Why is urine analysis done?Urine analysis is done to detect the following:
- To detect the presence of blood (Hematuria) or protein (protein urea) in the urine.
- To detect presence of pyuria (Increased number of WBC’s).
- To identify crystals in the urine which may be seen in stones.
- To identify casts. Due to damage to the kidney proteins, shed tubular cells, RBC’s, WBC’s aggregate and get molded as they pass through the kidney and are seen as casts in the urine.
What is the significance of urine color?The urine is normally light yellow in color. Change in the color of urine is seen in the following conditions:
- Dark colored urine: Seen when water intake is less or conditions like dehydration. Usually seen after excess sweating, as in exercise and more commonly in summer.
- Brownish color of urine: Seen when there is small amount of blood in urine. Called smoky urine. Seen in glomerulonephritis. It is accompanied by swelling of feet and decreased urine and maybe fever.
- Very dark yellow urine: Seen in jaundice. Accompanied by symptoms such as pain in the abdomen, nausea and fever.
- Many drugs e.g. Rifampicin, or ingestion of vegetables like beet root can make the urine look orange.
- Whitish discoloration when accompanied by burning urination seen in urinary tract infection.
- Frank red color is called hematuria.
What is Proteinurea?Increase urinary excretion of protein is called as protein urea. Normal excretion of urine protein is less than 150 milligrams/ 24 hours for adults. Anything in excess of this is called as protein urea.
How is Proteinurea detected?This urine protein is detected by a test which is called as dipstick and it depends on the ability of proteins specially albumin to alter the color reaction of a pH sensitive dye (tetrabromophenolpthalein) on a plastic strip. The Proteinurea is quantified as follows:
1+: Approx 30mg/dl
4+: > 2000mg/dl
What are some of the causes of protein urine?The following are some of the causes of Proteinurea:
- Diseases affecting the glomerulus: e.g. glomerulonephritis, nephrotic syndrome.
- Injury to kidney tubules from drugs, antiobiotics, metals or from very low blood pressure.
- Filtration of abnormal proteins across the glomerulus e.g.: Myeloma.
During routine examination a person is noted to have Proteinurea on dipstick. What should he or she do?It is important that the person should see a physician to work up the cause of the Proteinurea. Usually the amount of protein excreted in 24hrs is recorded. Some patients may even need a biopsy of the kidney.
What is pyuria?The excretion of white cells in the urine in excess of normal is called pyuria. The WBC’s are determined by examination of the urinary sediment after centrifugation of the sample of approximately 10ccs of urine.
Abnormal WBC in the urine exists when there are more than 5 White Blood Cells per high power field under the microscope. Most common cause is urinary tract infection but they can be seen in kidney stones, inflammation of the kidney such as interstitial nephritis.
What is Hematuria?Hematuria signifies the presence of blood in the urine.
How is this detected?Hematuria is detected by the use of the dipstick which includes a strip which is impregnated with orthotoluidine. The blood reacts with the reagent which changes the color of the test strip. Hematuria is usually quantified the number of Red blood cells per high power field under the microscope: Normal values: 0 to 1 in males and may be slightly higher in females. The persistence presence in males or females of even small numbers of blood cells in the urine should be investigated. It is important to remember that menstruating women may have some RBC’s in the urine. The urine examination should be repeated after the menstruation.
What are some of the causes of appearance of blood in the Urine?
- Urologic Causes: May be secondary to stones, tumors or infections.
- Patients with bleeding problems (coagulopathies).
- Glomerular causes: e.g.: glomerulonephritis.
- Diseases affecting the kidney tubules: injury from antibiotics, drugs metals etc.