Chemical and immunological features of pleural effusions: comparison between rheumatoid arthritis and other diseases.

Abstract

The value of determination of pleural fluid glucose, pH, lactic dehydrogenase, IgG, IgA, IgM, C3, C4, anti-IgG antibody, and hydroxyproline in distinguishing between pleural effusions caused by rheumatoid arthritis (RA) and those resulting from other diseases was studied. The series comprised seven patients with RA and 115 patients with other diseases including systemic lupus erythematosus, tuberculosis, malignant disease, empyema, pneumonia, congestive heart failure, and nonspecific pleural effusion. The low glucose concentration, the low pH and the low C4 level in rheumatoid pleural effusion were the most valuable diagnostic findings. The presence of anti-IgG antibody in pleural fluid was not specific for RA. The concentration of hydroxyproline in pleural fluid and the pleural fluid-to-plasma hydroxyproline ratio were significantly higher in RA than in tuberculosis and malignant disease. The results support the view that local metabolic and immunological phenomena as well as a high turnover of collagen occur in the pleural cavity in RA.

Pleuropulmonary complications in Rheumatoid Arthritis

“…The patients are predominantly females which are in accordance with previous studies done on RA. The incidence of respiratory abnormalities was higher in male patients (36.3%) when compared to female patients (16%) as reported previously by Walker WC, Lillington GA and Petterson T 17,18,19 . 47.3% of the patients had respiratory symptoms on admission.…”

BTS guidelines for the investigation of a unilateral pleural effusion in adults

“…107 The majority of patients with rheumatoid pleural effusions are men, even though the disease generally affects more women. 108 Pleural fluid can be serous, turbid, yellow green, milky, or haemorrhagic. 109 Rheumatoid arthritis is unlikely to be the cause of an effusion if the glucose level in the fluid is above 1.6 mmol/l, so this serves as a useful screening test.…”

“…107 Measurement of C4 complement in pleural fluid may be of additional help, with levels below 0.04 g/l in all cases of rheumatoid pleural disease and in only two of 118 controls reported in one study. 108 Rheumatoid factor can be measured on the pleural fluid and often has a titre of >1:320. However, it can be present in effusions of other aetiology and often mirrors the serum value, adding little diagnostically.…”

Cavitary Necrobiotic Nodule Imitating Malignant Lung Disease in a Patient Without Articular Manifestations of Rheumatoid Arthritis

“…12 A low pleural-fluid glucose level and a low pleural-fluid pH are not specific to RA; they are also found in cases of empyema, tuberculosis, and malignant tumors. 13 The RF in the pleural fluid is characteristically high, but it is also increased in cases of bacterial pneumonia, tuberculosis, and carcinoma. 14,15 The high LDH and low glucose levels in pleural fluid in our patient alarmed us to measure RF in serum and pleural fluid, and they were both positive, although not specific to RA.…”