Icodextrin lowers serum sodium in dose-dependent fashion: A case report.

Icodextrin (ICO) is widely used in peritoneal dialysis (PD). Hyperosmolar hyponatremia (hypoNa) has been reported as an adverse event of ICO, but it is unknown whether there is a dose effect relationship between the two. We present a case demonstrating this relationship. A 61-year-old woman with end-stage kidney disease (ESKD) and no history of diabetes, began PD with a single daily dwell of 1L of ICO. Her serum Na during the previous 6 months (n = 16) was 138.9 (mmol/L) ± 2.2 (SD). Within days of starting PD, the Na fell to 132 and over the ensuing 9 months (n = 27) it averaged 133.6 ± 2.1. As her PD prescription (Rx) was changed throughout two hospital admissions and subsequent outpatient management, she maintained normonatremia when using dextrose exchanges and became hyponatremic with ICO exchanges. With increasing daily doses of ICO, her hyponatremia became more severe (nadir of Na 121 with 3L of daily ICO use). She ultimately returned to exclusively dextrose cycles for two years and remained normonatremic. Years later a single 2L ICO dwell was started, and she developed hypoNa again (Na 131). ICO was stopped and Na normalized. We plotted serum Na vs total daily ICO dose and showed a strong correlation (R2 = 0.737). HypoNa is a risk factor for ESKD patients that lead to increased morbidity and mortality. This report demonstrates that the severity of ICO-induced hyponatremia is directly proportional to the amount of ICO used. For patients developing hyponatremia, instead of discontinuing ICO, practitioners might consider reducing the dose.