An 85-year-old man who resides in a nursing home presents with a 3-day history of lower abdominal pain and increasing fatigue and lethargy. He is afebrile, his BP is 160/92, and RR 16. His lungs are clear and his heart examination normal. There is diffuse abdominal tenderness on palpation and a large area of fullness and dullness to percussion starting just below the umbilicus and extending to the suprapubic area. His serum sodium is 130 mEq/L, potassium 4.9 mEq/L, BUN 75 mg/dL, and creatinine is 3.5 mg/dL. His baseline BUN and creatinine were 25 and 1.3 respectively as recently as 1 month ago. A Foley catheter is placed and 1200 cc of urine is obtained.
What will be the likely clinical course for this patient with regard to his renal function?
A. His creatinine will continue to rise slowly for 2 to 3 more daysThis patient has obstructive uropathy. With relief of the obstruction due to an enlarged prostate, which was causing bilateral obstruction, it is very likely that renal function will return to baseline over the ensuing week. If an obstruction has been present for 1 to 2 weeks, recovery may be only partial. Obstruction that has lasted several weeks often causes irreversible damage. A nuclear medicine renal scan performed following relief of the obstruction may give an indication of the prognosis. Relief of bilateral obstruction is associated with a post obstructive diuresis. Urine output in this situation can be brisk and may require careful attention to volume status of the patient. In most patients, however, this is associated with appropriate excretion of excess salt and water.