Recently hyperosmolar hyponatremia following excessive off-label use of two exchanges of 2L icodextrin daily during peritoneal dialysis (PD) was reported. We encountered a cluster of three cases of PD patients who developed hyperosmolar hyponatremia during on-label use of icodextrin. This appeared to be due to absorption of icodextrin, since, after stopping icodextrin, the serum sodium level and osmol gap returned to normal, while a rechallenge again resulted in hyperosmolar hyponatremia. We excluded higher than usual concentrations of specific fractions of dextrins in fresh icodextrin dialysis fluid (lot numbers of used batches were checked by manufacturer). We speculate that in our patients either an exaggerated degradation of polysaccharide chains by α-amylase activity in dialysate, lymph and interstitium and/or rapid hydrolysis of the absorbed larger degradation products in the circulation may have contributed to the hyperosmolality observed, with the concentration of oligosaccharides exceeding the capacity of intracellular enzymes (in particular maltase) to metabolize these products to glucose. Both hyponatremia and hyperosmolality are risk factors for poor outcomes in PD patients. Less conventional PD prescriptions such as off-label use of two exchanges of 2L icodextrin might raise the risk of this threatening side effect. This brief report is intended to create awareness of a rare complication of on-label icodextrin use in a subset of PD patients and/or PD prescriptions.
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