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Test ID FAPEP Fatty Acid Profile, Essential, Serum

Reporting Name

Fatty Acid Profile, Essential, S

Useful For

Evaluating the nutritional intake and intestinal absorption of essential fatty acids using serum specimens


Identifying deficiency of essential and other nutritionally beneficial fatty acids


Monitoring treatment of patients with essential fatty acid deficiencies who are receiving linoleic acid (C18:2w6) and alpha-linolenic acid (C18:3w3)

Specimen Type


Necessary Information

1. Patient's age is required.

2. Include information regarding treatment, family history, and tentative diagnosis.

Specimen Required

Patient Preparation:

1. For nutritional assessment, patient should fast overnight (12-14 hours); for patients with a suspected fatty acid oxidation disorder, collect prior to next feeding as fasting is contraindicated.

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

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions: Centrifuge and aliquot serum into plastic vial.

Specimen Minimum Volume

0.15 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Frozen (preferred) 92 days
  Refrigerated  72 hours

Reference Values

Lauric Acid, C12:0

<1 year: 6-190 nmol/mL

1-17 years: 5-80 nmol/mL

≥18 years: 6-90 nmol/mL


Myristic Acid, C14:0

<1 year: 30-320 nmol/mL

1-17 years: 40-290 nmol/mL

≥18 years: 30-450 nmol/mL


Hexadecenoic Acid, C16:1w9

<1 year: 21-69 nmol/mL

1-17 years: 24-82 nmol/mL

≥18 years: 25-105 nmol/mL


Palmitoleic Acid, C16:1w7

<1 year: 20-1,020 nmol/mL

1-17 years: 100-670 nmol/mL

≥18 years: 110-1,130 nmol/mL


Palmitic Acid, C16:0

<1 year: 720-3,120 nmol/mL

1-17 years: 960-3,460 nmol/mL

≥18 years: 1,480-3,730 nmol/mL


Gamma-Linolenic Acid, C18:3w6

<1 year: 6-110 nmol/mL

1-17 years: 9-130 nmol/mL

≥18 years: 16-150 nmol/mL


Alpha-Linolenic Acid, C18:3w3

<1 year: 10-190 nmol/mL

1-17 years: 20-120 nmol/mL

≥18 years: 50-130 nmol/mL


Linoleic Acid, C18:2w6

≤31 days: 350-2,660 nmol/mL

32 days-11 months: 1,000-3,300 nmol/mL

1-17 years: 1,600-3,500 nmol/mL

≥18 years: 2,270-3,850 nmol/mL


Oleic Acid, C18:1w9

<1 year: 250-3,500 nmol/mL

1-17 years: 350-3,500 nmol/mL

≥18 years: 650-3,500 nmol/mL


Vaccenic Acid, C18:1w7

<1 year: 140-720 nmol/mL

1-17 years: 320-900 nmol/mL

≥18 years: 280-740 nmol/mL


Stearic Acid, C18:0

<1 year: 270-1,140 nmol/mL

1-17 years: 280-1,170 nmol/mL

≥18 years: 590-1,170 nmol/mL


EPA, C20:5w3

<1 year: 2-60 nmol/mL

1-17 years: 8-90 nmol/mL

≥18 years: 14-100 nmol/mL


Arachidonic Acid, C20:4w6

<1 year: 110-1,110 nmol/mL

1-17 years: 350-1,030 nmol/mL

≥18 years: 520-1,490 nmol/mL


Mead Acid, C20:3w9

≤31 days: 8-60 nmol/mL

32 days-11 months: 3-24 nmol/mL

1-17 years: 7-30 nmol/mL

≥18 years: 7-30 nmol/mL


Homo-Gamma-Linolenic C20:3w6

<1 year: 30-170 nmol/mL

1-17 years: 60-220 nmol/mL

≥18 years: 50-250 nmol/mL


Arachidic Acid, C20:0

<1 year: 30-120 nmol/mL

1-17 years: 30-90 nmol/mL

≥18 years: 50-90 nmol/mL


DHA, C22:6w3

<1 year: 10-220 nmol/mL

1-17 years: 30-160 nmol/mL

≥18 years: 30-250 nmol/mL


DPA, C22:5w6

<1 year: 3-70 nmol/mL

1-17 years: 10-50 nmol/mL

≥18 years: 10-70 nmol/mL


DPA, C22:5w3

<1 year: 6-110 nmol/mL

1-17 years: 30-270 nmol/mL

≥18 years: 20-210 nmol/mL


DTA, C22:4w6

<1 year: 2-50 nmol/mL

1-17 years: 10-40 nmol/mL

≥18 years: 10-80 nmol/mL


Docosenoic Acid, C22:1

<1 year: 2-20 nmol/mL

1-17 years: 4-13 nmol/mL

≥18 years: 4-13 nmol/mL


Nervonic Acid, C24:1w9

<1 year: 30-150 nmol/mL

1-17 years: 50-130 nmol/mL

≥18 years: 60-100 nmol/mL


Triene/Tetraene Ratio

≤31 days: 0.017-0.083

32 days-17 years: 0.013-0.050

≥18 years: 0.010-0.038


Total Saturated Acid

<1 year: 1.2-4.6 mmol/L

1-17 years: 1.4-4.9 mmol/L

≥18 years: 2.5-5.5 mmol/L


Total Monounsaturated Acid

<1 year: 0.3-4.6 mmol/L

1-17 years: 0.5-4.4 mmol/L

≥18 years: 1.3-5.8 mmol/L


Total Polyunsaturated Acid

<1 year: 1.1-4.9 mmol/L

1-17 years: 1.7-5.3 mmol/L

≥18 years: 3.2-5.8 mmol/L


Total w3   

<1 year: 0.0-0.4 mmol/L

1-17 years: 0.1-0.5 mmol/L

≥18 years: 0.2-0.5 mmol/L


Total w6

<1 year: 0.9-4.4 mmol/L

1-17 years: 1.6-4.7 mmol/L

≥18 years: 3.0-5.4 mmol/L


Total Fatty Acids

<1 year: 3.3-14.0 mmol/L

1-17 years: 4.4-14.3 mmol/L

≥18 years: 7.3-16.8 mmol/L

Day(s) Performed

Monday through Friday

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
FAPEP Fatty Acid Profile, Essential, S 43676-6


