A complete urine test is performed routinely or for diagnostic purposes.
The results from the urine tests serve to detect many diseases, such as:
- Urinary tract infections
- Kidney disease
- Liver
- Diabetes
Preparation
Before the examination, do not eat foods that can stain urine, such as blackberries, beetroot and rhubarb.
Do not make any effort before the examination.
Inform the doctor about the expected start of the menstrual cycle. The doctor can then decide to wait with the examination.
The doctor may ask to stop taking some medications that stain urine. Among these are:
- Vitamin B
- Phenazopyridine (not approved in Germany)
- Rifa
- Phenytoin
One should discuss with the doctor whether the examination is necessary, how it is performed, and what the results mean.
Contents
How is the urine test performed? Instructions
The doctor may ask the patient to collect a urine sample at home and take it to the practice or laboratory for examination.
A urine sample is collected from a small child or an infant with a special plastic bag with a closure edge.
Mode for collecting a sterile and clean urine sample
Simple urine test
First, urinate a little in the toilet or urinal. A woman should keep the labia apart when urinating.
After the urine has run for a few seconds, hold the collection container under the urine stream and collect about 12 ml of urine.
Do not touch the edge of the vessel with the genital area. Do not add toilet paper, pubic hair, feces, menstrual blood or other things to the urine sample.
Stop urinating into the toilet or urinal.
Carefully close the collection container with the screw cap and bring it to the laboratory. If the urine is collected at home and you can not go to the laboratory within an hour, put the sample in the refrigerator.
For toddlers and infants, there are sachets that allow urine collection.
Collection of 24-hour urine
The doctor may order a 24-hour urine collection.
Usually, the collection starts in the morning. After awakening, urinate without preserving this urine. Note the time at which urine collection began over a 24-hour period.
For the following 24 hours, collect all urine. The doctor usually provides a large container for this, which can hold the amount of about 4 l and contains a small amount of a preservative. Urinate into a smaller clean container and then pour the urine into the large container. Avoid touching the inside of the container with your fingers.
During the collection period, store the large container in a refrigerator.
Urinate for the last time just before or at the end of the 24 hours. Add this urine to the large collection vessel and note the time.
Normal values and interpretation of urinalysis
A proper urinalysis usually includes the following tests:
Results of the complete urine examination
Color
Normal: from light yellow to dark yellow.
Abnormal: Many foods and medications can affect the color of urine. Colorless urine can be caused by chronic kidney disease or untreated diabetes. Dark yellow urine can be caused by dehydration. Red urine can be caused by blood in the urine.
Clarity
Normal: clear.
Abnormal: Dark urine (and opalescent) may be caused by:
- Pus (white blood cells)
- Blood (red blood cells)
- Semen
- Bacteria
- Yeasts
- Crystals
- Filaments of mucus
- Infections caused by parasites such as trichomoniasis
Smell
Normal: slightly “sharp” smell.
Abnormal: The urine may have an altered smell due to some foods (such as asparagus), vitamins, and antibiotics (such as penicillin). A sweet smell can come from untreated diabetes. A urinary tract infection can cause foul odor. Urine that smells of maple syrup can indicate maple syrup disease, which occurs when the body cannot break down certain amino acids.
Specific gravity
Normal: 1,005 – 1,030
Abnormal: A greatly increased specific gravity indicates that urine is highly concentrated, which occurs when a person drinks too little, loses too much fluid (excessive vomiting, sweating, or diarrhea), or there are substances (such as glucose or proteins) in the urine.
A very low density means that the urine is diluted. This can occur with excessive drinking, severe kidney disease or due to diuretics.
pH
Normal: 4.6 – 8.0
Abnormal: Some foods (such as citrus fruits and dairy) and medications (such as antacids) can alter the pH of urine. A high pH (alkaline) can be caused by massive vomiting, kidney disease, some urinary tract infections. A low pH (acidic urine) can be caused by:
- Severe lung diseases (emphysema)
- Asthma
- Untreated diabetes
- Overdose of aspirin
- Massive diarrhea
- Dehydration
- Massive alcohol consumption
Proteins
Normal: none.
Abnormal: Proteins in urine may refer to:
- Kidney lesions
- Infections
- Cancer
- Arterial hypertension
- Diabetes
- Systemic lupus erythematosus (SLE)
- Glomerulonephritis
- Heart failure
- Leukaemia
- Poison (poisoning with lead or mercury)
- Preeclampsia (in pregnancy)
Albumin
The protein “albumin” should not be present in the urine (albuminuria), but a small proportion does not always indicate a disease.
Causes of an increased albumin content in the urine are:
- Too many proteins in the diet
- Urinary tract infection
- Pregnancy
- Renal failure
- Diabetes
Glucose Normally, a single urine sample gives a negative value for glucose
.
Normal: 1 – 15 milligrams per deciliter (mg/dl) or 0.06 – 0.83 millimoles per liter (mmol/l) in a 24-hour urine sample.
Too much glucose in the urine may be present in the following cases:
- Untreated diabetes
- Some types of kidney disease
A healthy pregnant woman may have glucose in the urine, during pregnancy this is normal.
Ketones
Normal: none.
Abnormal: Ketones in urine can be caused by:
- Untreated diabetes
- Low-carbohydrate diet
- Hunger or nutritional disorders (such as anorexia nervosa or bulimia)
- Alcoholism
Ketones are often present in the urine when a person has not eaten for over 24 hours or more. This can be the case with a sick person who can no longer eat or vomits for several days.
