Flavin adenine dinucleotide test: FAD blood test meaning and levels

The flavin adenine dinucleotide test measures the active form of Vitamin B2 responsible for cellular energy production. Normal FAD levels range from 175 to 470 nmol/L in adults. Low FAD levels indicate a functional Vitamin B2 deficiency, while high values usually reflect supplementation or metabolic imbalance. This test helps assess mitochondrial function and metabolic health more accurately than standard riboflavin tests.

Contents

→ Result interpretation
→ Check your value Flavin Adenine Dinucleotide
→ What is Flavin Adenine Dinucleotide
→ Reference ranges
→ Causes of abnormal values
→ Flavin Adenine Dinucleotide in combination with other markers
→ Possible symptoms
→ When to see a doctor
→ What to do if abnormal
→ Frequently asked questions
→ Related markers

Result interpretation Flavin Adenine Dinucleotide

What your result means based on common reference ranges

🟢

Normal

FAD levels within range indicate efficient mitochondrial function and proper Vitamin B2-dependent enzyme activity in metabolism.

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Mildly elevated

Mildly elevated FAD levels usually reflect recent Vitamin B2 supplementation without clinical impact on metabolic function.

🔴

Significantly elevated

Significantly high FAD levels may indicate liver dysfunction or impaired cellular utilization of Vitamin B2 in metabolism.

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Below normal

Low FAD levels indicate functional Vitamin B2 deficiency leading to impaired energy production and possible anemia development.

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Flavin Adenine Dinucleotide, nmol/L

Sex

Age

What is Flavin Adenine Dinucleotide?

Flavin adenine dinucleotide (FAD) is the active coenzyme form of Riboflavin (Vitamin B2) that participates in redox reactions and ATP production within mitochondria. Unlike inactive riboflavin, FAD directly supports enzymes involved in energy metabolism, iron utilization, and oxidative stress regulation. A FAD blood test evaluates functional vitamin status rather than intake alone. Low levels are linked to Vitamin B2 deficiency, anemia, and impaired mitochondrial function, while abnormal elevations may reflect supplementation or liver dysfunction. This biomarker is often interpreted alongside homocysteine and ferritin to assess metabolic and nutritional balance.

Reference ranges

Group	Normal range	Unit
Men	175 – 470	nmol/L
Women	175 – 470	nmol/L
Children	160 – 450	nmol/L
Elderly	170 – 460	nmol/L

Causes of abnormal values

Causes of low Flavin Adenine Dinucleotide

• Poor diet lacking dairy and green vegetables reduces riboflavin intake and FAD synthesis
• Chronic alcohol use impairs intestinal absorption and conversion to active FAD
• Malabsorption syndromes damage gut lining reducing Vitamin B2 uptake
• Hypothyroidism reduces enzyme activity needed to convert riboflavin into FAD

Causes of high Flavin Adenine Dinucleotide

• High-dose Vitamin B2 supplementation increases circulating FAD levels directly
• Diet rich in liver or fortified foods elevates riboflavin availability and FAD production
• Liver cell damage releases stored cofactors into bloodstream increasing levels
• Dehydration concentrates blood components including FAD leading to falsely elevated readings
• Genetic enzyme defects impair FAD utilization causing accumulation in circulation

Flavin Adenine Dinucleotide in combination with other markers

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Low FAD + Low Hemoglobin Suggests impaired iron metabolism leading to anemia due to reduced cofactor-dependent erythropoiesis

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Low FAD + High Homocysteine Indicates disrupted methylation cycle increasing cardiovascular risk due to impaired enzyme activity

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High FAD + High ALT/AST Reflects liver injury releasing stored vitamins into blood rather than improved metabolic status

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Low FAD + Low T4 Suggests hypothyroidism reducing conversion of riboflavin into active FAD affecting metabolism

Possible symptoms

•Cracks at mouth corners (cheilosis)
•Inflamed or red tongue (glossitis)
•Sensitivity to light (photophobia)
•Seborrheic dermatitis (scaly skin)
•Persistent fatigue and low energy

When to see a doctor

Consult a doctor if FAD levels fall below 150 nmol/L or remain persistently abnormal across tests. Seek medical advice if low levels are combined with fatigue, mouth lesions, or elevated homocysteine.

What to do if abnormal

🥗 Improve diet with eggs, dairy, and green vegetables rich in riboflavin
🧪 Check thyroid function if FAD levels remain low despite adequate intake
🚫 Reduce alcohol consumption to improve Vitamin B2 absorption
💊 Adjust supplements if FAD levels are excessively high
🌑 Store vitamins away from light to prevent riboflavin degradation

The information on this page is intended for general understanding of test results and does not replace medical consultation. Accurate interpretation requires considering other blood markers and individual factors.

Content is based on medical literature and used within the PulseBook analytical system.

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Frequently asked questions

What is the flavin adenine dinucleotide test?

The flavin adenine dinucleotide test measures the active form of Vitamin B2 in the blood. Unlike standard riboflavin tests, it shows how much of the vitamin is usable by enzymes. This makes it more accurate for detecting functional deficiencies affecting metabolism and energy production.

What does FAD blood test meaning indicate?

FAD blood test meaning reflects how effectively your body converts Riboflavin into its active form. Normal levels indicate proper mitochondrial function, while low FAD suggests deficiency and impaired energy metabolism. High levels are often linked to supplementation or liver-related issues.

What is the FAD normal range?

The FAD normal range in adults is typically 175–470 nmol/L. Slight variations may occur between laboratories. Values below this range suggest Vitamin B2 deficiency, while higher levels are usually related to increased intake or reduced cellular utilization.

What causes low FAD levels?

Low FAD levels causes include poor diet, alcohol use, malabsorption conditions, and hypothyroidism. These factors either reduce riboflavin intake or impair its conversion into the active form, leading to metabolic and energy production issues.

What is Riboflavin and how is it related to FAD?

Riboflavin, also known as Vitamin B2, is a precursor that the body converts into FAD and FMN. FAD is the active coenzyme that participates in energy production. Without enough riboflavin, FAD levels drop, affecting metabolism and cellular function.

What are Vitamin B2 deficiency symptoms?

Vitamin B2 deficiency symptoms include fatigue, cracks at the mouth corners, sore throat, and skin inflammation. These signs reflect impaired cellular energy production due to low FAD levels and reduced enzyme activity.

Are Vitamin B2 supplements safe?

Vitamin B2 supplement use is generally safe because it is water-soluble. Excess amounts are excreted in urine, often turning it bright yellow. However, very high doses may cause mild digestive effects and unnecessary metabolic load.

What are Vitamin B2 side effects?

Vitamin B2 side effects are rare but may include increased urination or mild diarrhea at high doses. These effects are usually harmless, but persistent symptoms should be evaluated alongside FAD levels and overall vitamin intake.