Free Androgen Index Normal Range Women 7 Simple Facts

You’ve had a hormone blood test, and one line on the report says “free androgen index” with a number and a range you’ve never seen before. You search for it and find ranges that range from under 5 to over 10. Which one is right?

The short answer is that free androgen index normal range women depends on the lab, your age and how the result is expressed. Some NHS labs print one range, some websites print another, and none of them is a verdict on its own.

Disclaimer

This article is for general information only and is not a substitute for professional medical advice, diagnosis or treatment. Reference ranges vary between laboratories and change over time. Always speak to a qualified healthcare professional about your test results, symptoms or medicines. If you think you have a medical emergency, call 999 (UK) or your local emergency number immediately. SEO and content results vary by site, niche and competition, and no tactic can guarantee a ranking.

This guide explains what the free androgen index (FAI) is, why the ranges differ, what drives the number, how it compares with other tests and what to ask your doctor. It’s for general information and can’t tell you whether your own result is healthy.

This article is not medical advice. If you’re worried about a result or symptoms, speak to a GP or another qualified healthcare professional.

The Quick Answer

There’s no single standard range. Here are a few published examples.

Notice how much the upper limit moves, from about 5 to nearly 11. That doesn’t mean one source is wrong. It means labs use different methods and populations, and the only range that counts for you is the one printed on your own report.

What Is the Free Androgen Index?

Androgens are hormones such as testosterone. Women make them in small amounts, and they play a role in many body functions. Most testosterone in the blood is attached to proteins, mainly one called SHBG (sex hormone binding globulin). The part that’s “free” is the portion available to act on tissues.

The FAI is a calculation that estimates that free portion without measuring it directly. The NHS lab page notes that it’s calculated automatically in females when testosterone and SHBG are requested together.

The formula

The usual formula is:

FAI = (total testosterone in nmol/L ÷ SHBG in nmol/L) × 100

Some sources show a version for testosterone in ng/dL, which multiplies by about 0.0347 to convert units first.

A simple illustration

These numbers are made up to show how the maths works, not a typical result.

If SHBG were lower, say 25 nmol/L, the same testosterone would give an FAI of 6. That’s why the FAI can move without testosterone changing at all.

Why Ranges Differ So Much

1. How the result is expressed

Some labs show FAI as a plain number, and others as a percentage, as the NHS Severn Pathology page does. They’re the same calculation, but a quick glance can make them look different.

2. Age bands

Ranges often change with age and menopausal status. The NHS lab page uses three age bands, and one UK guide shows lower ranges after 50.

3. The lab’s population and method

Each lab sets its range using its own methods and reference group. One UK guide stresses that comparing an FAI from one lab against a range from another can be genuinely misleading.

4. Website ranges are generic

Many websites quote a single “normal” figure, such as below 7. Some say values above 10 to 12 together with symptoms warrant evaluation. Those are general framings, not a substitute for your report.

Why SHBG Drives the Result

Because SHBG is the bottom half of the fraction, the FAI is very sensitive to it. One summary describes SHBG as the primary driver of FAI variability.

From general knowledge, SHBG levels can be affected by:

• Body weight and metabolic health
• Thyroid conditions
• Liver health
• Some medicines, including hormonal contraception
• Age and menopausal status

I haven’t verified every one of these for this article, so ask a clinician how they might apply to you.

The key point is that a high or low FAI doesn’t necessarily mean your testosterone itself is high or low. It may mean SHBG is. That’s why doctors look at the individual results (testosterone and SHBG) alongside the index. free androgen index normal range women.

FAI vs Total Testosterone vs Free Testosterone

One medical reference calls equilibrium dialysis the “gold standard” for measuring free testosterone, while noting that it’s practical to use the index for most clinical purposes. A case report in another source shows that calculated free testosterone can look normal when direct measurement is low, in a patient with very low SHBG. That report was about a man, but it illustrates why an estimate has limits. free androgen index normal range women.

What a Higher Result Can Mean

A higher FAI can be associated with conditions that involve excess androgen activity. One guide mentions that persistently high values with symptoms such as irregular periods, acne or unwanted hair growth may prompt evaluation for conditions including polycystic ovary syndrome (PCOS), and rarely other causes. free androgen index normal range women.

Important points:

• A high FAI doesn’t diagnose anything. Doctors look at symptoms, periods, other hormone tests and sometimes scans. free androgen index normal range women.
• Many people with a high reading have no condition, and many people with PCOS have a normal reading. free androgen index normal range women.
• Don’t treat yourself from a number. Medicines and supplements that change hormones need medical advice. free androgen index normal range women.

