Importance of Urine Analysis

Urinalysis for Nurses.

Urinalysis is the technical term for “analysing urine” or “urine analysis”. It is an inexpensive way of getting objective information about a patient’s health. The procedure is both simple and cheap. Urinalysis involves testing the patient’s urine for pH value, proteins, specific gravity, leukocytes, ketones, glucose, bilirubin, blood, Nitrites and urobilinogen. All the information obtained is objective but must be assessed and related to the clinical picture of the patient.

First a clean specimen of urine is collected after obtaining consent. There are different of specimen collected for different purposes. A clean catch is sufficient for urinalysis. Five to ten ml of urine is sufficient. Do not use old specimen for testing.

Picture A: Reagent Strips of the type used for analysis.

Advantages of doing ward urinalysis.

1. Dipsticks in current use are fast and cheap.
2. User or tester does not require extensive training but must not be colour blind.
3. No pain or discomfort to the patient.
4. The tests can be performed daily as baseline measurement.
5. Wide range of applications.

Disadvantages of ward urinalysis.

Inaccuracy / false positives are high. False positives cause anxiety to the patient.
Flawed urine specimen collection is the most frequent cause of false positives.

Reagent strips (Trade names: multistix, Diascreen etc.) are strips of plastic on which small squares of blotting paper impregnated with different chemicals are mounted. Look at the picture of Reagent Strips and container above. When the chemically impregnated blotting paper is dipped in a clean specimen of urine from the patient it brings about chemical changes. The chemical changes are in proportion to the substances in the urine which are being measured. Always use reagent strips which are not expired or damaged. Close the lid after obtaining one dipstick. A clean container or a test tube should be used to contain the urine. The adsorbent silica gel should always be present in the container. If not, the reagent strips will deteriorate due to excessive humidity.

Urinalysis: The Procedure.

Place a small amount of urine to be tested in a container. A test tube is the most convenient container. However, a urine container, of the type used to send urine specimen to the laboratory will do equally well. Dip the reagent strip in the urine. Let is soak the urine for a second or two. Remove it form the container and tap it on a paper to remove excess of urine. This will prevent cross migration of chemicals between the different blots. A stop watch with a second hands needle should be available as some of these tests are time sensitive. Read off the results by comparing them with the colour strips on the side of the bottle at the appropriate times. If you are unable to read off the results with the specified time then repeat the test for only the items you were not able to read off the first time. If you are unsure of the result, please check it with a colleague or repeat it. The consequences of missed results could be wrong or delayed treatment. These fairly simple tests are not substitutes laboratory tests which are usually more accurate.

There are some tests which cannot be done in the ward. So the correct type and amount of specimen must be sent to the laboratory with the correct label and requisition. Such specimen must be enclosed in appropriate biohazard labelled plastic bags.

Urine is produced by kidneys, transported to the urinary bladder via the ureters. It is accumulated in the bladder until there is sufficient stretching of the muscled of the wall of the urinary bladder. Then it is excreted to the exterior by the urethra.

Studies of normal urine have established the normal range of waste products excreted by the kidneys. Testing a sample of urine give us an accurate, objective measure of the patient’s internal biochemical processes.

Before doing formal urinalysis procedure it is usual practice to observe and document about the following.

See: Colour is influenced by a multitude of factors. These include fluid balance, diet eaten, medications consumed, and the disease affecting the patient. Concentrated urine is more dark. Pale or colourless urine is usually more dilute. If urine is more yellow than normal then the patient may have had vitamin B supplements. Blood in urine will make it more concentrated. Reddish brown urine may be due to consumption of blackberries, beets or rhubarb.

Cloudy urine: Normal urine is usually clear. Opacity or turbidity is due to bacteria, blood, sperm, crystals or mucus.

Smell, Odor. Urine usually has a slight urea smell which is not very strong. Many diseases alter this balance e.g. E. coli bacterial infections result in foul smelling urine and diabetes mellitus produce a sweet and fruity smelling urine.

The following is a list of tests / items usually tested in a hospital ward by Registered or Enrolled Nurses. The results can be used to diagnose, treat and manage pathological conditions.

Picture 2. Comparing and reading diascreen Reagent strips during urinalysis.

pH value is an indicator of urinary tract infection, urolithiasis and state of acid base balance. In normal healthy adults the pH value of urine is from 4.5 to 8.0. In diabetes the pH is usually (Low, acidic) due to the presence of ketoacids. The pH is also lower in fevers and dehydration. Alkalinity (high pH) is likely to occur in chronic cystitis, GU infections, acute renal failure, renal tubular necrosis and intoxication.

The reagent used in vHospital is brick red when the pH is 5. Note the color change and document the which is best resemble the colours given on the container of the reagent strip.

