scholarly journals Opinions and Practice of US-Based Obstetrician-Gynecologists regarding Vitamin D Screening and Supplementation of Pregnant Women

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Sara A. Mohamed ◽  
Ayman Al-Hendy ◽  
Jay Schulkin ◽  
Michael L. Power
Keyword(s):  
Vitamin D ◽  
Pregnant Women ◽  
Patient Population ◽  
Vitamin D Insufficiency ◽  
Vitamin D Supplementation ◽  
Institute Of Medicine ◽  
Vitamin D Status ◽  
Online Questionnaire ◽  
Endocrine Society ◽  
Hydroxyvitamin D

Vitamin D deficiency/insufficiency is prevalent among pregnant women. Recommendations for adequate levels of circulating 25-hydroxyvitamin D and appropriate vitamin D supplementation during pregnancy differ between the Institute of Medicine and the Endocrine Society. Obstetrician-gynecologists must make clinical decisions in this environment of uncertain guidance. An online questionnaire regarding physician practice patterns for screening and supplementing pregnant women was administered to 225 randomly selected practicing obstetrician-gynecologists of whom 101 (45%) completed the questionnaire. A majority indicated that vitamin D insufficiency was a problem in their patient population (68.4%) and that most of their pregnant patients would benefit from vitamin D supplementation (66.3%). Half (52.5%) would recommend vitamin D supplementation during pregnancy to some patients, but only 16.8% to all. Only one in four (25.8%) routinely screen their pregnant patients for vitamin D status. Physicians who indicated that vitamin D status was a problem in their patient population were more likely to screen routinely (32.8% versus 9.7%,P=0.002) and believe their patients would benefit from supplementation (91.2% versus 16.1%,P=0.001). Opinion regarding supplementation levels and indicators of adequacy were split between the two competing recommendations, suggesting that clinical practice will likely remain variable across physicians, with uncertain public health consequences.

scholarly journals Vitamin D deficiency and insufficiency in pregnant women: a longitudinal study

2009 ◽  
Vol 102 (6) ◽  
pp. 876-881 ◽  
Author(s):  
Valerie A. Holmes ◽  
Maria S. Barnes ◽  
H. Denis Alexander ◽  
Peter McFaul ◽  
Julie M. W. Wallace
Keyword(s):  
Vitamin D ◽  
Longitudinal Study ◽  
Pregnant Women ◽  
Hypovitaminosis D ◽  
Vitamin D Insufficiency ◽  
Vitamin D Supplementation ◽  
Vitamin D Status ◽  
Maternal Vitamin ◽  
Hydroxyvitamin D ◽  
Supplement Use

Maternal vitamin D insufficiency is associated with childhood rickets and longer-term problems including schizophrenia and type 1 diabetes. Whilst maternal vitamin D insufficiency is common in mothers with highly pigmented skin, little is known about vitamin D status of Caucasian pregnant women. The aim was to investigate vitamin D status in healthy Caucasian pregnant women and a group of age-matched non-pregnant controls living at 54–55°N. In a longitudinal study, plasma 25-hydroxyvitamin D (25(OH)D) was assessed in ninety-nine pregnant women at 12, 20 and 35 weeks of gestation, and in thirty-eight non-pregnant women sampled concurrently. Plasma 25(OH)D concentrations were lower in pregnant women compared to non-pregnant women (P < 0·0001). Of the pregnant women, 35, 44 and 16 % were classified as vitamin D deficient (25(OH)D < 25 nmol/l), and 96, 96 and 75 % were classified as vitamin D insufficient (25(OH)D < 50 nmol/l) at 12, 20 and 35 weeks gestation, respectively. Vitamin D status was higher in pregnant women who reported taking multivitamin supplements at 12 (P < 0·0001), 20 (P = 0·001) and 35 (P = 0·001) weeks gestation than in non-supplement users. Vitamin D insufficiency is evident in pregnant women living at 54–55°N. Women reporting use of vitamin D-containing supplements had higher vitamin D status, however, vitamin D insufficiency was still evident even in the face of supplement use. Given the potential consequences of hypovitaminosis D on health outcomes, vitamin D supplementation, perhaps at higher doses than currently available, is needed to improve maternal vitamin D nutriture.

scholarly journals Longitudinal association of 25-hydroxyvitamin D with adipokines and markers of glucose metabolism among Brazilian pregnant women

