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Test Code LAB6557 Urinalysis Reflex to Microscopic and Culture

NOTICE

Includes color, clarity, specific gravity, pH, protein, glucose, ketones, bilirubin, blood, urobilinogen, nitrites, and leukocyte esterase.

Testing Algorithm (reflex criteria): 

If the macroscopic exam is positive for leukocyte esterase, nitrates, blood, or protein (1+ or above), a microscopic exam will be reflexed. The presence of >10 white blood cells (WBCs) per high power field (HPF) on the microscopic exam will reflex to a urine culture.

Performing Laboratory

St. Louis Children's Hospital Laboratory - Urinalysis

Specimen Requirements

Specimen must arrive n lab within 1 hour of collection

Patient Preparation: None

Collection Container/Tube:

Preferred: Clean, plastic screw-cap urine collection container with no preservatives

Acceptable: Yellow-top conical urine collection tube

Specimen Collection Volume: 20.0 mL (minimum 2.0 mL) urine

Submission Container/Tube: If specimen is coming from outside facility aliquot a minimum of 2.0 mL of urine into a plastic leak-proof, screw-capped tube for transport.at refrigerated temperature.

Special Instructions: 

  • Collect midstream (clean-catch) voided specimen
  • Catheterized specimen is also acceptable
  • Specimen should be received in laboratory within 1 hour of collection, if delayed, refrigerate specimen. Specimens >8 hours old will not be tested.

 

Sample Rejection

Mislabled or unlabeled specimens

Specimens collected with cotton balls

Specimen with urine preservatives

Specimens >2 hours old at ambient temperature or >8 hours old refrigerated

Specimens collected in a Becton-Dickinson Grey-top Urine collection tube

Logistics

Test Availability: Monday-Sunday

Cut-off time: None, performed as received

Turnaround Time: Same Day; 2 hours from receipt in lab

Reference Values

Reference Interval: 

Macroscopic Exam  
Specific Gravity: 1.003-1.030
Color: Yellow, Straw, or Amber
Clarity: Clear
pH: None established
Protein: Negative
Glucose, qualitative: Negative
Ketones, qualitative: Negative
Bilirubin, qualitative: Negative
Occult Blood: Negative
Urobilinogen: <2.0 mg/dL
Nitrites: Negative
Leukocyte esterase: Negative
Microscopic Exam  
RBC: 0-2/HPF
WBC: 0-5/HPF

Critical Value: 

NOTE: Physician or nurse will be notified for the following criteria (not flagged as critical in LIS)

  • Abnormal Glucose and Ketones on the same specimen
  • Presence of parasites/Trichomonas

Results will be called initially and every 72 hours thereafter.

 

Methodology

Dipstick (AUTION ELEVEN AE-4022 Chemistry Analyzer): Measures the end product of chemical reaction by reflectance spectroscopy on color reagent pads.
Urine Color: Spectrophotometric or visual observation
Specific Gravity: Refractometer
Clarity: Measurement of the transmission of scatter of light

Limitations

Analyte

Causes of false negative results

Causes of false positive results

Glucose

Large amounts of ascorbic acid

Presence of oxidizing substances such as chlorine or hypochlorite, urine with a pH <4.0

Protein

pH < 3.0

Large amount of hemoglobin, contrast medium, disinfectants including quaternary ammonium compounds, urine with a pH >8.0

Bilirubin

Ascorbic acid, uric acid, and nitrites

Urobilinogen, Ethodolac

Urobilinogen  

N/A

Carbapenem

Blood

Elevated specific gravity or protein, large amounts of ascorbic acid

Oxidizing substances such as chlorine or hypochlorite

Ketones

N/A

L-DOPA, BSP, PSP, Phenylketone, Cephalosporine, Aldose reductive antienzyme

Nitrite

Ascorbic acid, elevated specific gravity

N/A

Leukocytes

Glucose > 500 mg/dL, Protein > 300 mg/dL, Urine with low pH or elevated specific gravity
 

Formaldehyde

Additional Information

FOR SLCH CORE LABORATORY USE ONLY

Lab Processing Instructions: DO NOT SPIN Specimen should be given directly to urinalysis bench for testing 

Processed Volume: minimum 2.0 mL urine

Analyte Stability:

Specimen Type Temperature Time
urine (no preservative)     Ambient 2 hours  
  Refrigerated     8 hours   
  Frozen  Not acceptable    

 

NOTE: 

  • cancel if specimen is >8 hours old
  • Specimens that reflex to a culture should be labeled with culture order label and sent to BJS microbiology for culture.

Test Classification and CPT Code

81003

LOINC

Analyte LOINC code   
Color 5778-6
Clarity 32167-9
pH Ur Ql 5803-2
Specific Gravity Ur    5811-5
Albumin Ur Ql 20454-5
Blood Ur Ql 5794-3
Glucose Ur Ql 25428-4
Ketones Ur Ql 2514-8
Leuk Esterase Ur 5799-2
Nitrite Ur Ql 5802-4
Urobilinogen Ur Ql 19161-9

Last Reviewed

08/2025