Physical Examination of Urine

The various aspects studied for the physical examination of urine are:- Volume, colour, Appearance, Sediment formation, odor, Reaction and pH, Specific gravity.

Physical Examination of Urine

1. Volume

For an adult the normal average daily volume of urine is about 1200 – 1500 ml. More urine formation takes place during the day than at night. However. The normal range for 24 hours may be from 600 to 2000 ml. Polyuria is an abnormal increase in the excretion of urine more than 2500 ml. It is generally observed in diabetes mellitus and diabetes insipidus. Oliguria is a decrease in 24 hours urinary excretion less than 500 ml. Anuria means the complete suppression of urine formation inspite of high fluid intake.

2. Color

The colour of normal urine may vary pale yellow to dark amber, depending on the concentration of the pigment urochrome mainly and also due to the presence of urobilin and uroerythrin. There are many factors and constituents that can alter the normal urine colour. These include diet, medicine and various chemicals that can be present in disease. The pH of urine influences the colour produced by many chemicals. Very pale or colourless urine can result from high fluid consumptions, diuretic drugs, natural diuretics such as alcohol and coffee and also in clinical conditions such as diabetes insipidus and diabetes mellitus.

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3. Appearance

Normal urine is usually clear. It may appear cloudy. if amorphous phosphate are present in alkaline urine or amorphous urates are present in acidic urine. Amorphous phosphate from white precipitate, which dissolve when acid is added. Amorphous urates frequently from pink coloured precipitate which dissolve when the specimen is heated. Urine may appear cloudy or turbid from the presence of leucocyte and epithelial cells. This can be confirmed by microscopic examination. Bacteria can also cause cloudiness and mucus give hazy appearance to urine. Fat and chyle give urine a Milky colour. Presence of red blood cells may give urine turbid and smoky appearance.

4. Sediment Formation

If you urine contain amorphous phosphates, Amorphous urates, Large number of leucocytes, epithelial cell, etc. On standing it for sometime, sediment formation will take place at the bottom of the container.

5. Odor

Presence of ketone bodies gave urine a sweet or fruity smell, a contaminated urine with bacteria may be give pungent smell due to the formation of ammonia. The urine of an infant with phenylketonuria give musty odor.

6. Reaction and pH

The freshly voided normal urine is usually slightly acidic, and its pH may range from 4.6 to 7.0, (average, around 6.0). A high protein intake and ingestion of acidic fruits produce acidic urine. A diet that is high in vegetables and citrus fruit cause an alkaline urine. Post prandial urine become less acidic or slightly alkaline due to the excretion of acid into the stomach after eating.

Respiratory acidosis, (retention of carbon dioxide) and metabolic acidosis (as in uremia, diuretic ketosis, starvation, severe diarrhea) produce acidic urine. Urinary tract infection (UTI) caused by Escherichia coli result in an acidic urine. In respiratory alkalosis (hyperventilation) and in metabolic alkalosis, (excessive vomiting) and alkaline urine is excreted. Urinary infection caused by Proteus and Pseudomonas organisms (urea splitting bacteria) may cause an alkaline urine.

7. Specific gravity

The specific gravity at a constant temperature is the ratio of the weight of a volume of urine to the weight of same volume of distilled water. It depends upon the number of particles and weight of the particles in urine. The specific gravity determination is used to measure the concentrating and diluting power of kidneys. Usually the specific gravity rise when the fluid intake is low, and decrease when fluid intake is high. The specific gravity of urine thus varies throughout the day and the normal range for a random specimen is 1.003 to 1.035. Since a single random sample may not give the physician sufficient information, a 24 hours specimen is usually preferred for the determination of specific gravity. The range for a 24 hours specimen is 1.0152 1.030.

Polyuria is observed in both diabetes insipidus and diabetes mellitus. But is diabetes insipidus, the specific gravity of urine is very low, while in diabetes mellitus the specific gravity is high due to the presence of glucose in urine. High specific gravity of urine is observed in various conditions such as dehydration, eclampsia, proteinuria, lipoid nephrosis, etc. The excretion of urine of unusually high specific gravity is called hypersthenuria. Excretion of urine of a fixed specific gravity of 1.010 indicate poor tubular re observation and it is called as isosthenuria. Hyposthenuria is in terms that is used to describe a urine with a consistently low specific gravity. less than 1.007. There is a concentration problem in Hyposthenuria. The disease while can cause this problem, include phyelonephritis, hypertension, diabetes insipidus and protein malnutrition. Diuretic medicine and the natural diuretics such as alcohol and coffee also cause excretion of urine with low specific gravity. Water has a specific gravity of 1.000.