Test Catalog

Test Id : NEFA

Free Fatty Acids, Total, Serum

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluation of metabolic status of patients with endocrinopathies 


Monitoring of control of diabetes mellitus.


Monitoring the effects of therapeutic diet/exercise lifestyle changes

Method Name
A short description of the method used to perform the test

Enzymatic Colorimetric

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Free Fatty Acids, Total, S

Lists additional common names for a test, as an aid in searching

Fatty Acids, Free


Free Fatty Acids, Serum

NEFA (Nonesterified Fatty Acids)

Non Esterified Fatty Acids

Specimen Type
Describes the specimen type validated for testing


Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Patient Preparation:

1. Fasting-overnight (12-14 hours).

2. Patient must not consume any alcohol for 24 hours before the specimen is collected.

3. Patient should not be receiving therapeutic heparin.

Collection Container/Tube: 

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Centrifuge within 45 minutes of collection and aliquot 1 mL of serum into a plastic vial.

2. Immediately freeze specimen.


If not ordering electronically, complete, print, and send a Cardiovascular Test Request Form (T724) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

0.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Serum Frozen 7 days

Useful For
Suggests clinical disorders or settings where the test may be helpful

Evaluation of metabolic status of patients with endocrinopathies 


Monitoring of control of diabetes mellitus.


Monitoring the effects of therapeutic diet/exercise lifestyle changes

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Elevated serum concentrations of nonesterified fatty acids (NEFA) are associated with cardiovascular disease, metabolic syndrome, obesity, and type 2 diabetes mellitus. NEFA are causally linked with insulin resistance and inflammation of vascular endothelium.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

> or =18 years: 0.00-0.72 mmol/L

Reference values have not been established for patients who are <18 years of age.

Provides information to assist in interpretation of the test results

Abnormally high levels of free fatty acids are associated with uncontrolled diabetes mellitus and with conditions that involve excessive release of a lipoactive hormone such as epinephrine, norepinephrine, glucagon, thyrotropin, and adrenocorticotropin.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Patients receiving therapeutic heparin are unsuitable for this analysis. Heparin causes the release of free fatty acids by stimulating the activity of lipoprotein lipase, which causes triglycerides associated with blood lipoproteins to release free fatty acids.


In order to eliminate the generation of free fatty acids from triglycerides by serum lipases (causing erroneous elevations), serum should be frozen as soon as possible after it is collected and shipped frozen.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Boden G: Obesity and free fatty acids. Endocrinol Metab Clin North Am. 2008 Sep;37(3):635-646, viii-ix. doi: 10.1016/j.ecl.2008.06.007

2. Haus JM, Soloman TP, Marchetti CM, Edmison JM, Gonzalez F, Kirwan JP: Free fatty acid-induced hepatic insulin resistance is attenuated following lifestyle intervention in obese individuals with impaired glucose tolerance. J Clin Endocrinol Metab. 2010 Jan;95(1):323-327. doi: 10.1210/jc.2009-1101

3..Imrie H, Abbas A, Kearney M: Insulin resistance, lipotoxicity and endothelial dysfunction. Biochim Biophys Acta. 2010 Mar;1801 (3):320-326. doi: 10.1016/j.bbalip.2009.09.025

Method Description
Describes how the test is performed and provides a method-specific reference

In the presence of adenosine triphosphate (ATP) and coenzyme A (CoA), serum non-esterified fatty acids (NEFA) form acyl-CoA, adenosine monophosphate (AMP) and pyrophosphate (PPi) when treated with acylCoA synthetase (ACS). The acylCoA is then oxidized by adding acylCoA oxidase (ACOD) to produce hydrogen peroxide, which in the presence of added peroxidase allows for the oxidative condensation of 3-methyl-N- ethyl-N-(beta-hydroxyethyl)-aniline (MEHA) with 4-aminoantipyrine to form a purple colored end product.(Package insert: HR Series NEFA-HR(2). Fujifilm WAKO Pure Chemical Corp; 18.03.19K04)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

1 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

7 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.


LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
NEFA Free Fatty Acids, Total, S 15066-4
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
NEFA Free Fatty Acids, Total, S 15066-4

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports