procalcitonin as a biomarker of bacterial infection in sickle cell vaso-occlusive crisis.

Bacterial infection is an important trigger of vaso-occlusive crisis (VOC) in sickle cell anaemia (SCA). SCA Patients with VOC have signs of inflammation and it is difficult to diagnose bacterial infection in them. This study was undertaken to evaluate serum procalcitonin (PCT) as a biomarker of bacterial infection in acute sickle cell vaso-occlusive crisis. Hundred SCA patients were studied at Sickle Cell Clinic and Molecular Biology Laboratory, V.S.S. Medical College, Burla, Odisha, India. SCA was diagnosed by haemoglobin electrophoresis, HPLC and molecular analysis. Patients were divided into 3categories namely Category-A (VOC/ACS with fever but without evidence of bacterial infection-66 patients); Category-B (VOC with fever and documentedbacterial infection-24 patients); and Category-C (Patients in steady statewithout VOC/ACS or fever-10 patients). Investigations like complete blood count, C-reactive protein estimation and PCT measurement was done in all the cases. There was no significant difference in total leucocytes count and C-reactiveprotein values between category A and B. In category A the PCT level was <0.5ng/mL in 83.3% and 0.5-2ng/mL in 16.7% of cases. In category B all the cases had PCT value >0.5ng/mL with 87.5% of cases having >2ng/mL. In category C, PCT value was <0.5ng/mL.  The PCTvalue differed significantly (p<0.0001) in three categories. PCT had a highsensitivity (100%) and negative predictive value (100%) for bacterial infection at a cut-off value of 0.5ng/mL; whereas the specificity is excellent at a cutoff value of 2ng/mL. SCA patients with VOC/ACS with fever presenting with a PCT level of <0.5ng/mL do not have bacterial infection. In patients with VOC/ACS and fever, PCT value of >2ng/mL is indicative of bacterial infection necessitating antimicrobial therapy. Patients with indeterminate PCT value of0.5-2ng/mL, need a repeat PCT estimation or an empirical antibiotic therapyawaiting the availability of microbiological report as deemed necessary.