title: Serum indicators for the diagnosis of pneumocystis pneumonia.
abstract: BACKGROUND
  The diagnosis of pneumocystis pneumonia (PCP) is difficult because it requires microscopic examination to identify pneumocystis from induced sputum or BAL fluid.
  
  
  OBJECTIVE
  To evaluate the usefulness of four serum markers-lactate dehydrogenase (LDH), (1-->3) beta-D-glucan (beta-D-glucan), KL-6, and C-reactive protein (CRP)-in the diagnosis of PCP.
  
  
  METHODS
  Case-control retrospective study.
  
  
  METHODS
  We reviewed the medical records of 295 consecutive patients who underwent BAL for the diagnosis of PCP. Differential cell counts in BAL fluid and serum levels of LDH, beta-D-glucan, KL-6, and CRP were examined. Oxygenation index was determined using arterial oxygen tension and inspiratory oxygen concentration.
  
  
  RESULTS
  Based on the microscopic examination of BAL fluid, 57 patients were PCP positive and 238 patients were PCP negative. There were no significant differences in cell count or differentials in BAL fluid between the positive and negative cases. Serum levels of LDH, beta-D-glucan, and KL-6 were significantly higher in PCP-positive patients (p < 0.01). Receiver operating characteristic curves suggest that beta-D-glucan was the most reliable indicator. The cut-off level of beta-D-glucan was estimated to be 31.1 pg/mL, with which the positive and negative predictive values were 0.610 and 0.980, respectively. In PCP-positive patients, the oxygenation index was decreased and correlated with LDH. Both LDH and beta-D-glucan levels were correlated with the proportion of neutrophils in BAL fluid.
  
  
  CONCLUSIONS
  Serum beta-D-glucan is a reliable marker for the diagnosis of PCP. Since BAL procedure is invasive, measuring beta-D-glucan should be considered as a primary modality for a diagnosis of PCP, especially for patients with severe respiratory failure.
authors.affiliation: Division of Pulmonary Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. tasaka@cpnet.med.keio.ac.jp
authors.forename: Sadatomo
authors.initials: S
authors.lastname: Tasaka
authors.forename: Naoki
authors.initials: N
authors.lastname: Hasegawa
authors.forename: Seiki
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Wakako
authors.initials: W
authors.lastname: Yamada
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Nishimura
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Takeuchi
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Ishizaka
mesh_terms: D000328:Adult; D000368:Aged; D000951:Antigens, Neoplasm / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D018893:Bronchoalveolar Lavage / Q000379:methods; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002097:C-Reactive Protein / Q000378:metabolism*; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007118:Immunoassay; D045022:Lactate Dehydrogenases / Q000097:blood*; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D018396:Mucin-1; D009077:Mucins / Q000097:blood*; D009391:Nephelometry and Turbidimetry; D009504:Neutrophils / Q000473:pathology; D011020:Pneumonia, Pneumocystis / Q000097:blood* / Q000175:diagnosis*; D011379:Prognosis; D011509:Proteoglycans; D012189:Retrospective Studies; D012720:Severity of Illness Index; D047071:beta-Glucans / Q000097:blood*
chemical_list: D000951:Antigens, Neoplasm; D015415:Biomarkers; C060192:MUC1 protein, human; D018396:Mucin-1; D009077:Mucins; D011509:Proteoglycans; D047071:beta-Glucans; C010770:polysaccharide-K; D002097:C-Reactive Protein; D045022:Lactate Dehydrogenases