Maternal smoking and the vitamin D-parathyroid hormone system during the perinatal period

The association of 25 (OH) D3 serum level with ischemic cerebrovascular accident risk, severity and outcome in Iranian population

OBJECTIVES

The role of combined presence of vitamin D deficiency and other risk factors of stroke in ischemic cerebrovascular accident (CVA) development in Iranian adults has been unclear, so far. The association of vitamin D status at admission with ischemic CVA severity and outcome in this community is not yet well elucidated. This study aimed to clarify these ambiguities.

METHODS

In a cross-sectional study 104 hospitalized ischemic CVA patients and 104 healthy controls participated. The serum level of 25 (OH) D3 and baseline biochemical parameters were measured in ischemic patients within the first 24 h of admission, as well as healthy controls. The severity of CVA and clinical outcome were assessed using National Institutes Health Stroke Scale and Modified Rankin Scale, respectively. Data were analyzed using the Chi-square test, independent t-test, and multiple logistic regression.

RESULTS

There was a significant difference between patients and controls regarding the presence of vitamin D3 deficiency, hypertension, smoking, and baseline level of LDL and FBS. Vitamin D3 deficiency boosted the risk of ischemic in males and those having family history of CVA. A low serum level of 25 (OH) D3 was associated with more severity and poor outcome of CVA. The CVA severity, vitamin D3 deficiency, and hypertension were predictors of poor outcome.

CONCLUSIONS

The study highlights the increased risk of ischemia in Iranians by cooccurrence of vitamin D3 deficiency and other risk factors of CVA. Clinical significance of vitamin D3 deficiency control may be suggested in those at risk of CVA and functional poor outcomes.

Environmental Factors That Affect Parathyroid Hormone and Calcitonin Levels

Calciotropic hormones, parathyroid hormone (PTH) and calcitonin are involved in the regulation of bone mineral metabolism and maintenance of calcium and phosphate homeostasis in the body. Therefore, an understanding of environmental and genetic factors influencing PTH and calcitonin levels is crucial. Genetic factors are estimated to account for 60% of variations in PTH levels, while the genetic background of interindividual calcitonin variations has not yet been studied. In this review, we analyzed the literature discussing the influence of environmental factors (lifestyle factors and pollutants) on PTH and calcitonin levels. Among lifestyle factors, smoking, body mass index (BMI), diet, alcohol, and exercise were analyzed; among pollutants, heavy metals and chemicals were analyzed. Lifestyle factors that showed the clearest association with PTH levels were smoking, BMI, exercise, and micronutrients taken from the diet (vitamin D and calcium). Smoking, vitamin D, and calcium intake led to a decrease in PTH levels, while higher BMI and exercise led to an increase in PTH levels. In terms of pollutants, exposure to cadmium led to a decrease in PTH levels, while exposure to lead increased PTH levels. Several studies have investigated the effect of chemicals on PTH levels in humans. Compared to PTH studies, a smaller number of studies analyzed the influence of environmental factors on calcitonin levels, which gives great variability in results. Only a few studies have analyzed the influence of pollutants on calcitonin levels in humans. The lifestyle factor with the clearest relationship with calcitonin was smoking (smokers had increased calcitonin levels). Given the importance of PTH and calcitonin in maintaining calcium and phosphate homeostasis and bone mineral metabolism, additional studies on the influence of environmental factors that could affect PTH and calcitonin levels are crucial.

Smoking behavior and circulating vitamin D levels in adults: A meta-analysis

To determine the effect of smoking on circulating vitamin D in adults, we performed a meta-analysis. Literature before 9 May 2021 was retrieved from electronic literature databases such as EMBASE, PubMed, and Cochrane. The quality of the included studies was assessed by two researchers against the Newcastle-Ottawa scale and JBI Evidence-based Health Care Centre criteria. All eligible studies and statistical analyses were performed using STATA 14. Twenty-four studies with 11,340 participants meeting the criteria were included in the meta-analysis. The results of meta-analysis showed that the level of circulating 25(OH)D in smokers was lower than that in nonsmokers. A subgroup analysis based on vitamin D supplement use showed that both smokers who used vitamin D supplements and smokers who did not use vitamin D supplements had lower blood 25(OH)D levels compared with the control group. In addition, subjects were divided into different subgroups according to age for meta-analysis, and the results showed that the serum 25(OH)D level in each subgroup of smokers was lower than that in the control group. This meta-analysis revealed differences in circulating vitamin D levels between smokers and nonsmokers, with smokers likely to have lower circulating vitamin D levels.

