Background: Ischaemia-modified albumin (IMA) is a relatively new marker of ischaemia. IMA has not been studied previously in pleural effusions due to congestive heart failure (CHF). The aim of our study was to assess the diagnostic value of IMA in the pleural fluid (PF) and serum for the identification of pleural effusion due to CHF.
Methods: The concentrations of pleural fluid and serum IMA were measured in a total of 40 patients: 10 with CHF and 30 with non-cardiac failure (10 with acute pulmonary embolism, 10 with parapneumonic effusion and 10 with malignancy). The area under the curve (AUC) quantified the overall diagnostic accuracy of the tests.
Results: The study demonstrated that IMA concentration was higher in both pleural fluid and serum of CHF patients compared with non-cardiac patients. PF and serum IMA demonstrated AUCs of 0.927 (95% CI: 0.844-1.00, P < 0.001), and 0.792 (95% CI: 0.653-0.930, P = 0.006), respectively, for diagnosing effusions due to CHF. The sensitivity and specificity of PF-IMA for CHF at the cut-off concentration of ≥1.0 absorbance units was 90% and 80%, respectively. Its negative predictive value (NPV) was quite high (96%). Positive correlation was found between PF-IMA concentrations and serum-IMA (r = 0.540, P < 0.001).
Conclusions: Measuring IMA concentrations in serum and pleural fluid may be helpful in distinguishing pleural effusion due to a cardiac or non-cardiac aetiology.