelling older adults (aged ≥65 years) with normal nutritional status (Malnutrition Universal Screening Test score of 0) in Singapore and to identify factors associated with these biomarkers. The majority of the participants had normal levels of pre-albumin, albumin, total protein, creatinine, zinc, corrected calcium, vitamin B12, ferritin and hemoglobin. Females had significantly higher levels of corrected calcium and vitamin B12 than males, whereas males had significantly higher levels of pre-albumin, albumin, creatinine, serum ferritin, 25-hydroxyvitamin D (25(OH)D) and hemoglobin than females. About half of the participants (52%) had low level of 25(OH)D (<30 μg/L) and 10% had low zinc level (<724 μg/L). Among those with low level of 25(OH)D, 74% had 25(OH)D insufficiency (20–<30 μg/L) and 26% had 25(OH)D deficiency (<20 μg/L). Younger age, female gender, non-Chinese ethnicity and no intake of vitamin D supplement were associated with lower serum 25(OH)D level, whereas higher body mass index (BMI) was associated with low zinc level. These findings highlight the problem of hidden nutritional insufficiencies can be missed in seemingly normal nourished community-dwelling older adults.

Metabolic Bone Profile of Healthy Adult North Indian Population from Chandigarh Urban Bone Epidemiological Study (CUBES)

We aimed to estimate metabolic bone profile in a large cohort of healthy, adult Indian population to generate reference standards of serum calcium, phosphate and alkaline phosphatase (ALP), 25 (OH) Vitamin D and iPTH, and also to find out the prevalence of Vitamin D deficiency in healthy population. Apparently healthy people in the age group of 20-80 years, residing in the union territory of Chandigarh were chosen. Fasting samples for serum calcium, phosphate, albumin, alkaline phosphatase (ALP), 25 (OH) D and iPTH were collected and were processed on the same day. We recruited 930 healthy subjects from different subsectors of Chandigarh. Final analysis was done for 915 subjects. Out of this, 530 (58%) were women and 385 (42%) were men. The study participants were divided into two groups, less than and more than 50 years for the men and pre and post-menopausal for the women. The serum calcium, phosphate, ALP and iPTH were significantly higher in the post-menopausal women compared to the pre-menopausal women. The median plasma 25 (OH) D in men and women was 12.5 ng/mL and 14.3 ng/mL, respectively. 25 (OH) D deficiency was seen in 65.4% of individuals. 25 (OH) D levels co-related negatively with iPTH levels (r = - 0.4, p < 0.0001), and showed an increasing trend with age. We have thus presented metabolic bone profile of healthy, adult north Indian population. These reference values can be used for diagnosis and monitoring of various MBDs. Vitamin D deficiency is still rampant in our population in spite of increasing awareness.

Genotype effects of glucokinase regulator on lipid profiles and glycemic status are modified by circulating calcium levels: results from the Korean Genome and Epidemiology Study

Single nucleotide polymorphisms (SNPs) in the glucokinase regulator (GCKR) are associated with major cardiovascular risk factors (ie, lipid profile and glycemic status). Recently, GCKR was shown to be related to circulating calcium levels involved in lipid and glycemic controls. Therefore, we hypothesized that GCKR SNPs are associated with major cardiovascular risk factors in the Korean population, and the association is modified by circulating calcium levels. Epidemiological data and GCKR SNPs (rs780093T>C, rs780094 T>C, and rs1260326 T>C) were collected from a subset of Ansung-Ansan cohort in the Korean Genome and Epidemiology Study (n = 7815). Consistent with the results of previous studies, GCKR SNPs were significantly associated with decreased total cholesterol and triglyceride levels and increased glucose levels and insulin resistance. Minor C allele carriers, particularly CC homozygotes, had lower serum calcium levels than TT homozygotes for all 3 SNPs. Particularly, the effect of GCKR SNPs on total cholesterol, triglyceride, fasting glucose, and insulin resistance was apparent when serum calcium levels were in normal range (8.8-10.1 mg/dL). When serum calcium levels were high (≥10.2 mg/dL), CC homozygotes also had significantly lower triglyceride and higher fasting glucose than TT homozygotes. However, the associations were not observed when serum calcium levels were low (<8.8 mg/dL). In conclusion, GCKR SNPs are associated with lipid profiles and glycemic status in the Korean population, and the genetic effect is modified by basal circulating calcium levels, particularly in normal or high ranges. It provides important information for individualized prevention and management of cardiovascular risk associated with GCKR SNPs.

