Hyponatraemia

Hyponatraemia is a pathological situation involving deficiency of sodium ("natrium" in Latin) in the blood. It is present when sodium levels are below 130 mmol/L. Because of effects ofosmosis, extra-cellular fluid enters the intracellular space to rebalance sodium concentrations. Hyponatraemia can also cause neurological disorders which may result in loss of consciousness or coma in very severe cases.

Causes of hyponatraemia

. Hyponatraemia has several causes including:

• deficiency of sodium due to excessive loss or inadequate intake. It may be caused by some medicines such as diuretics. Other factors such as nephropathy (renal dysfunction) are occasionally involved;
• water excess, water retention in the extracellular space leading to excessive dilution of sodium. Potomania (or psychogenic polydispia), a disorder involving excessive drinking, can also cause hyponatraemia.

Treatment of hyponatraemia

Neurones are very sensitive to changes in sodium concentrations. Hyponatraemia must be treated gradually to avoid other serious symptoms such as altered consciousness or locomotor problems. To treat it therefore the source of the problem must be identified. If hyponatraemia is due to diuretics, these must immediately be stopped&nbsp. If it is due to overhydration, the patient's water intake must be restricted until the blood sodium returns to normal.