Correlation of leucocyte count and erythrocyte sedimentation rate with the day of illness in presumed bacterial pneumonia of childhood.

We investigated the effect of the duration of illness on the white blood cell (WBC) and total neutrophil counts and the erythrocyte sedimentation rate (ESR) in untreated children with clinical and roentgenographic findings compatible with bacterial pneumonia. According to the duration of illness before admission, the patients were divided into: Group I, 48 patients ill for < 24 h; Group II, 39 patients ill for 24-48 h; Group III, 21 patients ill for 48-72 h; and Group IV, eight patients ill for 72-96 h. In children with presumably bacterial pneumonia the number of the WBC was greater during the first 2 days of illness. Thereafter, the leucocyte count declined, reaching the lowest levels on the fourth day. A similar course was followed by the absolute number of total neutrophils. During the second day of illness, 92% and 72% of the patients had leucocyte counts > 10,000 and > 15,000/mm3, respectively, whereas on the fourth day of illness only half of the patients had > 10,000 and one-quarter > 15,000 WBC/mm3. The ESR followed an opposite course to that of the WBC. During the first day of illness it was normal or mildly elevated, increasing steadily thereafter. The validity of the WBC and total neutrophil counts in conjunction with the ESR in the evaluation of bacterial pneumonia is augmented when the day of illness is taken into consideration.