Screening colonoscopy after the age of 50 years has become the standard method for prevention of colon or rectal malignancies. Although the procedure itself is not unbearable, dread associated with the preceding bowel preparation process often results in postponement of the procedure. For years researchers have sought the optimum bowel preparation; it seems that oral sodium phosphate might be that preparation.(1) In brief, it is effective, economic, and most important, more palatable than swallowing 4 liters of polyethylene glycol in less than 3 hours.
Oral sodium phosphate is considered safe for the general population, without significant cardiovascular, renal, or gastrointestinal diseases. Only 1 to 5 serious experiences per million doses sold were reported to Fleet (Lynchburg, Va, the company sells Phospho-Soda), to the US Food and Drug Administration, or in the published literature.(2) In 2004, Markowitz et al(3) reported 5 cases of acute renal failure associated with oral sodium phosphate for bowel cleansing. The renal biopsies of these individuals revealed nephrocalcinosis, suggesting the pathogenetic role of oral sodium phosphate. Acute phosphate nephropathy has been used for this disease entity to distinguish it from other causes of nephrocalcinosis.4 These reports resulted in 2 Food and Drug Administration warnings. The labeling of oral sodium phosphate has been updated and now recommends cautious use by elderly patients and those with impaired renal function, heart disease, ascites, dehydration, and electrolyte disturbance. For the general population without these conditions, oral sodium phosphate remains the first choice for bowel preparation, with no data currently arguing against it.(5) Is it possible that acute phosphate nephropathy will occur in this population?
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– Yeong-Hau Howard Lien, MD, Ph.D.
This article was originally published in the November 2008 issue of The American Journal of Medicine.
