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Acute phosphate nephropathy

Glen S Markowitz, MD
Mark A Perazella, MD, FACP
Section Editor
Paul M Palevsky, MD
Deputy Editor
Alice M Sheridan, MD


Acute phosphate nephropathy is a form of kidney injury that occurs following the use of bowel purgatives that contain oral sodium phosphate (OSP) and has been reported following the administration of sodium phosphate-containing enemas [1,2]. OSP was formerly sold without prescription under the brand name "Fleet Phospho-soda" (C.B. Fleet Inc). Fleet no longer distributes OSP; however, generic versions of OSP are still available without prescription. OSP is also available by prescription in a pill form (Visicol, OsmoPrep). In both pill and liquid form, OSP is a hyperosmotic laxative that acts by drawing water into the gastrointestinal tract. Although long used as a laxative, OSP began to be used as a purgative for colonoscopy in 1990 [3]. It is frequently given in favor of standard polyethylene glycol (PEG)-based lavage solutions because of the smaller required volume, which results in better patient compliance and improved colonic cleansing [4-6].

However, there have been multiple cases of OSP-induced acute kidney injury (AKI) with defining histologic features on biopsy [7-11]. This clinicopathologic entity has been referred to as acute phosphate nephropathy.

In 2006, in response to published reports, the US Food and Drug Administration (FDA) issued a warning regarding the potential for AKI in patients who received OSP [12]. The warning was incorporated into a consensus document on bowel preparation by the American Society of Colon and Rectal Surgeons (ASCRS), the American Society of Gastrointestinal Endoscopy (ASGE), and the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) [13]. In December 2008, the FDA required that a boxed warning be added to labeling of Visicol and OsmoPrep, which are still available by prescription [14]. At the same time, following the recommendation of the FDA, over-the-counter preparations that contain OSP were voluntarily withdrawn from the market by Fleet; but, as noted above, generic versions are still available. In 2014, the FDA issued another warning that using more than one dose in 24 hours of OSP to treat constipation can cause "rare but serious harm to the kidneys and heart, and even death" [15].

This topic provides a review of the clinical features of acute phosphate nephropathy. AKI associated with an increased phosphate load has also been described in tumor lysis syndrome, especially with alkalinization of the urine by bicarbonate-containing intravenous (IV) fluids. Tumor lysis syndrome is discussed elsewhere. (See "Tumor lysis syndrome: Definition, pathogenesis, clinical manifestations, etiology and risk factors".)


The mechanism underlying acute phosphate nephropathy most likely relates to a transient but potentially severe increase in serum phosphate coupled with volume depletion, both of which may occur following the administration of bowel purgatives that contain oral sodium phosphate (OSP).

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Literature review current through: Nov 2017. | This topic last updated: Mar 08, 2017.
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