LABORATORY ABNORMALITIES IN PATIENTS WITH BACTERIAL PNEUMONIA

Study objectives: This study was undertaken to evaluate the laboratory abnormalities observed in patients with bacterial pneumonia as predic tors of the severity of illness. Design: Retrospective analysis. Setti ng: Tertiary care hospital. Patients and participants: We studied 302 consecutive patients who were admitted to the Long Island Jewish Medic al Center from January through December 1993 and treated for bacterial pneumonia. The patients were subdivided into two groups based on thei r serum phosphorus level either on hospital admission or 4 days before the onset of pneumonia, if this was acquired in-hospital. Hypophospha temia (group 1) was defined as serum phosphorus level of less than or equal to 2.4 mg/dL and normophosphatemia >2.4 mg/dL (group 2). Three h undred randomly selected hospitalized patients treated for conditions other than pneumonia comprised the control group (group 3). Measuremen ts: Groups 1 and 2 were compared,vith respect to laboratory data, mort ality rate, and duration of hospitalization. The laboratory data of pa tients in group 3 were compared with those treated for bacterial pneum onia (groups 1 and 2). Stepwise multivariate logistic regression analy sis was employed to identify the variables that best predicted the ons et of pneumonia. Results: In groups 1 and 2, a greater (p<0.0001) numb er of patients (135 of 302 patients with pneumonia, 44.7%) developed h ypophosphatemia compared with patients in group 3 (31 of 300 control s ubjects, 10.3%). Patients with pneumonia (groups 1 and 2) had higher l evels (p<0.01) of bicarbonate compared with control subjects. Moreover , patients with pneumonia demonstrated lower levels (p<0.01) of calciu m, phosphorus, albumin, cholesterol, and alanine aminotransferase comp ared with control patients (group 3). Among patients with pneumonia, t hose with hypophosphatemia (group 1) had significantly lower levels (p <0.05) of potassium, calcium, and albumin compared to those subjects w ith normophosphatemia (group 2). Furthermore, hypophosphatemic subject s manifested higher levels of glucose (p<0.01) and creatine phosphokin ase (p<0.05) compared to their normophosphatemic counterparts. In addi tion, hypophosphatemic patients experienced a longer duration of hospi tal stay (hypophosphatemia, 24.6+/-2.0 days, vs normophosphatemia, 14. 1+/-1.0, p<0.001) and higher (p<0.001) mortality compared to normophos phatemic subjects. The incidence of nosocomial pneumonia was higher (p <0.0001) in hypophosphatemic patients compared to those with normophos phatemia. Conclusion: We conclude that hypophosphatemia, hypocalcemia, hypokalemia, and hypoalbuminemia may be predictors of the severity of illness in patients admitted to the hospital with bacterial pneumonia .