Renal failure in prostate cancer

Quick post today - we discussed a case of a an elderly male with metastatic prostate cancer refractory to treatment who presents with an acute rise in creatinine 1118 from a baseline of 70. Given his history of prostate cancer urinary obstruction either at the level of the prostatic urethra, or higher at the level of the ureter, potentially from retroperitoneal masses, was the leading diagnoses. Foley catheter insertion yielded less than 50 cc of urine.
Physical examination was significant for a large palpable, firm abdominal mass spanning his upper abdomen. He also had asterixis and decreased LOC. Imaging showed a 15x20x20 cm retroperitoneal mass causing bilateral hydronephrosis. He was treated with nephrostomy tubes.

Always be aware of post-obstructive diuresis, that can occur after relief of obstruction. Often this is an appopriate diuresis as retained urea is expelled causing an osmotic diuresis, as well excess salt and water from the obstruction is also diuresed. However, this can persist leading to hypovolemia. Monitor urine lytes and replace urinary losses.

The question raised was whether he require bilateral or unilateral nephrostomy tubes to relieve his obstruction. There is little evidence to guide therapy of post renal obstruction in metastatic prostate cancer. In 2009, Nariculam et. al published a study in The British Journal of Radiology where they looked at 25 patients with metastatic prostate cancer presenting with acute renal failure from obstruction. 18 underwent bilateral neprhostomy tube insertion, and 7 underwent unilateral insertion. Ultimately there was no difference in recovery of renal function and overall no difference in mortality, suggesting that survival is based on the aggressiveness of the prostate cancer rather than the insertion of one or two nephrostomy tubes. 
Multiple issues need to be balanced in practice. There is the risk of complication with tube insertion and so if one is sufficient than why insert two? However, as this study showed, some tubes can become blocked, or one kidney may have sustained significant injury and not recover function and if kidney function fails to improve after one insertion, then the patient may require a second insertion anyways.

The article can be found here

For a recap of AKI see my post from July here

Sidenote, interesting examples of uremic frost:
One from the CMAJ and another from the NEJM

Uremic frost occurs in advanced renal failure with deposition of urea and other nitrogenous waste products that crystallize on the skin. First described by Hirschsprung in 1865