Importance of sputum differential cell counting in the diagnosis of airway diseases

J Formos Med Assoc. 1997 May;96(5):330-5.


We examined the sputum of 114 subjects by noninvasive methods (voluntary coughing or induced cough with hypertonic saline) to determine whether sputum examination could be used to separate patients with episodic wheezing, dyspnea or cough of unknown origin into different diagnostic categories. An increased percentage of sputum eosinophils was seen in 92% (48/52) of asthmatics, 36% (9/25) of patients with chronic obstructive pulmonary disease (COPD) and 28% (7/25) of chronic coughers, but not in any of the 12 patients with congestive heart failure (CHF). Eight patients with combined symptoms of COPD and asthma (mixed COPD subgroup) showed above average diurnal peak expiratory flow variation (10.3 +/- 2.1% vs 2.5 +/- 1.4%, p < 0.05) and an above average percentage of sputum eosinophils (19.8 +/- 9.1 vs 2.1 +/- 3.2, p < 0.01) than those in the pure COPD group. After therapeutic corticosteroid trial, all of the mixed COPD patients and six of the 17 pure COPD patients were steroid responders. Seven of the 25 chronic coughers had sputum eosinophilia, but no asthmatic symptoms. The cough symptoms subsided in five of these seven patients after steroid treatment but not in the other 18 chronic coughers. Further study is indicated to determine if simple eosinophilic bronchitis is an early stage of asthma. In conclusion, sputum differential cell counting is a useful noninvasive diagnostic tool in differentiating diseases with episodic wheezing or chronic cough.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Asthma / diagnosis
  • Cell Count
  • Child
  • Cough / etiology
  • Cough / pathology
  • Heart Failure / complications
  • Humans
  • Lung Diseases, Obstructive / diagnosis
  • Middle Aged
  • Prednisolone / therapeutic use
  • Respiratory Tract Diseases / diagnosis*
  • Respiratory Tract Diseases / drug therapy
  • Respiratory Tract Diseases / etiology
  • Sputum / cytology*


  • Prednisolone