Plasma isocitrate dehydrogenase as a marker of centrilobular hepatic necrosis in patients with hyperthyroidism

Isocitrate dehydrogenase (ICDH) may be useful for differentiating centrilobular from periportal necrosis in rats with liver injury. In this study, we assessed the usefulness of ICDH as a marker of centrilobular necrosis in patients with hyperthyroidism. Isocitrate dehydrogenase and alanine aminotransferase (ALT) activities were measured in the plasma of 56 patients with hyperthyroidism, 16 patients with chronic viral hepatitis (CVH), and 17 controls. Isocitrate dehydrogenase levels were higher in patients with hyperthyroidism than in those with CVH or in the controls (p < 0.01 and p < 0.001, respectively), even though ALT levels were higher in patients with CVH than in patients with hyperthyroidism (p < 0.01). Isocitrate dehydrogenase/ALT ratios were also higher in patients with hyperthyroidism than in those with CVH (p < 0.0001). Isocitrate dehydrogenase correlated to ALT levels in patients with hyperthyroidism or CVH (p < 0.05). In a patient with hyperthyroidism, ICDH levels decreased progressively to normal, and the ALT level and thyroid function were normalized. Thus, the plasma ICDH or ICDH/ALT ratio might be useful for differentiating centrilobular from periportal necrosis and for monitoring the degree of hepatic necrosis in patients with hyperthyroidism.