. Certain forms of nephritis (e.g. focal glomerulosclerosis and mesangiocapillary glomerulonephritis) recur in transplants, and it is helpful to know this for future management. 8. Special situations - (a) Uncontrolled hypertension may lead to renal impairment, hematuria and proteinuria, and this may occasionally result in nephrotic syndrome. Once hypertension is controlled, renal biopsy may be the sole criterion for determining whether the problem is due to pure hypertension or underlying nephritis. (b) In 10-20% of patients with diabetes mellitus, proteinuria and impaired renal function may be due to causes other than diabetic nephrosclerosis, particularly in those with no other evidence of microvascular disease e g diabetic retinopathy. 9. Renal allograft dysfunction -(a) It provides only reliable method of distinguishing rejection from cyclosporin nephrotoxicity. (b) It helps in deciding the scale of antirejection therapy and differentiating allograft nephropathy form recurrent or de novo nephritis. Contraindications