Thursday, November 29, 2012

Weight loss and CKD, one patient's experience.

I just discharged a patient from my CKD clinic. I first saw her in the CKD clinic in 2008. When she presented she had CKD stage 3/4 (eGFR of 30 mL/min) with a creatinine of 1.8. I was very concerned about her risk of progression to ESRD due to three elements from her history:
  1. Recent episode of ARF following a UTI. We know now that AKI is a risk factor CKD progression, especially in diabetics, but even 5 years ago I used it as a personal bias flagging patients with scant renal reserve and fragile kidneys.
  2. She had previously had a nephrectomy for renal cell carcinoma. I always worry about these patients getting hyperfiltration injury, though in my experience this is rare and they generally do much better than their peers with equally diminished GFRs.
  3. She had a BMI of 45, which also increasing her risk of hyperfiltration injury.
Image via Methodist Hospital
On her first visit, she asked if losing weight would help her kidney disease. I told her that I felt it would. She had already tried a variety of diet and exercise programs and had repeatedly failed. Over the ensuing year we discussed weight loss options and ultimately she consulted with a bariatric surgeon. In February 2009 she went for a laproscopic gastric band procedure.

Since that procedure she has lost 132 pounds. Her hemoglobin A1c has gone down from 9.9 to 5.7 in the face of stopping insulin and her three oral hypoglycemics. But the most remarkable thing for me has been the way her creatinine has melted away from 1.8 to 0.7. Her microalbuminuria went from 139 to 3 mg/g creatinine. She went from CKD 3/4 to CKD 1.

JASN recently published a report by Turgeon, showing increasing complications with bariatric weight loss procedures in patients with chronic kidney disease.

In a 2009 meta-analysis, Navaneethan found that bariatric surgery reduced proteinuria, blood pressure and GFR. The reduction in GFR was not in CKD patients and really relfected a normalization of hyper-filtration from a GFR of 140 to 117 mL/min.

Risks occur with bariatric surgery, as shown in Turgeon's study. In addition to the short term surgical complications, AKI, rhabdomyolysis, hyperoxaluria and kidney stones all can occur after weight loss surgery. An additional wild card in assessing how CKD patients do after surgery is the fact that using the MDRD in the morbidly obese is uncertain. Perhaps my patient's improvement is due simply to increased accuracy of the MDRD equation as her BMI approached a more typical level. That said, given the reduction in her albuminuria, the apparent curing of her type two diabetes and her remarkable fall in creatinine I feel she has truly benefitted from the surgery.
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