A urinalysis is a routine test performed to measure the levels of certain substances in the urine. It can be used to diagnose or rule out infection, diabetes, and other conditions. Normal urinalysis values vary among patients and labs. Some substances have an acceptable level range, while others shouldn’t be present in the urine at all.
The first thing technicians look at when performing a urinalysis is the specific gravity of the urine. This test uses a scale called a calibrated refractometer to measure how concentrated the urine is. The normal urinalysis value for specific gravity typically ranges between 1.002 and 1.035 on the scale.
The test also measures the pH balance of the urine, which determines how acidic it is. The kidneys play a large role in helping maintain the acid-base balance within the body. Normal urinalysis values for pH level range between 4.6 and 8 on a pH scale. A high pH can be caused by urinary tract infection, vomiting, or kidney failure. Low pH may be caused by starvation, diarrhea, or diabetes ketoacidosis.
The majority of the urinalysis is dedicated to looking for substances that shouldn’t be present, such as protein, glucose, ketones, and blood. There are no normal urinalysis values for these substances because they should not be found in healthy urine. Their presence indicates an underlying medical condition.
Technicians use a protein test pad to measure the levels of albumin, a type of water-soluble protein. In healthy urine, there should be no detectable quantities of the protein. Elevated levels can be an early sign of kidney disease. They can also be caused by inflammation or cancer of the urinary tract. In women, results can be skewed by vaginal secretions that get into the urine while providing a sample.
Normal urinalysis values should not indicate the presence of glucose in the urine. If glucose is present, it typically points to diabetes. When glucose levels in the blood are normal, the kidney is able to filter out the substance. When the levels in the blood rise too high, the kidneys cannot filter it all out, and some of the excess glucose is excreted through the urine.
Ketones in the urine are usually an indication that the patient is not eating enough carbohydrates, or that the body cannot properly use the carbohydrates being taken in. Starvation and high-protein diets can cause ketones to appear in the urine. Doctors of diabetic patients also use the test as an indicator that the patient is receiving enough insulin.
Very small amounts of red blood cells may be present in the urine without triggering a “positive” test. Higher numbers, however, are not part of normal urinalysis results and indicate a medical problem, such as kidney disease, urinary tract disease, or trauma to the urinary system. Smoking, medications, and strenuous exercise can also cause blood in the urine.
Abnormal urinalysis results do not always indicate significant medical problems. Certain foods and medications can cause temporary changes to the urine. In the same respect, normal urinalysis values do not always rule out disease. Further testing may be required to make a diagnosis.