Test Catalog

Test ID: FAPCP    
Fatty Acid Profile, Comprehensive (C8-C26), Serum

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

This serum test is a comprehensive profile that provides information regarding mitochondrial and peroxisomal fatty acid metabolism, and the patient's nutritional status


Monitoring patients undergoing diet therapy for mitochondrial or peroxisomal disorders (possibly inducing essential fatty acid deficiency in response to restricted fat intake)


Monitoring treatment of essential fatty acid deficiency


Monitoring the response to provocative tests (fasting tests, loading tests)

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

This test is a comprehensive profile that provides information regarding mitochondrial and peroxisomal fatty acid metabolism, and the patient's nutritional status.


While providing useful information regarding very long chain fatty acids, this test is not the recommended initial screening test for evaluating patients with possible peroxisomal disorders, single-enzyme defects of peroxisomal metabolism such as X-linked adrenoleukodystrophy, or peroxisomal biogenesis disorders (Zellweger syndrome spectrum). For this purpose POXP / Fatty Acid Profile, Peroxisomal (C22-C26), Plasma or POX / Fatty Acid Profile, Peroxisomal (C22-C26), Serum is preferred.

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

Fatty Acid Deficiency/Excess:

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 acid 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.


Fatty Acid Oxidation (FAO) Disorders:

Mitochondrial beta-oxidation is the main source of energy to skeletal and heart muscle during periods of fasting. When the body's supply of glucose is depleted, fatty acids are mobilized from adipose tissue and converted to ketone bodies thorough a series of steps providing an alternate source of energy. Deficient enzymes at any step in this pathway prevent the production of energy during periods of physiologic stress such as fasting or intercurrent illness.


The major clinical manifestations associated with FAO disorders include hypoketotic hypoglycemia, liver disease and failure, skeletal myopathy, dilated/hypertrophic cardiomyopathy, and sudden unexpected death in early life. Signs and symptoms may vary greatly in severity, combination, and age of presentation. Life-threatening episodes of metabolic decompensation frequently occur after periods of inadequate calorie intake or intercurrent illness. When properly diagnosed, patients with FAO disorders respond favorably to fasting avoidance, diet therapy, and aggressive treatment of intercurrent illnesses, with significant reduction of morbidity and mortality.


Disease-specific characteristic patterns of metabolites from FAO disorders are detectable in blood, bile, urine, and cultured fibroblasts of living and many deceased individuals. Quantitative determination of C8-C18 fatty acids is an important element of the work-up and differential diagnosis of candidate patients. Fatty acid profiling can detect quantitatively modest, but nevertheless significant, abnormalities even when patients are asymptomatic and under dietary treatment. Confirmatory testing via the FAO / Fatty Acid Oxidation Probe Assay, Fibroblast Culture and molecular analysis are also available for many of the FAO disorders at Mayo Clinic Laboratories.


Peroxisomal Disorders:

Peroxisomes are organelles present in all human cells except mature erythrocytes. They carry out essential metabolic functions including beta-oxidation of very long-chain fatty acids (VLCFA), alpha-oxidation of phytanic acid, and biosynthesis of plasmalogen and bile acids. Peroxisomal disorders include disorders of peroxisomal biogenesis with defective assembly of the entire organelle and single peroxisomal enzyme/transporter defects where the organelle is intact but a specific function is disrupted. Peroxisomal beta-oxidation of VLCFA is impaired in all disorders of peroxisomal biogenesis and in selected single enzyme deficiencies, particularly X-linked adrenoleukodystrophy, resulting in elevated concentrations of VLCFA in serum or plasma. POXP / Fatty Acid Profile, Peroxisomal (C22-C26), Plasma or POX / Fatty Acid Profile, Peroxisomal (C22-C26), Serum is the preferred screening test for evaluating patients with possible peroxisomal disorders, single-enzyme defects of peroxisomal metabolism such as X-linked adrenoleukodystrophy, or peroxisomal biogenesis disorders (Zellweger syndrome spectrum). Confirmatory testing for X-linked adrenoleukodystrophy (XALDZ / X-Linked Adrenoleukodystrophy, Full Gene Analysis) via molecular genetic analysis is available at Mayo Clinic Laboratories.

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.

