Enteric hyperoxaluria, nephrolithiasis, and oxalate nephropathy: potentially serious and unappreciated complications of Roux-en-Y gastric bypass.
BACKGROUND
Neither the presence nor prevalence of enteric hyperoxaluria has been recognized after Roux-en-Y gastric bypass (RYGBP). We have noted a high rate of oxalate nephrolithiasis and even 2 patients with oxalate nephropathy in this patient population postoperatively. Our aim was to determine the frequency of the occurrence and effects of enteric hyperoxaluria after RYGBP.


METHODS
Retrospective review of all patients at our institution diagnosed with calcium oxalate nephrolithiasis or oxalate nephropathy after standard (n = 14) or distal (n = 9) RYGBP. The mean postoperative follow-up was 55 months.


RESULTS
A total of 23 patients (14 men and 9 women; mean age 45 years; mean preoperative body mass index 55 kg/m(2)) developed enteric hyperoxaluria after RYGBP, defined by the presence of oxalate nephropathy (n = 2) or calcium oxalate nephrolithiasis (n = 21) and increased 24-hour excretion of urinary oxalate and/or calcium oxalate supersaturation. Enteric hyperoxaluria was recognized after a mean weight loss of 46 kg at 29 months (range 2-85) after RYGBP. Two patients developed renal failure and required chronic hemodialysis. Of the 21 patients with nephrolithiasis, 14 had no history of nephrolithiasis preoperatively, and 19 of 21 required lithotripsy or other intervention. Of the 23 patients, 20 tested had increased oxalate excretion, and 14 of 15 tested had high urine calcium oxalate supersaturation.


CONCLUSIONS
Enteric hyperoxaluria, nephrolithiasis, and oxalate nephropathy must be considered with the other risks of RYGBP. Efforts should be made to identify factors that predispose patients to developing hyperoxaluria.
Nelson
Wayne K
WK
Mayo Medical School, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
Houghton
Scott G
SG
Milliner
Dawn S
DS
Lieske
John C
JC
Sarr
Michael G
MG
D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass / Q000009:adverse effects*; D006801:Humans; D006959:Hyperoxaluria / Q000209:etiology*; D007669:Kidney Calculi / Q000737:chemistry / Q000209:etiology* / Q000628:therapy; D008096:Lithotripsy; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery; D010070:Oxalates / Q000032:analysis; D006435:Renal Dialysis; D051437:Renal Insufficiency / Q000209:etiology / Q000628:therapy; D012189:Retrospective Studies; D015607:Stents
D010070:Oxalates