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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Anion Gap

Test Code(s): LYTS / LYTE

CPT Code(s): See Electrolytes Panel

Test Description: Included In: Electrolytes panel, Basic Metabolic Panel (BMP) and Comprehensive Metabolic Panel (CMP)

Methodology: Ion Selective Electrode and/or Enzymatic

Days Performed: Daily, 24 hours.

Turnaround Time: Stat: 1 hour.
Routine: 4 hours.

Specimen Requirements

Specimen: Blood

Collection Instructions: Tube must be at least one quarter full.

Collection Container: Preferred: Green cap with yellow ring (PST)
Also Acceptable: Green top, Red cap with yellow ring (SST), Red top

Collection Volume: Preferred: 1 mL
Pediatrics: 0.5 mL

Sample Analyzed: Plasma or serum

Volume Required: Preferred: 0.5 mL
Pediatrics: 0.2 mL

Specimen Processing: Centrifuge.  If a complete barrier has not formed, transfer cell-free plasma/serum to plastic vial.  Tube must be at least one quarter full. Refrigerate specimen.

Specimen Transport: Transport specimen to the laboratory. Transport with coolant pack if coming from outreach location.


Reference Interval:

0 days and up: 7-14 mmol/L

Additional Information:

The anion gap is calculated by subtracting the sum of the chloride and total carbon dioxide from the sodium result.


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