Result ID Test Result Name Result LOINC Value
17021 Lauric Acid, C12:0 35150-2
17022 Myristic Acid, C14:0 35157-7
17023 Hexadecenoic Acid, C16:1w9 35155-1
17024 Palmitoleic Acid, C16:1w7 35162-7
17025 Palmitic Acid, C16:0 35161-9
17026 g-Linolenic Acid, C18:3w6 35163-5
17027 a-Linolenic Acid, C18:3w3 35164-3
17028 Linoleic Acid, C18:2w6 35165-0
17029 Oleic Acid, C18:1w9 35166-8
17030 Vaccenic Acid, C18:1w7 35167-6
17031 Stearic Acid, C18:0 35149-4
17032 EPA, C20:5w3 35173-4
17033 Arachidonic Acid, C20:4w6 35168-4
17034 Mead Acid, C20:3w9 35172-6
17035 h-g-Linolenic, C20:3w6 35171-8
17036 Arachidic Acid, C20:0 35169-2
17037 DHA, C22:6w3 35174-2
17038 DPA, C22:5w6 35181-7
17039 DPA, C22:5w3 35180-9
17040 DTA, C22:4w6 35182-5
17041 Docosenoic Acid, C22:1 35160-1
17042 Nervonic Acid, C24:1w9 35170-0
17043 Triene Tetraene Ratio 35411-8
17044 Total Saturated Acid 35175-9
17045 Total Monounsaturated Acid 35176-7
17046 Total Polyunsaturated Acid 35177-5
17047 Total w3 35178-3
17048 Total w6 35179-1
17049 Total Fatty Acids 24461-6
17054 Interpretation 59462-2

Clinical Information

Fats are important sources of energy for tissues and for the function and integrity of cellular membranes. Deficiencies are commonly caused by inadequate dietary intake of lipids due to an unbalanced diet, long-term parenteral nutrition, or by intestinal malabsorption. Linoleic acid, an omega-6 fatty acid, and alpha-linolenic acid, an omega-3 fatty acid, are considered essential fatty acids in that they cannot be made by the body and are essential components of the diet.


The major clinical manifestations associated with essential fatty acid deficiency (EFAD) include dermatitis, increased water permeability of the skin, increased susceptibility to infection, and impaired wound healing. Biochemical abnormalities may be detected before the onset of recognizable clinical manifestations. EFAD can be detected by diminished levels of the essential fatty acids, linoleic and alpha-linolenic acid, as well as by increases in the triene:tetraene ratio.


Excess dietary fatty acids have been linked to the onset of cardiovascular disease. Elevated levels of linoleic acid can contribute to overproduction of the proinflammatory 2-series local hormones. The Academy of Nutrition and Dietetics recommends that dietary fat for the healthy adult population should provide 20% to 35% of energy, with an increased consumption of n-3 polyunsaturated fatty acids and limited intake of saturated and trans fats.(1)


Concentrations below the stated reference ranges are consistent with fatty acid deficiencies.


An increased triene:tetraene ratio is consistent with essential fatty acid deficiency.


For nutritional assessment, a 12- to 14-hour fast is required; however, infants or persons suspected of having a fatty acid oxidation disorder should not fast before testing due to the possibility of acute metabolic decompensation. Instead, collect the specimen after the longest fast possible, just before feeding. In the case of a patient on total parenteral nutrition, specimen can be collected as normal.

Clinical Reference

1. Vannice G, Rasmussen H: Position of the Academy of Nutrition and Dietetics: Dietary fatty acids for healthy adults. J Acad Nutr Diet. 2014 Jan;1(114):136-153

2. Jeppesen PB, Chistensen MS, Hoy CE, Mortensen PB: Essential fatty acid deficiency in patients with severe fat malabsorption. Am J Clin Nutr. 1997 Mar;65(3):837-843

3. McCowen KC, Bistrian BR: Essential fatty acids and their derivatives. Curr Opin Gastroenterol. 2005 Mar;21(2):207-215

Method Description

Quantitation of fatty acids of specific chain lengths is performed as follows: a 2-step, acid-base hydrolysis is followed by hexane extraction and derivatization with pentafluorobenzyl bromide. Separation and detection are accomplished by capillary gas chromatography electron-capture negative ion-mass spectrometry. Quantitation is based on analysis in the selected ion-monitoring mode by using 13 stable isotope-labeled internal standards.(Lagerstedt SA, Hinrichs DR, Batt SM, Magera MJ, Rinaldo P, McConnell JP: Quantitative determination of plasma C8-C26 total fatty acids for the biochemical diagnosis of nutritional and metabolic disorders. Mol Genet Metab. 2001 May;73(1):38-45; Gramlich L, Ireton-Jones C, Miles JM, Morrison M, Pontes-Arruda A: Essential fatty acid requirements and intravenous lipid emulsions. JPEN J Parenter Enteral Nutr. 2019 Aug;43(6):697-707)

Report Available

3 to 5 days

Reject Due To

Gross hemolysis OK
Gross lipemia Reject
Gross icterus OK

Method Name

Gas Chromatography-Mass Spectrometry (GC-MS) Stable Isotope Dilution Analysis

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.