Is low-dose methotrexate nephrotoxic? Case report and review of the literature.

Methotrexate (MTX) has become the most commonly prescribed disease-modifying anti-rheumatic drug. However, toxicity is an important drawback of MTX therapy and permanent discontinuation of MTX for adverse effects occurs in 1 patient out of 10. Although high-dose MTX is known to be nephrotoxic, data on low-dose MTX renal effects are scanty. We report an insidious and progressive deterioration of renal function during long-term low-dose MTX in a 59-year-old woman. Kidney biopsy revealed advanced kidney fibrosis with extensive interstitial and glomerular fibrosis, and vascular sclerosis. We suggest that patients on low-dose MTX therapy even alone, should be periodically monitored for creatinine levels.