Monday, August 18, 2008

Oxalate Kidney Damage

Make sure you stay hydrated, and take precautions to help preventing oxalate kidney stones. Those precautions can also help preventing a condition called "Oxalate Nephropathy"

Some definitions:

Nephropathy: A disease or an abnormality affecting the kidneys

Oxalate: A chemical that, when combined with calcium, can form calcium oxalate stones (usually called oxalate stones)

Oxalate Nephropathy: An abnormal condition of the kidneys that results from precipitation of calcium oxalate crystals in the kidneys.

Oxalate nephropathy can lead to kidney failure. Oxalate nephropathy leading to kidney failure has been previously reported in a patient who took a high dose of Orlistat (the active ingredient in Xenical and Alli). That one reported patient had, before taking Orlistat, an abnormal kidney (chronic kidney disease from hypertension and possibly diabetes).

This time, I am commenting on a new article that appeared in the Clinical Journal of the American Society of Nephrology which reported cases of oxalate nephropathy complicating Roux-en-Y gastric bypass in patients who had, prior, an underlying mild chronic kidney disease from obesity, hypertension and /or diabetes.

The authors identified eleven patients with oxalate nephropathy after gastric bypass. Those patients developed end-stage kidney disease. The mean age was about 61 years. All patients had a history of high blood pressure disease, and 9 had diabetes. Patients were likely to have an underlying mild chronic kidney disease from obesity, hypertension and /or diabetes. There is actually a nice summary of the effects of obesity on the kidneys in Dr. Sharma's blog. The conslusion of the study we are discussing today is that, patients with kidney disease may be at a higher risk for oxalate nephropathy after gastric bypass.

Ways to help preventing oxalate kidney stones can also help preventing oxalate nephropathy, and they were described here. Remaining hydrated in this hot weather is particularly important. Low fat intake, restricting foods rich in oxalates, taking calcium supplements, low sodium diet, and possibly considering a medication (hydrochlorothioazide) in selected patients, my all help.


Nasr SH, D'Agati VD, Said SM, Stokes MB, Largoza MV, Radhakrishnan J, Markowitz GS. Oxalate Nephropathy Complicating Roux-en-Y Gastric Bypass: An Underrecognized Cause of Irreversible Renal Failure. Clin J Am Soc Nephrol. 2008 Aug 13. [PMID: 18701613] (Abstract)

Singh A, Sarkar SR, Gaber LW, Perazella MA. Acute oxalate nephropathy associated with orlistat, a gastrointestinal lipase inhibitor. Am J Kidney Dis. 2007 Jan;49(1):153-7. [PMID: 17185156] (Abstract)