Analgesic nephropathy
The chronic consumption of large amounts of analgesics (especially those containing phenacetin) and NSAIDs leads to chronic tubulointerstitial nephritis and papillary necrosis. COX II specific NSAIDs are still being evaluated. In Australia, the incidence of end-stage renal failure due to analgesic nephropathy has declined as 'over-the-counter' purchase of nephrotoxic analgesics has been reduced by legislation.
Clinical Features of Analgesic nephropathy
Analgesic nephropathy is twice as common in women as in men and presents typically in middle-age. Patients are often depressed or neurotic. Presentation may be with anaemia, chronic renal failure, symptoms of urinary infection (which may be difficult to eradicate), haematuria, or urinary tract obstruction (owing to sloughing of a renal papilla). Salt and water-wasting renal disease may occur.
Chronic analgesic abuse also predisposes to the development of uroepithelial tumours.
Treatment of Analgesic nephropathy
The consumption of analgesics should be discouraged. If necessary, dihydrocodeine or paracetamol are reasonable alternative choices. This may result in the arrest of the disease and even in improvement in function.
UTI, hypertension (if present) and saline depletion will require appropriate management.
The development of flank pain or an unexpectedly rapid deterioration in renal function should prompt ultrasonography or urography to screen for urinary tract obstruction due to a sloughed papilla.
Nephritis - Lupus Nephritis, Interstitial Nephritis, Analgesic Nephropathy
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