Comparison of anthropometric and metabolic parameters between normal and deficient vitamin D polycystic ovarian syndrome women

Anupama Bahadur; Rajlaxmi Mundhra; Jyotshna Kashibhatla; Neha Verma; Rashmi Rajput; Yogesh Bahurupi

doi:10.4103/JME.JME_4_20

ORIGINAL ARTICLE

Year : 2021 | Volume : 2 | Issue : 1 | Page : 4-8

Comparison of anthropometric and metabolic parameters between normal and deficient vitamin D polycystic ovarian syndrome women

Anupama Bahadur¹, Rajlaxmi Mundhra¹, Jyotshna Kashibhatla¹, Neha Verma¹, Rashmi Rajput¹, Yogesh Bahurupi²
¹ Department of Obstetrics and Gynecology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
² Department of Community and Family Medicine, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India

Date of Submission	28-Sep-2020
Date of Acceptance	18-Nov-2020
Date of Web Publication	25-Apr-2021

Correspondence Address:
Dr. Rajlaxmi Mundhra
Department of Obstetrics and Gynecology, All India Institute of Medical Sciences, Rishikesh, Uttarakhand
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/JME.JME_4_20

Abstract

Objective: To compare the anthropometric and metabolic parameters between normal and deficient Vitamin D PCOS women. Materials and Methods: All women with polycystic ovary syndrome (PCOS) women were analyzed over a period of eighteen months from- May 2016 to October 2017. The study participants were divided into two groups as per 25(OH)D level. Those with 25(OH)D level <20 ng/ml (Vitamin D deficient) were taken group I and those having 25(OH)D level ≥ 20 ng/ml i.e., sufficient vitamin D levels were group II. We measured anthropometric measurements and metabolic parameters like lipid profile, fasting insulin, fasting blood sugars and HOMA-IR. Results: Eighty-five women were evaluated during the time period. The mean age of the study sample was 23.34 ± 4.587. Almost 40 % (n=34) of the study sample were vitamin D deficient and more than half of PCOS women (n=51) had sufficient vitamin D levels. Out of 85 women analyzed in this study, 48.23% were obese (Group I: 52.9% and 45.1% in group II). The vitamin D deficient group was comparable with the sufficient group in terms of anthropometric and biochemical parameters, except fasting serum insulin levels, which was infact lower in the vitamin D deficient group as compared to vitamin D sufficient group. None of the parameter showed any significant correlation with vitamin D. Conclusion: Hypovitaminosis is a common occurrence in PCOS women, necessitating the need for screening to prevent future adverse outcome. Further large-scale trials need to be done.

Keywords: Metabolic parameters, polycystic ovarian syndrome, Vitamin D

How to cite this article:
Bahadur A, Mundhra R, Kashibhatla J, Verma N, Rajput R, Bahurupi Y. Comparison of anthropometric and metabolic parameters between normal and deficient vitamin D polycystic ovarian syndrome women. J Med Evid 2021;2:4-8

How to cite this URL:
Bahadur A, Mundhra R, Kashibhatla J, Verma N, Rajput R, Bahurupi Y. Comparison of anthropometric and metabolic parameters between normal and deficient vitamin D polycystic ovarian syndrome women. J Med Evid [serial online] 2021 [cited 2022 Aug 12];2:4-8. Available from: http://www.journaljme.org/text.asp?2021/2/1/4/314630

Introduction

Polycystic ovarian syndrome (PCOS) is a common endocrinopathy – affecting 15%–20% of women in early reproductive age or adolescence with a wide spectrum of aetiologies and clinical manifestations.^[1] Recently, an association is seen between the low levels of Vitamin D and PCOS symptoms including ovulation menstrual irregularities, hirsutism, infertility and insulin resistance (IR).^[2] However, the exact role of Vitamin D in the pathogenesis of PCOS remains unclear. Perhaps, it influences the development of PCOS via regulation of gene transcription and hormonal modulation of both insulin metabolism and reproductive function.^[3] Worsening of hyperandrogenaemia occurs due to reduction in the levels of sex hormone-binding globulin and increased production of parathyroid hormone in women with Vitamin D deficiency. Deficiency of Vitamin D is quite common in all age groups in our country.^[4] Studies focusing on PCOD and Vitamin D deficiency are sparse from India. With this study, we aim to identify the proportion of PCOS women affected by Vitamin D deficiency in our setting and to compare the anthropometric and metabolic parameters between normal and deficient Vitamin D PCOS women.

