What is the Triene/Tetraene ratio? High and low values | Lab results explained

The Triene/Tetraene (T/T) ratio is another marker for essential fatty acid status. It is calculated as the ratio of Mead acid to arachidonic acid. This ratio, combined with measurements of the essential fatty acids and Mead acid, gives a more complete picture of the degree and nature of fatty acid deficiency. An elevated ratio shows a relative excess of triene (3 double bonds) compared to tetraene (4 double bonds), which results from essential fatty acid deficiency.

What is an “Essential fatty acid deficiency”?

Essential fatty acid (EFA) deficiency is rare, occurring most often in infants fed diets deficient in EFAs. Signs include scaly dermatitis, alopecia, thrombocytopenia, and, in children, intellectual disability. Diagnosis is clinical. Dietary replenishment of EFAs reverses the deficiency.

For EFA deficiency to develop, dietary intake must be very low. Even small amounts of EFAs can prevent EFA deficiency. Total fat intake of people in many developing countries may be very low, but the fat is often vegetable based, with large amounts of linoleic acid and enough linolenic acid to prevent EFA deficiency.

Babies fed a formula low in linoleic acid, such as a skim-milk formula, can develop EFA deficiency. EFA deficiency used to result from long-term total parenteral nutrition (TPN) if fat was not included. But now, most TPN solutions include fat emulsions to prevent EFA deficiency. In patients with fat malabsorption or increased metabolic needs (eg, because of surgery, multiple trauma, or burns), laboratory evidence of EFA deficiency may be present without clinical signs.

General Biochemical and Physical Signs and Symptoms of Essential Fatty Acid Deficiency:


– Elevated Triene/Tetraene (T/T) ratio

– Elevated liver function tests

– Hyperlipidemia

– Thrombocytopenia

– Altered platelet aggregation


– Dry, scaly rash

– Hair loss

– Hair depigmentation

– Poor wound healing

– Growth restriction in children

– Increased susceptibility to infection

Normal ranges:

< or = 31 days: 0.017-0.083

32 days – 17 years: 0.013-0.050

> or = 18 years: 0.010-0.038

Higher levels:

– An elevated ratio shows a relative excess of triene (3 double bonds) compared to tetraene (4 double bonds), which results from essential fatty acid deficiency (=EFAD). 

– An elevated triene:tetraene ratio will manifest before any other signs or symptoms of EFAD

– Dietary replenishment of EFAs reverses the deficiency.





Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

The information on is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: