Methotrexate should not be used for patients with end-stage kidney disease.

Methotrexate is a widely used disease-modifying anti-rheumatic drug. Its effectiveness has been proven in placebo-controlled trials and in comparison with other disease-modifying anti-rheumatic drugs. The pharmacokinetics of methotrexate are highly variable and unpredictable. In patients with normal renal function, the recommended dose in rheumatoid arthritis ranges between 7.5 and 15 mg/week, but in recent years, even dosages up to 25 mg weekly are used. Toxicity includes myelosuppression, gastrointestinal adverse effects, hepatotoxicity and pneumonitis. Renal impairment and age are considered major risk factors for developing methotrexate toxicity, but studies show conflicting results. Whether methotrexate can be administered to patients with end-stage kidney disease has not been formally tested. The present case illustrates the severe side effects of low-dose methotrexate treatment in a patient with end-stage kidney disease. Seven other cases have reported similar and even more severe and irreversible consequences after low-dose regimen. In view of these side effects we strongly recommend to monitor toxicity rigorously in patients with stage 3 or stage 4 kidney disease and not to use methotrexate in patients with stage 5 kidney disease.

Alkaline encrusted pyelitis.

Alkaline encrusted pyelitis is an infectious disease characterised by encrustations in the wall of the upper urinary tract, surrounded by severe inflammation. Destruction of native kidneys and kidney grafts may occur, resulting in end stage renal failure. Corynebacterium group D2, an urea splitting microorganism, is nearly exclusively associated with this disease. The most important predisposing factors are previous urological procedures and an immunosuppressed state. In a suggestive clinical context, diagnosis should be made with unenhanced computed tomography findings and bacteriologic isolation of the responsible microorganism. The treatment is threefold: appropriate antibiotic therapy, by preference with glycopeptides, acidification of urine and chemolysis, and if needed, surgical removal of encrustations. We report the case of a patient who was diagnosed with this rare condition and could escape maintenance dialysis after correct diagnosis was made and conservative treatment was started using antibiotics and combined oral and local acidification.