N.A.M. Cobben

Usefulness of lactate dehydrogenase and its isoenzymes as indicators of lung damage or inflammation

This review describes the usefulness of monitoring the activity level of lactate dehydrogenase (LDH) and its isoenzyme pattern as indicators of pathological conditions in the lungs, such as cell damage or inflammation. Cytoplasmatic cellular enzymes, like LDH, in the extracellular space, although of no further metabolic function in this space, are still of benefit because they serve as indicators suggestive of disturbances of the cellular integrity induced by pathological conditions. Since LDH is an enzyme present in essentially all major organ systems, serum LDH activity is abnormal in a large number of disorders. Although the increase in total serum LDH activity is rather nonspecific, it is proposed that measurement of LDH activity levels and its isoenzyme pattern in pleural effusion and, more recently, in bronchoalveolar lavage fluid may provide additional information about lung and pulmonary endothelial cell injury.

RELATIONSHIP BETWEEN ENZYMATIC MARKERS OF PULMONARY CELL DAMAGE AND CELLULAR PROFILE: A Study in Bronchoalveolar Lavage Fluid

It has been suggested that alterations in bronchoalveolar lavage fluid (BALF) reflect pathologic changes in the lung. Cytoplasmatic enzymes such as lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and LDH isoenzymes are recognized indicators of cell damage or death. The aim of this study was to determine whether there is a relation between the enzyme activity and the cell types present in BALF. Therefore, BALF samples obtained from patients with various pulmonary disorders were studied. Out of these samples a group with mainly polymorphonuclear neutrophils (PMNs; n = 15; Group I) and another with mainly alveolar macrophages (AMs; n = 10; Group II) were selected. Additionally, the value of analysis of lysed cells in BALF for assessment of LDH-isoenzyme patterns was examined. The cell-free fraction of BALF of Group II showed lower LDH and ALP activity compared to Group I. The LDH-isoenzyme pattern also differed, with the LDH3/LDH5 ratios being lower in all BALF samples with predominantly PMNs than in BALF samples with predominantly AMs. Lysis of the cells present in the BALF samples by sonication prior to LDH-isoenzyme analysis provided no additional information beyond that found by analysis of the cell-free BALF. In conclusion, determination of enzyme activity appears to be useful in monitoring pulmonary inflammation.

Serum LDH : a marker of disease activity and its response to therapy in idiopathic pulmonary fibrosis

In the following case report the determination of serum lactate dehydrogenase (LDH)-a simple though non-specific test-reflects changes of disease activity and clinical improvement during treatment with cyclophosphamide and a tapered dose of prednisone from 100 to 0 mg daily in a 43-year-old woman with idiopathic pulmonary fibrosis. The trend observed in this case indicates that the serum LDH-activity may be directly proportional to the extent of this diffuse inflammatory pulmonary disease.

Serum beta-glucuronidase activity in a population of ex-coalminers.

BACKGROUND The aim of this study was to investigate whether BGD activity is of additional value in the assessment of pulmonary inflammation caused by coal dust exposure. DESIGN AND METHODS Ex-coalminers were included in this study. Forty-eight healthy male subjects, without a relevant medical history, were used as controls. RESULTS In ex-coalminers serum BGD activity was higher compared to the control group. Moreover, ex-coalminers with a normal chest radiograph and normal serum LDH demonstrated elevated serum BGD compared to the control group. However, no relation was found in the total group of ex-coalminers between serum BGD activity and pulmonary function parameters. CONCLUSIONS Our study adds in vivo human evidence to the already existing animal data that BGD is a potential biomarker useful in monitoring pulmonary inflammation caused by coal dust exposure.

Diagnostic Value of Lactate Dehydrogenase Isoenzyme Pattern in Pleural Effusions

Lactate dehydrogenase isoenzymes have been used to classify the nature of pleural effusion. Nevertheless, studies have reported conflicting results. The objective of this study was to evaluate the diagnostic value of lactate dehydrogenase isoenzymes in the analysis of pleural effusions. Pleural fluid samples obtained from three respective diagnostic groups: group I transudate (n = 23), group II parapneumonic effusion (n = 29) and group III malignant effusion or pleuritis carcinomatosa (n = 41) were evaluated. Total lactate dehydrogenase activity and lactate dehydrogenase (LDH) isoenzyme pattern were significantly different between transudative (group I) and exudative (group II and III) effusions. Group II and III showed a low percentage of LDH1 (p < 0.001), whereas the percentages of LDH4 (p < 0.001) and LDH5 (p < 0.001) were higher compared to group I. Moreover, in exudative effusions the percentage of LDH1 (p < 0.005), LDH4 (p < 0.005), as well as LDH5 (p < 0.005) were significantly different between parapneumonic and malignant effusions. In contrast to relative lactate dehydrogenase isoenzyme values, the absolute values of lactate dehydrogenase isoenzymes did not differ between group II and group III. Logistic regression analysis yielded a strong discrimination between group I and II+III, simultaneously using lactate dehydrogenase, glucose and protein as explanatory variables. Logistic regression analysis yielded only a weak discrimination between group II and III, simultaneously using lactate dehydrogenase, glucose and the absolute values of LDH2 and LDH4 as explanatory variables. In conclusion, the lactate dehydrogenase isoenzyme pattern differed between pleural effusions of transudative and exudative origin. However, including lactate dehydrogenase isoenzyme activities in the biochemical work-up of pleural effusions did not reveal an additional discriminatory value in the assessment of the classification of these effusions.

Usefulness of monitoring β-glucuronidase in pleural effusions

Background: The objective of the study was to evaluate the additional value of β-glucuronidase (BGD), a lysosomal enzyme in the analysis of transudative and exsudative pleural effusions, especially between malignant and non-malignant effusions. Design and methods: Pleural fluid samples obtained from four respective diagnostic groups: transudates parapneumonic effusions, malignant effusions or pleuritis carcinomatosa, and empyema were evaluated. Results: Beta-glucuronidase was significantly different between transudative and exsudative effusions (p < 0.001) as well as between parapneumonic and malignant effusions (p < 0.03), parapneumonic effusions and empyema (p < 0.002), and malignant and empyema (p < 0.002), respectively. Logistic regression analysis yielded a weak discrimination between the parapneumonic and malignant groups. Conclusions: Beta-glucuronidase activity differed between pleural effusions of various origin. However, including BGD in the biochemical work-up of pleural effusions did not reveal discriminatory value in the assessment of the classification of these effusions.