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A detailed guide to kidneys – what exactly is the cause of damage and how it occurs

We have been born and brought up among Hindi movies which have a certain elder father of the bride or hero dying of kidney failure or heart attack. While the percentage of onscreen death due to heart attacks are much higher, kidney failure is not far behind. But the sad part is that 75 years plus of Bollywood messaging has still not make us aware how to take care of the kidneys and what is the lifestyle that damages it. Let us understand in detail.

Since this will be a detailed article, it is recommended that you read it on a laptop or desktop PC. Here is the shorter version as a summary.

The short version

As a cleansing organ, kidneys maintain the right balance in blood by filtering it. Unlike the liver, a kidney cannot repair itself. Any sort of damage begin small and keeps building up to complete renal failure. That is why it is important to detect problems early and take the necessary precautions.

Health of the kidney is measured in terms of filtration rate and the first indication of unhealthy kidneys is frequent visits to pee at night.

Excessive consumption of carbs and sugars damages the tiny blood capillaries within the kidneys there by being the main cause of damage. So insulin resistance, fatty liver, diabetes, hypertension, high BP, excess abdominal fat and obesity are the dangerous signs you need to look out for.

Smoking increases insulin resistance which means it indirectly causes kidney disease.

It is however drinking and specifically social drinking which is the main danger to your kidneys because social drinking causes hangover and dehydration. Alcohol is a diuretic which means you end up urinating more after drinking.

Dehydration is the main risk to kidney because the filtration mechanism requires water to function, just like an RO filter plant.

Role of kidney

Kidneys are the cleaning mechanism of blood filtering out waste. It also maintains the balance of uric acid in the blood. Finally it is the kidney who maintains the correct water amount in the body. Also important it is to note that the kidney wakes up in the morning along with your body and starts with the first rays of the sun. It is also put to sleep four hours after sunset due to the production of melatonin. That is why it is extremely important to literally wake up your kidneys by gulping in lots of water, first thing in the morning and then allow the kidneys to go to sleep at the right time by stopping all kinds of meals and drinks well before bed time. Needless to say, bedtime is 10 pm, nothing beyond.

The functioning of kidney is such that like an RO water filter it needs water to work. That water is extracted from the blood. Being hydrated first thing in the morning is very important.

Kidneys also control the blood PH level, electrolyte balance and hormone production.

How does the kidney work

Blood enters the kidney via the renal artery which further divides into tiny arterioles. At the end of arterioles are Nephrons where the blood filtration takes place. Filtered blood comes out through the renal vein. Urine formed due to filtration is send out of the kidney via the collecting ducts into the Ureters.

At the centre of the nephron is glomerulus which is like a tiny bag of arteries in which blood enters through the Afferent arteriole and exits through Efferent arteriole which is a bit larger in diameter than the afferent arteriole. This creates a hydrostatic pressure which together with osmotic pressure removes water and other substances dissolved in the blood from the blood plasma. This membrane type of filtration allows water, ions, glucose, amino acids and metabolic wastes like urea and creatinine to be separated from the blood. This filtration process is controlled by a series of feedback mechanism within the kidney called renal auto-regulation. Change in diameter of the afferent arteriole controls the filtration rate by squeezing the nephron sack.

Side Note – It is the this renal auto regulation which is affected by substances like coffee and alcohol. Insulin resistance also affects the urate transporters in the kidney which regulate uric acid in blood.

Kidneys are one of the most hard working organs of the body, filtering almost 150 liters per day in case of men and 180 liters per day in women even though the amount of blood in the body of a woman is lesser a man. However only 1% of this is excreted as urine and rest is re absorbed.

Here is the part which gets interesting. There are two exits from the nephron, one is the efferent arteriole which carries filtered blood out and the other is nephron loop which ends in the renal tube which carries the waste out. Just outside the nephron, both these outlets come close to each other again. Here variation in the sodium level allow substances like glucose, amino acids and around half of the waste material from the nephron loop send back into the efferent arteriole and into the filtered blood again! Amazing isn’t it. Filtered waste going back into purified blood.

The kidneys therefore reduce the metabolic waste to a certain level but do not completely eliminate them.

Further down the nephron loop which is in a series of ups and downs, water and sodium is pumped in and out at different stages. Towards the end different salts are controlled by the hormones which is how the filtration actually takes shape as per body needs.

Finally at the collecting duct stage, conservation of water begins as the urine is made more saline by removing water through osmosis. The collecting duct is under the control of ADH or the Antidiuretic Hormone which is responsible for controlling the amount of water in urine. Have you ever heard about coffee being diuretic and hence making you pee more. This is the hormone which comes into play and reduces the amount of water being removed from the collecting duct. Another powerful diuretic is alcohol.

Kidney takes the decision of removing water based on the hydrated condition of the body. If the body is dehydrated, more water is reabsorbed by the collecting ducts.

Another side note – You must have heard about dry fast or waterless fast. There is a divided opinion among people who perform fasting as to whether dry fast is good for health or not. A dry fast means that the body will get dehydrated and a time will come when the functioning of the kidneys itself will fall in the danger category. Once a year the most stringent of Ekadashi falls during the summer months is nirjala ekadashi during which people in India observe a 24 hour waterless fast.

