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.

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We describe the case of a 26-year-old African female who was treated successfully with belimumab in a case of severe membranous lupus nephritis and retinal vasculitis, resistant to first line therapy. She presented initially with chronic dacryoadenitis and screening showed nephrotic-range proteinuria. Biopsy of the kidney confirmed the diagnosis of membranous lupus nephritis. Clinical features (joint pain, dacryoadenitis, retinal vasculitis and lupus nephritis) in combination with serology (positive anti-double-stranded DNA (ds-DNA) antibodies, hypocomplementemia) confirmed the diagnosis of systemic lupus erythematosus (SLE). Treatment was immediately initiated with glucocorticosteroids (GCS), mycophenolate mofetil (MMF) and hydroxychloroquine sulphate (Plaquenil®). Tacrolimus was associated but no effect was observed with the proteinuria remaining in the nephrotic range and secondary effects of the glucocorticosteroids becoming a real concern. The patient was started on add-on belimumab with quasi-immediate effect on the proteinuria, making it possible to decrease the dosage of the other immunosuppressants and gradually stop them, even the GCS. The patient is currently in complete remission after 3 years of treatment with belimumab. We were able to stop immunosuppressive treatment but will keep her on antimalarial treatment as the most recent guidelines in treatment of SLE recommend.