European Journal of Cardiovascular Medicine

Metabolic syndrome (MetS) is a major public health burden affecting nearly a quarter of world’s population ^[1]. The syndrome is associated with a 5-fold higher risk of developing type-2 diabetes mellitus (T₂DM) ^[2] and 2 to 3-fold higher risk of developing cardiovascular diseases ^[3].

Prevalence of MetS in India is around 33.5% (24.9% in males, 43.2% in females). Increasing prevalence of metabolic syndrome may be due to changes in nutrition, physical inactivity, rural to urban migration and increasing obesity ^[4].

According to NCEP ATP III criteria, MetS is diagnosed when any three out of five criteria are met: 1) Elevated waist circumference (WC) (with ethnicity specific values for South Asians) ≥90 cm in males and ≥80 cm in females, 2) Increased serum triglycerides (TG) ≥150 mg/dl, 3) Reduced serum high density lipoprotein cholesterol (HDL-C) <40 mg/dl in men and <50 mg/dl in women, 4) Increased blood pressure (≥130 bpm systolic, ≥85 bpm diastolic) or on antihypertensive in a patient with history of hypertension, 5) Impaired fasting glucose (FBS) ≥100 mg/dl or on drug treatment for elevated glucose ^[5-7].

Osteocalcin (OCN), a 49 amino acid osteoblast derived protein, formed in bone and stored in bone matrix and found in low concentrations in the circulation ^[8]. It acts as a hormone stimulating insulin secretion, insulin sensitivity and energy expenditure. A low level of serum OCN is found to associated with MetS that is characteristic of persistent low grade systemic inflammation ^[9].

MetS patients tend to have more adipose tissue, leading to excess production of proinflammatory cytokine like high sensitivity C-reactive protein (hs-CRP), secreted by monocyte derived macrophages in adipose tissues ^[10].

The aim of the current study is to determine the association of serum osteocalcin with MetS and to assess its correlation with hs-CRP.

• Study Population:Patients with MetS as cases and age and sex matched healthy individuals as controls.
• Study Design:a hospital-based case-control study
• Study Place:department of Biochemistry, VIMSAR, Burla, Sambalpur, Odisha
• Study Duration:Jan 2023-Dec 2023
• Sample Size: Sample size (n) was calculated using the formula

 n= (Zα+Zβ)² (SD)²/(Mean Differences)²

 Zα= The probability of falsely rejecting a true null hypothesis

 Zβ= The probability of failing to reject a false null hypothesis

 Confidence interval – 95%

 Power of study – 80%

The sample size was calculated to be 50.

• Inclusion Criteria:Patients between the age group of 25-60 years with MetS according to NCEP ATP III Criteria as cases and age and sex matched healthy individuals as controls.

• Exclusion Criteria: Pregnant females, lactating mothers and post-menopausal women and individuals with autoimmune diseases, systemic infections and cancers or on medications like- OCPs, antilipidemic drugs, antihypertensives, anti-inflammatory drugs, oral hypoglycemic agents, bisphosphonates, insulin, calcium supplements

• Study Techniques:After taking written informed consent, all the study participants underwent physical examination and then biochemical parameters are investigated.
• Physical Examinations:Height was measured using stadiometer, weight was measured using digital weighing machine, WC was measured using soft measuring tape on standing subjects midway between the lowest rib and superior border of iliac crest, blood pressure was measured in supine position using sphygmomanometer and BMI was calculated as {weight (kg)}/ {height (m)}²

• Biochemical Examination:Blood samples were collected under aseptic precautions after an overnight fasting. Fasting blood sugar, lipid profile (serum total cholesterol, serum triglyceride, serum HDL) and hs-CRP were assayedby enzymatic kit method in Roche Cobas-311 and serum osteocalcin was estimated by Enzyme-linked Immunosorbent Assay (ELISA) LISA SCAN READER.

STATISTICAL ANALYSIS

The statistical analysis was done using SPSS version 26.0. Descriptive analysis was done to compare the baseline characteristics between cases and controls. Continuous variables were reported as means with standard deviations (SD). Differences between groups were analysed with independent samples t-test for normally distributed continuous variables. Association of various components of MetS with serum osteocalcin was found and p-value was also found. The p-value ≤ 0.05 was considered significant. Pearson correlation of various components of MetS with serum osteocalcin was analysed and represented graphically in form of scatter plots.

The study was done to evaluate the serum osteocalcin in MetS, was carried out in total of 100 subjects, of which 50 with MetS were taken as cases and 50 healthy individuals as controls. The mean±SD values of BMI, WC, systolic and diastolic blood pressure, fasting blood sugar, serum total cholesterol, serum triglyceride and serum hs-CRP were found to be statistically significantly higher in cases of MetS as compared to healthy controls. But, the mean±SD of serum HDL and serum osteocalcin were found to be lower in cases as compared to controls and were statistically significant [Table/Fig-1]. Pearson correlation of various parameters of MetS with serum osteocalcin are shown in table/fig-4. Serum osteocalcin was found to be negatively correlated with all the parameters except for serum HDL which is positively correlated with serum osteocalcin in both cases and controls.

In the present study, serum osteocalcin level was found to be lower in MetS cases as compared to healthy controls and was statistically significant. These results are similar to the findings of other studies by Ayesha A. et al ^[4] and Tan A. et al ^[11].

Waist circumference was found to be significantly higher in cases as compared to controls having a negative correlation with serum osteocalcin.

In the present study higher values of both systolic blood pressure (SBP) and diastolic blood pressure (DBP) were found in cases of MetS with a statistically significant negative correlation with serum osteocalcin.

The mean of serum osteocalcin (ng/dl) levels were 6.17±2.18 and 20.62±4.77 in cases and controls, respectively. These results were in agreement with previous studies by Ayesha A. et al ^[4]., Tan A. et al ^[11].

In our study, serum osteocalcin is negatively correlated with all the compnents of MetS (WC, blood pressure, FBS, TG) except for HDL, which is positively correlated and was found to be statistically significant.

In the present study, serum hs-CRP showed a significant, positive relationship with MetS. But serum osteocalcin concentration was found to be significantly negatively correlated with hs-CRP in only MetS cases and not in controls.

MetS is not a disease by definition; rather it is a predictor of cardiovascular disease risk. Therefore, a diagnosis of MetS could be expected to predict the risks and prevent diseases, particularly cardiovascular disease and diabetes. In our study, serum osteocalcin shows negative correlation and hs-CRP shows positive correlation in MetS. Serum osteocalcin and hs-CRP was found to be negatively correlatd. Further large scale multicentric study is required to throw more light on this topic. In future, serum osteocalcin and hs-CRP may be used as potential diagnostic marker for early detection of MetS.