Bioavailable and free 25-hydroxyvitamin D and vitamin D binding protein in polycystic ovary syndrome: Relationships with obesity and insulin resistance

Negar Naderpoor, Soulmaz Shorakae, Sally K. Abell, Aya Mousa, Anju E. Joham, Lisa J. Moran, Nigel K. Stepto, Poli Mara Spritzer, Helena J. Teede, Barbora de Courten

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Abstract

Polycystic ovary syndrome (PCOS) is a common condition characterised by both reproductive and metabolic features (obesity, insulin resistance, diabetes risk). Some evidence suggests that women with PCOS have lower vitamin D levels compared to healthy controls. Vitamin D binding protein (DBP) is the main carrier of vitamin D in circulation and plays an important role in regulating vitamin D concentration and bioavailability for target tissues. To our knowledge, no previous studies have examined DBP, bioavailable and free 25-hydroxyvitamin D (25(OH)D) in women with PCOS. The primary aim of this study was to compare DBP, bioavailable and free 25(OH)D concentrations in women with PCOS and controls. The secondary aim was to investigate relationships between DBP, bioavailable and free 25(OH)D and metabolic features (anthropometric measures, insulin resistance, and lipid profile).In a cross sectional study using bio-banked samples, we measured 25(OH)D, DBP and albumin. Bioavailable and free 25(OH)D were calculated using previously validated formula. BMI, body composition (dual X-ray absorptiometry, DXA), insulin resistance (homeostatic model assessment of insulin resistance (HOMA-IR)) and glucose infusion rate (GIR) from hyperinsulinaemic euglycaemic clamp and serum lipids (ELISA) were also measured in a physically and biochemically well-characterised cohort of women with and without PCOS.We studied 90 women with PCOS and 59 controls aged 18-48 years. DBP concentrations were lower in PCOS compared to controls (median [IQR]: 443.40 [314.4] vs 482.4 [156.8] μg/ml, p = 0.02). No significant differences were found in bioavailable or free 25(OH)D concentrations between groups. DBP was not associated with BMI, percent body fat or markers of insulin resistance (all p. >. 0.2). High-density lipoprotein (HDL) was the main determinant of DBP in the overall cohort (β = -0.12, p = 0.02), after adjusting for covariates including PCOS/control status, age, BMI, total 25(OH)D and HOMA-IR. In PCOS, total and free 25(OH)D were related to markers of insulin resistance and lipids. Only the associations between free 25(OH)D and triglycerides (p = 0.02), and HDL (p = 0.03) remained significant after adjusting for age and BMI.In conclusion, women with PCOS had lower DBP, but similar bioavailable or free 25(OH)D concentrations compared to controls, independent of BMI and age. DBP was not associated with insulin resistance or BMI in PCOS. Further studies are needed to investigate the pathophysiology and clinical implications of reduced DBP in PCOS.

LanguageEnglish
Pages209-215
Number of pages7
JournalJournal of Steroid Biochemistry and Molecular Biology
Volume177
DOIs
StatePublished - Mar 2018

Keywords

  • Bioavailable 25(OH)D
  • Body mass index
  • Free 25(OH)D
  • Insulin resistance
  • Polycystic ovary syndrome
  • Vitamin D binding protein

