Chest
Volume 111, Issue 3, March 1997, Pages 595-600
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Clinical Investigations: Infection
Laboratory Abnormalities in Patients With Bacterial Pneumonia

https://doi.org/10.1378/chest.111.3.595Get rights and content

Study objectives

This study was undertaken to evaluate the laboratory abnormalities observed in patients with bacterial pneumonia as predictors of the severity of illness.

Design

Retrospective analysis.

Setting

Tertiary care hospital.

Patients and participants

We studied 302 consecutive patients who were admitted to the Long Island Jewish Medical Center from January through December 1993 and treated for bacterial pneumonia. The patients were subdivided into two groups based on their serum phosphorus level either on hospital admission or 4 days before the onset of pneumonia, if this was acquired in-hospital. Hypophosphatemia (group 1) was defined as serum phosphorus level of ≤2.4 mg/dL and normophosphatemia >2.4 mg/dL (group 2). Three hundred randomly selected hospitalized patients treated for conditions other than pneumonia comprised the control group (group 3).

Measurements

Groups 1 and 2 were compared with respect to laboratory data, mortality rate, and duration of hospitalization. The laboratory data of patients in group 3 were compared with those treated for bacterial pneumonia (groups 1 and 2). Stepwise multivariate logistic regression analysis was employed to identify the variables that best predicted the onset of pneumonia.

Results

In groups 1 and 2, a greater (p<0.0001) number of patients (135 of 302 patients with pneumonia, 44.7%) developed hypophosphatemia compared with patients in group 3 (31 of 300 control subjects, 10.3%). Patients with pneumonia (groups 1 and 2) had higher levels (p<0.01) of bicarbonate compared with control subjects. Moreover, patients with pneumonia demonstrated lower levels (p<0.01) of calcium, phosphorus, albumin, cholesterol, and alanine aminotransferase compared with control patients (group 3). Among patients with pneumonia, those with hypophosphatemia (group 1) had significantly lower levels (p<0.05) of potassium, calcium, and albumin compared to those subjects with normophosphatemia (group 2). Furthermore, hypophosphatemic subjects manifested higher levels of glucose (p<0.01) and creatine phosphokinase (p<0.05) compared to their normophosphatemic counterparts. In addition, hypophosphatemic patients experienced a longer duration of hospital stay (hypophosphatemia, 24.6 ± 2.0 days, vs normophosphatemia, 14.1 ± 1.0, p<0.001) and higher (p<0.001) mortality compared to normophosphatemic subjects. The incidence of nosocomial pneumonia was higher (p<0.0001) in hypophosphatemic patients compared to those with normophosphatemia.

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.

Section snippets

MATERIALS AND METHODS

We reviewed the medical records of 353 consecutive patients admitted to Long Island Jewish Medical Center, New Hyde Park, NY, from January 1, 1993 through December 31, 1993, who had bacterial pneumonia as their discharge diagnosis. Of these, 302 patients had documented evidence of bacterial pneumonia, based on chest radiographic evidence of infiltrate with or without positive sputum culture. All of them had at least one full blood chemistry panel drawn at the time of hospital admission.

RESULTS

The total medical admissions to the Long Island Jewish Medical Center over a 3-month period included 7,994 patients. Of these, 640 had documented hypophosphatemia at admission or some time during their hospital stay (8%). In the control group of 300 patients, 31 had documented hypophosphatemia (10.3%). Among 302 patients with a discharge diagnosis of bacterial pneumonia, 135 patients had documented hypophosphatemia (44.7%) (p<0.0001 compared to all hospitalized patients and control group). The

DISCUSSION

The elderly ambulatory patient who comes to the emergency department with fever is very likely to have a serious pneumonia and in most instances will require hospitalization.21 Even in young, healthy naval personnel, pneumonia has been found to be the major medical cause of lost workdays.22 Although in western countries pneumonia has been replaced by more chronic pulmonary disorders as the chief cause of respiratory death, it still remains a very important cause of mortality in the United

CONCLUSION

We conclude that laboratory abnormalities, especially hypophosphatemia, may be a significant risk factor predicting the severity of the underlying illness in hospitalized patients with bacterial pneumonia.

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    Reprint requests: Dr. Singhal, Division of Nephrology, Room 228, Long Island Jewish Medical Center, New Hyde Park, NY 11040

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