Serum calcium levels independently predict in-hospital mortality in patients with acute myocardial infarction

BACKGROUND AND AIM

Serum calcium levels (sCa) were reported to be associated with cardiovascular risk factors, incidence of coronary artery disease and acute myocardial infarction (AMI). The current study evaluated the association between sCa and in-hospital mortality among AMI patients.

METHODS AND RESULTS

Patients admitted in a tertiary medical center for AMI throughout 2002-2012 were analyzed. For each patient, mean sCa, corrected to albumin, was calculated and categorized to seven equally-sized groups: <8.9, 8.9-9.12, 9.12-9.3, 9.3-9.44, 9.44-9.62, 9.62-9.86, ≥9.86 mg/dL. The primary outcome was all-cause in-hospital mortality. Out of 12,121 AMI patients, 11,446 were included, mean age 67.1 ± 14 years, 68% Males. Mean number of sCa values for patient was 4.2 ± 7.3. Mean sCa was 9.4 ± 0.53 mg/dL, range 5.6-13.2 mg/dL sCa was significantly associated with cardiovascular risk-factors, in-hospital complications, more frequent 3-vessel coronary artery disease and decreased rate of revascularization, often in a U-shaped association. Overall 794 (6.9%) patients died in-hospital. Multivariate analysis showed a significant U-shaped association between sCa and in-hospital mortality with sCa below 9.12 mg/dL and above 9.86 mg/dL as independent predictors of significantly increased in-hospital mortality: OR = 2.4 (95% CI:1.7-3.3) and 1.7 (95%CI:1.2-2.4), for Ca<8.9 and Ca≥9.86 mg/dL respectively p < 0.01, as compared with middle rage sCa group (9.3-9.44 mg/dL).

CONCLUSION

sCa is an independent predictor of in-hospital mortality in patients with AMI with a U-shaped association. Both increased and decreased sCa levels are associated with increased risk of in-hospital mortality.

Association of bone metabolism markers with coronary atherosclerosis and coronary artery disease in postmenopausal women

This study aimed to evaluate the association of bone metabolism markers with coronary atherosclerosis and coronary artery disease (CAD) in postmenopausal women. Based on the findings of coronary angiography, 111 women with CAD and 116 women without CAD were recruited. Serum calcium, phosphate, parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), osteocalcin, N-terminal propeptide of type I procollagen (P1NP) and C-terminal cross-linked telopeptide of type I collagen (CTX) were measured. The Gensini score was used to assess the severity of coronary atherosclerosis. Compared with women with serum calcium ≤2.29 mmol/L, women with serum calcium >2.29 mmol/L had a 2.63-fold increased risk of CAD after adjusting for multiple cardiovascular risks, PTH and 25OHD [odds ratio (OR) = 2.91, 95% confidence interval (CI) 1.35-6.28]. In the fully adjusted model plus PTH and 25OHD, the risk of CAD increased 1.87-fold with every 1-SD increment of serum calcium (OR = 1.87, 95% CI 1.21-2.88). To further analyze the potential strong confounding effect of albumin, the absolute levels of calcium were replaced by their albumin-corrected values in the regression model. Compared with women with albumin-corrected calcium ≤2.27 mmol/L, women with albumin-corrected calcium >2.27 mmol/L had a 2.36-fold increased risk of CAD in the fully adjusted model plus PTH and 25OHD (OR = 2.36, 95% CI 1.13-4.92). The risk of coronary atherosclerosis as defined by Gensini score >0 increased 1.73-fold with every 1-SD increment of serum calcium in the fully adjusted model plus PTH and 25OHD (OR = 1.73, 95% CI 1.09-2.73). However, albumin-corrected calcium was not associated with coronary atherosclerosis either as a categorical variable or as a continuous variable in all models. No significant association of PTH, 25OHD, osteocalcin, CTX and P1NP with CAD or coronary atherosclerosis was found in this study. Higher serum calcium levels were independently associated with CAD in postmenopausal women.

Prediagnostic serum calcium and albumin and ovarian cancer: A nested case-control study in the Norwegian Janus Serum Bank Cohort

BACKGROUND

Women with higher serum calcium may be more likely to be diagnosed and die of ovarian cancer. We evaluated that finding in a large, prospective cohort.

