Natriuresis and "dilutional" hyponatremia after infusion of glycine 1.5%

To challenge the view that the hyponatremia resulting from absorption of glycine 1.5% is attributed to the expansion of the extracellular fluid (ECF) volume, and that the change in serum sodium is therefore widely used to calculate the amount of irrigant absorbed.

Retrospective analysis of six studies.

University-affiliated hospital.

Approximately 1.2 L of glycine 1.5% was infused in 23 volunteers (two studies), 1 L in 10 prostatectomy patients, 2.4 L in 6 sheep, 4 L in 6 other sheep, and 3 L in 9 piglets. The distribution of the irrigant water was estimated from the difference between the measured and the expected serum sodium levels, taking into account the urinary losses of sodium and water.

Between 30% and 50% of the irrigant volume had diffused into the cells 30 minutes after the infusion, and only between 0% and 50% of the fluid remained in the ECF. One hour later, natriuresis accounted for 100% of the residual hyponatremia in the small-volume experiments, and it accounted for approximately 50% in the large-volume experiments. The change in serum sodium could not be used to quantify the small infusion volumes, but the large ones could be quantified fairly accurately if assessed at the very end of the infusion.

Diffusion of water into the cells and natriuresis reduced and prolonged the hyponatremia associated with infusions of glycine 1.5%. This finding makes IV fluid with sodium added a more rational alternative than furosemide in the treatment of fluid overload with this irrigating solution.