Did you know that the consumption of too much water during strenuous exercise, without the adequate replacement of sodium, can lead to “water intoxication” or hyponatremia? The disorder is caused due to lower-than-normal levels of sodium in the blood and is the most common electrolyte disorder, with the frequency being higher in women, the elderly and patients that are hospitalised.

Today, however, many young people are cutting out salt from their diets in a bid to stay slim. Salt, they feel, makes them retain water and therefore look fat. But sodium is essential for many body functions like the maintenance of fluid balance, regulation of blood pressure and normal function of the nervous system. Normal blood sodium levels should range between 135-145 milli-Equivalents/litre (mEq/L), or in international units between 135-145 millimoles/litre (mmol/L).
Hyponatremia is defined as a serum level of less than 135 mEq/L and is considered severe when the serum level dips below 125 mEq/L.

The causes
A low sodium level in the blood may result from excess water or fluid in the body, diluting the normal amount of sodium so that the concentration appears low. This type of hyponatremia could be the result of chronic conditions such as kidney failure and congestive heart failure, in which excess fluid accumulates in the body. Other causes of hyponatremia include:
w SIADH (syndrome of inappropriate anti-diuretic hormone), which is a disease whereby the body produces too much anti-diuretic hormone (ADH), resulting in water retention.
w Consuming excess water during strenuous exercise, without the adequate replacement of
sodium.
w Prolonged sweating and severe vomiting or diarrhoea when fluids are lost from the body in plenty.
w Consuming too much fluid during endurance events, people who fast on juice and water for extended periods and people whose dietary sodium intake is chronically insufficient.
w The consumption of large quantities of beer or use of the recreational drug MDMA (ecstasy).
Medical conditions that can sometimes be associated with hyponatremia include adrenal insufficiency, hypothyroidism and cirrhosis of the liver.
A number of medications can also lower blood sodium levels, examples of these include diuretics and antidepressants.

The symptoms
When sodium levels in the body are low, water tends to enter the cells, causing them to swell. When this occurs in the brain, it is referred to as cerebral edema. In chronic hyponatremia, in which the blood sodium levels drop gradually over time, symptoms are typically less severe. Symptoms can be very nonspecific and can include: headache, confusion or altered mental state, seizures and decreased consciousness, which can proceed to coma and death. Nausea and vomiting may accompany any of the symptoms. Many medical illnesses such as congestive cardiac failure, liver failure, renal failure, or pneumonia may be associated with hyponatremia.

Diagnosis and treatment
The symptoms of hyponatremia are nonspecific, so a blood test measuring sodium levels is required to confirm the diagnosis.
The treatment of hyponatremia often depends on the underlying cause. If a person is truly aymptomatic or has only subtle symptoms, little treatment other than water restriction may be required. In a setting of volume depletion, the intravenous administration
of normal saline may well be effective.
In the end it would be safe to say that if you are young and feel that cutting the salt out of your diet would be the way to stay slim, think again. You could be on the road to disaster if your salt/sodium levels dip dangerously.
The writer is Senior Consultant, General Physician,
Max Healthcare