Nitrite. Bacteria that cause a urinary tract infection produce an enzyme that converts the nitrates in the urine into nitrite. Nitrites in the urine indicate a urinary tract infection.
Leukocyte esterase. Leukocyte esterase indicates the presence of leukocytes (white blood cells) in the urine. White blood cells in the urine indicate a urinary tract infection.
Bence-Jones protein. This is an abnormal protein found in the urine of approximately 50% of individuals with a rare type of cancer called myeloma. Often, a urine test is performed when multiple myeloma is suspected. The protein test performed in a regular test does not detect the presence of Bence Jones protein.
Volume
Normal: 800 – 2,500 milliliters (ml) in 24-hour urine.
Microscopic analysis
Microscopic analysis. In this examination, the urine is filtered in a special apparatus (centrifuge) so that the individual ingredients (sediments) are deposited on the bottom. The sediment is applied to a glass sheet and examined under the microscope. What can be seen on the slide includes:
Red and white blood cells. Normally, there are no blood cells in the urine. Erythrocytes (red blood cells) in the urine can be caused by inflammation, disease, or injury to the kidneys, ureter, bladder, or urethra. Also, intense physical activity (such as a marathon) can lead to blood in the urine. White blood cells can be signs of infection or kidney disease.
Kidney stones. Some types of kidney disease can lead to the formation of particles of material (kidney stones or concrements) in the small renal tubules. The kidney stones are then excreted in the urine. Renal concrements can be formed from red or white blood cells and may contain waxy, fatty portions or proteins. The type of kidney stones in the urine can help to find out what kind of kidney disease is causing the symptoms.
Crystals. Often healthy people have few crystals in their urine. A high number of crystals or some types of crystals may indicate kidney stones or a metabolic problem.
Bacteria, yeast cells or parasites. Normally, there are no bacteria, yeast cells or parasites in the urine. If these are present, this may indicate an existing infection.
Dandruff cells. The presence of scale cells may mean that the test material is not as pure as it should be. These cells do not indicate disease, but the doctor may need to request another urine sample.
How should the microscopic analysis be?
Normal: There are no red and white blood cells, hemoglobin or kidney concrements. There are no bacteria, yeasts, parasites or cell scales present. Normally you see few crystals.
Abnormal: An increased number of red blood cells in the urine may indicate:
- Injuries to the kidneys or bladder
- Kidney stones
- Urinary tract infection
- Inflammation of the kidneys (glomerulonephritis)
- Bladder or kidney tumor
- Lupus erythematosus (SLE)
Hemoglobin in the urine can be caused by:
- Glomerulonephritis
- Kidney tumor
- Paroxysmal nocturnal hemoglobinuria
- Pyelonephritis
- Kidney infarction
- Sickle cell disease, from medication or hemolytic anemia
- DIC (disseminated intravascular coagulation)
- Hemolytic uremic syndrome
- Extensive burns
White blood cells in the urine can be caused by:
- Urinary tract infection
- Bladder tumor
- Nephritis
- Systemic lupus erythematosus (SLE)
Calcium oxalate in urine
If the amount of calcium oxalate in the blood is greatly increased, this can lead to kidney stones.
Normal reference values are between 10 and 45 mg in 24-hour urine.
Causes include a diet containing oxalate foods or intestinal inflammatory diseases (ulcerative colitis or Crohn’s disease).
Urobilin and urobilinogen
Normally, urobilinogen is excreted from the body through the intestine, but in liver disease or bile duct occlusions, it can get into the urine.
Urea in urine
In 24-hour urine, normal values are between 12 and 20 g.
Causes of an increase in urea in the urine are:
- a diet that is too high in protein,
- excess protein breakdown in the body, for example, due to fasting.
An increase in bacterial flora in the urine means a urinary tract infection. Yeast cells or parasites (for example, the causative agent of trichomoniasis) can mean a urinary tract infection.
In this case, the doctor may order a urine culture to identify the pathogenic microorganisms.
The presence of dandruff cells may mean that the urine sample is not properly pure. These cells do not indicate any disease, but the doctor may again order another urine sample.
Smoke
Urine samples may contain traces of THC (tetrahydrocannabinol), which is an active ingredient of cannabis.
Occasional smokers excrete this substance in the urine until 1 week after the last smoking. However, if this person smokes regularly, he will still excrete this substance for 3-4 weeks.
Urine self-monitoring
You can do some urine tests yourself using urine test strips sold at the pharmacy.
Other substances tested during urine testing include:
Ketones
Home test for urinary tract infections
Bilirubin. This is a substance produced by the breakdown of red blood cells. It is excreted from the body via the faeces. There is no bilirubin in the urine. When it occurs, it often means that the liver is damaged or bile flow from the gallbladder is blocked.
Urobilinogen. This is a substance produced by the breakdown of bilirubin. It is also excreted from the body via the faeces. There are only small amounts of urobilinogen in the urine. Urobilinogen in the urine can be a sign of liver disease (cirrhosis, hepatitis) or that bile flow from the gallbladder is blocked.
Pregnancy When talking about normal pregnancy values on urine examination, the appearance of the hormone hCG (human chorionic gonadotropin) serves to confirm that the woman is pregnant. Because the urinary system involves the kidneys, many different results are related to kidney disease. Other diseases that can be derived from the urine tests include:
- Infections (bacteria and yeasts)
- Diabetes (increased sugar level in the urine)
- Liver problems (increased bilirubin)
- Kidney stones (presence of crystals)
- Sometimes also the formation of a urinary tract tumor