2018 ◽  
Vol 121 (1) ◽  
pp. 42-54 ◽  
Author(s):  
Camila Benaim ◽  
Paula Guedes Cocate ◽  
Erica Guimarães de Barros ◽  
Nadya Helena Alves-Santos ◽  
Amanda Caroline Cunha Figueiredo ◽  
...  
Keyword(s):  
Vitamin D ◽  
Glucose Metabolism ◽  
Pregnant Women ◽  
Model Assessment ◽  
Vitamin D Status ◽  
Mixed Effect ◽  
Endocrine Society ◽  
Hydroxyvitamin D ◽  
Longitudinal Association ◽  
25 Hydroxyvitamin D

AbstractThis study aimed to evaluate the longitudinal association of vitamin D status with glycaemia, insulin, homoeostatic model assessment of insulin resistance, adiponectin and leptin. A prospective cohort with 181 healthy, pregnant Brazilian women was followed at the 5th–13th, 20th–26th and 30th–36th gestational weeks. In this cohort, 25-hydroxyvitamin D (25(OH)D) plasma concentrations were analysed using liquid chromatography–tandem MS. Vitamin D status was categorised as sufficient or insufficient using the Endocrine Society Practice Guidelines (≥75/<75 nmol/l) and the Institute of Medicine (≥50/<50 nmol/l) thresholds. Linear mixed-effect regression models were employed to evaluate the association between vitamin D status and each outcome, considering interaction terms between vitamin D status and gestational age (P<0·1). At baseline, 70·7 % of pregnant women had 25(OH)D levels <75 nmol/l and 16 % had levels <50 nmol/l. Women with sufficient vitamin D status at baseline, using both thresholds, presented lower glycaemia than those with insufficient 25(OH)D. Pregnant women with 25(OH)D concentrations <75 nmol/l showed lower insulin (β=−0·12; 95 % CI −0·251, 0·009;P=0·069) and adiponectin (β=−0·070; 95 % CI −0·150, 0·010;P=0·085) concentrations throughout pregnancy than those with 25(OH)D levels ≥75 nmol/l. Pregnant women with 25(OH)D <50 nmol/l at baseline presented significantly higher leptin concentrations than those with 25(OH)D levels ≥50 nmol/l (β=−0·253; 95 % CI −0·044, 0·550;P=0·095). The baseline status of vitamin D influences the biomarkers involved in glucose metabolism. Vitamin D-sufficient women at baseline had higher increases in insulin and adiponectin changes throughout gestation than those who were insufficient.

scholarly journals Effect of vitamin D supplementation on vitamin D status in pregnant women: findings from the MO-VITD study

2020 ◽  
Vol 79 (OCE2) ◽  
Author(s):  
Raghad Alhomaid ◽  
Maria Mulhern ◽  
Laura Cassidy ◽  
Eamon Laird ◽  
Martin Healy ◽  
...  
Keyword(s):  
Vitamin D ◽  
Cord Blood ◽  
Pregnant Women ◽  
Vitamin D Insufficiency ◽  
Vitamin D Supplementation ◽  
Normal Weight ◽  
Vitamin D Status ◽  
Obese Women ◽  
Maternal Vitamin ◽  
Treatment Groups

