What your urine colour says about your health
From the ancient Egyptians until Victorian times, the colour, smell and even the taste of urine was used as the primary diagnostic tool for many health conditions. Numerous Victorian medical texts describe how an unfortunate doctor’s assistant would be summoned to taste a sample of the patient’s pee, with sweet urine known to be a sign of diabetes.
Thankfully for the modern-day NHS doctor, such practices have long been consigned to antiquity, but urine characteristics are still regarded as a valuable way of assessing things like hydration status, picking up early signs of disease, and even indicating that a person carries certain genetic variants in their DNA.
“There are various health conditions, foods and even medication that can change the colour of your urine, and sometimes that’s related to genetics,” says Mary Garthwaite, the chairman of The Urology Foundation and a former consultant urologist. “This all goes back to how urine has always been highly valued by the medical profession.”
So what is the benchmark for how urine should look, how does it vary and what does that mean?
What is normal?
Urine should always have a slight yellow tinge, a colour which is caused by the presence of a chemical called urobilin, made in the liver.
If your urine is completely colourless, that could be a sign that you’re drinking too much water, but overall, that your urine should ideally be a fairly clear fluid, says Prasanna Sooriakumaran, a professor of urology at the University of Oxford,.
“I would suggest that producing around two to two and a half litres per day, with at least two thirds of that being produced during daylight hours, is normal and healthy,” he says. “Overall, most people should be going about six to eight times during the course of the day.”
This is the optimal situation. But for many of us, both how our urine looks and when we tend to excrete it, can be quite different.
From dark yellow to blue
The biggest factor which can impact the colour of your urine is how hydrated you are. “If your urine looks like a glass of white wine, you’re drinking plenty, whereas if it looks like an Irn-Bru or Tango, you’re not drinking enough,” says Garthwaite.
However, if your urine begins to turn a dark brown or even black, this can be a sign of serious medical conditions such as liver dysfunction or even rhabdomyolysis, a rare degenerative condition where your muscles start to break down following an injury or excessive exercise, causing toxic components of your muscle fibres to enter the kidneys. Some darker shades can be an indicator of more common diseases.
“If you have a very soft orangey urine or it’s veering towards a reddish brown, that can indicate liver or kidney disease, or even infections,” Garthwaite warns. “There’s also a genetic type of kidney stone called cystine stones, which can affect the urine colour.”
But urine can take some even stranger shifts. Between 10 and 14 per cent of the population are genetically predisposed to a condition called beeturia, which means their urine turns red or pink after consuming beetroot, or even blackberries and red berries. While harmless, this occurs because they struggle to break down certain pigments which give these foods their distinctive colouring.
“It’s more of a purply blue red, rather than blood red,” says Garthwaite. “It’s also more prominent if you have both the genetic deposition for beeturia and an iron deficiency.”
Other foods such as asparagus or even consuming too much vitamin B through an excessive intake of supplements can cause urine to turn a greenish yellow colour. Medications can also impact the colour of urine, initiating changes which can range from red to even blue.
Again, most of this is nothing to be concerned about.
“Blood thinners can make you more prone to getting blood in your urine, while there are things like amitriptyline that can even turn your urine to a greeny blue,” explains Garthwaite. “There’s also a very rare genetic condition called benign familial hypercalcemia, which means that people excrete a high amount of calcium in their urine which can change it to a blue colour.”
However, the most important sign to watch out for is blood in urine. While the cause may be benign – marathon runners sometimes experience this, for reasons which are unknown – it can be a sign of bladder or kidney stones, urinary tract infections, an enlarged prostate, kidney injury or even cancer.
“It tends to be a bright red, as if you’re peeing a lot of blood,” Garthwaite notes. “It very much looks like pure blood. But if you ever see any red in your urine, you need to seek medical advice and assessment because it can be something serious.”
Smell
Pungent urine can also be a sign of dehydration as without sufficient fluid intake, urine is far more concentrated with various proteins and other toxins which the body is shedding.
Garthwaite points out that diet can also have a strong effect on the smell of urine. “Some people feel that if they drink a lot of coffee, or they eat a lot of onions, garlic, or even fish, their urine gets quite smelly,” she says.
While sweet-smelling urine may sound slightly more pleasant, this isn’t usually a good sign. People with uncontrolled diabetes have excess sugar in their urine which the body is trying to get rid of, as well as high amounts of fruity-smelling chemicals called ketones which accumulate in the blood and spill over into urine. These ketones are an indicator that the body is burning fat as a source of fuel, because it has lost the ability to properly metabolise sugar.
New parents are sometimes warned to watch out in case their baby’s nappy starts smelling unusually sweet. Garthwaite says that this is usually due to a genetic condition called maple syrup urine disease, which is usually picked up in infants and requires a referral to a specialist dietitian who will prescribe a low-protein diet.
“It means that the baby can’t break down certain amino acids in protein due to an enzyme deficiency. This leads to a harmful build-up of substances in the blood which make urine smell sweet when they’re excreted.”
Frequency
Regularly urinating more than six to eight times a day can indicate a number of different conditions, from diabetes-related damage to the kidneys to an overactive bladder or even obstructive sleep apnea.
When this happens in older men, Prof Sooriakumaran says that it can be a sign of an obstruction in the urethra due to causes such as an enlarged prostate. “In these cases, you would go and see a urologist, do a variety of tests to check if you’re emptying your bladder properly, check kidney function and they will also look inside the bladder to check there’s nothing causing it to be unstable,” he says.
While it’s best for us to urinate most often during the day to avoid sleep disruption, a condition called nocturia, the medical need for getting up in the night to urinate, becomes progressively more common in both men and women as we age. Studies have found that nocturia can affect between 69 and 93 per cent of men over 70.
However Dr Hussain Al-Zubaidi, a lifestyle and physical activity lead for the Royal College of GPs, says that there are still steps which people can take to mitigate nocturia at any age.
“Really focus on trying to drink earlier in the day,” he says. “You want to have at least a quarter of your daily fluid intake in the first two hours in the morning, and then you can drink little and often throughout the day. Try and avoid more than 330 millilitres or a can’s worth of fluid, within the three hours before bed.”
Consistency
While the causes of cloudy urine are often relatively benign, ranging from dehydration to a urinary tract infection, frothy urine tends to be more of a cause for concern when it comes to health status.
“It can mean that you’ve got abnormally high protein levels in your urine which can be a marker of primary kidney disease,” says Garthwaite.
Because the kidneys are effectively highly specialised sieves which sift through and filter out tiny toxins from the bloodstream, frothy urine can be a sign that they’ve become leaky and are letting bigger proteins, which should remain in the blood, seep out into urine.
In some rare cases, frothy urine can even indicate the presence of a fistula or an abnormal connection between two organs. “If you have something like diverticular disease and your bowel and bladder have become connected, you may not become immediately poorly, but you might start to get frothy urine because you’re getting air coming through which shouldn’t be there,” says Garthwaite.
When to see a doctor
Prof Sooriakumaran advises seeing a doctor if you have any unusual changes in urine colour, smell or consistency which cannot be attributed to hydration.
“If your urine consistently looks dehydrated but you’re still drinking lots, or you have other associated symptoms such as pain in the loins or difficulty emptying your bladder, that would be an indication to see a doctor,” he says.
He urges anyone who sees blood in their urine to seek medical attention without delay. “That is an immediate indicator to go see a doctor and a urologist if possible.”