Serum 25 Hydroxyvitamin D Levels During Pregnancy in Women with Asthma: Associations with Maternal Characteristics and Adverse Maternal and Neonatal Outcomes

Low 25-hydroxyvitamin D (25(OH)D) levels are common in pregnancy and associated with adverse maternal/neonatal outcomes. In pregnant women with asthma, this study examined the association of lifestyle- and asthma-related factors on 25(OH)D levels and maternal/neonatal outcomes by vitamin D status. Serum 25(OH)D was measured at 16 and 35 weeks gestation in women with asthma (n = 103). Body mass index (BMI), gestational weight gain (GWG), smoking status, inhaled corticosteroid (ICS) use, asthma control, airway inflammation, and exacerbations, and maternal/neonatal outcomes were collected. Baseline and change (Δ) in 25(OH)D were modelled separately using backward stepwise regression, adjusted for season and ethnicity. Maternal/neonatal outcomes were compared between low (25(OH)D < 75 nmol/L at both time points) and high (≥75 nmol/L at one or both time points) vitamin D status. Fifty-six percent of women had low vitamin D status. Obesity was significantly associated with lower baseline 25(OH)D (Adj-R² = 0.126, p = 0.008); ICS and airway inflammation were not. Excess GWG and season of baseline sample collection were significantly associated with Δ25(OH)D (Adj-R² = 0.405, p < 0.0001); asthma-related variables were excluded (p > 0.2). Preeclampsia was more common in the low (8.6%) vs. high (0%) vitamin D group (p < 0.05). Obesity and excess GWG may be associated with gestational 25(OH)D levels, highlighting the importance of antenatal weight management.

Vitamin D status and its determinants in healthy pregnant women living in Switzerland in the first trimester of pregnancy

OBJECTIVES

Our study aimed at assessing the prevalence and determinants of vitamin D deficiency (25-hydroxy-vitamin D [25(OH)D] < 20 ng/mL) in pregnant women in the first trimester living in Switzerland.

METHODS

From September 2014 through December 2015, 204 pregnant women were conveniently recruited during their first clinical appointment at the Clinic of Obstetrics of the University Hospital Zurich (between week 6 and 12 of pregnancy). Blood samples were collected and a questionnaire focusing on lifestyle and skin colour was completed face-to-face with the responsible physician. Logistic regression analyses were performed with vitamin D status as dependent variable.

RESULTS

63.2% of the participating women were vitamin D deficient, and the median vitamin D concentration in the overall sample was 17.1 ng/mL [Q1, Q3: 9.78, 22.3]. The highest proportions of vitamin D deficiency were detected in women originating from Africa and Middle East (91.4% deficient, median vitamin D concentration of 10.7 ng/mL [Q1, Q3: 6.55, 14.45]) and from South-East Asia/Pacific (88.5% deficient, median vitamin D concentration of 8.4 ng/mL [Q1, Q3: 6.10, 14.88]). Multivariable logistic regression showed that significant risk factors of vitamin D deficiency were country of origin (women born in Switzerland and Germany had a lower risk than women born in other countries), smoking status (lower risk for former smokers) and intake of vitamin D supplements.

CONCLUSIONS

Our results confirm a high prevalence of vitamin D deficiency in this Swiss cohort, in particular in women coming from Asian and African countries, and underline the importance of appropriate counseling and vitamin D supplementation in early pregnancy.

Air pollution, environmental chemicals, and smoking may trigger vitamin D deficiency: Evidence and potential mechanisms