AbstractPregnant women who are overweight/obese are particularly vulnerable to vitamin D insufficiency owing to higher physiological requirements and lower status (25(OH)D concentrations) associated with obesity. Achieving adequate maternal vitamin D status with current recommendations (10μg/d) remains controversial.This study examined supplementation effects (10μg-vs-20μg vitamin D3/d) throughout pregnancy (12 weeks gestation until delivery) on vitamin D status of normal weight, overweight and obese pregnant women and on cord blood, using a double-blind randomised vitamin D intervention study (MO-VITD). 240 pregnant women were recruited throughout the year at antenatal clinics in Northern Ireland (equal numbers of normal weight (18.5–24.9 kg/m2), overweight (25–29.9 kg/m2), and obese (> 30kg/m2)). Non-fasting maternal blood samples were collected at 12, 28 and 34–36 weeks gestation and from the umbilical cord after delivery and analysed for total serum 25(OH)D using LCMS.A high prevalence of vitamin D insufficiency (25–50nmol/L) was found in the 1st trimester in both treatment groups (41.5% and 48.8%; 10μg vs. 20μg respectively). Maternal 25(OH)D concentrations increased from the 1st to 3rd trimester in both the 10μg/d and 20μg/d groups, with a higher increase in the 20μg group (17.1 ± 24.7 and 28.8 ± 33.3nmol/L, P = 0.002). There was no difference in cord blood 25(OH)D concentrations between treatment groups.Women who started pregnancy with insufficient 25(OH)D concentrations remained insufficient throughout pregnancy in the 10μg/d group (49.9 ± 28.2nmol/L at trimester 3). In the 20μg/d group, women starting pregnancy as insufficient achieved levels of sufficiency in the 2nd (58.9 ± 30.6nmol/L) and 3rd (64.0 ± 35.9nmol/L) trimesters. Women who started pregnancy with sufficient vitamin D status (25(OH)D > 50nmol/L), maintained levels of sufficiency throughout pregnancy irrespective of treatment group (83.1 ± 24.4 and 96.7 ± 30.7 at trimester 3 in 10μg/d and 20 μg/d groups respectively); findings were similar across all BMI categories.Obese women who started pregnancy with an insufficient status were found to have deficient cord blood (25(OH)D < 25 nmol/L) in both the 10μg/d and 20μg/d groups (19.4 ± 20.2 vs. 19.5 ± 9.4nmol/L respectively), whilst obese women who started pregnancy with sufficient status (> 50nmol/L) had cord blood concentrations considered insufficient (40.2 ± 18.4 vs. 44.2 ± 15.6nmol/L; 10μg vs. 20μg groups respectively).Based on our findings of the high prevalence of vitamin D insufficiency in early pregnancy, maternal vitamin D supplementation of 20μg/d is advisable to maintain maternal vitamin D status in pregnant women in Northern Ireland.

High Prevalence of Vitamin D Deficiency in Pregnant Women in South China

2020 ◽  
Vol 90 (3-4) ◽  
pp. 273-278 ◽  
Author(s):  
Xueli Li ◽  
Yuanliu Wang ◽  
Gan Gao ◽  
Xiaoyong Guan ◽  
Peixu Qin ◽  
...  
Keyword(s):  
Vitamin D ◽  
Cord Blood ◽  
Pregnant Women ◽  
Vitamin D Deficiency ◽  
Vitamin D Supplementation ◽  
Vitamin D Status ◽  
Hydroxyvitamin D ◽  
Severe Deficiency ◽  
Vitamin D Levels ◽  
Different Seasons

Abstract. Objective: To investigate the vitamin D status of pregnant women in the Liuzhou area and assess the effects of maternal vitamin D status on the cord blood of their newborns. Subjects and methods: This study included 8852 pregnant women and 2000 newborns. The serum 25-hydroxyvitamin D [25(OH)D] levels of the 8852 pregnant women and the cord blood of 2000 newborns were measured. Results: The results showed that the average level of 25(OH)D in pregnant women in this area was 76.55 nmol/L, and women in different trimesters had different vitamin D levels ( p < 0.001). The overall prevalence of vitamin D deficiency (<75 nmol/L) in pregnant women was 62.34%, and the proportion of severe deficiency (<25 nmol/L) was 0.25%. Vitamin D deficiency was more prevalent in the winter and spring than in the summer and autumn ( p < 0.001). Pregnant women who had regular vitamin D supplementation had higher levels of 25(OH)D than the women with discontinuous supplementation or no supplementation ( p < 0.001). Conclusions: Vitamin D deficiency was prevalent in pregnant women in the Liuzhou area. There were differences in vitamin D levels between the three trimesters and different seasons. For pregnant women with vitamin D deficiency, it is important to scientifically determine the appropriate level of vitamin D supplementation to ensure the health of mothers and babies.

scholarly journals Vitamin D Status and Severe COVID-19 Disease Outcomes in Hospitalized Patients

2021 ◽  
Vol 12 ◽  
pp. 215013272110412
Author(s):  
Jennifer L. Pecina ◽  
Stephen P. Merry ◽  
John G. Park ◽  
Tom D. Thacher
Keyword(s):  
Vitamin D ◽  
Assisted Ventilation ◽  
Vitamin D Supplementation ◽  
Hospitalized Patients ◽  
Vitamin D Status ◽  
Icu Admission ◽  
Hydroxyvitamin D ◽  
Duration Of Hospitalization ◽  
D Values ◽  
Relationship Of

Background: Vitamin D deficiency may increase the risk of severe COVID-19 disease. Objectives: To determine if 25-hydroxyvitamin D [25(OH)D] levels in patients hospitalized for COVID-19 were associated with the clinical outcomes of days on oxygen, duration of hospitalization, ICU admission, need for assisted ventilation, or mortality. Methods: We conducted a retrospective study of 92 patients admitted to the hospital with SARS-CoV-2 infection between April 16, 2020 and October 17, 2020. Multivariable regression was performed to assess the independent relationship of 25(OH)D values on outcomes, adjusting for significant covariates and the hospitalization day the level was tested. Results: About 15 patients (16.3%) had 25(OH)D levels <20 ng/mL. Only 1 patient (3.4%) who had documented vitamin D supplementation prior to admission had 25(OH)D <20 ng/mL. Serum 25(OH)D concentrations were not significantly associated with any of our primary outcomes of days on oxygen, duration of hospitalization, intensive care unit (ICU) admission, need for mechanical ventilation, or mortality in any of the adjusted multivariable models. Adjusting for the hospital day of 25(OH)D sampling did not alter the relationship of 25(OH)D with any outcomes. Conclusion: Vitamin D status was not related to any of the primary outcomes reflecting severity of COVID-19 in hospitalized patients. However, our sample size may have lacked sufficient power to demonstrate a small effect of vitamin D status on these outcomes.

Vitamin D status in infancy and cardiometabolic health in adolescence

2020 ◽  
Vol 113 (1) ◽  
pp. 104-112
Author(s):  
Joshua Garfein ◽  
Kerry S Flannagan ◽  
Sheila Gahagan ◽  
Raquel Burrows ◽  
Betsy Lozoff ◽  
...  
Keyword(s):  
Vitamin D ◽  
Body Fat ◽  
Early Life ◽  
Vitamin D Supplementation ◽  
Lower Percentage ◽  
Cardiometabolic Health ◽  
Vitamin D Status ◽  
Percentage Body Fat ◽  
Hydroxyvitamin D ◽  
25 Hydroxyvitamin D

ABSTRACT Background Vitamin D deficiency is associated with obesity-related conditions, but the role of early life vitamin D status on the development of obesity is poorly understood. Objectives We assessed whether serum 25-hydroxyvitamin D [25(OH)D] at age 1 y was related to metabolic health through adolescence. Methods We quantified serum 25(OH)D in samples obtained at age 1 y from 306 participants in a cohort study in Santiago, Chile. Anthropometry was performed at ages 5, 10, and 16/17 y. At 16/17 y, we determined body composition using DXA and quantified metabolic parameters in a blood sample. We examined the associations of infancy 25(OH)D with BMI-for-age z-score (BMIZ) at ages 5, 10, and 16/17 y; with percentage fat and percentage lean body mass at age 16/17 y; and with a metabolic syndrome (MetS) score and its components at age 16/17 y. Results Infancy 25(OH)D was inversely associated with BMIZ in childhood. Every 25-nmol/L difference in 25(OH)D was related to an adjusted 0.11 units lower BMIZ at age 5 y (95% CI: −0.20, −0.03; P = 0.01) and a 0.09 unit lower BMIZ change from ages 1 to 5 y (95% CI: −0.17, −0.01; P = 0.02). Also, every 25-nmol/L 25(OH)D in infancy was associated with an adjusted 1.3 points lower percentage body fat mass (95% CI: −2.2, −0.4; P = 0.005) and an adjusted 0.03 units lower MetS score (95% CI: −0.05, −0.01; P = 0.01) at age 16/17 y, through inverse associations with waist circumference and the HOMA-IR. Conclusions Serum 25(OH)D at age 1 y is inversely associated with childhood BMIZ, percentage body fat at age 16/17 y, and a MetS score at age 16/17 y. Intervention studies are warranted to examine the effects of vitamin D supplementation in early life on long-term cardiometabolic outcomes.

scholarly journals Skeletal and Extraskeletal Actions of Vitamin D: Current Evidence and Outstanding Questions

2018 ◽  
Vol 40 (4) ◽  
pp. 1109-1151 ◽  
Author(s):  
Roger Bouillon ◽  
Claudio Marcocci ◽  
Geert Carmeliet ◽  
Daniel Bikle ◽  
John H White ◽  
...  
Keyword(s):  
Vitamin D ◽  
Vitamin D Deficiency ◽  
Human Subjects ◽  
Osteoporotic Fractures ◽  
Vitamin D Supplementation ◽  
Current Evidence ◽  
Elderly Subjects ◽  
Vitamin D Status ◽  
Hydroxyvitamin D ◽  
25 Hydroxyvitamin D

