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Test ID NEFA Free Fatty Acids, Total, Serum

Reporting Name

Free Fatty Acids, Total, S

Useful For

Evaluation of metabolic status of persons with endocrinopathies


Detection of pheochromocytoma and of glucagon-, thyrotropin-, and adrenocorticotropin-secreting tumors


Monitoring of control of diabetes mellitus (serum-free glycerol is a very useful companion test in assessing diabetes and may be ordered by special request from Mayo Clinic Laboratories). The correlation with insulin resistance and downstream cardiovascular risk may be a useful treatment aid in some patients.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type


Specimen Required

Patient Preparation:

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

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

Collection Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Spin down within 45 minutes of draw.

2. Immediately freeze specimen.

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen

Reference Values

≥16 years: 0.00-0.72 mmol/L

Reference values have not been established for patients who are <16 years of age.

Day(s) and Time(s) Performed

Monday through Friday; 7 a.m.-5 p.m.

Test Classification

This test has been cleared or approved by the U.S. 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


LOINC Code Information

Test ID Test Order Name Order LOINC Value
NEFA Free Fatty Acids, Total, S 15066-4


Result ID Test Result Name Result LOINC Value
NEFA Free Fatty Acids, Total, S 15066-4

Clinical Information

All but 2% to 5% of serum fatty acids are esterified. The "nonesterified" or "free" fatty acids are protein-bound. The amount of free fatty acids in the serum rises after a fatty meal, but tends to fall after ordinary meals. Levels are elevated in obesity.


Lipoactive hormones such as epinephrine, norepinephrine, glucagon, thyrotropin, and adrenocorticotropin release free fatty acids. Tumors producing such hormones cause release of excessive quantities of free fatty acids. Serum free fatty acids are also increased in patients with uncontrolled type 2 diabetes mellitus and are an indicator of insulin resistance. Free fatty acids are associated with increased reactive oxygen species (ROS), probably mediated by free fatty acid activation of NADPH oxidase. The link between increased ROS and decreased nitric oxide production is a contributor to endothelial dysfunction.


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.


Patient should fast for 12 to 14 hours; however, in prolonged fasting or starvation, free fatty acid levels rise as much as 3-fold.


Patient should abstain from alcohol for at least 24 hours.


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

Clinical Reference

1. Dole VP: A relation between non-esterified fatty acids in plasma and the metabolism of glucose. J Clin Invest 1956;35:150-154

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

Analytic Time

1 day (not reported on Saturday or Sunday)

Reject Due To


Mild OK; Gross reject


Mild OK; Gross reject


Mild OK; Gross reject



NY State Approved


Method Name

Enzymatic Colorimetric


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