Beyond vitamin D (VD) effect on bone homeostasis, numerous physiological functions in human health have been described for this versatile prohormone. In 2016, 95% of the world's population lived in areas where annual mean ambient particulate matter (<2.5 μm) levels exceeded the World Health Organization guideline value (Shaddick et al., 2018). On the other hand, industries disperse thousands of chemicals continually into the environment. Further, considerable fraction of populations are exposed to tobacco smoke. All of these may disrupt biochemical pathways and cause detrimental consequences, such as VD deficiency (VDD). In spite of the remarkable number of studies conducted on the role of some of the above mentioned exposures on VDD, the literature suffers from two main shortcomings: (1) an overview of the impacts of environmental exposures on the levels of main VD metabolites, and (2) credible engaged mechanisms in VDD because of those exposures. To summarize explanations for these unclear topics, we conducted the present review, using relevant keywords in the PubMed database, to investigate the adverse effects of exposure to air pollution, some environmental chemicals, and smoking on the VD metabolism, and incorporate relevant potential pathways disrupting VD endocrine system (VDES) leading to VDD. Air pollution may lead to the reduction of VD cutaneous production either directly by blocking ultraviolet B photons or indirectly by decreasing outdoor activity. Heavy metals may reduce VD serum levels by increasing renal tubular dysfunction, as well as downregulating the transcription of cytochrome P450 mixed-function oxidases (CYPs). Endocrine-disrupting chemicals (EDCs) may inhibit the activity and expression of CYPs, and indirectly cause VDD through weight gain and dysregulation of thyroid hormone, parathyroid hormone, and calcium homeostasis. Smoking through several pathways decreases serum 25(OH)D and 1,25(OH)2D levels, VD intake from diet, and the cutaneous production of VD through skin aging. In summary, disturbance in the cutaneous production of cholecalciferol, decreased intestinal intake of VD, the modulation of genes involved in VD homeostasis, and decreased local production of calcitriol in target tissues are the most likely mechanisms that involve in decreasing the serum VD levels.

Maternal risk factors and newborn infant vitamin D status: a scoping literature review

Low vitamin D (VitD) status is common among newborn infants, more so in temperate latitudes with evidence that maternal VitD deficiency is a major risk factor given that the neonate relies solely on maternal-fetal transfer of VitD. This scoping review was conducted to provide an overview of the latest evidence from studies regarding the impact of maternal risk factors on infant 25-hydryoxyvitamin D [25(OH)D] concentrations with a focus on studies in Canada and the United States. Several maternal risk factors that contribute to low maternal-fetal 25(OH)D concentrations have been reported over many decades, but no clear pattern has been established for multiethnic populations. For example, darker skin pigmentation and ethnicity are common risk factors for low VitD status. Studies in predominantly white women showed that supplementation of VitD during pregnancy causes significant increases in maternal serum 25(OH)D which often improves cord serum 25(OH)D values. In addition, VitD recommendations by health care professionals and adherence to supplementation by pregnant women appear to positively influence maternal and infant 25(OH)D concentrations. Conversely, winter season, obesity, lower socioeconomic status including lifestyle factors (smoking), and use of medication pose risk for lower maternal-fetal transfer of VitD. However, there is still a dearth of pertinent data on the relationship between some of the maternal risk factors and newborn 25(OH)D concentrations, for instance, relationships between gestational diabetes and neonatal VitD status. Additional research is required to determine if the same target for 25(OH)D concentrations applies for pregnant women, neonates, and infants.

Tobacco smoke exposure is an independent predictor of vitamin D deficiency in US children

IMPORTANCE

The role of tobacco-smoke exposure on serum vitamin D concentration in US pediatric population is not known. We hypothesized that tobacco smoke exposure would increase the prevalence of vitamin D deficiency in US children.

METHODS

Representative national data were accessed from the National Health and Nutrition Examination Survey (NHANES) 2009-2010 databank on 2,263 subjects of ages 3 to 17 years. Subjects were categorized into two groups based on their age: children, if <10 years; and youth if 10 to 17 years. Descriptive and multiple logistic regression analyses were conducted to determine the effect of serum cotinine-verified tobacco smoke exposure on vitamin D status after controlling for key sociodemographic confounders. Vitamin D deficiency was defined as 25(OH)D <20 ng/mL, insufficiency as 25(OH)D of 20-29.9 ng/mL, and sufficiency as 25(OH)D of ≥30 ng/mL. Tobacco smoke exposure status was defined by serum cotinine concentration as follows: unexposed and non-smoking (<0.05 ng/mL) and exposed (passive and active smokers combined) (≥0.05ng/mL). Specifically, passive and active smoking were defined as cotinine of 0.05-10 ng/mL, and ≥10ng/mL respectively.