METHODS

We conducted a nested case-control study using a population-based biobank from Norway. We compared 202 ovarian cancer cases and 202 controls, matched for age, date at blood draw, and county of residence, with respect to serum calcium and albumin, adjusted for anthropometric variables. We evaluated risks using the entire follow-up period as well as 2-15 years and 16-25 years ("early" and "late", respectively).

RESULTS

For the entire follow-up, risk was significantly increased in the highest tertile of albumin and for high albumin and calcium jointly. Risks for ovarian cancer differed markedly by follow-up time. In early follow-up, women in the highest tertile of serum calcium had a 2.5-fold increased risk, adjusted for height and body mass index (OR=2.47, 95% C.I. 1.12-5.45) with a significant dose-response (p=0.024). Risk was not elevated in late follow-up (OR=0.62, 95% C.I. 0.27-1.36). Similarly, in early follow-up, women in the highest tertile of serum albumin had an increased risk (OR=2.55, 95% C.I.1.22-5.49) with a significant dose-response (p=0.009). Conversely, risk was not increased in late follow-up (OR=1.36, 95% C.I. 0.65-2.83).

CONCLUSIONS

These data confirm a prospective association between higher serum calcium and ovarian cancer. An association in early, but not late, follow-up suggests that the higher calcium reflects the presence of existing cancer. A positive association with serum albumin is novel and should be interpreted cautiously.

Serum Calcium and the Risk of Incident Metabolic Syndrome: A 4.3-Year Retrospective Longitudinal Study

BACKGROUND

An association between serum calcium level and risk of metabolic syndrome (MetS) has been suggested in cross-sectional studies. This study aimed to evaluate the association between baseline serum calcium level and risk of incident MetS in a longitudinal study.

METHODS

We conducted a retrospective longitudinal study of 12,706 participants without MetS who participated in a health screening program, had normal range serum calcium level at baseline (mean age, 51 years), and were followed up for 4.3 years (18,925 person-years). The risk of developing MetS was analyzed according to the baseline serum calcium levels.

RESULTS

A total of 3,448 incident cases (27.1%) of MetS developed during the follow-up period. The hazard ratio (HR) for incident MetS did not increase with increasing tertile of serum calcium level in an age- and sex-matched model (P for trend=0.915). The HRs (95% confidence interval [CI]) for incident MetS comparing the second and the third tertiles to the first tertile of baseline serum calcium level were 0.91 (95% CI, 0.84 to 0.99) and 0.85 (95% CI, 0.78 to 0.92) in a fully adjusted model, respectively (P for trend=0.001). A decreased risk of incident MetS in higher tertiles of serum calcium level was observed in subjects with central obesity and/or a metabolically unhealthy state at baseline.

CONCLUSION

There was no positive correlation between baseline serum calcium levels and incident risk of MetS in this longitudinal study. There was an association between higher serum calcium levels and decreased incident MetS in individuals with central obesity or two components of MetS at baseline.

Serum Calcium and the Risk of Breast Cancer: Findings from the Swedish AMORIS Study and a Meta-Analysis of Prospective Studies

To investigate the association between serum calcium and risk of breast cancer using a large cohort and a systematic review with meta-analysis. From the Swedish Apolipoprotein Mortality Risk (AMORIS) Study we included 229,674 women who had baseline measurements of serum total calcium and albumin. Multivariable Cox regression was used to assess the association between total and albumin-corrected calcium and breast cancer risk. For the systematic review, an electronic search of MEDLINE and EMBASE databases was performed to identify other prospective cohorts assessing the relationship between serum calcium and breast cancer risk. We pooled the results of our AMORIS cohort with other eligible studies in a meta-analysis using a random effects model. I² test was used to assess heterogeneity. In the AMORIS study, 10,863 women were diagnosed with breast cancer (mean follow-up: 19 years). We found an inverse association between total serum calcium and breast cancer when comparing the fourth quartile to the first quartile (HR: 0.94, 95% CI: 0.88–0.99, p value for trend 0.04) and similar results using albumin-corrected calcium. In the systematic review, we identified another two prospective cohorts evaluating pre-diagnostic serum total calcium and breast cancer. Combining these studies and our findings in AMORIS in a meta-analysis showed a protective effect of serum calcium against breast cancer, with a summary RR of 0.80 (95% CI: 0.66–0.97). No substantial heterogeneity was observed. Our findings in AMORIS and the meta-analysis support an inverse association between serum calcium and breast cancer risk, which warrants mechanistic investigations.

