[Hyponatremia: etiopathogenetic observations in the personal experiences]

Hyponatremia, an electrolyte disturbance, can be due to loss of solutes or to an increase of ''free'' water concentration, predominantly caused by excessive antidiuretic hormone (ADH) secretion. When acute, hyponatremia is threatening, because it can cause cell swelling and severe neuromuscular symptoms (central pontine myelinolysis).

In a sample of 220 subjects with hyponatremia (123 males, 97 females) aged from 47 to 83, hospitalized in the Department of Clinic Medicines and Emergent Pathologies, from 2000 till today, age, serum and urinary sodium concentration, urine specific gravity, signs, symptoms and causes of electrolyte disturbance were evaluated. Student's t-test was applied for parametric spread data, Mann-Whitney Test for no parametric spread data, ANOVA test for statistic comparison between groups.

Hyponatremia due to an increase of ''free'' water prevails in respect to hyponatremia due to loss of solutes (55.9% vs 44%). In the first case the prevalent causes are: decompensated hepatic cirrhosis (37.3%), heart failure (31.7%), glucosate solutions at 5% (17.8%) and drugs that can potentially increase ADH secretion (antidepressants, etc.) (13%), especially in elderly people. In the second case chronic diarrhea, vomiting (40%, 32.9%) and diuretic-induced hypernatriuresis (18.5%) prevail. Laboratory results follow the grade of efficient volemia, registering statistically significant differences between the two variants of hyponatremia.

Different diagnosis and adequate treatment are essential when hyponatremia is acute. Particular attention must be reserved to elderly people with hyponatremia, in which the mechanisms of ''free'' water clearance are inefficient and such hypotonic glucosate solutions as medicines that increase ADH secretion (psychodrugs) must be administered with caution and under clinical control.