Aspartate Aminotransferase (AST with P5P)
Label Mnemonic: AST
Epic code: LAB131
Downtime form: Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Chemistry
6240 RCP
356-3527
Specimen(s):
Plasma
Collection Medium:
Plasma Separator Tube 4.5 mL
Alternate Collection Media:
Call laboratory for additional acceptable specimen collection containers.
Minimum:

3 mL light green top tube or 1 light green top Microtainer® for pediatric patients

Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:
1 hour (upon receipt in laboratory)
Reference Range:

Adult Male: 0-50 U/L

Adult Female: 0-35 U/L

 

Pediatric Ranges:

Age AST (U/L)
Up to 15 days 40-175
15 days up to 1 year 28-77
1-6 years 29-53
7-11 years 26-45
12-18 years (female) 21-34
12-18 years (male) 22-44

Adult and pediatric reference intervals were updated on 2/25/2025.

Comments:

Effective 2/25/2025, AST activity is measured using an assay supplemented with pyridoxal-5’-phosphate (P5P), a required co-factor for measuring AST activity. AST results from P5P supplemented assays are approximately 20 – 30% higher than results from non-supplemented assays. AST values should always be interpreted in conjunction with clinical history, physical examination findings, and, if applicable, data from other diagnostic tests.

 

This test is also performed in the Iowa River Landing (IRL) clinical laboratory (for specimens drawn at that site).

 

This test is also performed in the North Dodge clinical laboratory (for specimens drawn at that site).

Test Limitations:

Hemolysis interferes due to AST activity from erythrocytes and should be avoided. AST will not be reported for specimens with severe enough hemolysis (55 – 500 mg/dL hemoglobin depending on AST activity).

The assay is unaffected by icterus (bilirubin less than 60 mg/dL) and lipemia (Intralipid less than 150 mg/dL). Criterion: recovery within 10% of initial value.

 

Glick MR, Ryder KW, Jackson SA. Graphical Comparisons of Interferences in Clinical Chemistry Instrumentation. Clin Chem 1986;32:470-474.

 

Higgins V, Chan MK, Nieuwesteeg M, Hoffman BR, Bromberg IL, Gornall D, Randell E, Adeli K. Transference of CALIPER pediatric reference intervals to biochemical assays on the Roche cobas 6000 and the Roche Modular P. Clin Biochem. 2016 Jan;49(1-2):139-49. doi: 10.1016/j.clinbiochem.2015.08.018. Epub 2015 Aug 19. PMID: 26297116.

Methodology:

Spectrophotometric with pyridoxal phosphate activation

CPT Code:
84450