Materials and Methods

This was a cross-sectional study carried out over a period of 18 months from May 2016 to October 2017. All women aged 15–45 years presenting to the outpatient clinic at the Department of Gynecology at All India Institute of Medical Sciences, Rishikesh, India, fulfilling the Rotterdam's diagnostic criteria,^[5] were enrolled in the study cohort. Exclusion criteria were pregnant or lactating women and those using hormonal contraceptives. Informed consent was taken from the patients, after explaining the detailed plan, purpose and duration of the study in their own language. A detailed clinical history including menstrual history, obstetric history and family history was taken. All women underwent detailed clinical examination involving the following anthropometric measurements: height (in cm), weight (in kg), hip circumference (widest part of the hip) and waist circumference (WC) (horizontal to umbilicus), which were measured using a calibrated digital weighing scale. Waist-to-hip circumference ratio was also noted. Body mass index (BMI) was derived as weight in kilograms divided by height in meter square (kg/m²). Regarding their BMI, they were divided according to the Standard Consensus Statement for Indian Population^[6] as underweight: <18.5, normal BMI: 18.5–22.9 kg/m², overweight: 23.0–24.9 kg/m² and obese: >25 kg/m². A per-vaginal bimanual examination (except in adolescents and unmarried women with PCOS) was carried out to rule out any local pelvic pathology. A transvaginal ultrasonography (transabdominal if unmarried) was done on day 2 of menstrual cycle to assess ovarian follicles and number of antral follicles. Identification of polycystic ovaries on transvaginal ultrasound without any clinical or biochemical features is not categorised as a case of PCOS though it may represent a mild variety of ovarian hyperandrogenism and IR. Hirsutism scoring was done according to the Ferriman and Gallwey score.^[7] Blood samples for 25-hydroxyvitamin D (25[OH]D) and metabolic (fasting glucose, fasting insulin, total cholesterol, high-density lipoprotein [HDL]-cholesterol, low-density lipoprotein [LDL]-cholesterol and triglycerides [TGs]) parameters were obtained in the morning between 7:00 am and 9:00 am after overnight fasting during the early follicular phase of each patient's spontaneous or progestin/induced menstrual cycle. IR was estimated using the Homeostasis Model Assessment-IR (HOMA-IR). HOMA-IR was calculated as the product of the fasting plasma insulin level in miU/ml with fasting blood glucose (FBG) in mg/dl divided by 405.^[8] According to consensus in clinical practice, Vitamin D deficiency was defined as serum level of 25(OH)D level <20 ng/ml. The study participants were divided into the following two groups as per 25(OH)D level:

Group I – Vitamin D deficient; 25(OH)D level <20 ng/ml
Group II – Sufficient Vitamin D; 25(OH)D level ≥20 ng/ml.

Biochemical analysis Serum 25(OH)D levels were measured using a commercially available radioimmunoassay kit with intra- and inter-assay coefficients of variation of 5.0% and 7.3%, respectively. Hormonal levels of luteinising hormone and follicle-stimulating hormone were determined using chemiluminescent microparticle immunoassay. Fasting insulin was assessed using radio-immunologically kits. Fasting glucose, total cholesterol, HDL-cholesterol, LDL-cholesterol and TGs were measured by routine methods. Statistical analysis The data were entered in MS Excel spreadsheet and analysis was done using Statistical Package for Social Sciences version 21.0 (Chicago, USA). Data were presented as mean with standard deviation. Independent t-test was used to compare the data between the groups. Pearson's correlation was used to find the association between 25(OH)D and other clinical parameters. A two-tailed P < 0.05 was considered statistically significant.

Results

Ninety-four women were assessed for eligibility during the study period, but nine cases were excluded owing to incomplete data entry and lack of pelvic ultrasound. Hence, the study sample included a total of 85 women with PCOS [Figure 1].

Figure 1: Patient flow diagram

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[Table 1] shows the baseline characteristics of the study population. The mean age in the study sample was 23.34 ± 4.587 years. Approximately 50.58% of the cases had WC ≥80 cm; HDL <50 mg/dl was noted in 98.82%; high TGs in 3.52%; blood pressure ≥140/90 mmHg in 4.70% and 10.58% showed high FBG levels. The mean Vitamin D levels and HOMA-IR in the study cohort were 21.28 ± 5.79 and 3.35 ± 10.14, respectively.

Table 1: Baseline characteristics of the study population

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More than half of the study sample (n = 51) had sufficient Vitamin D levels and 40% (n = 34) were Vitamin D deficient. In the Vitamin D-deficient group, the frequency of underweight, normal, overweight and obese women was 8.8% (n = 3), 23.5% (n = 8), 14.7% (n = 5) and 52.9% (n = 18), respectively, whereas the frequency of underweight, normal, overweight and obese women in Group II was 9.8% (n = 5), 31.4% (n = 16), 13.7% (n = 7) and 45.1% (n = 23), respectively [Figure 2].

Figure 2: Prevalence of hypovitaminosis according to body weight

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[Table 2] lists the anthropometric and biochemical parameters of the study sample. The Vitamin D-deficient group was comparable with the sufficient group in terms of anthropometric and biochemical parameters, except fasting serum insulin levels, which were in fact lower in the Vitamin D-deficient group as compared to that of Vitamin D-sufficient group.

