Urine analysis
How the Tests Are Obtained
Kidney function tests usually require a 24-hour urine sample and a blood test.
24-Hour Urine Sample
A 24-hour urine sample is a creatinine clearance test. It gives an idea of how much creatinine the body expels over a single day.
Spot urine
The sampling of a single, untimed urine specimen, voided spontaneously by the patient. The sample is analyzed to determine its protein,
creatinine, or electrolyte content. This type of specimen differs from a timed urinary specimen, which represents all the urine a patient
produces over a 12- or 24-hr period. Both types of specimen are used in
the diagnosis and treatment of renal disease.
Routine Urinalysis
A urinalysis is important in accessing the chemical constituents in the urine and the relationship to various disease states.
Macro and Microscopic Analyzes
The urine sample's color
Appearance
Specific gravity
pH
Protein levels
Glucose
Ketones
Blood
Leukocyte esterase
Nitrite
Bilirubin
Urobilinogen
Macroscopic urinalysis
Macroscopic urinalysis is the direct visual observation of the urine, noting its quantity, color, clarity or cloudiness, etc.
Normal urine is typically light yellow and clear without any cloudiness.
Obvious abnormalities in the color, clarity, and cloudiness may suggest possibility of
an infection (cloudy urine),
Dehydration (dark urine color),stains urine a tea or cola color),
blood in the urine (visible to the eye may indicate urinary tract infection, stones, tumors, or injuries), or breakdown of muscle (orange- or tea-
colored urine).
Microscopic urine analysis
This test looks at a sample of urine under a microscope. It can see cells from your urinary tract, blood cells, crystals, bacteria, parasites, and cells from tumors.
This test is often used to confirm the findings of other tests or add
information to a diagnosis.
Laboratory Reference Ranges in Healthy Adults
Each laboratory has specific reference ranges.
Reference range values are for apparently healthy people and often overlap significantly with values for those who are sick.
Actual values may vary significantly due to differences in assay
methodologies and standardization. Institutions may also set up their
ownreference ranges based on the particular populations that they
serve, thus regional differences may occur.
Protein and Glucose Test
The protein test provides a rough estimate of the amount of albumin in the urine. When urine protein is elevated, a person has a condition
called proteinuria.
Glucose is normally not present in urine. When glucose is present, the condition is called glucosuria. It results from:
An excessively high glucose level in the blood, such as person who have uncontrolled diabetes
Some other conditions: hormonal disorders, liver disease, medications, and pregnancy.
When glucosuria occurs, other tests such as a fasting blood glucose are
usually performed to further identify the specific cause.
Leukocytes and nitrites
Both of which are potential indicators of infection.
The presence of nitrite in the urine is highly specific of a bacterial infection.
If there is no leukocyte esterase in the urine, this means an infection is
unlikely.
Bilirubin
Bilirubin is primarily derived from metabolism of hemoglobin. Only conjugated bilirubin is excreted into the urine and normally only trace amounts can be detected in urine. Elevated urinary bilirubin occurs in patients with obstructive jaundice or jaundice due to hepatocellular
disease or injury. Hyperbilirubinemia due to hemolysis is principally due
to unconjugated bilirubin, and therefore does not result in increased
urinary bilirubin.
Normal Urine Characteristics
Characteristic Normal values
Color Pale yellow to deep amber
Odor Odorless
Volume 750–2000 mL/24 hour
pH 4.5–8.0
Specific gravity 1.003–1.032
Osmolarity 40–1350 mOsmol/kg
Urobilinogen 0.2–1.0 mg/100 mL
White blood cells 0–2 HPF (per high-power field of microscope)
Leukocyte esterase None
Protein None or trace
Bilirubin <0.3 mg/100 mL
Ketones None
Nitrites None
Blood None
Glucose None
