Background: Polycystic Ovarian Syndrome (PCOS) is a prevalent endocrine disorder in women of reproductive age, characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. Emerging evidence suggests a potential role of vitamin D in modulating reproductive and metabolic functions. This study aims to evaluate the association between serum vitamin D levels and patients diagnosed with PCOS. Materials and Methods: A cross-sectional study was conducted over six months involving 100 women aged 18–35 years. Fifty women diagnosed with PCOS based on the Rotterdam criteria formed the study group, while fifty age- and BMI-matched healthy women served as controls. Blood samples were collected to assess serum 25-hydroxyvitamin D [25(OH)D] levels using chemiluminescent immunoassay. Clinical features including body mass index (BMI), menstrual irregularities, acne, and hirsutism were recorded. Statistical analysis was performed using SPSS v25, with significance set at p < 0.05. Results: The mean serum vitamin D level in the PCOS group was 14.2 ± 4.8 ng/mL, significantly lower than the control group (22.5 ± 5.1 ng/mL) (p < 0.001). Among PCOS patients, 76% had vitamin D deficiency (<20 ng/mL), compared to 38% in the control group. A significant inverse correlation was observed between serum vitamin D levels and BMI (r = -0.52, p = 0.003) and Ferriman-Gallwey score (r = -0.46, p = 0.007) in the PCOS group. Conclusion: The findings indicate that women with PCOS are more likely to have lower serum vitamin D levels, which may contribute to the severity of clinical manifestations. Vitamin D assessment and correction may play a supportive role in the management of PCOS.
Polycystic Ovarian Syndrome (PCOS) is a multifactorial endocrine disorder affecting approximately 6–15% of women of reproductive age and is a leading cause of infertility due to anovulation (1). It is characterized by a constellation of symptoms including oligo/anovulation, clinical or biochemical hyperandrogenism, and polycystic ovarian morphology on ultrasonography, as defined by the Rotterdam criteria (2). In addition to reproductive dysfunction, PCOS is often associated with metabolic disturbances such as insulin resistance, obesity, dyslipidemia, and an increased risk for type 2 diabetes mellitus and cardiovascular disease (3,4).
Recent research has explored the role of micronutrients, particularly vitamin D, in the pathophysiology of PCOS. Vitamin D, a fat-soluble secosteroid hormone, is known to influence various metabolic and reproductive processes, including insulin secretion, inflammatory response, and ovarian follicular development (5). Vitamin D receptors are expressed in multiple reproductive tissues such as the ovaries, endometrium, and placenta, indicating its potential regulatory role in female fertility (6). Hypovitaminosis D has been linked with several features of PCOS, including hyperandrogenism, menstrual irregularities, and insulin resistance (7,8).
Despite growing evidence, the exact relationship between serum vitamin D levels and PCOS remains controversial and understudied in specific populations. Some studies have shown a significant deficiency of vitamin D in PCOS women compared to healthy controls, whereas others suggest that low vitamin D may be more closely related to obesity or insulin resistance, rather than PCOS per se (9,10). Given these inconsistencies, further investigation is warranted to clarify the association between serum vitamin D levels and clinical features of PCOS. This study aims to evaluate and compare serum vitamin D levels in women with PCOS and healthy controls and explore the correlation of vitamin D with metabolic and clinical parameters in PCOS patients.
A total of 100 women aged between 18 and 35 years were included in the study. Fifty women diagnosed with polycystic ovarian syndrome (PCOS) according to the Rotterdam criteria (presence of at least two of the following: oligo/anovulation, clinical/biochemical signs of hyperandrogenism, and polycystic ovarian morphology on ultrasound) constituted the study group. Fifty age- and body mass index (BMI)-matched healthy women with regular menstrual cycles and no signs of hyperandrogenism served as the control group.
Detailed clinical evaluation was performed for all participants, including recording of demographic data, menstrual history, presence of acne, hirsutism (assessed using the modified Ferriman-Gallwey score), and BMI measurement. Fasting blood samples were collected from each participant during the early follicular phase (days 2–5 of the menstrual cycle) for biochemical analysis.
Serum levels of 25-hydroxyvitamin D [25(OH)D] were measured using a chemiluminescence immunoassay. Vitamin D status was classified as sufficient (>30 ng/mL), insufficient (20–30 ng/mL), or deficient (<20 ng/mL). Additional parameters such as fasting blood glucose and insulin levels were also measured to assess metabolic status.
Statistical analysis was performed using SPSS version 25. Data were expressed as mean ± standard deviation (SD). Comparisons between the two groups were made using the independent t-test for continuous variables and the chi-square test for categorical variables. Pearson’s correlation coefficient was used to analyze the relationship between vitamin D levels and clinical features. A p-value less than 0.05 was considered statistically significant.
The study included 100 women, with 50 participants in the PCOS group and 50 in the control group. The mean age of the PCOS group was 24.8 ± 3.5 years, while that of the control group was 25.1 ± 3.1 years (p = 0.68). The body mass index (BMI) was significantly higher in the PCOS group (27.4 ± 2.9 kg/m²) compared to the control group (23.2 ± 2.4 kg/m²; p < 0.001) (Table 1).
