Assessment of serum calcium, phosphorus, creactive protein and procalcitonin in tuberculosis patients

Introduction: Procalcitonin (PCT), a 116 amino acid is the prohormone precursor of calcitonin, is expressed primarily in C-cells of the thyroid gland and to a smaller extent in neuroendocrine tissue of other organs, such as lungs and intestines. PCT is a marker of inflammatory response to infection. C-reactive protein (CRP) is a widely used marker for diagnosis of infections. Objective: The purpose of our study was to assess the levels of serum PCT, CRP, calcium and phosphorus in patients with pulmonary tuberculosis. Method: Forty patients diagnosed with tuberculosis were recruited from The Institute of Thoracic Medicine, Chennai, India and compared with age- and sex-matched healthy volunteers (n=40). Serum procalcitonin concentration was analyzed using semi-quantitative PCT-Q kit (B.R.A.H.M.S Diagnostica GmBH, Germany). According to standard procedures, CRP level was determined by immunoturbidimetic assay, calcium and phosphorus by photometric Arsenazo III and phosphomolybdate methods respectively. Results: Levels of PCT in 27 out of 40 healthy volunteers was <0.5 ng/dl, 3 showing >2 ng/dl. However, 15 out of 40 patients had PCT >2 ng/dl and 25 had PCT>10 ng/dl. CRP levels was significantly elevated in TB patients (p<0.001); Calcium and phosphorus were significantly decreased (p<0.001and p<0.01 respectively) when compared to healthy volunteers. Conclusion: Several studies have reported that PCT values were not significantly elevated in TB patients, the contrary results in this study calls for further research on PCT in TB based on the differences in severity of the disease.