Cite this

@article{17adccd0414c4b57809e792875b28ca4,
title = "Bioavailable and free 25-hydroxyvitamin D and vitamin D binding protein in polycystic ovary syndrome: Relationships with obesity and insulin resistance",
abstract = "Polycystic ovary syndrome (PCOS) is a common condition characterised by both reproductive and metabolic features (obesity, insulin resistance, diabetes risk). Some evidence suggests that women with PCOS have lower vitamin D levels compared to healthy controls. Vitamin D binding protein (DBP) is the main carrier of vitamin D in circulation and plays an important role in regulating vitamin D concentration and bioavailability for target tissues. To our knowledge, no previous studies have examined DBP, bioavailable and free 25-hydroxyvitamin D (25(OH)D) in women with PCOS. The primary aim of this study was to compare DBP, bioavailable and free 25(OH)D concentrations in women with PCOS and controls. The secondary aim was to investigate relationships between DBP, bioavailable and free 25(OH)D and metabolic features (anthropometric measures, insulin resistance, and lipid profile).In a cross sectional study using bio-banked samples, we measured 25(OH)D, DBP and albumin. Bioavailable and free 25(OH)D were calculated using previously validated formula. BMI, body composition (dual X-ray absorptiometry, DXA), insulin resistance (homeostatic model assessment of insulin resistance (HOMA-IR)) and glucose infusion rate (GIR) from hyperinsulinaemic euglycaemic clamp and serum lipids (ELISA) were also measured in a physically and biochemically well-characterised cohort of women with and without PCOS.We studied 90 women with PCOS and 59 controls aged 18-48 years. DBP concentrations were lower in PCOS compared to controls (median [IQR]: 443.40 [314.4] vs 482.4 [156.8] μg/ml, p = 0.02). No significant differences were found in bioavailable or free 25(OH)D concentrations between groups. DBP was not associated with BMI, percent body fat or markers of insulin resistance (all p. >. 0.2). High-density lipoprotein (HDL) was the main determinant of DBP in the overall cohort (β = -0.12, p = 0.02), after adjusting for covariates including PCOS/control status, age, BMI, total 25(OH)D and HOMA-IR. In PCOS, total and free 25(OH)D were related to markers of insulin resistance and lipids. Only the associations between free 25(OH)D and triglycerides (p = 0.02), and HDL (p = 0.03) remained significant after adjusting for age and BMI.In conclusion, women with PCOS had lower DBP, but similar bioavailable or free 25(OH)D concentrations compared to controls, independent of BMI and age. DBP was not associated with insulin resistance or BMI in PCOS. Further studies are needed to investigate the pathophysiology and clinical implications of reduced DBP in PCOS.",
keywords = "Bioavailable 25(OH)D, Body mass index, Free 25(OH)D, Insulin resistance, Polycystic ovary syndrome, Vitamin D binding protein",
author = "Negar Naderpoor and Soulmaz Shorakae and Abell, {Sally K.} and Aya Mousa and Joham, {Anju E.} and Moran, {Lisa J.} and Stepto, {Nigel K.} and Spritzer, {Poli Mara} and Teede, {Helena J.} and {de Courten}, Barbora",
year = "2018",
month = "3",
doi = "10.1016/j.jsbmb.2017.07.012",
language = "English",
volume = "177",
pages = "209--215",
journal = "Journal of Steroid Biochemistry and Molecular Biology",
issn = "0960-0760",
publisher = "Elsevier",

}

TY - JOUR

T1 - Bioavailable and free 25-hydroxyvitamin D and vitamin D binding protein in polycystic ovary syndrome

T2 - Journal of Steroid Biochemistry and Molecular Biology

AU - Naderpoor,Negar

AU - Shorakae,Soulmaz

AU - Abell,Sally K.

AU - Mousa,Aya

AU - Joham,Anju E.

AU - Moran,Lisa J.

AU - Stepto,Nigel K.

AU - Spritzer,Poli Mara

AU - Teede,Helena J.

