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Protocol - Free Fatty Acids

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Description:

This protocol provides instructions for drawing, processing, and storing blood according to the National Health and Nutrition Examination Survey (NHANES) and uses capillary gas chromatography with flame ionization or electron capture negative chemical ionization mass spectrometry to measure free fatty acids (FFA) in the serum or plasma sample.

Protocol:

The following is a summary version of the full National Health and Nutrition Examination Survey (NHANES) 2007-2008 protocol.

Exclusion Criteria

Persons will be excluded from this component if they:

  • report that they have hemophilia, or
  • report that they have received cancer chemotherapy in the last 4 weeks.

SP = Sample Person

1. Do you have hemophilia?

1 [ ] Yes

2 [ ] No

7 [ ] Refused

9 [ ] Don’t Know

If the SP answers "Yes," the SP is excluded from the blood draw.

If the SP answers "No" or "Don’t Know," blood is drawn from the SP.

2. Have you received cancer chemotherapy in the past 4 weeks, or do you anticipate such therapy in the next 4 weeks?

1 [ ] Yes

2 [ ] No

7 [ ] Refused

9 [ ] Don’t Know

If the SP answers "Yes," the SP is excluded from the blood draw.

If the SP answers "No" or "Don’t Know," blood is drawn from the SP.

Note from the Infectious Diseases and Immunity Working Group (WG): The investigator should record the reason a person is excluded from the blood draw.

Venipuncture Procedures

Editor’s Note: Please review chapter 4 of the Laboratory Procedures Manual from the NHANES for a full description of Phlebotomy procedures: 2007-2008 NHANES Lab Manual.

Venipuncture should generally be performed using the median cubital, cephalic, or basilica veins in the left arm unless this arm is unsuitable. If the veins in the left arm are unsuitable, look for suitable veins on the right arm. If the veins in the antecubital space on both arms are not suitable, then look for veins in the forearm or dorsal side of the hand on the left arm/hand and then right arm/hand.

Recording the Results of the Venipuncture Procedure

Immediately after completing the venipuncture, record the results of the blood draw, the reasons for a tube not being drawn according to the protocol, and any comments about the venipuncture.

Note from the Infectious Diseases and Immunity WG: The Infectious Diseases and Immunity WG recommends that the investigator record whether the blood was drawn and whether the full amount was obtained.

Process the Sample for the Serum

Editor’s Note: Please review chapter 8 of the Laboratory Procedures Manual from the NHANES 2007-2008 for a full description of Blood Processing procedures: 2007-2008 NHANES Lab Manual.

  • Allow the blood to clot by setting aside for 30-45 minutes at room temperature. Do not clot for more than 1 hour.
  • Centrifuge the tube at room temperature to separate the serum and aliquot into an appropriate storage tube.

Determine if the serum is hemolyzed, turbid, lipemic, or icteric. If so, enter a comment to describe the plasma.

Protocol Name from Source:

This section will be completed when reviewed by an Expert Review Panel.

Availability:

Publicly available

Personnel and Training Required

Certified phlebotomist

Laboratory capable of performing required assays

Equipment Needs

Phlebotomy supplies

Requirements
Requirement CategoryRequired
Major equipment No
Specialized training No
Specialized requirements for biospecimen collection No
Average time of greater than 15 minutes in an unaffected individual No
Mode of Administration

Bioassay

Life Stage:

Infant, Toddler, Child, Adolescent, Adult, Senior

Participants:

All ages

Specific Instructions:

The Working Group recommends measurement of 6 saturated fatty acids, 7 monounsaturated fatty acids, and 11 polyunsaturated fatty acids. Participants are asked to fast for at least 8 hours prior to the blood draw.

Selection Rationale

The NHANES 2003-2004 protocol was selected as the best standardized methodology for blood collection, processing, and storage because of high feasibility, relatively low cost, and low subject burden.

Language

English

Standards
StandardNameIDSource
Common Data Elements (CDE) Blood Free Fatty Acids Measurement Value 4994235 CDE Browser
Derived Variables

None

Process and Review

This section will be completed when reviewed by an Expert Review Panel.

Source

Centers for Disease Control and Prevention (CDC). National Center for Health Statistics (NCHS). National Health and Nutrition Examination Survey Data. Hyattsville, MD: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2003-2004, http://wwwn.cdc.gov/nchs/nhanes/2003-2004/SSFA_C.htm

General References

Caudill, S. P., Schleicher, R. L., & Pirkle, J. L. (2008). Multi-rule quality control for the age-related eye disease study. Statistics and Medicine, 27, 4094-4106.

Clinical Laboratory Improvement Amendment. Public Law 100-578. 1988. 10-31-1988.

Lagerstedt, S., Hinrichs, D., Batt, S., Magera, M., Rinaldo, P., & McConnell, J. (2001). Quantitative determination of plasma C8-C26 total fatty acids for the biochemical diagnosis of nutritional and metabolic disorders. Molecular Genetics & Metabolism, 73, 38-45.

Protocol ID:

230901

Variables:
Export Variables
Variable NameVariable IDVariable DescriptionVersiondbGaP Mapping
Research Domain Information
Measure Name:

Free Fatty Acids

Release Date:

September 9, 2015

Definition

This is a bioassay to measure free fatty acids (FFA), which are organic acids with a long saturated or unsaturated side chain circulated in free form, but also bound in triglycerides and phospholipids.

Purpose

The measure is reflective of dietary fat composition and intermediary metabolism. FFAs serve as a fuel for muscular contraction and general metabolism. Blood biochemistries reflecting consequential pathways of obesity are important measures for assessing health and nutritional status, and metabolic risk.

Keywords

Free fatty acids, FFA, obesity, dietary fat composition, intermediary metabolism, National Health and Nutrition Examination Survey, NHANES