AbstractThe etiology of endemic rickets was discovered a century ago. Vitamin D is the precursor of 25-hydroxyvitamin D and other metabolites, including 1,25(OH)2D, the ligand for the vitamin D receptor (VDR). The effects of the vitamin D endocrine system on bone and its growth plate are primarily indirect and mediated by its effect on intestinal calcium transport and serum calcium and phosphate homeostasis. Rickets and osteomalacia can be prevented by daily supplements of 400 IU of vitamin D. Vitamin D deficiency (serum 25-hydroxyvitamin D <50 nmol/L) accelerates bone turnover, bone loss, and osteoporotic fractures. These risks can be reduced by 800 IU of vitamin D together with an appropriate calcium intake, given to institutionalized or vitamin D–deficient elderly subjects. VDR and vitamin D metabolic enzymes are widely expressed. Numerous genetic, molecular, cellular, and animal studies strongly suggest that vitamin D signaling has many extraskeletal effects. These include regulation of cell proliferation, immune and muscle function, skin differentiation, and reproduction, as well as vascular and metabolic properties. From observational studies in human subjects, poor vitamin D status is associated with nearly all diseases predicted by these extraskeletal actions. Results of randomized controlled trials and Mendelian randomization studies are supportive of vitamin D supplementation in reducing the incidence of some diseases, but, globally, conclusions are mixed. These findings point to a need for continued ongoing and future basic and clinical studies to better define whether vitamin D status can be optimized to improve many aspects of human health. Vitamin D deficiency enhances the risk of osteoporotic fractures and is associated with many diseases. We review what is established and what is plausible regarding the health effects of vitamin D.

scholarly journals Oral vitamin D supplementation has a lower bioavailability and reduces hypersecretion of parathyroid hormone and insulin resistance in obese Chinese males

2014 ◽  
Vol 18 (12) ◽  
pp. 2211-2219 ◽  
Author(s):  
Ji-Chang Zhou ◽  
Yu-Mei Zhu ◽  
Zheng Chen ◽  
Jun-Luan Mo ◽  
Feng-Zhu Xie ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Vitamin D ◽  
Parathyroid Hormone ◽  
Vitamin D Supplementation ◽  
Normal Weight ◽  
Vitamin D Status ◽  
Intervention Trial ◽  
Oral Vitamin ◽  
Hydroxyvitamin D ◽  
25 Hydroxyvitamin D

AbstractObjectiveTo examine the vitamin D status, SNP of the vitamin D receptor gene (VDR) and the effects of vitamin D supplementation on parathyroid hormone and insulin secretion in adult males with obesity or normal weight in a subtropical Chinese city.DesignAn intervention trial.SettingShenzhen City, Guangdong Province, China.SubjectsFrom a cross-sectional survey conducted from June to July, eighty-two normal-weight and ninety-nine obese males (18–69 years) were screened to analyse their vitamin D status and for five SNP of VDR. From these individuals, in the same season of a different year, obese and normal-weight male volunteers (twenty-one per group) were included for an intervention trial with oral vitamin D supplementation at 1250 µg/week for 8 weeks.ResultsFor the survey, there was no significant difference (P>0·05) in baseline circulating 25-hydroxyvitamin D concentrations or in the percentages of participants in different categories of vitamin D status between the two groups. The VDR SNP, rs3782905, was significantly associated with obesity (P=0·043), but none of the examined SNP were correlated with serum 25-hydroxyvitamin D when adjusted for age, BMI and study group. After vitamin D supplementation, serum 25-hydroxyvitamin D concentration, hypersecretions of parathyroid hormone and insulin, and insulin resistance in the obese were changed beneficially (P<0·05); however, the increase in serum 25-hydroxyvitamin D was less than that of the normal-weight men.ConclusionsFor obese and normal-weight men of subtropical China, the summer baseline vitamin D status was similar. However, oral vitamin D supplementation revealed a decreased bioavailability of vitamin D in obese men and ameliorated their hypersecretion of parathyroid hormone and insulin resistance.

scholarly journals Prediction of Bone Mass Density Variation by Bone Remodeling Markers in Postmenopausal Women with Vitamin D Insufficiency Treated with Calcium and Vitamin D Supplementation

