Significance of elevated serum LDH (lactate dehydrogenase) activity in atopic dermatitis.

Serum lactate dehydrogenase activity (LDH) was elevated in most cases with the severe type of atopic dermatitis (AD). We examined whether LDH correlated specifically with the clinical courses and the severity of AD skin eruptions. Blood eosinophil numbers (Eo), LDH and its isoenzymes, and serum IgE (IgE) levels in eighty patients with AD were measured before and after treatment. In improved groups, Eo and LDH decreased or returned to normal values after treatment. In contrast, both levels increased in patients who worsened after treatment. Thus changes in Eo and LDH correlated well with the clinical picture. However, IgE levels did not correlate with the clinical condition. High LDH levels were detected in the severe type of AD more frequently than in the mild type. A large majority of patients with elevated LDH (higher than 300 IU/l) before treatment had more severe skin eruptions. When the LDH before treatment was within normal limits, the LDH levels in improved patients showed a further decrease. Eo, LDH and IgE were correlated closely with the clinical scores of AD, and the relationship between LDH and clinical score was the highest. Elevations of LDH5 and LDH4 among the LDH isoenzymes were more prominent in the severe type of AD than in the mild type. We concluded that LDH was useful as a marker for evaluating the disease condition and severity of skin eruption of AD.