RESULTS

The prevalence of second-hand smoke exposure was 42.0% (95%CI, 36.7%-47.5%); while the prevalence of active smoking among teenagers was 9.0% (95%CI, 6.2%-12.5%). Vitamin D deficiency occurred at a frequency of 15.1% in children unexposed to tobacco smoke, 20.9% in children exposed to passive tobacco smoke, and 18.0% among actively smoking youth (p<0.001). Tobacco smoke exposure independently predicted vitamin D deficiency after controlling for age, sex, race, BMI, maternal education, and family socio-economic status (OR:1.50; 95%CI, 1.14-1.85, p = 0.002).

CONCLUSIONS

This analysis of a nationwide database reports that tobacco smoke exposure is an independent predictor of vitamin D deficiency in US children.

Vitamin D: Effects on human reproduction, pregnancy, and fetal well-being

Pregnancy places exceptional demands on vitamin D and calcium availability; thus, their deficiencies during pregnancy threaten the woman and her fetus. Globally, vitamin D and other micronutrient deficiencies are common during pregnancy, especially in developing countries where pregnant women have less access to nutritional supplements. Vitamin D deficiency has been reported to be as high as 40% among pregnant women. As a pregnancy progresses, the requirements for vitamin D increase and thus, can worsen preexisting hypovitaminosis D. Consequently, hypovitaminosis D is increasingly associated with a higher incidence of fetal miscarriage, preeclampsia, gestational diabetes, bacterial vaginosis, and impaired fetal and childhood growth and development. This review explores the recent advances in the understanding of vitamin D and the pivotal role it plays in human reproduction, with an emphasis on pregnancy and its outcomes. Given the seriousness of the issue, there is a pressing need for clinicians to become aware of the risks associated with not identifying and correcting vitamin D deficiency. Identifying and correcting vitamin D deficiency, including safe exposure to sunlight, is particularly relevant for those who seek assistance with fertility issues or prenatal counseling, and those in the beginning of their pregnancy. The data point to a significant protective effects of vitamin D during pregnancy when the 25(OH)D serum level exceeds 30 ng/mL before pregnancy and during the first trimester and, sufficient levels are maintained throughout the pregnancy.

Vitamin D Status and Gestational Diabetes: Effect of Smoking Status during Pregnancy

BACKGROUND

Vitamin D status, as measured by serum 25-hydroxyvitamin D (25(OH)D), has been shown in some studies to be inversely associated with gestational diabetes risk. Recently, it has been suggested that maternal smoking status may modify this relationship. We explored the association between 25(OH)D concentration and gestational diabetes and determined if there was an interaction between smoking and 25(OH)D.

METHODS

A nested case-control study was conducted in Halifax, Nova Scotia and Quebec City, Quebec. Women were recruited before 20 weeks gestation and 25(OH)D was measured. Cases were women who developed gestational diabetes and controls were frequency matched to cases on study site, gestational age at blood draw, and season and year of blood draw. Logistic regression models estimated adjusted odds ratios (aOR) and 95% confidence intervals (CI). Models were tested for multiplicative and additive interaction, which was estimated by relative excess risk due to interaction (RERI).

RESULTS

The study included 395 gestational diabetes cases and 1925 controls. Women who smoked during pregnancy and had 25(OH)D concentrations <30 nmol/L had an aOR = 3.73 [95% CI 1.95, 7.14] compared to non-smokers with 25(OH)D concentrations ≥50 nmol/L. Additive interaction was detected between smoking status and 25(OH)D [RERI = 2.44, 95% CI 0.03, 4.85].

CONCLUSION

Our study supports the inverse association of vitamin D status with gestational diabetes risk, particularly among women who smoke during pregnancy. More research is needed to confirm this finding and, if confirmed, to determine the mechanism by which the combined effect of smoking and low vitamin D status increases the risk of developing gestational diabetes.

