KOCHI: Let’s start with the basics. How important is water for health? What’s the role of the kidneys in water balance?
Water constitutes 60 per cent of one’s body weight, and it plays an important role in physiological and biochemical functions. Reduced water intake may lead to dehydration and kidney damage, while excessive consumption may result in water intoxication, both are harmful conditions.
Under normal conditions, kidneys are the primary organs for water balance. Every day, kidneys filter more than 150 litres of body fluid, and less than 1 per cent (1.5 litres) of the filtered fluid is excreted as urine.
How does a person know how much water is to be consumed?
It is important to ensure that the body is adequately hydrated. Good urine output, pale brown urine, absence of significant thirst and healthy skin are markers of adequate hydration.
Can dehydration per se cause kidney trouble?
Reduced water intake and dehydration due to extreme hot climate have been found to contribute to permanent kidney damage in certain parts of the world, including Srikakulam in Andhra Pradesh and Sri Lanka. With increasing heat and hot summers, it could possibly happen here as well. Moreover, dehydration can cause further worsening in people who have some degree of kidney damage.
Are there any conditions where water intake plays a key role?
Increased fluid intake has a special role in preventing or reducing the severity of certain types of kidney diseases. Patients with kidney stones should drink plenty of water to prevent crystallisation of certain salts, such as calcium oxalate. It is important that they pass at least 2,500ml of urine every day.
Patients with a genetic disorder of the kidney called autosomal dominant polycystic disease (ADPKD) should also drink plenty of water as adequate water intake suppresses a hormone called ADH, which has a role in the progression of kidney disease.
What is the recommendation for water intake with regard to the upcoming summer?
Over the past couple of decades, the planet has been experiencing progressive warming.The upcoming summer is predicted to be the hottest ever so far.
People who work outdoors have a very high risk of dehydration and developing heat stroke, which is a lethal condition. Also, as mentioned earlier, dehydration may lead to kidney damage and worsening of kidney functions in those with preexisting kidney diseases. Hence, it is essential for everyone to make sure they are well-hydrated.
Plain water, buttermilk or rice water are good options. Soft drinks, fruit juices or beer are not preferred options, as these only cause further dehydration.
How much water should a healthy person ideally drink?
This is often discussed in social media. Several recommendations that we see – such as, drink ‘X’ or ‘Y’ litres of water daily – are not based on any scientific observations. There is no evidence to suggest that excess water intake will enhance the removal of toxins from the body and improve the functions of the kidney and other internal organs.
Scientific recommendation is that water intake should be sufficient to avoid dehydration and to maintain a good urine flow. On an average, however, we can say 2.5 to 3 litres of water a day is sufficient for a healthy adult. There are no rigid rules here. Go with the body mechanism; just respond to thirst.
Should p eople with pre-existing medical conditions drink a lot of water?
With declining kidney, heart or liver functions, ability of the body to handle water load comes down. Though they may not have any visible swelling of the body, excess water intake is likely to cause hyponatremia (low sodium level) and congestion of the body as they are unable to handle this extra water load. People with kidney, heart or liver disease should check with their doctors regarding the recommended intake of water, as it may vary from person to person.
The writer is director & chief of nephrology & renal transplant services, VPS Lakeshore Hospital