How the colour of your urine can be a warning of health problems.
Yellow
“Healthy urine goes from clear to pale yellow, dark yellow to amber,” says consultant urologist Tim Terry. This depends on hydration levels, but if you’re somewhere in the yellow team, you can breathe easy.
Green 
“Some antiseptics and anaesthetics give urine a green tinge,” says Terry. This is thanks to methylene blue, a dye which kidneys sometimes struggle with. Nothing too much to worry about though.
Orange
“This is a sign of liver dysfunction,” warns Terry. If your urine is this colour and you notice that your stools are white, it could be obstructive jaundice. Put down that beer – it’s GP time.
Brown
Muddy-looking pee means kidney problems. “This can be a sign of serious renal disease, even a fistula,” says Terry. That’s when your bowel leaks into your bladder. Taxi to casualty now.
Red
This is really bad. Blood in your urine can mean a haemorrhage or cancer. “In anyone over 40 we assume it’s bladder cancer, unless proven otherwise,” says Terry. Get yourself to the doctor, quickly.
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The blogger is pleased to append below comments from his most-learned e-buddy the Great Sifu Dr JB Lim on the above post:
Sunday, 27 May, 2012 10:29 PM
From: lim juboo
Thanks.
This is something we have been doing all the time by visual inspection, and chemically using dip sticks to detect for sugars, protein, acetone and other metabolites that cannot be seen using colours alone.
There are other also colours too not described here. For example, those who consume a lot of riboflavin (vitamin B 2) will have their urine turning bright orange-yellow. But that does not mean there is something wrong with their kidneys, just that the metabolites of riboflavin are being excreted out normally.
Those whose urine are frothy may indicate kidney disease, example: nephrotic syndrome as large amount of protein (proteinuria) are not retained, are thrown out. But there are other signs and symptoms too, example: fluid retention and swelling of the legs (oedema), weight loss, low blood pressure, easily free tired and unwell, etc.
So we cannot depend on color of urine alone to make a diagnosis.
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While the colour of urine can tell a lot about the renal (kidney) patho-physiology (in disease and health) in a very simple and cheap way through self examination, it should not be the only criterion in the assessment of renal health and its function. Symptoms the patient feels, and the signs the physician elicits and can see, touch, palpate, percuss (tap) or auscultate (listen) are all part of the assessment of renal diseases or any disease or in health (a small part of it).
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In the colour of urine for instance, if a person drinks very little water in the last 24 hours, we can expect the urine to be concentrated, and it will be deep yellow or orange in color. This is caused by dehydration, which concentrates the urine to make it much deeper in color. The urine output is also scanty.
Depending on body weight and body surface area, environmental temperatures, humidity, metabolic rate, etc, the obligatory urine output is a minimum 800 ml a day whether or not a person drinks any fluid at all in the last 24 hours. This output volume is very crucial in our assessment on fluid nutrition and electrolyte balance.
That does not mean there is something wrong with his kidneys or bladder. If he drinks a lot of water, the urine will almost be colorless. There is nothing wrong with that.
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Then again some foods like beet root, fava beans, rhubarb, senna, and also some food dyes can also color the urine, making it red or pink. That does not mean blood is passed out unless in cancers of the urogenital system.
There are certain drugs such as phenazopyridine, sulfasalazine, and antibiotics like rifampin that also colour the urine. So are other medications like antimalarial drugs chloroquine and primaquine, and metronidazole, nitrofurantoin, and laxatives containing cascara or senna, and methocarbamol. All these color the urine. Other medications including amitriptyline, indomethacin (Indocin) and propofol (Diprivan) may cause urine to become blue, green, or other colours. It is just the color of the drug breakdown (metabolites) in the body.
Similarly, orange coloured urine can indicate disorders with the liver or bile duct, but this is usually accompanied by pale-colored stools.
While colour of urine gives a good and simple guide on kidney, liver and body health, that should not the only diagnostic criterion.
One of the simplest lab tests using only a microscope is a urinary FEME (Full Examination, Microscopic Examination) also called a microscopic urinalysis. It involves the physical and/or chemical examination of the urine. This test looks for suspended sediment like crystals, casts, squamous cells, blood cells and other large objects under a low power of a microscope.
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Renal Profile Tests:
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More elaborate urinalysis consists of chemical and microscopic tests to screen for urinary tract infections, renal (kidney) disease, and diseases of other organs that result in the appearance of abnormal metabolites (break-down products) in the urine.
Urinalysis can reveal diseases that may have gone unnoticed because they do not produce striking signs or symptoms or colours of the urine. Examples include diabetes mellitus, various classes of glomerulonephritis, and chronic urinary tract infections.
However all routine urinalysis must begin with a simple physical examination of the urine sample such as colour, appearance and frothiness. The urine is then examined for urine sediments by urinary FEME. Examination of urinary sediments gives the physician an idea of urinary tract morphology in order to get better diagnosis and prognosis later.
These are simple tests before more elaborate renal function tests need to be done to look for concentrations of the waste substances like creatinine and urea as well as electrolytes. These measures are adequate to determine whether a patient is suffering from kidney disease.
Renal function tests:
In renal profile tests that can only be done in a clinical biochemistry lab, blood urea nitrogen (BUN) and creatinine are determined. This is normally not be elevated above the normal range until the kidneys have lost about 60% of its function. A better assessment for renal function is to determine the glomerular filtration rate and creatinine clearance.
Another prognostic marker for kidney disease is a raised level of protein in the urine. The most sensitive marker of proteinuria (protein in the urine) is to detect urine albumin. Its presence of more than 30 mg albumin per gram creatinine in the urine over a 24 hour period is diagnostic of chronic kidney disease.
Microalbumin:
The presence of microalbuminuria in the range of 30–299 mg/g may be indicative of renal damage - an end organ target of high blood pressure (example). A concentration of albumin in the urine is not detected by usual urine dipstick method. A good biochemical lab is needed for this.
Neither can micro albumin be detected by any colour in the urine except perhaps the presence of large amounts of blood in the urine. Small amounts of blood may easily be seen under a microscope for the presence of erythrocytes or red blood corpuscles (RBC).
Ultrasonography:
Of course the morphology of the kidneys and bladder for shape, size and other deformity cannot be detected biochemically. Special contrast x-rays, ultrasound and other imaging techniques are needed. But that is another story, and we shall not discuss this here.
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jb lim