Outcome and Prognosis



The outcome of patients who develop ATN is quite variable and dependent upon the nature of the underlying disease. With the availability of dialysis, deeth is rarely due to renal failure di­rectly. In modern acutecare hospitals, mortality rates may be in excess of 50 per cent, a figure that reflects the advanced age, severity of disease, and number of coexisting illnesses in this patient pop­ulation. Outcome is considerably more favorable in younger patients with fewer coexisting dis­eases. As a generalization, patients with anti­biotic-induced acute renal failure appear to have a more favorable outcome than those with vaso­motor nephropathy. The same generalization is true of patients presenting with nonoliguric as compared to oliguric ATN.

In a patient with established ATN who is not exposed to additional insults to the kidney, renal function may recover. The onset of recovery av­erages 7 to 10 days, although shorter and longer periods of renal dysfunction are not uncommon. In patients who are oliguric, recovery is heralded by an increase in urine output. Generally, in a pa­tient not undergoing dialysis, the urine output doubles every 24 to 48 hours until an output of 3000 to 4000 ml/day is attained. The serum con­centration of urea nitrogen and creatinine de­creases 48 to 72 hours after the onset of the in­crease in urine output. The progressive increase in urine output should be carefully monitored. A patient with oliguric ATN who begins to manifest an increase in urine output usually demonstrates complete progression to urine output of 3000 ml or more per day. If a patient fails to reach this value or if urine output decreases after an initial increase, the possibility of an additional renal in­sult should be carefully considered.