SEVERE HYPERPHOSPHATEMIA INDUCED BY A PHOSPHATE-CONTAINING ORAL LAXATIVE

OBJECTIVE: To describe a case of severe hyperphosphatemia following un intentional overdosage with an oral phosphate laxative, and raise atte ntion to the risks of using such medications in the elderly. CASE SUMM ARY: An 84-year-old white woman was admitted with confusion 8 hours af ter inadvertently ingesting 12 fluid ounces of Fleet Phospho-Soda (ins tead of the prescribed 1 1/2 fluid ounces) prior to a colonoscopy. Her serum phosphate and ionized calcium concentrations were 10.3 mmol/L a nd 0.56 mmol/L, respectively. She was treated conservatively with oral phosphate binders and made an uneventful recovery. DISCUSSION: Severa l previous reports have described hyperphosphatemia in association wit h phosphate laxatives, especially in patients with renal or colonic di sease. Our case again presents two important issues in the use of phos phate laxatives by the elderly: (1) the frequently overlooked underlyi ng renal insufficiency in which, despite ''normal'' serum creatinine v alues, renal phosphate handling may be impaired; and (2) the potential for drug misuse and poor compliance in the elderly. CONCLUSIONS: Caut ion should be taken with the use of phosphate laxatives in the elderly in the face of potentially serious metabolic abnormalities that may b e generated.