Experimental crystal nephropathy (one year study in the pig).

An acute crystal nephropathy was produced in pigs by feeding a mixture of guanine and allopurinol. The pathogenesis of the lesion produced was studied by serial histology and renal function tests over 12 months. Tubular blockage by the crystals produced erosion of the basement membrane and an accompanying interstitial nephritis. Tubular degeneration around the crystal mass transferred the crystals to the interstitium. Despite rapid subsequent disappearance of these crystals the interstitial nephritis was still evident nine months later. An early return of renal function to near normal was not sustained beyond nine months. It was shown that even brief periods of intratubular crystal deposition caused irreversible changes, resulting eventually in a reduction in kidney size, nephron population and renal function.