Paging Dr. Frischer: Urinalysis
What is a urinalysis, and what is it good for?
A urinalysis is a set of tests. A patient gives a urine sample, either by peeing into a cup or having it taken with a catheter. Testing the sample might be as simple as a dipstick test in the doctor’s office while you wait, or the urine could be sent out to a lab.
It starts with a visual exam. The urine is evaluated for color and clarity, or anything else that can be seen with the naked eye. Normal pee should be some shade of yellow, depending on how concentrated it is. Shades of red indicate the presence of blood. Cloudiness indicates that it contains substances, such as proteins.
Next, a dipstick exam uses plastic strips with patches of chemicals. These chemicals change color when they come into contact with certain substances. It measures:
Acidity, which is useful because urinary tract infections (UTIs) can cause a high pH, and diabetes-related ketoacidosis and diarrhea can cause a low pH.
Bilirubin levels, which might indicate liver or bile duct issues.
Blood, which can indicate the presence of infection, damage in the urinary tract, high blood pressure, kidney stones, or cancer.
Glucose levels, which can indicate diabetes or gestational diabetes.
Ketones, which are most often seen due to fasting before a blood and urine test. In a diabetic, ketones are more worrisome, and can indicate diabetes-related ketoacidosis.
Leukocyte esterase, an enzyme which helps to fight infection. A positive reading implies the presence of inflammation or infection.
Nitrites, which are created by bacteria. Therefore, their presence indicates a likely UTI.
Protein, likely caused by heart failure, kidney damage, overexertion and/or dehydration.
Specific gravity, which shows the concentration of all chemical particles. Many different conditions can cause abnormal results.
As you can see, many conditions can be suggested by a simple dipstick urine test. However, some substances can only be seen in a lab under a microscope. These include:
Crystals, which can be a sign of kidney stones.
Bacteria, yeast and parasites, which suggest an infection due to bacteria, yeast, or a sexually transmitted disease.
Red blood cells, which means blood in the urine.
Urinary casts, which usually come from a problem in the kidneys.
White blood cells, indicating infection.
Epithelial cells, which usually indicate a contaminated sample, since they typically do not appear in the urine.
Your health care provider will usually order a urinalysis as a part of a physical exam, or if there are signs of infection, to monitor certain health conditions, during pregnancy, or in preparation for surgery. Note that the most useful urine sample is a “clean catch.” Drink plenty of water beforehand, use a cleansing wipe, and then give a midstream sample (the initial stream may be contaminated).
A urinalysis does NOT detect heart disease or blocked arteries, high cholesterol levels, most cancers, thyroid disorders, or hormone imbalances. However, it can be incredibly useful and help to identify kidney disease, kidney stones, diabetes and prediabetes, UTI’s, liver problems, severe dehydration, and bleeding in the urinary tract.
Dr. Alan Frischer is former chief of staff and former chief of medicine at Downey Regional Medical Center. Write to him in care of this newspaper at 10927 Downey Ave., Suite C, Downey, CA 90241.