While working as a urologist, in England, a nurse casually asked me if bed wetting could be a serious problem. I said “Yes, it can be, but depends on the duration and age of the person.” She told me her father, an otherwise fit man, had recently started wetting the bed at night. But he was too embarrassed to see his family doctor. I asked her to bring him to me as soon as possible, since I knew from her description that he was probably dealing with a problem that might have affected the kidney.

As expected, on examining the patient I found that a enlarged bladder was the reason behind the bed wetting. A subsequent ultrasound scan revealed swollen kidneys and further blood tests showed that he was in the early stages of kidney failure (accumulation of waste products in the body) which fortunately reversed once his bladder was emptied with a catheter. One of the fallouts of this was that his prostate had enlarged preventing his bladder from emptying. As a result the patient had to undergo laser prostate surgery to solve his problem.

How does bed wetting and a failure to empty the bladder result in kidney failure? The kidneys situated on either side of the upper lumbar spine filter the blood. They help retain essential salts and proteins as the blood gushes through them at great speed and lets go of nearly two liters of water together with waste products. The blood is brought into the kidney at great pressure to allow the filtration process. Once the filtration process is completed urine is produced and falls into the collecting system called calyces and pelvis, which are like funnels. The ureters are tubes, which then ease the urine into the bladder by a gentle wave like action called the peristalsis. For the filtration process to take place effectively the pressure has to be low in the collecting system and even lower in the ureters.

Any disease in the bladder or in the outflow tract which creates a high pressure in the bladder to force open the gates can disrupt the filtering process resulting in kidney failure.

This can happen in children due to faulty gates (vesico-ureteric reflux), blockage while passing urine called Posterior Urethral Valves and Congenital Urethral Stricture, a problem common among boys. It can also occur in adults due to interference in the nerve supply, due to neurological disease or spine injuries.

Failure to empty bladder, transmission of high pressure to the kidneys can result in bladder irritability, which are the first signs of a serious kidney disease. Some children don’t grow out of bed wetting. This is usually of no consequence as they settle with time, but the problem still needs investigating to rule out bladder or kidney problem.

The writer is the CEO of Dr Ramayya’s Urology, Nephrology Institute and Hospitals