Alterations in total lactate dehydrogenase and its isoenzyme-5 in hepatic disorders.

Values for total lactate dehydrogenase (LD, EC 1.1.1.27) and LD isoenzyme-5 were determined in serum of 106 patients with benign hepatic disorders, 54 of whom had acute liver disorders, either acute hepatitis (39 patients) or acute circulatory disturbances (15 patients). Fifty-two had chronic hepatic disorders, either cirrhosis (25 patients) or chronic right heart failure (27 patients). Overall, values for LD were above normal for 86 percent of the 106 patients with benign hepatic disorders. In 83 percent of 30 patients with non-fulminant viral hepatitis, LD values were below 350 U per L, while in all nine patients with either fulminant viral or toxic hepatitis, and in all 15 patients with acute circulatory disturbances, LD values were above 500 U per L. In all 52 patients with chronic hepatic disorders, LD values were below 350 U per L. In patients with acute liver disorders, both the total LD and LD-5 proportions were sensitive for liver injury (87 percent and 91 percent, respectively). On the other hand, LD-5 proportion was much less sensitive than total LD in patients with chronic liver disorders (40 percent versus 85 percent). In conclusion, a difference was found in LD values and LD-5 ratios between patients with non-fulminant viral hepatitis and patients with other causes for acute liver injury. The LD-5 proportions are more sensitive for hepatic injury in patients with acute liver disorders than in those with chronic liver disorders.