Methotrexate hepatotoxicity and concentrations of methotrexate and folate in erythrocytes--relation to liver fibrosis and cirrhosis.

Assessment of folate and methotrexate concentrations in erythrocytes has been suggested as criterion for when to institute liver biopsy surveillance during methotrexate treatment of psoriasis. We report an investigation of these parameters in thirty psoriatics on long-term methotrexate treatment. The patients were six psoriatics with histologically verified methotrexate-induced liver cirrhosis, eleven patients in which a blind histological evaluation had established a liver fibrosis in progression during treatment, and thirteen patients, who either had no liver fibrosis or no progression in the degree of fibrosis. There was no statistically significant difference in erythrocyte folate between the groups. When the two groups with progression were combined and compared with the group without progressive hepatic disease, erythrocyte methotrexate was found significantly higher in the patients with progression. Individual data, however, did not support the idea that assessment of folate and methotrexate in erythrocytes can limit the number of necessary liver biopsies during methotrexate treatment.