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Normal Urine Properties M.Prasad Naidu MSc Medical Biochemistry, Ph.D,.
Colour: Normal urine is amber coloured due to urochrome - Indoxyl—sulphate[ indican] Yellow • Bilirubin obstructive jaundice or due to vitamin B complex tablets. On standing turns black in alkaptunuria due to oxidation of homogentisic acid . • Malignant melanoma – Black from the beginning melanuria
Red colour urine is seen in • Hematuria • Rifampicin(Anti tubercular drug ) • Specific gravity normal is 1.015 to 1.025 • Fixed specific gravity at 1010 in chronic renal failure
Specific gravity decreased in • Excessive water intake • Chronic nephritis • Steatorrhoea • Diabetes insipidus
Specific gravity increased in Diabetes mellitus Nephrosis Excessive perspiration
Specific gravity is tested by urinometer • Volume: • Normal around 1.5 liters / day • Increased urinary volume in 1. excessive intake of water • Increased salt intake • Diuretic therapy • Diabetes mellitus • Diabetes insipidus
Urine Volume decresed in excessive sweating • Dehydration • Low blood pressure & shock • Oedema of any etiology • Kidney damage • Antidiuretic overactivity
Appearance • Normal urine is perfectly clear and transparent when freshly voided. • May become turbid by phosphates or by pus ( Infection of the urinary tract ) or by chyle due to obstruction of lymphatics.
Odour: • Normal urine is faintly aromatic due to presence of volatile organic acids , when urine undergoes decomposition converted to ammonium carbonate giving unpleasant smell. • In Diabetic ketoacidosis urine is sweety smell due to acetone
Clinical Properties • Reaction to litmus • PH of urine is 5.5 to 7.5 • A few hrs after meal alkaline as active secretion of Hcl from the stomach and make the blood more alkaline. So to counter act this kidney excretes more alkaline urine.
If the diet is rich in proteins more acidic urine is excreted. If more vegetable are taken urine will be alkaline as more acids are produced and these are converted to bicarbonate on keeping for some time pH may be changed due to bacterial activity.