Lactate dehydrogenase in bronchoalveolar lavage fluid of patients with active pulmonary tuberculosis

Background: Serum lactate dehydrogenase (LDH) concentration is an indicator of tissue injury. It may be increased in a variety of interstitial disease s and in pulmonary tuberculosis (PTB). Objective: To investigate the value of LDH levels in bronchoalveolar lavage fluid (BALF) for the diagnosis of a ctive PTB and to assess its relationship with serum LDH levels. Methods: Th e study was a prospective clinical study. It included 25 consecutive patien ts with documented active PTB and 20 healthy adults who underwent bronchosc opy with bronchoalveolar lavage (BAL). Both total serum and LDH levels were measured. Results: BALF LDH level was increased in all patients with activ e PTB. The mean BALF LDH level was significantly higher in patients with PT B (198.84 +/- 88.31 mIU/ml) as compared to controls (14.01 +/- 8.69 mIU/ml) (p = 0.0001). There was a significant correlation between BALF LDH and ser um LDH levels in patients with PTB (r = 0.55, p = 0.006). Conclusion: BALF LDH levels are not specific and may be increased in many diseases. A very l ow value (possibly less than 60 mIU/ml) may, on the other hand, be useful t o exclude the diagnosis of active PTB.