Table 2: Characteristics of participants based on serum 25-hydroxy vitamin D concentrations

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[Table 3] shows univariate correlation analysis between 25(OH)D and clinical and biochemical parameters. None of the parameters showed any significant correlation with Vitamin D.

Table 3: Correlation between Vitamin D and metabolic parameters

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Discussion

Vitamin D deficiency is linked to several chronic diseases such as Type 2 diabetes; cardiovascular, autoimmune and infectious diseases; malignancies; depression and chronic pain.^[9] The Institute of Medicine establishes serum 25(OH)D level of 20 ng/ml and above as normal, whereas the Endocrine Society categorises levels as deficiency, insufficiency and sufficiency if 25(OH)D levels are below 20 ng/ml (50 nmol/L), 21–29 ng/ml (52.5–72.5 nmol/L) and 30–100 ng/ml (75–250 nmol/L), respectively.^[10],[11] Nearly one-third of studies from all over the world had Vitamin D level <20 ng/ml (50 nmol/L) as per a recent systematic review.^[12] Interestingly, even though India is a hot country with abundant sunshine, the prevalence of Vitamin D deficiency is almost 70%–90% across all age groups.^[13],[14] In our study, the proportion of Vitamin D deficiency was 40% in PCOS women. Worldwide, the deficiency of this vitamin is quite common, with data suggesting levels of Vitamin D being lower than 20 ng/ml in 10%–60% of adults.^[15] Wehr et al. in their study observed 72.8% of Vitamin D deficiency in PCOS women, however their study did not have a control group.^[16] However, their limit for insufficient Vitamin D levels was <30 ng/ml. Similarly, in our study, if we take the cut-off for deficient Vitamin D level as 30 ng/ml, only five women (5.88%) would be within normal range and the remaining 94.11% would be deficient. In another study by the same group, low levels of Vitamin D (25.7 ng/ml vs. 32 ng/ml) were observed in 545 PCOS women compared to 145 women without PCOS.^[17] Our data suggest that deficiency of this vitamin is quite high in PCOS women, necessitating the need for replacement therapy. In two meta-analyses comprising 47 studies investigating the effect of Vitamin D on clinical and biochemical parameters in women with PCOS, the authors reported an inverse relationship between Vitamin D and HOMA-IR.^[18],[19] In the present study, the Vitamin D-deficient group was comparable with the sufficient group in terms of anthropometric and biochemical parameters, except fasting serum insulin levels, which were in fact lower in the Vitamin D-deficient group as compared to that of Vitamin D-sufficient group. An inverse relationship between Vitamin D levels and BMI has been well documented in literature, however a cause-and-effect relationship is unclear. Obesity is an independent factor for low levels of this fat-soluble vitamin, and sequestration of this vitamin in adipose tissue is proposed as a mechanism for low circulating levels of Vitamin D in overweight and obese women.^[20] However, in our study, no statistically significant relation was noted with anthropometric and metabolic parameters, similar to that seen by Kumar et al.^[21] A striking feature of our study was presence of IR in almost 100% of cases, similar to that seen by Kumar et al.^[21] Interestingly, the HOMA-IR was higher in Group II as compared to Group I. This could probably be attributed to the lower cut-off level of deficiency in our sample. A recent meta-analysis has revealed that Vitamin D supplementation is known to reduce IR and hyperandrogenism with improvements in lipid metabolism.^[22] Though no significant correlation was seen in terms of clinical and biochemical profile of PCOS cases in our study, still considering a high proportion of such women to be Vitamin D deficient, we suggest the need to screen them and treat them for deficiency. There is a need to effectively treat this special group with suitable dose and duration of Vitamin D supplementation to correlate the clinical and metabolic improvements. The main limitation of this study was small sample size and cross-sectional design. Even though we treated the deficient group of females with Vitamin D supplementation, we did not follow them up to analyse the effects on metabolic and anthropometric measurements. Large-scale studies need to be undertaken in various parts of the world to determine the growing prevalence of Vitamin D deficiency in PCOS women. High-quality randomised controlled trials are necessary for assessing the effectiveness of Vitamin D screening with supplementation (when needed) to identify the potential biochemical and metabolic improvements.

Conclusion

Emerging data suggest that Vitamin D is not only critical in the maintenance of calcium homeostasis and bone health but also has a plausible role in reproductive physiology, overall well-being and health. There is a dearth of appropriately designed prospective interventional studies that comprehensively define the role of Vitamin D in women with PCOS. Our study did not identify any relation between Vitamin D levels with clinical and biochemical profile of patients with PCOS, so screening of PCOS patients for Vitamin D deficiency with the aim of improving PCOS symptoms is not recommended, but universal screening may be carried out due to the high prevalence of Vitamin D deficiency in women to prevent future adverse events. Vitamin D is recognised as a safe, accessible and easily administered vitamin that can prove cost-effective in improving symptoms relating to its deficiency in women with PCOS. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

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