Severe interstitial nephritis in a patient with renal amyloidosis and exacerbation of Crohn's disease.

A 57-year-old man with long-term untreated Crohn's disease presented with exacerbation of his bowel disease, volume depletion, nephrotic syndrome and rapid decline in renal function. Renal biopsy revealed amyloidosis and extensive interstitial infiltration. Initiation of steroid therapy was associated with improvement in renal function and postponement of dialysis, suggesting that control of interstitial inflammation might have a therapeutic role in renal amyloidosis. We hypothesize that volume depletion could magnify toxicity of proteinuria, thus augmenting interstitial inflammation and accelerating the deterioration in renal function.