A prospective study of plasma 25-hydroxyvitamin D concentration and prostate cancer risk

Mechanistic hypotheses suggest that vitamin D and the closely related parathyroid hormone (PTH) may be involved in prostate carcinogenesis. However, epidemiological evidence is lacking for PTH and inconsistent for vitamin D. Our objectives were to prospectively investigate the association between vitamin D status, vitamin D-related gene polymorphisms, PTH and prostate cancer risk. A total of 129 cases diagnosed within the Supplémentation en Vitamines et Minéraux Antioxydants cohort were included in a nested case-control study and matched to 167 controls (13 years of follow-up). 25-Hydroxyvitamin D (25(OH)D) and PTH concentrations were assessed from baseline plasma samples. Conditional logistic regression models were computed. Higher 25(OH)D concentration was associated with decreased risk of prostate cancer (ORQ4 v. Q1 0·30; 95 % CI 0·12, 0·77; P trend=0·007). PTH concentration was not associated with prostate cancer risk (P trend=0·4) neither did the studied vitamin D-related gene polymorphisms. In this prospective study, prostate cancer risk was inversely associated with 25(OH)D concentration but not with PTH concentration. These results bring a new contribution to the understanding of the relationship between vitamin D and prostate cancer, which deserves further investigation.

The cross-sectional relationship between dietary calcium intake and metabolic syndrome among men and women aged 40 or older in rural areas of Korea

BACKGROUND/OBJECTIVES

Studies conducted in Western populations have suggested that dietary calcium may protect against metabolic abnormalities, but there is little evidence of this effect in Asians, who have relatively low calcium intake. We evaluated the cross-sectional relationship between dietary calcium and metabolic syndrome among Korean men and women aged 40 years and over.

SUBJECTS/METHODS

A total of 6,375 subjects aged 40 years and over and were recruited between January 2005 and February 2010 from the baseline study of the Multi-Rural Communities Cohort Study in Rural Communities (MRCohort). A food frequency questionnaire was used to collect dietary information. Metabolic syndrome was defined using the modified criteria published in the Third Report of the National Cholesterol Education Program Adult Treatment Panel.

RESULTS

Calcium intake was related inversely to metabolic syndrome in women (P-value = 0.0091), but not in men (P = 0.1842). Among metabolic components, high waist circumference (WC) (P = 0.0426) and high blood glucose (P = 0.0027) in women and hypertriglyceridemia (P = 0.0017) in men were inversely correlated with calcium intake. Excluding those who used calcium or multinutrient supplements did not attenuate the relationship between dietary calcium and metabolic abnormalities.

CONCLUSION

Dietary calcium intake from foods may be inversely related to metabolic syndrome, WC, and blood glucose among women in rural areas of Korea.

Vitamin D3 supplementation: Response and predictors of vitamin D3 metabolites - A randomized controlled trial

BACKGROUND & AIMS

Large parts of the population are insufficiently supplied with vitamin D, in particular when endogenous synthesis is absent. Therefore many health care providers recommend the use of vitamin D supplements. The current study aimed to investigate the efficacy of an once-daily oral dose of 20 μg vitamin D3 to improve the vitamin D status and to evaluate predictors of response.

METHODS

The study was conducted as a double-blind, randomized, placebo-controlled parallel trial from January till April 2013. In total, 105 subjects (20-71 years) were allocated to receive either a vitamin D3 supplement (20 μg/d) or a placebo for 12 weeks. Circulating levels of vitamin D3 metabolites such as the 25(OH)D3 and the 24,25(OH)2D3, and biomarkers of calcium and phosphate metabolism were quantified.

RESULTS

The 25(OH)D3 serum concentrations in the placebo group decreased from 38 ± 15 nmol/L at baseline to 32 ± 14 nmol/L and 32 ± 13 nmol/L at weeks 8 and 12 of the study, respectively (p < 0.01). In the vitamin D3 group, the serum 25(OH)D3 concentration increased from 38 ± 14 nmol/L at baseline to 70 ± 15 nmol/L and 73 ± 16 nmol/L at weeks 8 and 12 of vitamin D3 supplementation (p < 0.001), respectively. As a result, 94% of the vitamin D3-supplemented participants reached 25(OH)D3 concentrations of ≥50 nmol/L and thereof 46% attained 25(OH)D3 levels of ≥75 nmol/L until the end of the study. The extent of the 25(OH)D3 increase upon vitamin D3 supplementation depended on 25(OH)D3 baseline levels, age, body weight and circulating levels of triglycerides. In contrast to 25(OH)D3, the response of 24,25(OH)2D3 to the vitamin D3 treatment was affected only by baseline levels of 24,25(OH)2D3 and age.

