Thrombocytosis as an additional predictor of serious bacterial infection in febrile young infants

Merin Eapen, Sreelatha P. R., Jayakumar C.


Background: To estimate the incidence of Reactive Thrombocytosis among febrile young infants and to assess the utility of platelet count as a potential predictor of Serious bacterial infection (SBI).

Methods: This study was conducted as a prospective study between January 2014 to September 2015 at the tertiary care pediatric unit, Alappuzha, India. The participants were all infants 30 to 89 days of age, admitted with rectal temperature >38°C. The results of the sepsis evaluation on admission were recorded. SBI included cases of occult bacteremia, urinary tract infection, bacterial meningitis, pneumonia, bacterial gastroenteritis and infections of the soft tissues and bones.

Results: Of the 120 infants studied, 24 (28%) had SBI. Platelet count was significantly higher in infants with SBI compared to those without {Platelet count ≥ 4.5lakhs /mm3 in SBI (70.3%) vs. Non SBI (30.2%). Mean platelet count 4.82±1.4 in SBI vs. 3.9±1.2 in non SBI which was statistically significant (p<0.05). Thrombocytosis had moderate ability in predicting SBI (Area under curve area under the curve: 0.720). The combination of platelet count ≥450,000/mm3, WBC ≥15,000/mm3, C-reactive protein ≥1 mg/dl, pyuria ≥5 White blood cells (WBC) per High power field (HPF) and erythrocyte sedimentation rate (ESR) >30mm/hr resulted in identification of all infants with SBI.

Conclusions: Thrombocytosis in combination with leukocytosis, elevated C-reactive protein, ESR, and pyuria, may help in early recognition of febrile young infants at risk for SBI. 


Diagnosis, Fever, Infants, Serious bacterial infection, Thrombocytosis

Full Text:



Slater M, Krug SE. Evaluation of the infant with fever without source: An evidence based approach. Emerg Med Clin North Am. 1999;17:97-126.

Isaacman DJ, Shults J, Gross TK, Davis PH, Harper M. Predictors of bacteremia in febrile infants 3 to 36 months of age. Pediatr. 2000;106:977-82.

Trautner BW, Chantal Caviness A. Prospective evaluation of the risk of serious bacterial infection in children who present to the emergency department with hyperpyrexia. Pediatr. 2006;118(1):34-40.

Bleeker SE, Moons KGM, Lubsen DG. Predicting serious bacterial infection in young children with fever without apparent source. Acta Pediatrica. 2001;90(11):1226-31.

Fouzas S, Mantagou L, Skylogianni E. Thrombocytosis as a Predictor of Serious Bacterial Infection. Indian Pediatr. 2011;47(11):937-43.

Hsiao, Allen L, Baker, Douglas M. Fever in the new millennium a review of recent studies of markers of serious bacterial infection in febrile children. Pediatrics. 2005;17:56-61.

Regui O, Hernandez U, Munoz JA, Emparanza JI, Landa JJ. Markers that predict serious bacterial infection under 3 months of age presenting with fever of unknown origin. Arch Dis Childhood. 2009;94:501-5.

Heng JT, Tan AM. Thrombocytosis in childhood. Singapore Med J. 1998;39:485-7.

Hoberman A, Wald ER. Urinary tract infections in young febrile children. Pediatr Infect Dis J. 1997;16:11-7.

Bachur R, Perry H, Harper M. Occult pneumonias: empiric chest radiographs in febrile children with leukocytosis. Ann Emerg Med. 1999;33:166-73.

Prober CG, Dyner L Acute bacterial meningitis beyond the neonatal period In: Kliegman RM, Stanton BF, Schor NF, St. Geme JW, Behrman RE, eds. Nelson Textbook Of Pediatrics 19th ed. New Delhi: Reed Elsevier; 2013:2087-2095.

Mantadakis E, Tsalkidis A, Chatzimichael A. Thrombocytosis in childhood. Indian Pediatr. 2008;45:669-77.

Dodig S, Raos M, Kovac K, Nogalo B, Benko B, Glojnaric I, et al. Thrombopoietin and interleukin-6 in children with pneumonia-associated thrombocytosis. Arch Med Res. 2005;36:124-8.

Matsubara K, Fukaya T, Nigami H, Harigaya H, Hirata T, Nozaki H, et al. Age-dependent changes in the incidence and etiology of childhood thrombocytosis. Acta Haematol. 2004;111:132-7.

Dame C, Sutor AH. Primary and secondary thrombocytosis in childhood. Br J Haematol. 2005;129:165-77.

O’Shea J, Sherlock M, Philip R. Thrombocytosis in childhood. Acta Haematol. 2005;113:212.