A urinalysis (UA), also known as routine and microscopy (R&M), is an array of tests performed on urine, and one of the most common methods of medical diagnosis. The word is a portmanteau of the words urine and analysis.
The target parameters that can be measured or quantified in urinalysis include many substances and cells, as well as other properties, such as specific gravity.
A part of a urinalysis can be performed by using urine test strips, in which the test results can be read as color changes. Another method is light microscopy of urine samples.
Target parameters
Urine test results should always be interpreted using the reference range provided by the laboratory that performed the test, or using information provided by the test strip/device manufacturer.
In addition to the substances mentioned in tables below, other tests include a description of color and appearance.
Ions and trace metals
A sodium-related parameter is fractional sodium excretion, which is the percentage of the sodium filtered by the kidney which is excreted in the urine. It is a useful parameter in acute renal failure and oliguria, with a value below 1% indicating a prerenal disease and a value above 3% indicating acute tubular necrosis or other kidney damage.
Proteins and enzymes
Blood cells
Other molecules
Other urine parameters
Illicit substances
Urine may be tested to determine whether an individual has engaged in recreational drug use. In this case, the urinalysis would be designed to detect whatever marker indicates drug use.
Methods
When doctors order a urinalysis, they will request either a routine urinalysis or a routine and microscopy (R&M) urinalysis, with the difference being a routine urinalysis does not include microscopy or culture.
Urine test strip
A urine test strip can quantify:
- Leukocytes â€" with presence in urine known as leukocyturia
- Nitrite â€" with presence in urine known as nitrituria
- Protein â€" with presence in urine known as proteinuria, albuminuria, or microalbuminuria
- Blood â€" with presence in urine known as hematuria
- specific gravity
Microscopic examination
The numbers and types of cells and/or material such as urinary casts can yield a great detail of information and may suggest a specific diagnosis.
- Hematuria â€" associated with kidney stones, infections, tumors and other conditions
- Pyuria â€" associated with urinary infections
- Eosinophiluria â€" associated with allergic interstitial nephritis, atheroembolic disease
- Red blood cell casts â€" associated with glomerulonephritis, vasculitis, or malignant hypertension
- White blood cell casts â€" associated with acute interstitial nephritis, exudative glomerulonephritis, or severe pyelonephritis
- (Heme) granular casts â€" associated with acute tubular necrosis
- Crystalluria â€" associated with acute urate nephropathy (or acute uric acid nephropathy, AUAN)
- Calcium oxalatin â€" associated with ethylene glycol
- Waxy casts â€" associated with chronic renal disease
Other methods of urinalysis
- Urine culture â€" a microbiological culture of urine samples, detecting bacteriuria, is indicated when a urinary tract infection is suspected.
- Ictotest â€" this test is used to detect the destruction of old red blood cells in the urine.
- Hemoglobin test â€" this tests for hemolysis in the blood vessels, a rupture in the capillaries of the glomerulus, or hemorrhage in the urinary system, which cause hemoglobin to appear in the urine.
