Red blood cell intracellular electrolyte concentration in children with acute hyponatremia.

OBJECTIVE

To determine the relationship between intra- and extracellular red blood cell (RBC) sodium and potassium concentration in children with acute hyponatremia.

DESIGN

Prospective case control study.

SETTING

Pediatric intensive care unit of a tertiary care university-affiliated community hospital.

PATIENTS AND METHODS

Plasma and RBC sodium and potassium concentrations were measured in nine consecutive children with acute hyponatremia (sodium <136) (hyponatremic group) and compared to those in nine healthy children with normal plasma sodium levels (control group). Measurements were taken on admission and after 12, 24, 36 and 48 hours by means of an atomic absorption spectrophotometric method.

RESULTS

An inverse correlation was found between RBC intracellular sodium concentration and plasma levels in the acute hyponatremic group (p < 0.016, r = -0.76).

CONCLUSIONS

Plasma levels of sodium may not accurately reflect intracellular concentration in the assessment of acute hyponatremia in children. Further studies on the relationship between acute hyponatremia and red blood cell sodium concentration are warranted.