Background: Thrombocytopenia has been recognized as an important manifestation of acute febrile illness caused by various types of. Early diagnosis of aetiology is very important to reduce morbidity and mortality. This study was planned to evaluate clinical profile, aetiology, differential diagnosis, clinical course and outcome of such patients.

Methods: Present prospective cross-sectional study was conducted on 400 consecutive patients of fever with thrombocytopenia admitted during 1st May 2022 to 31st October 2022 in the Department of Medicine, S.P. Medical College & Associated Group of P.B.M. Hospitals, Bikaner. All patients were evaluated as per proforma including detail clinical history and physical examination. Laboratory evaluation including CBC, RFT, LFT, blood sugar, LDH, Rapid diagnostic test for malaria, PBF for MP, test for dengue, HBsAg, Anti HCV, HIV, PBF detail, Blood culture, D–dimer, test for Scrub typhus and leptospirosis, Ultrasonography and chest X-Ray was done in all cases. Other investigations were done as per requirement. All patients were treated as per guidelines and followed-up during hospitalization.

Results: Out of 400 patients 227 were males (age ranging 15-87 years, mean 35.46 ±15.63) and 173 females (age ranging 15-92 years, mean 39.75 ± 17.36). Dengue fever was found to be the commonest cause (29.5%) followed by Malaria, COVID-19 infection (0.75%) and one each HIV and Hepatitis B. In 54.25% of the cases definite etiological diagnosis could not be ascertained. 14.25% patients were having life threatening thrombocytopenia, 45% severe grade, 21.75% moderate and 19% mild thrombocytopenia. Severity of thrombocytopenia was associated with longer duration of illness (p<0.02). Bleeding manifestations were observed in 5.75% but did not corelated with severity of thrombocytopenia. Mean duration of hospital stay was found to be inversely proportion to total platelet count on admission.

Conclusion: Acute Febrile illness patients should be investigated for platelet count irrespective of the bleeding manifestations as decreased platelet count could be severe without external manifestations and could be an indicator of bad prognosis.