Hypovitaminosis D in pregnancy in the Mediterranean region: a systematic review

Despite high levels of sunshine, maternal hypovitaminosis D during pregnancy is prevalent in the Mediterranean region. The aim of this study is to systematically review trials that investigated vitamin D concentrations during pregnancy in this region, in order to determine predictors of hypovitaminosis D and explain this phenomenon. After applying inclusion/exclusion criteria, 15 studies were entered into the systematic review involving 2649 pregnant women and 820 neonates. The main outcome was maternal vitamin D status, assessed by serum 25-hydroxy-vitamin D (25(OH)D) concentrations. Possible predictors of the outcome included maternal age, body mass index (BMI), race, socioeconomic status, skin type, gestational age, sun exposure, calcium and vitamin D intake and supplementation, smoking status, parity and season of delivery. Studies differed widely in vitamin D deficiency criteria, method of measurement and outcomes. The prevalence of vitamin D insufficiency ranges from 9.3 to 41.4%, whereas that of vitamin D deficiency from 22.7 to 90.3%. A positive association with 25(OH)D concentrations exists for light skin color, white race, uncovered dressing pattern, maternal vitamin D supplementation and season of gestation (spring/summer). An inverse association exists for BMI and gestational age, whereas data for smoking and socioeconomic status are controversial. We concluded that vitamin D deficiency in pregnancy seems to be quite common, even in the Mediterranean region. Racial, social and cultural habits, as well as the absence of preventive supplementation/dietary strategies, seem to negate the benefits of sun exposure.

Effect of maternal nicotine/thiocyanate exposure during gestational period upon pituitary, thyroid and parathyroid function/morphology of 1-month-old rat offspring

INTRODUCTION

Impact of in utero exposure to nicotine, on the structure of the thyroid-pituitary axis and the parathyroid glands have been examined in 1-month-old rats and compared with that of thiocyanate.

MATERIALS AND METHODS

Three pregnant female groups were used; control, nicotine and thiocyanate. Treatment started from gestation day (4-20) and the specimens were harvested from the male offspring of all groups at the age of 1 month and processed for light, electronmicroscopic and immunohistochemical examination. Total triiodothyronine (tT3), total thyroxine (tT4) and total thyrotropin (TSH) were quantitatively determined in serum.

RESULTS

Both nicotine and thiocyanate activated the thyroid follicular cells, with an increase in height (about 30 %) and a negative feedback on the pituitary thyrotrophs which revealed a reduction in the number of cytoplasmic secretory granules, particularly the thiocyanate group. However, in thiocyanate group there was signs of impaired secretory activity of the thyroid gland. The arbitrary area of parathyroid chief cells, increased (about 45 %) particularly in nicotine group, with signs of reduced activity and a positive feedback on the parafollicular cells which revealed hypertrophy, proliferation (25 %) and increased intensity of positive immunohistochemical reaction for calcitonin.

CONCLUSION

Nicotine impaired chief parathyroid cells activity and consequently activated parafollicular cells. Thiocyanate reduced pituitary thyrotrophs activity, whereas both nicotine and thiocyanate increased thyroid follicular cells activity. This impact of in utero exposure persisted for 1-month postnatal.

Linking vitamin d deficiency to inflammatory bowel disease

Inflammatory bowel disease is associated with industrialization, and its incidence has increased markedly over time. The prospect of reversing these trends motivates the search for the agent(s) involved. Modernity entails several physical and behavioral modifications that compromise both the photosynthesis of cholecalciferol in the skin and of its bioavailability. Although deficiency in this "vitamin" has therefore emerged as a leading candidate, and despite the publication of a randomized control trial that showed a trend toward statistically significant benefit in Crohn's disease, its causal agency has yet to be demonstrated by an adequately powered study. We discuss the strengths and weaknesses of the case being made by epidemiologists, geneticists, clinicians, and basic researchers, and consolidate their findings into a model that provides mechanistic plausibility to the claim. Specifically, converging data sets suggest that local activation of vitamin D coordinates the activity of the innate and adaptive arms of immunity, and of the intestinal epithelium, in a manner that promotes barrier integrity, facilitates the clearance of translocated flora, and diverts CD4 T cell development away from inflammatory phenotypes. Because smoking is an important risk-altering exposure, we also discuss its newly established melanizing effect and other emerging evidence linking tobacco use to immune function through vitamin D pathways.

The effect of cigarette smoke exposure on vitamin D level and biochemical parameters of mothers and neonates

BACKGROUND

Exposure to cigarette smoke during pregnancy leads to several adverse effects on mother and child. The purpose of this study was to evaluate the effect of being a passive smoker during pregnancy on vitamin D level and related biochemical indices including parathyroid hormone, calcium, phosphorus and alkaline phosphatase in mothers and newborns.

METHODS

One hundred eight pregnant women and their newborns participated in a historical cohort study in two equal groups (n = 54) with and without cigarette smoke exposure. Maternal blood and urine samples and blood samples of umbilical cord were obtained in the delivery room. Concentration of 25-hydroxy vitamin D and related biochemical indices in samples of maternal and cord blood were investigated. Exposure to cigarette smoke was evaluated through questionnaire and maternal urine and umbilical cord serum cotinine levels.

