70% of earth surface is covered with water and 50-70% of human body composition is water. Water is one of the predominant aspects of our physical existence and imbalance of this composition can cause serious ill effects on the body. The vital organs in our bodies which regulate this water composition of our body are the kidneys and their health also depends on the water intake.
In the nature as water is distributed in different compartments like the ground water, the surface water ( lakes, rivers and oceans),similarly water is distributed throughout the body in different compartments , inside and outside of every cell and in the blood and all the supporting structures. There is a fine balance of water between these different compartments, and this balance depends on the total water and electrolyte composition of the blood and the cellular channels /gates for influx and efflux of these electrolytes and water . As the natural water bodies are replenished by rains similarly our water reserves are replenished when we consume water. When there are heavy rains we open the gates of the dams on the rivers to allow water levels to recede, similarly when we
consume more water the kidneys flush that extra water out and when we drink less kidneys conserve water and salts.This fine regulation of body water and salts is done by different sensors(baro receptors), hormones – for water(ADH) and salt (Aldosterone) handeling , which give inputs to the kidneys. When the rains are torrential and overwhelm the capacity of the river boundaries then there is flooding and damage , similarly when the water intake overwhelms the capacity of these sensors and hormones and the kidneys to handle them it causes ill effects on the body in the form of swelling , electrolyte imbalance- low sodium levels and water intoxication.
Ill effects of dehydration:
Acute severe dehydration:
Water is the main component of blood, the blood pressure depends on the water and electrolyte composition of blood. If there is sudden dehydration due to profuse diarrhea or vomitings or inadequate intake with excessive losses due to sweating , leakage of blood water into other compartments of body due to severe infections causing sepsis or due to inability to drink water due to decreased level of consciousness either due to intoxication or any neurological diseases , the Kidneys try to compensate by trying to conserve water and salts, but when their capacity to compensate is overwhelmed then there can be drop in the blood pressure causing poor blood supply to vital organs. When the blood supply of organs is compromised there is lack of oxygen and energy reaching at the cellular level leading to initially preferential sharing of resources between different organs, followed by cellular death if things are not corrected early. Each Kidney has a million filtering units called nephrons which have plenty of energy-dependent channels working constantly and so as the blood pressure drops these channels are the first to get affected and these nephrons get damaged causing acute Kidney failure which if detected early and treated early is reversible in few hours, days or weeks but if not corrected early by raising the blood pressure or by
hydrating then they get damaged sometimes permanently with only partial or no recovery.70% of earth surface is covered with water and 50-70% of human body composition is water. Water is one of the predominant aspects of our physical existence and imbalance of this composition can cause serious ill effects on the body. The vital organs in our bodies which regulate this water composition of our body are the kidneys and their health also depends on the water intake.
Chronic mild dehydration:
If dehydration is not severe , kidneys concentrate the urine and conserve water.Some times it becomes a habit to drink less water due to either personal habits or social circumstances like working in places with inadequate rest room facilities (eg. employees in shops or taxi drivers), or working in circumstances where there is profuse sweating (eg. labours, miners,farmers, athletes, marathon runners, army personnel, in difficult physical training camps etc).These people may have chronic dehydration which may cause the risk of recurrent kidney stones formation, urinary tract infections, mild injuries to the kidney eventually casing chronic Kidney disease etc. These subjects are at higher risk of kidney failure when they consume pain killers or get any sickness causing further
dehydration. Those with kidney stones are thus advised to drink enough water to atleast form 2 litres of urine, to avoid recurrent stone formation.
Ill effects of overhydration:
Acute water intoxication:
Although kidneys are able to manage excess water intake by diluting the urine and flushing that extra water out but in certain circumstances that capacity may be overwhelmed, the classical example are the long marathon runners who if keep drinking water with the fear of dehydration while running for long hours, they keep losing salts in the sweat and if they keep drinking excess water that can lead to sudden drop in their blood sodium levels , that leads to extra water shifting from outside the cells into the cells and swelling of body cells, especially when the brain cells swell, they have no space to expand in the bony skull, causing rise in the intra cranial pressure causing sudden death.
Those who have acute or chronic kidney failure , they are unable to excrete salt and water adequately and if they drink excess water then that excess salt and water leads to rise in blood pressure, swelling of feet and puffiness of face, when this excess exceeds the hearts capacity to handle this water load then there is accumulation of this water in the air filled alveoli of the lungs and the person experiences shortness of breath earlier on walking and later even at rest and further later the person may not be able to lie down at all and even has to sleep sitting up in chair. So those with kidney disease are advised to restrict their salt and water intake.
Chronic water intoxication:
It is a popular belief that one should drink plenty of water. Yes its good to drink water, but how much is optimum, it is difficult to give one value for all, as it depends on the age , sex, level of physical activity, living and working conditions and different health conditions(heart failure/Kidney failure/Liver failure, etc). Therefore it is not wise to just drink excess water thinking that it will be flushed through the kidneys. As we grow older the kidneys capacity to handle water decreases, so if you were drinking 4-5 litres of water when you were young doesn't mean you will be able to continue that when you are above 60. Many a times this excessive habitual drinking may cause the blood sodium levels to decrease in elderly individuals causing an unsteadiness in their gait and
incresed risk of fall and fractures,low sodium levels can cause loss of appetite, nausea, altered behaviour, irritability, drowsiness and even altered level of consciousness.
Generally, water intoxication is uncommon in healthy young individuals but can be seen in people with psychological obsessive-compulsive disorders.
Conclusion:
Ill effects of dehydration are well known to most of us. Thus optimum water intake is essential , but just drinking excess water thinking it is good for health may not be always true, it may even be counter-productive, especially in those with kidney dysfunction, heart failure or elderly people. Young healthy individuals can handle water excess better and may not get water intoxication unless they have obsessive compulsive drinking habits or disorders but same thing need not continue when they are ageing and need to understand their physiological changing needs. Thirst is the best guide for all except those with altered levels of consciousness. Average water intake can be upto 3 litres for healthy young individuals but may vary based on their level of physical activity and ambient temperatures at working conditions.Those with kidney or heart failure may be advised to restrict their water intake to less than a litre per day. Thus it is wise to seek help from your physician if you have any significant ailments before just drinking water for some water therapies or just like that.
– Dr. Krishna Patil,
MD,DM, FASN, FICN(Canada)
Consultant Nephrologist,
Sunshine Hospitals, Gachibowli, Hyderabad.