Blood in your urine? Here's what you need to know

Written by: Dr David Game
Edited by: Karolyn Judge

What should you do if you find blood in your urine? Why does it occur? And what are the reasons that our urine can look more or less concentrated at different times of the day?


Here to answer these questions, and more, in expert detail is leading London-based nephrologist Dr David Game. Find out more in this informative article. 


Worried young woman looking in a bathroom mirror


What are the most common reasons for blood in the urine?

Blood in the urine is not a normal finding. The most serious findings of blood in the urine is somebody who's older, will be cancer. Cancer in the kidney, in the ureter (the tube going from the kidney to the bladder), within the bladder or occasionally in the urethra. Particularly if one has risk factors for cancer, then this must be excluded first. In general, if somebody is over 40 and they have blood in the urine then cancer of the urinary tract needs to be excluded before looking for other things.


If someone's younger than 40 and has never smoked, for example, then the risk of having kidney cancer is less. In this case, it's common to see a nephrologist first, rather than a urologist. I'm a nephrologist. 


We look for causes of blood in the urine that come from the filters in the kidney. So, the kidneys, as you may know, are composed of millions of filtration units. The blood is filtered and urine is produced. Filters are normally so tight that blood doesn't leak out. Sometimes blood can leak out through the filters; this can be a benign, inherited problem or not even a problem at all - a benign, inherited condition. Sometimes it can reflect inflammation in the kidneys that's causing disruption of the filters. If that's the case, a kidney biopsy may be needed to determine the cause to see if there's treatment indicated for this inflammation.



When should you see a doctor about blood in the urine?

If blood is seen in the urine, then you should see a doctor. If blood is detected in your urine on a dipstick, you should see a doctor. In any event, it should be assessed properly, particularly because there can be serious causes for this. 



If the results of a urine test show higher than normal levels of protein, what does this indicate? 

Higher levels of protein in the urine than normal, indicate disruption of filter units in the kidney in most cases. As I've explained previously the kidneys are made of millions of filtration units that filter the blood and urine is produced. The filter units are normally so tight that protein cannot leak out. Therefore, if there's protein in the urine, this implies disruption of the filtration units in the kidney and this needs to be assessed properly. In most cases, a kidney biopsy isn't needed to assess protein in the urine unless it's very high, unless it's getting worse, or a diagnosis cannot be made with blood tests.


If you have one kidney, there's an increased chance of protein leaking into the urine because of something called hyperfiltration. The kidneys are working extra hard and if you like, protein is forced out through the filters in this case. The commonest cause of hyperfiltration in the world, is diabetes. In this case, diabetes disrupts the filters of the kidneys and protein therefore leaks out. 


In diabetes, often there is a very low level of protein the in the urine, as the diabetic kidney problem progresses, the amount of protein increases. There are other conditions that cause very large amounts of protein in the urine, and if this is very high, this causes something called nephrotic syndrome where the body is very swollen. The blood level of protein is low and the urine level of protein is very high. It almost always needs a kidney biopsy to make a diagnosis. So, any protein in the urine needs an assessment; if it's significant, it needs assessment by a nephrologist. 



What further tests are done to determine the cause of protein in the urine?

Protein in the urine reflects an abnormality of the filtration units in the kidney. The normal assessment process is to do a series of blood tests to look for immune conditions that can cause disruption of the filters. An ultrasound scan, to look for the structural integrity of the whole kidneys and an assessment of the urine to see how much protein there is, and in some cases, what sort of protein there is. 


In some cases, this is enough to make a diagnosis. In many cases, however, this isn't sufficient, or we need to work out more detail of the kidney condition, how severe it is and how likely it is to progress. The only way to do this, is with a kidney biopsy



Can a high level of protein in the urine resolve itself?

High levels of protein in the urine can be due to conditions which resolve spontaneously. Most do not, however, and most need treatment, particularly treating blood pressure - sometimes to treat the blood pressure lower than normal. To be sure that you have a condition that will resolve on its own, you would need a specialist assessment. The risks and benefits of doing a biopsy or not doing a biopsy, risks and benefits of waiting versus treating, can only really be discussed properly with a specialist. 



What can the colour of urine indicate to us about our health?

The colour of the urine normally reflects how concentrated the urine is. In other words, how well hydrated you are at the time. We often see these charts around on the Internet, sometimes in toilets, that show us the gradation of very concentrated urine and a very light-coloured urine. In general, if your kidneys are working properly then they will concentrate your urine when you're a bit dehydrated and dilute your urine when you're over hydrated. That's normal physiology. 


For most people, to have this fluctuation isn't a sign of ill health and of course, most of us know, when we pass urine the first time in the morning it's quite dark because we haven't drunk fluid overnight and also the hormone in the body, ADH, concentrates the urine overnight as well. 


If you see this in the context of being well-hydrated then there may be an issue. If the urine is very dark, there may be blood in it and this needs to be assessed


Other colours of urine can change with supplements for example, some very strong vitamin C can cause a green-coloured urine and eating high concentrations of beetroot can give you a red-coloured urine. If you're worried, you can discuss this with your doctor but a general fluctuation of light and dark urine during the day, variable according to how much you've had to drink, is normal



If you're concerned about blood in your urine or have any other kidney-health concerns, arrange an appointment with Dr Game via his Top Doctors profile. 

By Dr David Game

Dr David Game is a leading consultant nephrologist based in London who specialises in transplantation, dialysis and chronic disease of the kidney. He is additionally expert in hypertension as well as acute kidney injuries and kidney stones.

Dr Game studied for a bachelor’s degree in pharmacology at the University of Cambridge before qualifying in medicine at the University of Oxford in 1996. He was later awarded the prestigious Medical Reserve Corps (MRC) fellowship and additionally completed a PhD in transplant immunology at Imperial College London. Following further specialist training on the esteemed North Thames rotation, he was appointed as a consultant at Guy's Hospital in 2009, where he continues to see private patients. He additionally sees private patients at HCA at the Shard and the Lister Hospital in central London.

Dr Game is a leading name in medical education and has been an honorary senior lecturer at King’s College London since 2015. Prior to this, he was a clinical lecturer at Imperial College London, based at the Hammersmith Hospital for several years and was also voted Guy's Teacher of the Year by the establishment’s junior doctor trainees. Additional to his teaching roles, Dr Game continues to be an active researcher in transplant immunology. He was the principal investigator in a highly anticipated €14 million clinical trial of cell therapy for transplant tolerance which was funded by the EU.

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