RESULTS

The mean level of 25-hydroxyvitamin D in maternal serum was 9.28 ± 5.19 ng/mlin exposed and 10.75 ± 5.26 ng/ml in non-exposed group(p > 0.05). The mean concentration of 25-hydroxy vitamin D in cord serum was 10.83 ± 6.68 ng/ml in the exposed and 11.05 ± 4.99 ng/ml in the non-exposed group(p > 0.05). The exposed mothers had significantly higher parathyroid hormone level (p = 0.013), lower serum calcium (p = 0.024) and higher serum alkaline phosphatase (p = 0.024). There was a significant correlation between maternal and umbilical cord serum 25-hydroxyvitamin D within both exposed and non-exposed groups (p < 0.001).

CONCLUSION

Maternal exposure to cigarette smoking during pregnancy negatively influences serum calcium level and increase parathyroid hormone and alkaline phosphatase in mothers.

Association of self-reported passive smoking in pregnant women with cotinine level of maternal urine and umbilical cord blood at delivery

Passive smoking during pregnancy leads to adverse effects on mother and infant. The present investigation was designed to evaluate the association between maternal reported passive smoking with the cotinine concentration of maternal urine and umbilical cord blood at delivery and to determine the accuracy of maternal reporting of exposure to cigarette smoke during pregnancy. This was a cross-sectional study. From the 108 non-smoker pregnant women who were referred for delivery, 54 were passive smokers. Urine samples were collected from the mothers in the delivery room and blood samples after birth were taken from the umbilical cord. Passive smoking was evaluated through questionnaire and cotinine level of urine and umbilical cord blood. The geometric mean cotinine concentration of the maternal urine and the umbilical cord serum were, respectively, 27.4 ± 29.96 ng/mL and 3.71 ± 1.22 ng/mL in the exposed group (P < 0.001) and 0.75 ± 2.29 and 0.40 ± 0.63 in the non-exposed group (P < 0.001). There was a statistically significant correlation between maternal urinary and umbilical cord serum level of cotinine (P < 0.001, r = 0.58). Significant associations were shown between maternal reports of exposure to cigarette smoking with cotinine level of urine (kappa = 96%) and umbilical cord (kappa = 98%) (P < 0.001). This study shows that the pregnant woman's report of passive smoking during pregnancy in Iran is accurate. The questionnaire is an appropriate method to evaluate smoke exposure and could replace cotinine measurement.

First trimester serum 25-hydroxyvitamin D status and factors related to lower levels in gravids living in the Spanish Mediterranean coast

OBJECTIVE

To assess first trimester serum 25-hydroxyvitamin D [25(OH)D] status and factors related to deficient levels in pregnant Spanish women.

METHODS

This cross-sectional study was carried out among 502 gravids (11 to 14 weeks) living in the Spanish Mediterranean sea coast (near Almería at latitude 36° N, longitude 2° W) to whom serum 25(OH)D levels were measured by electrochemiluminescence immunoassay. Logistic and multiple linear regression analysis were performed to assess the influence of ethnicity, immigration status, season of the year at blood sampling, body mass index (BMI), parity and smoking habit over 25(OH)D levels.

RESULTS

The median (interquartile range, IQR) serum 25(OH)D levels for the entire sample was 27.4 ng/mL (IQR = 20.9-32.8). Only 35.9% of participants had adequate serum 25(OH)D levels (≥30 ng/mL) whereas in 41.4% and 22.7% these levels were found to be insufficient (20-29.9 ng/mL) and deficient (<20 ng/mL), respectively. Vitamin D status was found to be significantly lower in Arab women as compared to Caucasian women. 25(OH)D levels were positively correlated with gestational age at sampling and inversely with BMI values (univariate analysis). Logistic regression analysis determined that non-Caucasian ethnicity, season at sampling (autumn/winter), and nulliparity were factors related to deficient 25(OH)D levels. Multiple linear regression found a similar model yet also including maternal weight inversely correlating with 25(OH)D levels.

CONCLUSION

Despite living in one of the sunniest, warmest, and driest climates of Europe, gravids displayed a high prevalence of first trimester insufficient/deficient serum 25(OH)D levels related to season at sampling, nulliparity, maternal weight, and non-Caucasian ethnicity.

