Role of pleural viscosity in the differential diagnosis of exudative pleural effusion.
OBJECTIVE
Determining the aetiology of an effusion involves assessing if it is an exudate or a transudate. However, a reliable test for determining the aetiology of a pleural effusion is lacking. Pleural viscosity has a high sensitivity and specificity and a high positive and negative predictive value for discriminating exudative and transudative pleural effusions. The aim of this study was to use pleural fluid viscosity to discriminate between various aetiologies of exudative effusions, namely malignant, parapneumonic and tuberculous.


METHODS
Seventy consecutive patients (24 women, 46 men, mean age = 67 years) with exudative pleural effusion due to pneumoniae in 24 patients, tuberculous pleurisy in 21 and lung cancer in 25 were studied prospectively. Measurements of pleural fluid and plasma viscosity were performed using Brookfield DV-II viscometer.


RESULTS
Pleural viscosity and pleural LDH were highest in the tuberculous pleurisy patients and lowest in the lung cancer patients. Pleural viscosity > or = 1.57 was found to be indicative of tuberculous pleurisy with a sensitivity of 100% and specificity of 95%. Pleural viscosity < 1.39 was found to be indicative of lung cancer with a sensitivity of 100% and specificity of 94%. Pleural viscosity was significantly correlated with pleural albumin (r = 0.34, P = 0.004), protein (r = 0.40, P = 0.001), LDH (r = 0.70, P < 0.001) and plasma viscosity (r = 0.44, P < 0.001), having the most significant value with pleural LDH.


CONCLUSIONS
The pleural fluid viscosity of patients with parapneumonic, tuberculous and malignant effusions are significantly different from each other. Among these groups, tuberculous effusions had the highest viscosity, and malignant effusions from lung cancer the lowest.
Yetkin
Ozkan
O
Department of Chest Disease, Inonu University School of Medicine, Malayta, Turkey. ozkanyetkin@hotmail.com
Tek
Ibrahim
I
Yetkin
Funda
F
Numanoglu
Numan
N
D000368:Aged; D000418:Albumins / Q000032:analysis; D003937:Diagnosis, Differential; D005122:Exudates and Transudates / Q000737:chemistry / Q000166:cytology; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008297:Male; D010949:Plasma / Q000737:chemistry; D010996:Pleural Effusion / Q000737:chemistry / Q000175:diagnosis* / Q000209:etiology; D011446:Prospective Studies; D014396:Tuberculosis, Pleural / Q000150:complications / Q000175:diagnosis; D014783:Viscosity
D000418:Albumins; D007770:L-Lactate Dehydrogenase