CONCLUSIONS

The average improvement of 25(OH)D3 levels in individuals who received 20 μg vitamin D3 per day during the winter months was 41 nmol/L compared to individuals without supplementation. As a result almost all participants with the vitamin D3 supplementation attained 25(OH)D3 concentrations of 50 nmol/L and higher. The suitability of 24,25(OH)2D3 as a marker of vitamin D status needs further investigation. Clinical trial registration number at clinicaltrials.gov: NCT01711905.

Plasma–Parathyroid Hormone Is Associated With Subclinical and Clinical Atherosclerotic Disease in 2 Community-Based Cohorts

Objective—

Cardiovascular risk factors have different impact on different arterial territories. Diseases with elevated circulating parathyroid hormone (PTH) such as primary hyperparathyroidism and chronic renal failure have been shown to be associated with an increased risk of cardiovascular disease, predominantly heart or cerebrovascular diseases. However, data on the associations between circulating PTH and peripheral atherosclerosis are limited.

Approach and Results—

Two prospective, community-based studies were used. In 306 men and women, who were 70 years old, from the Prospective investigation of the vasculature in Uppsala seniors (PIVUS) study, cross-sectional relations between PTH and atherosclerotic burden assessed by whole-body magnetic resonance angiography were investigated. In 998 men, who were 71 years old, from the Uppsala longitudinal study of adult men (ULSAM) study, the association between PTH concentration and risk of subsequent nonfatal atherosclerotic disease (excluding coronary or cerebrovascular disease) was investigated. Adjusting for established vascular risk factors, PTH was associated with burden of atherosclerosis (increase in total atherosclerotic score per SD PTH increase: 0.04, 0.003–0.08; P =0.03) in the PIVUS study. During follow-up in the ULSAM study (median 16.7 years), 89 men were diagnosed with nonfatal atherosclerotic disease. In Cox-regression analyses adjusting for established vascular risk factors and mineral metabolism, higher PTH was associated with an increased risk of nonfatal atherosclerotic disease (hazard ratio for 1 SD increase of PTH: 1.55, 1.33–1.88; P <0.0001). Results were similar when including fatal atherosclerotic disease in the outcome.

Conclusions—

In 2 independent community-based cohorts, PTH was associated to the degree of atherosclerosis and risk of clinically overt atherosclerotic disease, respectively. Our data confirm and extend previous studies supporting a role for PTH in the development of atherosclerotic disease.

Tea and coffee consumption in relation to vitamin D and calcium levels in Saudi adolescents

BACKGROUND

Coffee and tea consumption was hypothesized to interact with variants of vitamin D-receptor polymorphisms, but limited evidence exists. Here we determine for the first time whether increased coffee and tea consumption affects circulating levels of 25-hydroxyvitamin D in a cohort of Saudi adolescents.

METHODS

A total of 330 randomly selected Saudi adolescents were included. Anthropometrics were recorded and fasting blood samples were analyzed for routine analysis of fasting glucose, lipid levels, calcium, albumin and phosphorous. Frequency of coffee and tea intake was noted. 25-hydroxyvitamin D levels were measured using enzyme-linked immunosorbent assays.

RESULTS

Improved lipid profiles were observed in both boys and girls, as demonstrated by increased levels of HDL-cholesterol, even after controlling for age and BMI, among those consuming 9-12 cups of coffee/week. Vitamin D levels were significantly highest among those consuming 9-12 cups of tea/week in all subjects (p-value 0.009) independent of age, gender, BMI, physical activity and sun exposure.

CONCLUSION

This study suggests a link between tea consumption and vitamin D levels in a cohort of Saudi adolescents, independent of age, BMI, gender, physical activity and sun exposure. These findings should be confirmed prospectively.

Serum calcium, tumor size, and hormone receptor status in women with untreated breast cancer

Elevated serum levels of calcium are frequently observed in advanced breast cancer, but data on serum calcium and breast cancer characteristics at the time of breast cancer diagnosis are limited. We conducted a cross-sectional study of 555 women with newly-diagnosed, untreated breast cancer in North Dakota. We examined the relationship between tumor size, serum calcium and other clinical characteristics of breast tumors, including age and hormone receptor status, using multiple linear regressions. Tumors that were estrogen receptor negative tended to be associated with higher serum calcium levels (p = 0.07). We observed a significant positive correlation between tumor volume and serum calcium levels (adjusted for patient age, body mass index, hormonal receptors, stage at diagnosis, and grade). The association between tumor volume and serum calcium was limited to post-menopausal women. Our finding that postmenopausal women with larger breast tumors had significantly higher serum calcium levels is consistent with a calciotropic effect of early breast cancer in postmenopausal women.

