Urine Colour
“Urine Colour. Just how significant is it?!”
Human Urine – the biochemical masterpiece “manufactured” by our Kidneys as a by-product of all the work that they do – is normally a clear, pale / straw yellow to dark (but transparent) yellow in colour. This is attributed to the pigment Urochrome normally found in urine.
In good health, how yellow your urine appears directly relates to your water/liquid intake. The more dehydrated you are, the denser & more concentrated your urine is, and the darker is the yellow colour as depicted in the image below.
Samples in the image above aptly show the normal variation in Urine Colour in good health. For all practical diagnostic purposes, this urine colour range qualifies as normal. Now, Urine is not a topic that would usually make the cut in any polite conversation in non-specialist social gatherings.
But did you know?
Something as humble and underappreciated as your Urine Colour is a reliable clinical criterion used by physicians to substantiate their clinical opinion on your health status.
Urine Colour can provide insight on and sometimes aid in the timely diagnosis of disease states arising not just from your kidneys or other parts of the urinary system but also from Liver, Lungs, Heart, Blood disorders and the Immune system.
However, keeping in sync with the focus of this website, this article will elucidate on the specific Urine colour variations commonly associated with diseases of the kidney & urinary tract and those induced by medication to treat some of these conditions.
Let’s start then, shall we?
RED URINE
What is the first thing associated with the human body that comes to your mind when you hear the word “Red”? It’s a no-brainer, it’s blood! Red blood cells are abundantly present in our bloodstream. They happen to carry a pigment called “Haemoglobin” within them. This is what gives our blood that red colour. The commonest cause of Red Urine in members with Kidney or urinary tract disease is the presence of Red Blood Cells in Urine. The fancy term for this condition is “Haematuria”. Haematuria could be of two types.
“MICROSCOPIC” HEMATURIA
Here, the blood in urine is NOT visible to the naked eye, the sample “appears” clear pale yellow and the red blood cells are detected through a Microscopic analysis during a routine urine test.
“GROSS” OR “FRANK” HEMATURIA
In this case, the blood in urine is clearly visible to the naked eye. A routine urine test can then confirm the presence of red blood cells in urine. The extent of bleeding could make the urine appear orangish to a deep red as depicted in the image below.
In adults, bleeding in Urine is seen in the following conditions:
VIA THE KIDNEY
1. Kidney Stones (associated with pain in the flanks during urination)
2. Immune system-mediated damage of kidney filters as in:
- IgA Nephropathy
- Lupus nephritis
- Polyarteritis nodosa
- Wegener’s Granulomatosis
- Goodpasture’s disease
3. Abnormal structures in kidneys such as:
- Fluid-filled cysts blocking the delicate urine tubes
4. Kidney Cancer
5. Inherited conditions such as:
- Polycystic Kidney Disease (PCKD)
- Alport Syndrome
VIA THE URINARY TRACT DOWNSTREAM
Anything that blocks the passage of urine from the kidney to the bladder and further to the toilet, such that you need to strain during urination can potentially “injure” the cells lining the inner walls of these structures. This can potentially cause bleeding into the urine. Causes include:
- Stone(s) in the Ureter (tubes carrying urine from kidneys to the bladder)
- Urinary tract infection that affects the bladder
- Bladder Cancer
- Tumour(s) in the ureter or along the urethra
BROWN URINE
Muscles in our limbs & heart contain a reddish-brown pigment called “Myoglobin”. Along with blood, this pigment helps to supply Oxygen to these muscles as per need.
In some people, it is possible that strenuous exercise & constant weight-lifting leads to muscle breakdown. Before you panic, let me clarify that unlike it sounds, muscle breakdown refers to the microscopic rupture of some cells that comprise the muscle tissue, over time. When this happens, myoglobin pigment from muscle cells leaks into the bloodstream and can pass into our Urine damaging the delicate kidney filters on the way.
It is this combination of the Myoglobin pigment in Urine plus the cells from damaged kidney filters that together make the Urine look brown. Technically, this is called Myoglobinuria [Myo-globin-uria].
The image below depicts various shades of brown urine encountered in the clinic.
The more the myoglobin content is, the greater will be the damage to the tiny Urine-forming tubules.
