Serum osmolality in different types of dehydration

ABSTRACT

Seventy patients with acute diarrhea and dehydration attending the Rehydration Center, children's Hospital, Ain Shams University, were studied. Their ages ranged from 2 to 24 months [mean 9.54 +/- 4.99], 44 were males and 26 were females. Thirty five normal infants and children of comparable age, sex and socioeconomic status were studied as controls. All children were subjected to complete clinical examination. Laboratory investigations included determination of serum sodium, potassium, osmolality, glucose, albumin and total serum proteins estimation before and after treatment of dehydration. Isonatremic dehydration was the most common type of dehydration [54%]. There was no statistically significant difference in the mean serum sodium, in patients with isonatremic dehydration before and after treatment. On the other hand, statistically highly significant difference was noticed in patients with hypo and hypernatremic dehydration. A positive correlation was found between the mean value of measured serum osmolality and serum sodium, urea, glucose and calculated serum osmolality in all types of dehydration. In mild and moderate isonatremic dehydration, the cases were isosmolal due to the normal serum urea and glucose while cases with severe degree of isonatremic dehydration had high serum urea and glucose leading to hyperosmolality. All patients with hyponatremic dehydration had hyperosmolality due to the high serum urea and glucose. In dehydrated patients serum proteins were significantly higher before treatment compared with after treatment. In conclusion, serum osmolality is a useful tool in evaluating and following up patients with diarrheal dehydration being rapid, accurate and needs only very small amount of serum