The mean serum 25(OH)D level in women with PCOS was 14.2 ± 4.8 ng/mL, which was significantly lower than the control group (22.5 ± 5.1 ng/mL; p < 0.001). Vitamin D deficiency (<20 ng/mL) was observed in 76% of the PCOS group and in 38% of the control group (Table 2). The distribution of vitamin D status between groups showed a statistically significant difference (p < 0.001).
A correlation analysis revealed a significant inverse relationship between serum vitamin D levels and BMI (r = -0.52, p = 0.003) as well as the Ferriman-Gallwey hirsutism score (r = -0.46, p = 0.007) among PCOS participants. Additionally, serum vitamin D levels were positively correlated with menstrual cycle regularity scores (r = 0.41, p = 0.012) (Table 3).
These findings support a strong association between low vitamin D levels and clinical severity in PCOS patients, including obesity and hirsutism (Tables 2 and 3).
Table 1. Baseline Demographic Characteristics of Study Participants
Parameter |
PCOS Group (n=50) |
Control Group (n=50) |
p-value |
Age (years) |
24.8 ± 3.5 |
25.1 ± 3.1 |
0.68 |
BMI (kg/m²) |
27.4 ± 2.9 |
23.2 ± 2.4 |
<0.001 |
Ferriman-Gallwey Score |
14.6 ± 3.2 |
6.1 ± 2.4 |
<0.001 |
Table 2. Comparison of Serum Vitamin D Status Between Groups
Vitamin D Status |
PCOS Group (n=50) |
Control Group (n=50) |
p-value |
Deficient (<20 ng/mL) |
38 (76%) |
19 (38%) |
<0.001 |
Insufficient (20–30) |
10 (20%) |
21 (42%) |
|
Sufficient (>30) |
2 (4%) |
10 (20%) |
|
Mean Vitamin D (ng/mL) |
14.2 ± 4.8 |
22.5 ± 5.1 |
<0.001 |
Table 3. Correlation of Serum Vitamin D with Clinical Parameters in PCOS Group
Parameter |
Correlation Coefficient (r) |
p-value |
BMI |
-0.52 |
0.003 |
Ferriman-Gallwey Score |
-0.46 |
0.007 |
Menstrual Regularity Score |
+0.41 |
0.012 |
As shown in Table 1, patients with PCOS had significantly higher BMI and hirsutism scores. Table 2 highlights a marked prevalence of vitamin D deficiency in the PCOS group. Correlation results in Table 3 suggest that lower vitamin D levels are associated with worsening clinical parameters in PCOS.
The present study evaluated the relationship between serum vitamin D levels and women diagnosed with Polycystic Ovarian Syndrome (PCOS), revealing a significant deficiency of vitamin D in the PCOS group compared to healthy controls. These findings are consistent with several prior studies that have established a high prevalence of hypovitaminosis D in women with PCOS, suggesting a possible role of vitamin D in the pathogenesis and clinical expression of the disorder (1,2).
Vitamin D plays an important role in glucose homeostasis, insulin sensitivity, and regulation of inflammatory pathways, which are often altered in PCOS patients (3). The vitamin D receptor (VDR) is expressed in the ovaries, endometrium, and other reproductive tissues, indicating that vitamin D may influence follicular development, ovulatory function, and steroidogenesis (4,5). In our study, the inverse correlation between vitamin D levels and BMI is in agreement with earlier observations that obesity contributes to reduced bioavailability of vitamin D due to its sequestration in adipose tissue (6). Similar associations between low vitamin D and higher Ferriman-Gallwey scores reflect its possible role in the modulation of androgen activity and hair follicle physiology (7,8).
Multiple mechanisms have been proposed to explain the link between vitamin D deficiency and the metabolic and endocrine features of PCOS. Vitamin D deficiency has been shown to impair insulin receptor expression and β-cell function, contributing to insulin resistance, a hallmark of PCOS (9). Studies have also found that vitamin D supplementation improves menstrual regularity and insulin sensitivity in PCOS women, further supporting its therapeutic relevance (10,11). Furthermore, a deficiency of vitamin D may exacerbate the inflammatory milieu associated with PCOS by increasing levels of cytokines like TNF-α and IL-6, which may in turn worsen insulin resistance and ovarian dysfunction (12,13).
Our findings also resonate with reports from other geographic regions. A study conducted in Iran found that 72% of PCOS women were vitamin D deficient, and their deficiency was significantly associated with elevated androgen levels (14). Another cross-sectional study in India reported that over 80% of PCOS women had serum 25(OH)D levels below 20 ng/mL, paralleling our observation of 76% deficiency in the PCOS group (15).
However, certain limitations should be acknowledged. Being a cross-sectional study, causality between vitamin D deficiency and PCOS cannot be established. Additionally, the relatively small sample size and lack of follow-up data on the effect of vitamin D supplementation limit the generalizability of the findings. Despite these limitations, the results highlight the need for routine screening and possible correction of vitamin D levels as part of PCOS management strategies.
Future longitudinal and interventional studies are required to establish the mechanistic role of vitamin D in PCOS and to determine whether supplementation can yield consistent clinical benefits across various phenotypes of the syndrome.
This study demonstrates a significant association between low serum vitamin D levels and Polycystic Ovary Syndrome. Women with PCOS exhibited higher rates of vitamin D deficiency, which correlated with increased BMI, hirsutism, and menstrual irregularities. These findings suggest that vitamin D may play a role in the pathophysiology and clinical severity of PCOS, highlighting the potential benefit of routine screening and correction of vitamin D levels in its management.