What tests should be ordered for urine studies?

From the Guidelines

Urine studies should include a urinalysis and, if pyuria is present or clinical suspicion is high, a urine culture with antimicrobial susceptibility testing, as recommended by the most recent guidelines 1. The choice of tests should be guided by the patient's symptoms, medical history, and clinical presentation.

• A standard urinalysis examines physical characteristics, chemical parameters, and microscopic elements.
• For suspected urinary tract infections, a urine culture should be ordered to identify specific pathogens and determine antibiotic sensitivity, especially in complicated cases or recurrent UTIs 1.
• Additional specialized tests may be considered based on clinical suspicion, such as a 24-hour urine collection, urine cytology, or drug screening.
• Proper collection technique, such as a clean-catch midstream sample, is essential for accurate results, although this may not always be feasible in certain patient populations, such as frail elderly residents in long-term care facilities, who may require alternative collection methods like a freshly applied, clean condom external collection system or in-and-out catheterization 2. The most recent guidelines suggest that the diagnostic value of urinalysis for UTI is limited, and clinical symptoms should be the primary basis for diagnosis, with urinalysis findings used to support or rule out infection 1.

From the FDA Drug Label

Urinalyses with careful microscopic examination and renal function tests should be performed during therapy, particularly for those patients with impaired renal function

The tests that should be ordered for urine studies are:

• Urinalyses with careful microscopic examination
• Renal function tests

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From the Research

Urine Studies Tests

To conduct urine studies, the following tests can be ordered:

• Physical examination of urine, including description of color, odor, clarity, volume, and specific gravity 4
• Chemical examination of urine, including the identification of:
  • Protein
  • Blood cells
  • Glucose
  • pH
  • Bilirubin
  • Urobilinogen
  • Ketone bodies
  • Nitrites
  • Leukocyte esterase 4, 5
• Microscopic examination of urine, including the detection of:
  • Crystals
  • Cells
  • Casts
  • Microorganisms 4, 6
• Dipstick urinalysis, which can be used to screen for urinary tract infections, but results must be interpreted in context of the patient's pretest probability based on symptoms and characteristics 7
• Urine culture, which is the gold standard for detection of urinary tract infection, particularly in cases where the probability of urinary tract infection is moderate or unclear 7, 5

Specific Tests for Urinary Tract Infections

For patients with symptoms of urinary tract infections, the following tests can be ordered:

• Nitrites test, which is more specific for bacterial infection 7, 5
• Leukocyte esterase test, which may occur from inflammation and infection 7, 5
• Urine culture, which can confirm the presence of a urinary tract infection and guide antibiotic treatment 7, 5

Additional Tests

In certain cases, additional tests may be ordered, such as:

• Quantitative tests, such as a spot urine albumin/creatinine ratio, to confirm proteinuria 5
• Microscopic urinalysis to detect significant urinary findings not disclosed by macroscopic examination 6