When such kidney damage sets-in within a short time frame of days to weeks, it may turn into a dangerous kidney condition called Acute Tubular Necrosis (ATN) – a common cause of Acute Kidney Injury and failure. This condition is potentially reversible when diagnosed and treated in good time. And observing Urine Colour changes is a great way to seek timely medical advice in such cases!
MILKY / UNIFORMLY CLOUDY URINE
As explained in a previous article, healthy urine samples are transparent and vary from pale or straw yellow to a dark yellow colour.
When a Urinary tract infection (UTI) sets-in, what happens is the offending agent such as bacteria or yeasts (fungus) literally “invade our urinary tract and settle there by force”. This kicks-in our immune system made of White Blood Cells (WBCs) into urgent action. As a result, huge numbers of WBCs enter our urine, rush to the spots where the invading organisms have settled and actively fight them off. It is this flurry of WBCs in Urine that makes most infected urine samples appear milky or “uniformly” cloudy.
The urine does not appear transparent anymore as you can see in the picture below where blue gloves are completely invisible through the cloudy urine sample.
Urinary tract infections are usually completely curable with a full-course of the specific antibiotic(s) or anti-fungal(s). These will be prescribed by your doctor based on the reports of a test called Urine Culture and Sensitivity.
In addition, your doctor will also usually prescribe you medicines to make your urine less acidic and reduce pain during urination. You will also be advised to increase your water intake and maintain local hygiene.
GREEN URINE
This urine colour variation is a subtype of Milky / uniformly cloudy urine usually seen in most UTI samples. Urine infections caused by bacteria belonging to the Pseudomonas (pronounced as “sue-do-monas”) species present with greenish discolouration of Urine. This urine is cloudy, non-transparent but shows a distinct green discolouration due to Pyocyanin (“paio-sai-a-nin”) pigment released into the urine by this group of bacteria.
It is worth noting that hospitals are the commonest places that harbour Pseudomonas species in the environment. It is common to contract Urinary tract infection by this group of bacteria there.
Taking the full course of specific antibiotics and supporting medication completely cures this variant of UTI (unless the infection spreads to other organs). Your doctor will prescribe the necessary antibiotic(s) based on the reports of your Urine Culture test.
ORANGE URINE
Pertaining to diseases of the kidney & urinary tract, orange discolouration of urine is seen in patients with UTI treated with the drug “Phenazopyridine” also called Pyridium to help reduce the pain during Urination that accompanies UTI.
This discolouration is not permanent. Urine gradually assumes the normal colour range (pale yellow to transparent dark yellow) once you discontinue taking this medicine.
In addition, the urine also assumes an Orange Discolouration in patients undergoing treatment for Tuberculosis with the drug called “Rifampicin” also called “Rifampin”. It is true, that the focus of this article is on Urine discolouration in Kidney and Urinary tract diseases. However, apart from the lungs, tuberculosis can affect bones, skin, and kidneys as well. Hence orange urine from rifampicin drug finds a mention here.
GENERAL RULE OF THUMB
If you do happen to notice a variation in your urine colour, try not to panic at the first instance. Consult your doctor and make sure you mention the following:
Any other associated symptoms (if present) such as pain during urination either in the belly or flanks. All medication, vitamins or supplements that you may have been taking prior to the urine colour change. If you have had any recent illness (flu, fever, diarrhoea etc.) and how you were treated for it.A family history of similar nature. History of any known illness running in families (such as PKD, Alport’s Syndrome, Hemophilia, Sickle Cell Disease)NOTE
1. This article does not list all possible Urine Colour Variations recorded to date. It selectively enlists colour variations associated with diseases of the kidney & the Urinary Tract keeping in sync with the nature of this website.
2. Again, these urine colour variations are not exclusive to kidney disease. For instance, some people may pass reddish urine after they eat beetroot. Similarly, Green Urine can result from a general anaesthetic used during surgeries called Propofol.
So, that’s a brief rundown of the different urine colour variations that we commonly encounter in day to day nephrology.
Here’s hoping that the post helps you understand how significant your Urine Colour Changes can be, and has taught you to become more vigilant towards your urine health and overall well-being.
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