How can kidneys fail – Chronic Kidney Disease and Acute Kidney Injury

Acute Kidney Injury happens over a period of a few weeks while Chronic Kidney Disease happens over a period of months or years.

The top three most common reasons for CKD or Chronic Kidney Disease is Diabetes, High Blood Pressure or hypertension and metabolic syndrome or excessive abdominal fat. There are other reasons too but they are mostly due to medication and physical injury. Hereditary reasons are the most important cause of concern. So if you have a family history, you need to be careful from the word go.

Functioning of kidneys is measured and calibrated with the help of Glomerular filtration rate or (GFR) at the nephron level. That figure has to be more than 90. In case of renal failure that rate drops to 15 or below. As filtration reduces, the ability of kidney to filter the waste from the blood diminishes. Measuring these wastes is another way to check the health of your kidney. A urine test should have little or no albumin in your urine. That is a sign of a healthy kidney.

Initially there are no symptoms at all because the workload of the failed tissues are taken over by the healthy parts of the kidney in a process of adaptation. However, the first signs of renal insufficiency is frequent trips to the bathroom especially at night. It is the first sign which is usually ignored by everyone.

Now at this point let us get back to the beginning of the article where we mentioned that the kidneys have to be put to sleep four hours after sunset. That also means that once you have done with your last pee before you sleep, ideally you should then pee next only in the morning. Imagine the devastating effect that will happen on your body in situations when you force your body to urinate in the night. The big fat Indian weddings begin late evening and go on till late night, the perfect recipe for renal disaster. Also the parties and get-togethers usually happen late into the night leading to all sorts of stresses on the body. What are we trying to do with the body is a big mystery.

Other early signs are fatigue, loss of appetite and decreased mental capabilities. This happens because of the rise of urea in blood. In the quest to clear up the waste, the heart starts pumping blood faster which results in high blood pressure.

Effect of carbs and sugars

Glucose in blood makes red blood cells sticky losing their flexibility. That makes it difficult for blood to flow in tiny capillaries. High blood sugar can lead to blockages of the capillaries inside the kidney. Also carbs and sugars act like sandpaper causing inflammation in the inner walls of the arteries.

Presence of excess blood glucose puts a strain on the filtering mechanism in the glomerulus. Over time the damage builds up allowing proteins to pass though the filter in the urine. This is the protein which shows up in the urine as albumin.

Excessive consumption of carbs and sugars generally leads to a fatty liver condition which further takes you towards insulin resistance. As you put on weight at your waist, your metabolic condition deteriorates, blood pressure also increases. This too puts a lot of pressure on the filtration mechanism damaging the delicate capillaries which carry blood inside the kidney.

There is a very simple way to check if you have fatty liver condition. Just look down and if you have signs of a belly forming, you have a fatty liver. A healthy liver is when you do not have any fat around your belly. That would also be an indirect sign of healthy kidneys.

Effect of smoking

Smoking introduces harmful chemicals in the body which ultimately end up in the blood stream. Any organ which is affected by cigarette smoke finally dumps the waste in the blood. This results in more work for the kidneys.

If you are under medication of any sorts for blood related condition, smoking inhibits that medication resulting in hypertension and high BP which will ultimately affect the kidneys.

Smoking also increases insulin resistance which leads to diabetes, high blood pressure, hypertension and metabolic syndrome. All these conditions directly result in CKD or chronic kidney disease.

Effect of alcohol

Alcohol can definitely affect your liver. That is a done deal because it directly causes scarring of the liver tissue or cirrhosis. However incase of liver, this is a huge organ and it is able to repair itself. But the kidneys won’t be able to do that. Here are the three ways you should be aware how alcohol will affect the kidneys.

Alcoholic Drink is empty calories – The lowest carb drink would still be at least 100 calories while a cocktail can go as high as 500. Alcohol induces appetite thereby making you eat more. It also makes you lose inhibitions. If you are facing an obesity situation or fatty liver condition, alcohol will increase insulin resistance as well as help you weight gain, not a good option for a healthy kidney.

Social drinking is most harmful – Social events by their nature do not happen in the day time or afternoons. Usually late into the night, they delay both food with drinks. A person who thinks that he or she is drinking occasionally and socially is not at risk. However that is not the case. Regular drinkers usually wind up by 7 am followed by an early dinner and sleep. But social drinkers once in a while abuse their liver and kidneys beyond repair. A stressed liver can still recover from damage and show, but the kidney cannot. Kidney damage is irreversible and accumulates in the system.

Dehydration caused by alcohol – If your alcohol hangover lasts for days, the associated dehydration will also last that long. A dehydrated system is putting a load on the filtration system within the kidneys. This condition remains for days sometimes, till the liver is able to fully remove ethanol from your body.

Alcohol also disrupts the urate transporters in the kidney which regulate the levels of uric acid in the blood. This causes the overall acidity levels in the body to increase. This does not actually cause any damage to the kidney per se but just confuses it for some time.


It is time Bollywood movies also explain the reason for kidney failure for just a few minutes. Now that you know, restrict the consumption of refined carbs, sugars and stay away from any kind of tobaccos and alcohol.

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