Octanoic Acid, C8:0

<1 year: 7-63 nmol/mL

1-17 years: 9-41 nmol/mL

> or =18 years: 8-47 nmol/mL


Decenoic Acid, C10:1

<1 year: 0.8-4.8 nmol/mL

1-17 years: 1.6-6.6 nmol/mL

> or =18 years: 1.8-5.0 nmol/mL


Decanoic Acid, C10:0

<1 year: 2-62 nmol/mL

1-17 years: 3-25 nmol/mL

> or =18 years: 2-18 nmol/mL


Lauroleic Acid, C12:1

<1 year: 0.6-4.8 nmol/mL

1-17 years: 1.3-5.8 nmol/mL

> or =18 years: 1.4-6.6 nmol/mL


Lauric Acid, C12:0

<1 year: 6-190 nmol/mL

1-17 years: 5-80 nmol/mL

> or =18 years: 6-90 nmol/mL


Tetradecadienoic Acid, C14:2

<1 year: 0.3-6.5 nmol/mL

1-17 years: 0.2-5.8 nmol/mL

> or =18 years: 0.8-5.0 nmol/mL


Myristoleic Acid, C14:1

<1 year: 1-46 nmol/mL

1-17 years: 1-31 nmol/mL

> or =18 years: 3-64 nmol/mL


Myristic Acid, C14:0

<1 year: 30-320 nmol/mL

1-17 years: 40-290 nmol/mL

> or =18 years: 30-450 nmol/mL


Hexadecadienoic Acid, C16:2

<1 year: 4-27 nmol/mL

1-17 years: 3-29 nmol/mL

> or =18 years: 10-48 nmol/mL


Hexadecenoic Acid, C16:1w9

<1 year: 21-69 nmol/mL

1-17 years: 24-82 nmol/mL

> or =18 years: 25-105 nmol/mL


Palmitoleic Acid, C16:1w7

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

1-17 years: 100-670 nmol/mL

> or =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

> or =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

> or =18 years: 16-150 nmol/mL


Alpha-Linolenic Acid, C18:3w3

<1 year: 10-190 nmol/mL

1-17 years: 20-120 nmol/mL

> or =18 years: 50-130 nmol/mL


Linoleic Acid, C18:2w6

< or =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

> or =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

> or =18 years: 650-3,500 nmol/mL


Vaccenic Acid, C18:1w7

<1 year: 140-720 nmol/mL

1-17 years: 320-900 nmol/mL

> or =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

> or =18 years: 590-1,170 nmol/mL


EPA, C20:5w3

<1 year: 2-60 nmol/mL

1-17 years: 8-90 nmol/mL

> or =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

> or =18 years: 520-1,490 nmol/mL


Mead Acid, C20:3w9

< or =31 days: 8-60 nmol/mL

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

> or =1 year: 7-30 nmol/mL


Homo-Gamma-Linolenic Acid, C20:3w6

<1 year: 30-170 nmol/mL

1-17 years: 60-220 nmol/mL

> or =18 years: 50-250 nmol/mL


Arachidic Acid, C20:0

<1 year: 30-120 nmol/mL

1-17 years: 30-90 nmol/mL

> or =18 years: 50-90 nmol/mL


DHA, C22:6w3

<1 year: 10-220 nmol/mL

1-17 years: 30-160 nmol/mL

> or =18 years: 30-250 nmol/mL


DPA, C22:5w6

<1 year: 3-70 nmol/mL

1-17 years: 10-50 nmol/mL

> or =18 years: 10-70 nmol/mL


DPA, C22:5w3

<1 year: 6-110 nmol/mL

1-17 years: 30-270 nmol/mL

> or =18 years: 20-210 nmol/mL


DTA, C22:4w6

<1 year: 2-50 nmol/mL

1-17 years: 10-40 nmol/mL

> or =18 years: 10-80 nmol/mL


Docosenoic Acid, C22:1

<1 year: 2-20 nmol/mL

> or =1 year: 4-13 nmol/mL


Docosanoic Acid, C22:0

0.0-96.3 nmol/mL


Nervonic Acid, C24:1

<1 year: 30-150 nmol/mL

1-17 years: 50-130 nmol/mL

> or =18 years: 60-100 nmol/mL


Tetracosanoic Acid, C24:0

0.0-91.4 nmol/mL


Hexacosenoic Acid, C26:1

<1 year: 0.2-2.1 nmol/mL

> or =1 year: 0.3-0.7 nmol/mL


Hexacosanoic Acid, C26:0

0.00-1.30 nmol/mL


Pristanic Acid, C15:0(CH3)4

< or =4 months: 0.00-0.60 nmol/mL

5-8 months: 0.00-0.84 nmol/mL

9-12 months: 0.00-0.77 nmol/mL

13-23 months: 0.00-1.47 nmol/mL

> or =2 years: 0.00-2.98 nmol/mL


Phytanic Acid, C16:0(CH3)4

< or =4 months: 0.00-5.28 nmol/mL

5-8 months: 0.00-5.70 nmol/mL

9-12 months: 0.00-4.40 nmol/mL

13-23 months: 0.00-8.62 nmol/mL

> or =2 years: 0.00-9.88 nmol/mL


Triene/Tetraene Ratio

< or =31 days: 0.017-0.083

32 days-17 years: 0.013-0.050

> or =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

> or =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

> or =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

> or =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

> or =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

> or =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

> or =18 years: 7.3-16.8 mmol/L

Interpretation Provides information to assist in interpretation of the test results

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


Fatty acid oxidation disorders are recognized on the basis of disease-specific patterns that are correlated to the results of other investigations in plasma (carnitine, acylcarnitines) and urine (organic acids, acylglycines).


Increased concentrations of serum very long-chain fatty acids (VLCFA) C24:0 and C26:0 are seen in peroxisomal disorders, X-linked adrenoleukodystrophy, adrenomyeloneuropathy, and Zellweger syndrome (cerebrohepatorenal syndrome).


Increased concentrations of serum phytanic acid (along with normal pristanic acid concentrations) are seen in the Refsum disease (phytanase deficiency). Serum phytanic acid concentration also may be increased in other peroxisomal disorders and, when combined with the VLCFA, pristanoic acid and pipecolic acid allow differential diagnosis of peroxisomal disorders.

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

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 owing 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 (TPN), specimen can be drawn as normal.

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

1. Rinaldo P, Matern D, Bennett MJ: Fatty acid oxidation disorders. Ann Rev Physiol 2002;64:477-502

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

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