CORRELATION OF SERUM CALCIUM, PHOSPHATE, AND PARATHYROID HORMONE LEVELS IN OSTEOPOROSIS: A BIOCHEMICAL STUDY

Background: Osteoporosis is a metabolic disease of the bones, which is accompanied by a loss of bone mineral density and high risks of fractures. The most important bone remodeling regulators include calcium, phosphate and parathyroid hormone (PTH), and their imbalance contributes to the pathophysiology of the disease. the purpose of the study was to determine the relationship between serum calcium, phosphate, and pth in patients diagnosed with the osteoporosis. Methods: The cross-sectional study was carried out on 60 patients diagnosed with osteoporosis according to the criteria of the dual-energy X-ray absorptiometry (DEXA) scan (T-score ≤ -2.5) in the Department of diagnostic pathology between January 2023 and December 2023 at the University of Faisalabad TUF and PU Lahore. Age, sex and body mass index (BMI) were used as demographic variables. Venous blood samples in the fasting state were collected and assayed of the total serum calcium, phosphate and intact PTH was done using standardized automated biochemical assays. Bivariate relationships between variables were evaluated by means of Pearson correlation. Simple linear regression to assess the predictive value of serum calcium and phosphate on PTH levels was used. The SPSS version 26.0 was used to analyze data. Results: The mean age of the participants was 62.7 ± 8.6 years and 68 percent of them were female. The mean serum calcium was 8.4 ± 0.6 mg/dL, phosphate 3.2 ± 0.5 mg/dL, and PTH 78.5 ± 25.3 pg/mL. The correlation between serum calcium and PTH revealed that a significant negative correlation existed between the two variables (r = -0.49, p = 0.01), whereas the correlation between phosphate and PTH was negative but not significant (r = -0.31, p = 0.06). Linear regression analysis revealed that serum calcium was a significant predictor of PTH levels (β = –5.1, p = 0.002, R² = 0.24), meaning that about 24% of the PTH variance could be attributed to calcium. Phosphate was not found to be a predictor of PTH in the regression model (β = –2.8, p = 0.08). Conclusion: This study indicated that there is a considerable biochemical correlation between serum calcium and parathyroid hormone levels in osteoporotic patients, indicating there are compensatory changes in hormones to the disturbed calcium homeostasis. Observation of these indicators can improve the quality of diagnosis and guide the use of treatment in the management of osteoporosis.