Strange urine

Dr Margaret [biog] answers users' embarrassing problems in this problem page feature (new products every 2 weeks

How is urine made?
Your urine is made by the kidneys and stored in the bladder. The kidneys act as a filter, draining the water and waste products from the blood and keeping the blood cells and larger protein molecules in the circulation. Most of the water is absorbed back into the blood, leaving the waste substances as a more concentrated solution. The amount of water absorbed depends on how much is in the blood - the kidneys work hard to keep blood at its usual concentration. When you are slightly dehydrated, your urine will be stronger and dark yellow as most of the water is absorbed back into the blood. When you have drunk a lot of fluids, the urine will be paler as the waste products in urine are more diluted.

My urine’s a strange colour
The remains of bile made by the liver cause urine to be yellow. As urine also contains waste products from the blood, its colour is affected by what else is in the blood, such as foods and chemicals. About one in ten people find their urine turns red after they have eaten beetroot, though most people do not experience this. It seems to be more common in people with anaemia.

Red, brown or smoky-coloured urine can also be caused by taking medication, such as senna, phenolphthalein or the tuberculosis drug rifampicin. However, it may also indicate bleeding into the kidneys or bladder. This is usually due to an infection, but can be caused by a tumour. Cystitis, a urine infection in the bladder, makes you want to pass urine more frequently than usual. You have to rush to get to the toilet in time, but pass only a small volume of urine each time. There is a burning or stinging pain as the urine is passed, and there may be a pain at the bottom of the abdomen. With this infection, the urine may be cloudy, if not pink, and often has an unpleasant smell. Antibiotics can clear up the infection, and you should make sure you drink plenty of fluids each day to flush the bacteria from the bladder. Cranberry juice is thought to stop the bacteria sticking to the bladder and help clear up the infection, though this has not been proved.

Red urine. If the infection spreads into the kidneys, you will develop pyelonephritis. This usually causes a pain in the side, fever and makes you feel sick, with vomiting, diarrhoea and fits of shivering. The urine may be red or pink, and there may be symptoms like those of cystitis. This condition needs to be treated with antibiotics to prevent kidney damage. Drink lots of fluids too. Any change in the colour of your urine that you can’t link to anything you’ve eaten should be checked by your doctor.

Bubble trouble?
If the ‘holes’ in the kidney ‘filter’ become too big, they start to let protein through into the urine. Infections, drugs, diabetes, certain types of cancer or the body’s immune system attacking its own cells by mistake can cause this to happen. The protein makes the urine frothy. This condition tends to cause swelling of the ankles and other body areas, and can make the blood more likely to form clots in the blood vessels. This condition, called ‘nephrotic syndrome’, usually gets better with medication that can be prescribed by your doctor, but there is a risk that the kidneys will not work as effectively as before. You will probably need to be admitted to hospital for tests and treatment if you have this condition to find out why it has happened and to ensure that your symptoms are getting better.

Jonathan Belsey and Alison Martin

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