[Changes in mental health index, serum biochemical parameters and neutrophil function after start of the wheelchair use at a nursing home in Korea]

OBJECTIVES

In Korea, long-term care insurance has been provided to the elderly since 2008. We conducted a health survey of the elderly in a nursing home in Korea from 2007 to 2010. Since the introduction of the insurance system, many of the elderly have started using wheelchairs. We aimed to determine the effect of using wheelchairs on mental health index, serum biochemical parameters, and neutrophil function.

METHODS

The subjects were 32 elderly persons (mean age: 74.44 ± 5.79 years) who could walk unaided in 2007 and were not bedridden until 2010. We classified the subjects into the walking group (subjects could walk unaided or with a cane until 2010; 10 men, 9 women) and the wheelchair group (subjects required the use of a wheelchair from 2007 to 2010; 2 men, 11 women). We determined stress score, stress tolerance, subjective well-being score in accordance with the Philadelphia Geriatric Center Morale Scale, and serum biochemical parameters. We also analyzed oxidant production and phagocytosis by neutrophils and estimated the balance between oxidant production and phagocytosis by correlation analysis.

RESULTS

Increases in the stress tolerance of the wheelchair group in 2008 and 2009 and the subjective well-being score in 2009 in the survey were observed. However, in 2010, the stress tolerance and the subjective well-being score decreased to the levels in 2007. In 2010, the levels of serum albumin and high-density lipoprotein cholesterol of the wheelchair group were significantly lower than those of the walking group, and the balance between phagocytosis and oxidant production in the wheelchair group improved.

Interactions of single nucleotide polymorphisms with dietary calcium intake on the risk of metabolic syndrome

BACKGROUND

Gene-nutrient interactions may be important in modulating susceptibility to metabolic disorders.

OBJECTIVES

The objectives of this study were to assess the association of dietary calcium intake with the risk of metabolic syndrome and to investigate the interaction effects between dietary calcium intake and candidate gene polymorphisms.

DESIGN

Subjects were participants in the Korea Association Resource project, which was initiated in 2007 as a large-scale, genomewide association analysis. A total of 8031 subjects were included in the study. Associations were assessed by using multivariable-adjusted logistic regression analyses.

RESULTS

High calcium intake appeared to be associated with a low risk of metabolic syndrome after covariates in both men (P-trend = 0.03) and women (P-trend = 0.0002) were controlled for. Among 27 single nucleotide polymorphisms (SNPs) selected as possible candidate gene polymorphisms affecting the risk of metabolic syndrome, 3 SNPs [rs6445834 in Rho guanine nucleotide exchange factor 3 (ARHGEF3), rs10850335 in T-box 5 (TBX5), rs180349 in BUD13 homolog (Saccaromyces cerevisiae) (BUD13)] showed significant interaction effects with calcium intake tertiles or sufficiency in both men and women. Subjects with major allele homozygotes of these gene polymorphisms and high calcium intakes generally had a lower risk of metabolic syndrome than did those with minor allele homozygotes and low calcium intakes.

CONCLUSION

Dietary calcium intake appears to be inversely associated with the risk of metabolic syndrome and may modulate susceptibility to the syndrome in subjects who are minor allele carriers of rs6445834 in ARHGEF3, rs10850335 in TBX5, or rs180349 in BUD13.

Calcium intake and prostate cancer among African Americans: effect modification by vitamin D receptor calcium absorption genotype

