UCSF Navigation Bar

UCSF Departments of Pathology & Laboratory Medicine Home Page

Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

Internal Resources

Click here for more information about laboratory operations and procedures

If you have additional questions regarding this test, please call: 415-353-1667

Search Our Test Menu

Factor 2 Activity

Item Value
Approval req'd? No
Available Stat? No
Test code F2
Test group Coagulation Factor Activities
Performed by Parnassus Hematology
In House Availability Test run 0800-1500 Monday-Friday
Method Clotting assay (Stago - STAR)
Collection Instructions 1. Check the expiration date on the label of the blue top vacutainer before drawing the patient.

2. For blood collection in a sodium citrate blue top, the tube must be filled to above the Minimum Fill Indicator on the tube. It is crucial to wait and allow the tube to stop filling before removing it from the needle.

3. With use of a butterfly needle, draw about 1 cc using a separate blue top to remove air from tubing, discard the first tube and then draw a second blue top tube filled to the full extent of the vacuum.

4. Tubes should not be filled past the Maximum Fill dashed line by either using a syringe or removing the tube cap.

Deliver immediately to the laboratory.

For patients with Hct's ≥ 55% please contact Hematology (Parnassus: 3-1747, Mission Bay 6-1094) to obtain blue top tubes with adjusted citrate volumes in order to maintain the proper citrate to plasma ratio for coagulation studies.
Container type Blue top filled to full extent of vacuum
Amount to Collect 2.7 mL blood
Sample type Citrated plasma
Preferred volume 1 mL plasma
Min. Volume 0.5 mL plasma
UCSF Rejection Criteria Samples collected in outdated blue top vacutainer. Over-filled or under-filled tubes may be rejected
Processing notes Provide sample(s) to Hematology section asap.
Units % activity
Normal range
0-4 days 26-70%
5-30 days 33-93%
1-3 months 34-102%
3-6 months 45-105%
6 months – 1 year 60-116%
1-5 years 71-116%
6-10 years 67-107%
11-17 years 61-104%
≥ 18 years 81-127%

UCSF HAS NOT ESTABLISHED NORMAL REFERENCE RANGES FOR FACTOR LEVELS FOR CHILDREN <18 YEARS OLD. The table above gives age-adjusted reference ranges for Pediatric Factor 2 Levels as percentages. The values are expressed by the upper and lower boundary encompassing 95% of the population.

These values are based upon these references:
Andrew M. et al. Development of the Human Coagulation System in the Full Term Infant. Blood 1987 70:165
Andrew M, et al. Maturation of the Hemostatic System During Childhood. Blood October 1992, 80(8): 1998-2005

Values are converted from the original tables, which express values as units/ml. Original tables provide values for infants at 1 day, 5 days, 30 days, 90 days, and 180 days of age as well as for children 1-5 years, 6-10 years, and 11-16 years. The published tables have been converted to the reference range shown.
Synonyms Prothrombin; F2; Factor 2; Factor II
Stability Factor assays should generally be performed within four hours of specimen collection or the plasma frozen; the latter is stable for 2 weeks at -20C or 6 months at -70C.
Turn around times 1-3 days
Additional information If unusual findings are noted a pathologist review and interpretation may be performed and separately billed for
CPT coding 85210
LOINC code 3289-6
Last Updated 6/20/2016 11:59:45 AM
Entry Number 359
UCSF home page UCSF home page About UCSF Search UCSF UCSF Medical Center