Effects of smoking on severity of disease in primary hyperparathyroidism

In healthy subjects, smoking is associated with lower plasma levels of parathyroid hormone (PTH) and decreased bone mineral density (BMD). The effect of smoking on PTH, skeletal metabolism, and size/histology of the parathyroid glands in primary hyperparathyroidism (PHPT) is unknown. We investigated, in a cross-sectional study, whether smoking affects PTH levels, BMD, and weight/histology of removed parathyroid tissue in PHPT. We studied 344 (285 women) parathyroidectomized patients with PHPT (24% smokers). Biochemistry was determined at the time of diagnosis. BMD was measured before and after surgical cure. Smoking was associated with lower PTH (9.9 ± 1.8 [SD] vs. 12.2 ± 1.8 pmol/l, P < 0.01) and higher phosphate (0.95 ± 0.17 vs. 0.86 ± 0.17 mmol/l, P < 0.01) levels. Adjustments for between-group differences in age, sex, body weight, plasma creatinine, and 25-hydroxyvitamin D (25OHD) levels did not change the findings. Neither weight of removed adenomatous and hyperplastic tissue nor BMD differed according to smoking status. After adjustment for body weight, age, sex, and 25OHD levels, smokers had slightly lower BMD at the whole body but not at the spine, hip, or forearm. Independent of smoking status, surgical cure caused a significant increase in BMD at all measurement sites. In PHPT smoking is associated with lower plasma PTH and higher phosphate levels. Adjustment for confounders of PTH did not change the results. In contrast to healthy subjects, smoking seems not to decrease BMD in PHPT. Smoking may compromise the correct diagnostic evaluation of borderline hyperparathyroidism. It is unknown to what extent smoking in PHPT affects fracture risk and indication for surgery.

From the American Academy of Pediatrics: Technical report--Secondhand and prenatal tobacco smoke exposure

Secondhand tobacco smoke (SHS) exposure of children and their families causes significant morbidity and mortality. In their personal and professional roles, pediatricians have many opportunities to advocate for elimination of SHS exposure of children, to counsel tobacco users to quit, and to counsel children never to start. This report discusses the harms of tobacco use and SHS exposure, the extent and costs of tobacco use and SHS exposure, and the evidence that supports counseling and other clinical interventions in the cycle of tobacco use. Recommendations for future research, policy, and clinical practice change are discussed. To improve understanding and provide support for these activities, the harms of SHS exposure are discussed, effective ways to eliminate or reduce SHS exposure are presented, and policies that support a smoke-free environment are outlined.

Association of serum intact parathyroid hormone with lower estimated glomerular filtration rate

BACKGROUND AND OBJECTIVES

The prevalence of mineral metabolism abnormalities is almost universal in stage 5 chronic kidney disease (CKD), but the presence of abnormalities in milder CKD is not well characterized.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data on adults > or =20 yr of age from the National Health and Nutrition Examination Survey 2003-2004 (N = 3949) were analyzed to determine the association between moderate declines in estimated GFR (eGFR), calculated using the Modfication of Diet in Renal Disease formula, and serum intact parathyroid hormone (iPTH) > or = 70 pg/ml.

RESULTS

The geometric mean iPTH level was 39.3 pg/ml. The age-standardized prevalence of elevated iPTH was 8.2%, 19.3%, and 38.3% for participants with eGFR > or = 60, 45 to 59, and 30 to 44 ml/min/1.73 m(2), respectively (P-trend < 0.001). After adjustment for age; race/ethnicity; sex; menopausal status; education; income; cigarette smoking; alcohol consumption; body mass index; hypertension; diabetes mellitus; vitamin D supplement use; total calorie and calcium intake; and serum calcium, phosphorus, and 25-hydroxyvitamin D levels-and compared with their counterparts with an eGFR > or = 60 ml/min/1.73 m(2)-the prevalence ratios of elevated iPTH were 2.30 and 4.69 for participants with an eGFR of 45 to 59 and 30 to 44 ml/min/1.73 m(2), respectively (P-trend < 0.001). Serum phosphorus > or = 4.2 mg/dl and 25-hydroxyvitamin D < 17.6 ng/ml were more common at lower eGFR levels. No association was present between lower eGFR and serum calcium < 9.4 mg/dl.

CONCLUSIONS

This study indicates that elevated iPTH levels are common among patients with moderate CKD.