Urine Test, Urine analysis, Dipstick Testing

URINE DIPSTICK TEST

Question 1. What is urine dipstick test?

A small strip of filter paper-like ribbon is dipped into freshly collected urine to perform the test. The strip is impregnated with chemicals that change colour when dipped into abnormal urine or urine with chemical composition different from normal. It changes colour in the presence of abnormal levels of red cells (blood), white cells (leucocytes), nitrite, bilirubin, protein, urobilinogen, glucose and ketones and abnormal changes to pH and specific gravity of urine. Please refer to sections on urine drug testing and urine pregnancy testing for additional information.

Question 2. How is it performed?

The strip is dipped into fresh urine sample for few seconds and left on the bench for 30seconds to 2minutes. This allows time for the chemicals impregnated on the strip to react with the urine. When the time has lapsed, results are read and interpreted.

Question 3. What are the diseases diagnosed by it?

Urine dipstick can diagnose the following condition:

Urine infection

Diabetes mellitus

Drugs of abuse

Diabetic ketoacidosis

Dehydration & over-hydration

Muscle damage (myoglobin)

Hemolysis (hemoglobin & red cells)

Bleeding urine tract (eg kidney stones)

Special urine dipstick tests are available for microalbumin and pregnancy test

Question 4. I have blood in urine. What does it mean?

Blood in urine is called haematuria and can be seen by simple inspection or only picked up through dipstick testing. Positive blood (red cells) could indicate many diseases as urine infection, kidney stones or cancer of bladder. Rarely blood in urine also occurs in bleeding disorder.

Other conditions that can show positive test for red cells are;

Contamination by menstruation

Hemoglobinuria (hemoglobin in urine –hemolysis)

Myoglobinuria (myoglobin in urine) – rhabdomyolysis, muscle breakdown

Some medicines

Always see your doctor for discussion if are worried about positive blood in urine.

Question 5. What do protein +, ++ and +++ results mean?

Results of urine protein is reported as +, ++ or +++ or <100mg/L, 101-150mg/L and >150mg /L respectively, which corresponds to the amount of protein present in urine. Very high levels are seen in kidney glomerular damage and nephrotic syndrome whereas as mild to moderate levels are a feature of urine infection.

Question 6. What is the sign that I have urine infection?

Signs of urine infection on dipstick testing include;

Presence of bacteria

Positive nitrites

Positive leukocytes or pus

Positive Blood

High Protein (+, ++,or ++)

Changes in pH

Changes in specific gravity

Question 7. What is nitrite in Urine?

Nitrate in urine is broken down to nitrite by gram negative bacteria like E.coli, proteus, or klebsiella which are the common causes of urine infection. Hence, positive nitrite test is seen in urine infection. Rarely, nitrite is still negative despite urine infection if the infection is caused by uncommon gram positive bacteria (, streptococcus or staphylococcus) or fungus candida.

Question 8. What is specific gravity?

Urinary specific gravity (SG) is a measure of the concentration of solutes in the urine. It measures the ratio of urine density compared with water density and provides information on the kidney's ability to concentrate urine. Normal SG is between 1.002-1.030.  The urine SG above 1.010 is observed in mild dehydration.

In dehydrated person either due to not drinking enough fluids or loss in diarrhoea and vomiting or kidneys retaining lots of water due to abnormal response to anti-diuretic hormone (SIADH), the urine will be highly concentrated and the SG will be higher than 1.030.

On the other hand, over-hydrated person (by drinking a lot of water) or a person whose kidney is damaged and cannot keep water (diabetes insipidus & glomerulonephritis) will pass highly dilute urine with SG lower than 1.002.

 Question 9. What is normal pH of urine?

Urine comprises water, salts, and waste products from the kidneys. The balance of these compounds can affect the urine's acidity levels, which is measured as pH. The pH is the measurement of how acid or alkaline a person's urine is.

Average pH of urine is around 6. Normal range is usually 6-7.5.  Low (acid) or high (alkaline) urine pH, are favorable environment for formation of kidney stones or development of infection.

Question 10. What are ketones?

Ketones are metabolic acids used to monitor treatment of type I diabetic mellitus. Ketones are released when fatty acids are breakdown for fuel or energy. Fatty acids are great source of alternate energy when there is no glucose or carbohydrate as in starvation. However, excess ketones are toxic and cause the blood to become more acid and cause electrolyte problems (e.g., high K+).

In diabetics, patients are unable to use glucose due to no insulin so patients switch to fatty acid for energy. Hence, a lot ketone is generated when fat is broken down for energy and the excess ketones released into blood appear in urine. Urine ketone is therefore measured to monitor diabetic treatment of insulin. Insulin switches off excess fat breakdown and allows the diabetic to use glucose again improving ketone levels.  The results are improved acidity of blood and correction of hyperglycemia and associated electrolyte problem, like hyperkalemia (high K+).

Question 11. What is bilirubin & urobilinogen?

Bilirubin is a metabolic product of hemoglobin released upon destruction or lyses of red cells. Urine bilirubin is conjugated and high urine levels indicate liver disease or bile duct obstruction. Urobilinogen is produced from bilirubin in the intestines. It is increased in urine in the presence of hemolysis or liver disease and absent in complete obstruction of bile ducts.

Question 12. Are there any interference?

Certain medicines and diets containing reducing substances can falsely interfere with urine dipstick test. For this reason, you should disclose all medications and special diet you are taking including herbal supplements. Because no single lab test is reliable on its own, your doctor always uses various test results along with clinical findings to identify the cause of your illness.

Question 13. My urine dipstick test is normal. Can I still have urine infection?

There are many reasons why you might still have negative test, even though you may still have urine infection.  Some of these reasons are;

Your sample was poorly collection

You have low level of bacteria in urine

Bacteria causing infection cannot be growth on routine media e.g. tuberculosis

You have taken antibiotics before collection

Your infection may be due to non-bacterial causes (virus, worms, fungus)