The FDA has conducted a safety review on oral sodium phosphate using the agency's databases and medical literature. The review shows that serious electrolyte disturbances (hypernatremia, hypokalemia, hyperphosphatemia, and hypocalcemia), dehydration, metabolic acidosis, renal failure, tetany, and death have been attributed to patients receiving more than a 45-mL dose of oral sodium phosphate (usually a minimum of 90 mL during a 24-hour period). Changes in hematocrit, serum sodium, blood urea nitrogen, serum osmolality, and body weight after ingesting sodium phosphate oral solution suggest that a mild contraction of intravascular volume can occur in this population.
Schwetz BA. Oral Sodium Phosphate. JAMA. 2001;286(21):2660. doi:10.1001/jama.286.21.2660-JFD10012-2-1