High dietary intake of calcium has been classified as a probable cause of prostate cancer, although the mechanism underlying the association between dietary calcium and prostate cancer risk is unclear. The vitamin D receptor (VDR) is a key regulator of calcium absorption. In the small intestine, VDR expression is regulated by the CDX-2 transcription factor, which binds a polymorphic site in the VDR gene promoter. We examined VDR Cdx2 genotype and calcium intake, assessed by a food frequency questionnaire, in 533 African-American prostate cancer cases (256 with advanced stage at diagnosis, 277 with localized stage) and 250 African-American controls who participated in the California Collaborative Prostate Cancer Study. We examined the effects of genotype, calcium intake, and diet-gene interactions by conditional logistic regression. Compared with men in the lowest quartile of calcium intake, men in the highest quartile had an approximately twofold increased risk of localized and advanced prostate cancer (odds ratio [OR] = 2.20, 95% confidence interval [CI] = 1.40, 3.46), with a significant dose-response. Poor absorbers of calcium (VDR Cdx2 GG genotype) had a significantly lower risk of advanced prostate cancer (OR = 0.41, 95% CI = 0.19, 0.90). The gene-calcium interaction was statistically significant (p = 0.03). Among men with calcium intake below the median (680 mg/day), carriers of the G allele had an approximately 50% decreased risk compared with men with the AA genotype. These findings suggest a link between prostate cancer risk and high intestinal absorption of calcium.

Serum calcium level is associated with metabolic syndrome in elderly women

OBJECTIVE

To investigate the association between serum calcium level and metabolic syndrome, defined using the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) definition, in Korean elderly women.

STUDY DESIGN

We conducted a cross-sectional study of 1941 elderly women (mean age: 65.16±4.58 years) who participated in annual health examinations at Korea university Medical Center between January 1, 2006 and December 31, 2009 and had normal serum calcium levels.

RESULTS

Women with metabolic syndrome had higher serum calcium levels than those without metabolic syndrome (9.26±0.35 vs. 9.20±0.33, P<0.001). In multiple logistic regression analysis, serum calcium level within normal range was positively associated with the risk of having metabolic syndrome (odds ratio 2.12, 95% confidence interval 1.50-2.98). With regard to components of metabolic syndrome, serum calcium level was also positively associated with the risk of having high triglyceride, and high glucose, whereas it was inversely associated with the risk of having low high density lipoprotein. However, there was no association of serum calcium level with abdominal obesity or high blood pressure.

CONCLUSIONS

The higher was the level of calcium within normal range, the greater were the odds of metabolic syndrome in healthy and elderly women. Prospective studies are needed to investigate the role of calcium in the development of metabolic syndrome in the future.

Serum levels of vitamin D, PTH and calcium and breast cancer risk-a prospective nested case-control study

Previous studies indicate that calcium and its regulating hormones, i.e., parathyroid hormone (PTH) and vitamin D, might affect breast cancer risk. Evidence also suggests that this relationship could be influenced by menopausal status and BMI. We examined breast cancer risk related to prediagnostic serum levels of vitamin D (25OHD(2) and 25OHD(3)), PTH and calcium using a nested case-control design within the Malmö Diet and Cancer Study. There were 764 incident breast cancer cases, and 764 controls were selected by incidence density matching, using age as the underlying time scale, matching on calendar time at inclusion, menopausal status and age at inclusion. Using logistic regression analysis, odds ratios (OR) with 95% confidence intervals were calculated for breast cancer risk in different quartiles of the analyzed factors. All analyses were adjusted for risk factors for breast cancer, and for levels of albumin, creatinine and phosphate. Analyses were repeated stratified for BMI and menopausal status, and for low vs. high levels of 25OHD(3), PTH and calcium. There was a weak, nonsignificant inverse association between breast cancer risk and 25OHD(3), and the OR for the 2nd, 3rd and 4th quartiles, as compared to the first, were 0.84 (0.60-1.15), 0.84 (0.60-1.17) and 0.93 (0.66-1.33). Serum calcium was positively associated with breast cancer in premenopausal women (OR for the 4th quartile = 3.10:1.33-7.22 and p for quartile trend = 0.04), and in women with BMI > 25 (OR for the 4th quartile = 1.94:1.12-3.37 and p for trend < 0.01). There was no association between baseline serum PTH and breast cancer risk.

Microcontroller-based system for estimate of calcium in serum samples

In this study, a microcontroller-based control unit was designed and constructed for the estimation of serum calcium in blood samples. The proposed optoelectronic instrument used a red light emitting diode (LED) as a light source and photodiode as a sensor. The performance of the system was compared with that of a commercial instrument in measuring calcium ion. The quantitative analysis of calcium in a catalyst using arsenazo III as colorimetric reagent was used to test the device. The calibration curve for calcium binding with arsenazo III was drawn to check the range of linearity, which was between 0.1 to 4.5 mM L⁻¹. The limit of detection (LOD) is 0.05 mM L⁻¹. Absorbance changes over the pH range of 2-12 were determined to optimize the assay, with maximum absorption at pH 9.0. Interferences in absorbance from monovalent (K+ and Na+) and divalent (Mg²+) cations were also studied. The results show that the system works successfully.

