How do urine tests help in diagnosis of diseases?

          Diagnosis of different diseases by urine examination has been a common practice since a long time. But the traditional methods were not very scientific as the modern methods. Although special urine tests in laboratory can reveal many diseases, even a casual examination can indicate certain diseases. Let us see how different urine tests help in diagnosing some diseases.

          Normal urine is straw yellow in colour due to the presence of the pigment ‘urochrome’. If a person has fever, it becomes deep yellow. In case of jaundice, it becomes still deeper in colour. Consumption of vitamin B-complex also makes the urine deep yellow. This is because of the presence of riboflavin in the tablets. If the colour of urine changes to brown or black due to atmospheric pressure, it indicates a congenital disease called alcaptonuria. If its colour is brown or black, it suggests derangement of haemoglobin metabolism.

          If the urine of a diabetic patient is left in the open for some time, it would attract ants. This is due to the presence of glucose in it. Its taste is also sweetish. To test the presence of sugar in urine, it is boiled with Benedict solution. If a red precipitate is formed, it indicates the presence of glucose. 


          To test albumin in the urine, dilute acetic acid is added to it and heated. If a white precipitate is formed, it indicates the presence of albumin. Normal urine should not contain albumin.

          Another test is performed to detect the derangement of fat metabolism in the body. In this test, urine is treated with ammonium sulphate, sodium nitroprusside and alkali. If red colour develops it indicates abnormality. Normal urine should have no such colour.

          Urine culture test also provides valuable information regarding the bacterial infections in the body. It is done only when the doctor advises it. Nowadays many more complicated urine tests like urine culture are done to detect the diseases and sensitivity to antibiotics.