Abstract
Total plasma lactate dehydrogenase (LDH) activity may be elevated in cryptogenic fibrosing alveolitis (CFA) and extrinsic allergic alveolitis (EAA), and may be a useful monitor of disease progress. In a retrospective, primary referral centre study, we compared LDH at presentation, prior to bronchoalveolar lavage BAL, and after treatment and follow-up with changes in pulmonary function, in patients with CFA, EAA and pulmonary sarcoidosis. Plasma levels of LDH at presentation in CFA (n = 47) and EAA (n = 10) were significantly higher than in patients with sarcoidosis (n = 36). LDH activity decreased in patients with improving lung function (EAA, p = 0.008; CFA, p = 0.02), whereas it increased in CFA patients with deteriorating lung function (p = 0.015). Total plasma LDH is a simple, though nonspecific test, which appears to reflect changes of disease activity in patients with CFA and EAA.