Urinalysis: physical, chemical, microscopic exam

• Urinalysis is the physical, chemical, and microscopic examination of urine.
• It involves various tests to detect and measure different compounds that pass through the urine.
• Urinalysis can help detect certain diseases and disorders.

Purpose of Urinalysis

• Urinalysis can be part of a routine medical exam to screen for diseases and assess overall health.
• It can help identify the cause of symptoms such as abdominal pain, back pain, or painful urination to diagnose medical conditions.
• It can monitor conditions such as kidney disease, urinary tract infections, or diabetes.

How Urinalysis is Performed

• A urine sample is needed, collected using the clean-catch method.
• The sample is visually examined for color and clarity.
• A dipstick is dipped into the urine to test for various substances.
• The urine is examined under a microscope to identify cells, crystals, and other components.

Physical Examination

• Normal urine color ranges from pale yellow to dark amber. Abnormal colors can indicate various conditions, such as red (blood), dark yellow/orange (bilirubin), or other colors due to medications or food.
• Normal urine is clear. Cloudiness can indicate the presence of infection, blood, sperm, crystals, mucus, or other substances.
• Urine typically has a mild odor. Unusual odors can suggest infection, metabolic disorders, or dietary factors.

Chemical Examination

• pH measures the acidity or alkalinity of urine; a normal range is typically 4.5-8.0. Abnormal pH levels can indicate kidney disorders, infections, or metabolic imbalances.
• Specific gravity indicates the concentration of particles in the urine. High specific gravity suggests dehydration, and low specific gravity suggests dilute urine.
• Protein: Normally, urine contains little to no protein. Proteinuria can indicate kidney disease, infection, or other medical conditions.
• Glucose: Normally, urine contains no glucose. Glucosuria can indicate diabetes or kidney problems.
• Ketones are produced when the body breaks down fat for energy. Ketonuria can indicate diabetes, starvation, or other metabolic disorders.
• Normally, urine should not contain bilirubin. Bilirubinuria can indicate liver disease or biliary obstruction.
• Normally, urine should not contain blood. Hematuria can indicate kidney disease, infection, injury, or other medical conditions.
• Leukocyte esterase indicates the presence of white blood cells in the urine, suggesting a urinary tract infection.
• Nitrites indicate the presence of bacteria in the urine, also suggesting a urinary tract infection.

Microscopic Examination

• Normally, only a few RBCs are present. Increased RBCs can indicate kidney disease, infection, injury, or other medical conditions.
• Normally, only a few WBCs are present. Increased WBCs can indicate a urinary tract infection or inflammation.
• Small numbers of epithelial cells are normal. Increased numbers can indicate inflammation or contamination.
• Crystals can be normal or abnormal depending on the type and quantity; some crystals indicate kidney stones or metabolic disorders.
• Casts are cylindrical structures formed in the kidney tubules. Different types of casts can indicate various kidney diseases.
• The presence of bacteria can indicate a urinary tract infection.
• The presence of yeast can indicate a yeast infection, particularly in women.
• The presence of parasites such as Trichomonas vaginalis can indicate an infection.

Factors Affecting Urinalysis Results

• Certain foods can affect urine color and composition.
• Some medications can alter urine color and chemical levels.
• Dehydration can concentrate urine and affect specific gravity.
• Menstrual blood can contaminate the urine sample.
• Strenuous exercise can cause proteinuria or hematuria.
• Urine concentration varies throughout the day.
• Improper collection can lead to contamination of the sample.

Potential Risks

• Urinalysis is generally a safe test.
• There are no significant risks associated with providing a urine sample.
• False-positive or false-negative results are possible.

Interpreting Results

• Urinalysis results are interpreted in conjunction with other clinical findings and medical history.
• Abnormal results may require further testing to determine the underlying cause.
• A healthcare provider will discuss the results and recommend appropriate treatment if necessary.
• Normal values can vary slightly between laboratories.

Urinalysis is a series of tests performed on urine. It can detect and measure different compounds in the urine. Urinalysis helps diagnose and monitor conditions like kidney disease, urinary tract infections, and diabetes.