Hyponatremia

The electrolyte disturbance hyponatremia exists when sodium levels in the blood are below 135mmol/l. Hyponatremia may lead to dehydration.

Hyponatremia is mainly caused by solute loss, such as vomiting or diarrhea. Water retention resulting in hyponatremia essentially occurs only when there is a defect in renal water excretion, either through diminished generation of free water in the loop of Henle and distal tubule, or via enhanced water permeability of the collecting tubules due to the presence of antidiuretic hormone.

Symptoms of hyponatremia can include dizziness and disorientation, cramping, nausea, weight gain or bloating, and in severe cases seizures or coma.

Primary polydipsia is a very rare cause of hyponatremia.

Pseudohyponatremia is a laboratory abnormality caused by the failure to correct for the volume of lipid present in plasma in conditions such as hyperlipidemia.

External Articles

• http://www.emedicine.com/emerg/topic275.htm
• http://sportsmedicine.about.com/cs/hydration/a/aa051200.htm
• http://www.honoluluclub.com/pulse.php?ID=31