Proteinuria is an indicator of renal disease. It is present in the urine because the permeability of the glomerulus is increased. Other conditions which can cause proteinuria are Acute pylonephritis, acute glomerulonephritis and malignant hypertension. Toxaemia of pregnancy, CCF, DM and benign HTN can also cause protein to be excreted in the urine.

This test is time sensitive and must be read at the right time. Document the colour which most close resembles the comparison guide on the bottle of reagent strips.

Specific Gravity measures the relative degree of dilution or concentration of urine to pure water. If there are more dissolved contents the specific gravity rises. Very dilute urine, as produced in by a patient suffering from diabetes insipidus is usually very dilute. Normal range of specific gravity for a healthy patient is from 1.010 to 1.025. The specific gravity of water is at 4 degrees Centigrade is 1.0

Vomiting and Diarrhoea: Sp. Gr rises

Excessive fluid intake, adrenal insufficiency, hepatic disease, congestive heart failure: Sp Gr. Falls.

Kidney problems: Sp Gr falls because ability of kidneys to concentrate urine is decreased. E.g. acute renal failure, renal tubular defects, glomerulenephritis, puelonephritis.

Leukocytes. This test measures the presence of bacteria in the urine by an indirect method. It indicates the presence of bacteria in the urinary tract by measuring the presence of esterase. This enzyme in not present in normal urine. This test must be read at the end of one or two minutes depending upon the type of reagent strip used. Note the colour change at the specified time.

Presence of leukocytes indicates that a mid-stream specimen of urine must be sent to the laboratory for microscopy, culture and sensitivity.

Ketones and Acetone. Ketones and acetones are not found in the urine of healthy individuals. These are by-products of fat metabolism. This occurs when the body is deprived of carbohydrates. Individuals who are on carbohydrate deprived diets or suffer from diabetes mellitus are likely to have acetones in their urine.

Note the colour change at the specified time.

Glucose is a simpler form of a carbohydrate. The presence of glucose in urine is called glycosuria. In normal health adults glycosuria may occur when the renal threshold is exceeded. This occurs when an individual consumes two bars of chocolate over a short period of time. However, in diabetic patients all or most of the glucose which is eaten is not usable because the enzyme insulin is lacking. So, most of the glucose is passed out with water and urine. It is for this reason that diabetic patients can eat a lot but not put on weight, in the absence of insulin. Most of the sugar or glucose is passed out with the urine. It is not unusual for patients from remote Australia to say that ants gathered at the site where the patient passed urine. Glucose is also passed in the urine when the kidneys are damaged.

This test is time sensitive. Read off the result at the specified time.

Bilirubin is by-product of normal break down of red blood cells in the reticuloendothelial system. In the liver it is conjugated (into glucuronide) and excreted by the liver into the large intestine. In the intestine it is reduced to urobilinogen. Normally: No bilirubin is found in the urine. Bilirubinuria is the presence of bilirubin in urine. Bilirubinuria indicates hepatitis, cirrhosis, ca of head of pancreas, bile duct obstruction, poisoning and CCF asociated with jaundice. This test is time sensitive.

When bilirubin levels are high, a condition called jaundice is said to occur. However, further testing will be needed to determine the exact disease. Physiologic jaundice of the newborn may be seen between day one and day three. This is because the liver at birth is not fully formed. In some conditions, the RBCs of a newborn may be destroyed by blood incompatibilities. This condition is known as haemolytic disease of the new born.

Patients with sickle cell disease and haemolytic anaemia will experience occasional periods when RBC destruction is excessive and this will be indicated by the rising level of bilirubin.

Blood in urine is called hematuria. Sometimes it is microscopic hematuria, (not visible to the naked eye) at other times it is frank hematuria (visible to the observer). Hematuria is seen in many renal conditions. These include renal, uretheral and ureteric calculi, acute nephritis, malignant papiloma, renal ca, and chronic kidney diseases. Sometimes the administration of sulfonamides and/or anticoagulants may cause hematuria.

This test is time sensitive. Compare the colour change with the sample on the container and document accordingly.

Nitries are salts of nitrous acids. When urine is positive of nitrites it is a firm indicator of urinary tract infection i.e. bacteriuria. This is usually indicative of pyelonephritis, cystitis, urethritis.

This test is time sensitive. Compare the colour change with the sample on the container and document accordingly.

Urobilinogen: This compound is formed by bacteria in the intestine from bilirubin after the conjugated glucuronic acid has been separated. Larger amounts of bilirubin are formed by hemolysis when there are hepatic diseases (hepatitis). Intrahepatic urobilinogen is increased and large amounts of urobilinogen appear in the urine. In the urine it is converted to urobilin to be excreted.

Like most other tests, this test is time sensitive and must be recorded at the appropriate time for accurate results.