Independent and joint effects of serum 25-hydroxyvitamin D and calcium on ovarian cancer risk: a prospective nested case-control study

INTRODUCTION

Ovarian cancer has very few known modifiable risk factors but dietary studies suggest a role for vitamin D and calcium in the prevention of ovarian cancer. Thus, we investigated the association between pre-diagnostic serum calcium and 25-hydroxyvitamin D (25-OHD) on the risk of later development of ovarian cancer.

METHODS

We conducted a population-based nested case-control study within the Finnish Maternity Cohort (FMC). The cohort subset comprised 172 ovarian cancer cases with 172 matched controls (age ± 1 year, parity and season of blood donation ± 2 weeks).

RESULTS

We observed a significant inverse association between calcium and ovarian cancer risk. Relative risk (estimated as odds ratio, OR) comparing the highest quartile to the lowest quartile was significantly decreased; 0.41 [95% confidence interval (CI) 0.19-0.85, P-trend 0.004]. Even though a comparable association between 25-OHD and ovarian cancer did not reach statistical significance (OR 0.57, 95% CI 0.26-1.24, P-trend 0.07), having sufficient (> 75 nmol/L) serum 25-OHD levels compared to insufficient serum 25-OHD was associated with a significantly decreased risk of ovarian cancer (OR 0.32; 95% CI 0.12-0.91, p-value 0.03). No synergistic protective interaction between high levels of calcium and 25-OHD against ovarian cancer was observed, the joint effect being just multiplicative.

CONCLUSION

Calcium and vitamin D act independently to reduce the risk of ovarian cancer. The decreased risk of ovarian cancer associated with pre-diagnostic serum calcium and vitamin D needs to be evaluated further for possible new insights into ovarian cancer prevention.

Serum calcium levels are elevated among women with untreated postmenopausal breast cancer

OBJECTIVE

Reports of an association between primary hyperparathyroidism in women and risk of breast cancer suggest an etiologic role for high serum calcium. However, data on the association between serum calcium levels and breast cancer in women without clinical hyperparathyroidism are limited.

METHODS

We conducted a hospital-based case-control study among postmenopausal women in Fargo, ND. Cases were women aged 65 and older with newly diagnosed, histologically confirmed breast cancer. Controls were aged 65 and older without clinical cancer who were seen at the same hospital.

RESULTS

We obtained data on 190 white cases and 172 white controls. Primary hyperparathyroidism (an abnormally high calcium level confirmed by an abnormally high serum PTH) was found in 3/190 cases and in 0/172 controls (p = 0.25). After excluding the women with primary hyperparathyroidism, the mean calcium levels among cases was 9.6 mg/dL (range, 7.5-11.0, SD = 0.47) vs. 9.4 mg/dL (7.7-10.5, 0.43) among the controls (p < 0.0001). Comparing women in the top with women in the bottom tertile of serum calcium, the multivariable-adjusted odds ratio (OR) for breast cancer was 5.21 (95% CI: 2.59-10.48). There was no relationship between serum calcium and tumor size or stage.

CONCLUSION

The distribution of serum calcium levels among postmenopausal women with incident breast cancer was shifted significantly toward the right. These findings are consistent with an effect of early breast tumors on calcium homeostasis. However, the lack of association between serum calcium levels and tumor size or stage supports the hypothesis that subclinical hyperparathyroidism may increase the risk for breast cancer.

A prospective study of total and ionized serum calcium and fatal prostate cancer

We recently reported a significant positive association in the National Health and Nutrition Examination Survey between high levels of total calcium in serum, measured prospectively, and risk of fatal prostate cancer. To confirm this, we examined associations between total and ionized serum calcium and prostate cancer mortality in an independent cohort, the Third National Health and Nutrition Examination Survey. Twenty-five prostate cancer deaths occurred over 56,625 person-years of follow-up. Compared with men in the lowest tertile of total serum calcium, the multivariate-adjusted relative risk for death from prostate cancer for men in the highest tertile was 2.07 (95% confidence interval, 1.06-4.04). For ionized serum calcium, the physiologically active fraction of total serum calcium, the relative risk for men in the highest tertile was 3.18 (95% confidence interval, 1.09-9.28). These findings support the hypothesis that serum calcium is a prospective biomarker of fatal prostate cancer.