AU - de Courten,Barbora

PY - 2018/3

Y1 - 2018/3

N2 - Polycystic ovary syndrome (PCOS) is a common condition characterised by both reproductive and metabolic features (obesity, insulin resistance, diabetes risk). Some evidence suggests that women with PCOS have lower vitamin D levels compared to healthy controls. Vitamin D binding protein (DBP) is the main carrier of vitamin D in circulation and plays an important role in regulating vitamin D concentration and bioavailability for target tissues. To our knowledge, no previous studies have examined DBP, bioavailable and free 25-hydroxyvitamin D (25(OH)D) in women with PCOS. The primary aim of this study was to compare DBP, bioavailable and free 25(OH)D concentrations in women with PCOS and controls. The secondary aim was to investigate relationships between DBP, bioavailable and free 25(OH)D and metabolic features (anthropometric measures, insulin resistance, and lipid profile).In a cross sectional study using bio-banked samples, we measured 25(OH)D, DBP and albumin. Bioavailable and free 25(OH)D were calculated using previously validated formula. BMI, body composition (dual X-ray absorptiometry, DXA), insulin resistance (homeostatic model assessment of insulin resistance (HOMA-IR)) and glucose infusion rate (GIR) from hyperinsulinaemic euglycaemic clamp and serum lipids (ELISA) were also measured in a physically and biochemically well-characterised cohort of women with and without PCOS.We studied 90 women with PCOS and 59 controls aged 18-48 years. DBP concentrations were lower in PCOS compared to controls (median [IQR]: 443.40 [314.4] vs 482.4 [156.8] μg/ml, p = 0.02). No significant differences were found in bioavailable or free 25(OH)D concentrations between groups. DBP was not associated with BMI, percent body fat or markers of insulin resistance (all p. >. 0.2). High-density lipoprotein (HDL) was the main determinant of DBP in the overall cohort (β = -0.12, p = 0.02), after adjusting for covariates including PCOS/control status, age, BMI, total 25(OH)D and HOMA-IR. In PCOS, total and free 25(OH)D were related to markers of insulin resistance and lipids. Only the associations between free 25(OH)D and triglycerides (p = 0.02), and HDL (p = 0.03) remained significant after adjusting for age and BMI.In conclusion, women with PCOS had lower DBP, but similar bioavailable or free 25(OH)D concentrations compared to controls, independent of BMI and age. DBP was not associated with insulin resistance or BMI in PCOS. Further studies are needed to investigate the pathophysiology and clinical implications of reduced DBP in PCOS.

AB - Polycystic ovary syndrome (PCOS) is a common condition characterised by both reproductive and metabolic features (obesity, insulin resistance, diabetes risk). Some evidence suggests that women with PCOS have lower vitamin D levels compared to healthy controls. Vitamin D binding protein (DBP) is the main carrier of vitamin D in circulation and plays an important role in regulating vitamin D concentration and bioavailability for target tissues. To our knowledge, no previous studies have examined DBP, bioavailable and free 25-hydroxyvitamin D (25(OH)D) in women with PCOS. The primary aim of this study was to compare DBP, bioavailable and free 25(OH)D concentrations in women with PCOS and controls. The secondary aim was to investigate relationships between DBP, bioavailable and free 25(OH)D and metabolic features (anthropometric measures, insulin resistance, and lipid profile).In a cross sectional study using bio-banked samples, we measured 25(OH)D, DBP and albumin. Bioavailable and free 25(OH)D were calculated using previously validated formula. BMI, body composition (dual X-ray absorptiometry, DXA), insulin resistance (homeostatic model assessment of insulin resistance (HOMA-IR)) and glucose infusion rate (GIR) from hyperinsulinaemic euglycaemic clamp and serum lipids (ELISA) were also measured in a physically and biochemically well-characterised cohort of women with and without PCOS.We studied 90 women with PCOS and 59 controls aged 18-48 years. DBP concentrations were lower in PCOS compared to controls (median [IQR]: 443.40 [314.4] vs 482.4 [156.8] μg/ml, p = 0.02). No significant differences were found in bioavailable or free 25(OH)D concentrations between groups. DBP was not associated with BMI, percent body fat or markers of insulin resistance (all p. >. 0.2). High-density lipoprotein (HDL) was the main determinant of DBP in the overall cohort (β = -0.12, p = 0.02), after adjusting for covariates including PCOS/control status, age, BMI, total 25(OH)D and HOMA-IR. In PCOS, total and free 25(OH)D were related to markers of insulin resistance and lipids. Only the associations between free 25(OH)D and triglycerides (p = 0.02), and HDL (p = 0.03) remained significant after adjusting for age and BMI.In conclusion, women with PCOS had lower DBP, but similar bioavailable or free 25(OH)D concentrations compared to controls, independent of BMI and age. DBP was not associated with insulin resistance or BMI in PCOS. Further studies are needed to investigate the pathophysiology and clinical implications of reduced DBP in PCOS.

KW - Bioavailable 25(OH)D

KW - Body mass index

KW - Free 25(OH)D

KW - Insulin resistance

KW - Polycystic ovary syndrome

KW - Vitamin D binding protein

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U2 - 10.1016/j.jsbmb.2017.07.012

DO - 10.1016/j.jsbmb.2017.07.012

M3 - Article

VL - 177

SP - 209

EP - 215

JO - Journal of Steroid Biochemistry and Molecular Biology

JF - Journal of Steroid Biochemistry and Molecular Biology

SN - 0960-0760

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