2003 ◽  
Vol 88 (11) ◽  
pp. 5175-5179 ◽  
Author(s):  
Franck Grados ◽  
Michel Brazier ◽  
Saïd Kamel ◽  
Marc Mathieu ◽  
Nathalie Hurtebize ◽  
...  
Keyword(s):  
Vitamin D ◽  
Bone Remodeling ◽  
Elderly Women ◽  
Vitamin D Insufficiency ◽  
Vitamin D Supplementation ◽  
Hydroxyvitamin D ◽  
Bone Remodeling Markers ◽  
25 Hydroxyvitamin D ◽  
Total Body

Abstract The aim of this study was to determine whether early changes in bone markers could predict long-term response in bone mineral density (BMD) after calcium (500 mg) and vitamin D (400 IU) supplementation twice daily in ambulatory elderly women with vitamin D insufficiency (25-hydroxyvitamin D, &lt;12 ng/ml). One hundred and ninety-two women (mean age, 75 ± 7 yr) were randomized to receive either the supplementation (n = 95) or a placebo (n = 97) in a double-blind, controlled clinical trial for 1 yr. In comparison with the placebo group, supplementation significantly increased BMD, normalized 25-hydroxyvitamin D and significantly decreased intact PTH and bone remodeling markers. The initial values of telopeptide cross-links were correlated with improvement in total body BMD [urinary N-telopeptides (NTX), r = 0.38; C-telopeptides (CTX), r = 0.32; serum CTX, r = 0.28], and the 3-month changes in the same markers were correlated with improvement in total body (urinary N-telopeptides, r = −0.29; serum CTX, r = −0.26) and vertebral BMD (CTX, r = −0.26; all P &lt; 0.05). We concluded that short-term changes in bone resorption markers can predict long-term variations in BMD in elderly women with vitamin D insufficiency receiving calcium and vitamin D supplementation.

scholarly journals Suppression of Parathyroid Hormone as a Proxy for Optimal Vitamin D Status: Further Analysis of Two Parallel Studies in Opposite Latitudes

Nutrients ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 942 ◽  
Author(s):  
Marcela M. Mendes ◽  
Kathryn H. Hart ◽  
Susan A. Lanham-New ◽  
Patrícia B. Botelho
Keyword(s):  
Vitamin D ◽  
Parathyroid Hormone ◽  
Total Sample ◽  
Vitamin D Insufficiency ◽  
Vitamin D Supplementation ◽  
Vitamin D Status ◽  
Low Latitude ◽  
Vitamin D Levels ◽  
Cubic Model ◽  
The Relationship

Optimal vitamin D status has commonly been defined as the level of 25-hydroxyvitamin D (25(OH)D) at which parathyroid hormone (PTH) concentrations would be maximally suppressed, represented by an observed minimum plateau. Previous findings indicate a large variation in this plateau, with values ranging from <30 nmol/L up to 100 nmol/L. This disparity in values might be explained by differences in study design and methodology, ethnicity, age, gender and latitude. This study aimed to investigate the concentration of 25(OH)D at which PTH concentrations were suppressed in Brazilian women living in opposite latitudes (high vs. low: i.e., UK and Brazil), during wintertime. Using data from the D-SOL study (Interaction between Vitamin D Supplementation and Sunlight Exposure in Women Living in Opposite Latitudes), the association between 25(OH)D status and PTH levels were examined in 135 Brazilian women (56 living in England and 79 living in Brazil, aged 20–59 years old). Mean PTH concentrations for Brazilian women with vitamin D deficiency (<25 nmol/L) were significantly higher compared to those with vitamin D insufficiency (25–49.9 nmol/L) (p < 0.01), vitamin D adequacy (50–74.9 nmol/L) (p < 0.01) and those with optimal vitamin D status (>75 nmol/L) (p < 0.001). Regression modelling was used to investigate the relationship between serum 25(OH)D and PTH for the sample as a whole and for each group separately. A cubic model was statistically significant for the total sample (p < 0.001), whereas a linear model presented the best fit for Brazilian women living in England (p = 0.04) and there were no statistically significant models fitted for Brazilian women living in Brazil. The cubic model suggests that 25(OH)D concentrations above 70–80 nmol/L are optimal to suppress the parathyroid gland in Brazilian women. These findings contribute to a better understanding of the relationship between 25(OH)D and PTH in populations living in a low latitude location and are of great relevance for discussions regarding the estimation of optimal cut-offs for vitamin D levels in the Brazilian population as well as for other low latitude locations.

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