What a Lower Result Can Mean

A lower FAI is less often the focus, and it can reflect lower testosterone, higher SHBG or both. Levels naturally decline with age, which is why ranges are often lower after menopause. A low reading without symptoms usually isn’t a concern, but discuss it with your clinician if you have symptoms or questions. free androgen index normal range women.

How the Test Works

1. Your GP requests it, usually because of symptoms such as irregular periods, acne or excess hair growth. free androgen index normal range women.
2. A blood sample is taken. Ask about timing. Hormone levels can vary through the day and across the menstrual cycle, so some labs ask for a morning sample or a specific cycle day.
3. Tell the clinician about your medicines. Hormonal contraception and other medicines can affect SHBG and the result. free androgen index normal range women.
4. The lab measures total testosterone and SHBG, and calculates the FAI.
5. Your clinician interprets the results with your symptoms and other tests. The NHS lab lists a turnaround time of about 7 days for its test, though this varies by lab.

What about home tests?

Home tests can measure testosterone, SHBG and FAI, and some UK companies sell them. They can start a conversation, but a result needs a clinician’s interpretation, and ranges can differ from those used by NHS labs. Check that the lab is accredited and don’t act on the result alone.

Questions to Ask Your GP

• Which range does my lab use, and for which age group?
• Is my result expressed as a number or a percentage?
• What were my testosterone and SHBG results?
• Could my medicines, weight, thyroid or cycle have affected the result?
• Do I need other tests, such as other hormones or an ultrasound?
• What could explain my symptoms?
• What are my options, and what are the risks and benefits?
• When should I retest?

When to See a Doctor

Speak to a GP if you:

• Have irregular or absent periods
• Notice new or increased facial or body hair, or persistent acne
• Have hair thinning on the scalp
• Are having difficulty conceiving free androgen index normal range women
• Have a test result outside the range and don’t understand it
• Are taking supplements or products that claim to change hormones
• Have symptoms that affect your daily life or mood

Seek urgent help if you feel very unwell. If you’re struggling with your mental health or have thoughts of harming yourself, call 999 in an emergency, or Samaritans on 116 123 at any time.

For Publishers: Why Health Ranges Are Tricky Content

This is RankRX, so here’s the content-strategy side. Free androgen index normal range women is the kind of query where lots of pages repeat a single “normal” figure. If you publish health content, a few habits matter. free androgen index normal range women.

• Health is a sensitive (YMYL) topic. Google applies higher standards of experience, expertise, authority and trust, and nobody can guarantee rankings.
• Don’t copy a single range. As the table above shows, sources disagree. Explain why, and point readers to their own report. free androgen index normal range women.
• Use credible sources. NHS lab pages, medical references and clinical guidance carry more weight than product pages. free androgen index normal range women.
• Have a qualified person review it. Add a reviewer’s name and credentials where possible.
• Flag commercial interests. Many “range” pages come from companies selling tests, so disclose any links you earn from. free androgen index normal range women.
• Keep it up to date. Reference ranges and guidance change.

If your site isn’t a health site, consider whether this topic fits your audience at all. Results vary by site, niche and competition. free androgen index normal range women.

Common Mistakes to Avoid

1. Using a range from a different lab. Check the one on your report.
2. Confusing the percentage and plain-number versions.
3. Assuming a high FAI means high testosterone. SHBG may be driving it.
4. Ignoring SHBG and total testosterone. Look at all three results.
5. Not telling the clinician about contraception or other medicines.
6. Diagnosing PCOS or any condition yourself. free androgen index normal range women.
7. Buying hormone supplements on the strength of one result.
8. Treating “normal” as the same as “healthy for me.”
9. Retesting too often. Hormones fluctuate, so discuss timing.
10. Skipping follow-up if your symptoms continue.

A Quick Checklist

• I’ve found the reference range on my own report
• I know whether my result is a number or a percentage
• I’ve looked at testosterone and SHBG as well as the FAI
• I’ve told my clinician about my medicines and contraception
• I’ve noted my symptoms and cycle pattern
• I’m not changing treatment without advice
• I’ve booked a follow-up if I’m unsure

Final Thoughts

The free androgen index normal range women see on their reports varies with the lab, age and method, from upper limits under 5 to over 10 in published examples. The number itself is a calculated estimate shaped heavily by SHBG, so it’s best read alongside total testosterone, SHBG, your symptoms and your doctor’s judgement. free androgen index normal range women.

READ MORE: Google Business Profile Manager The Complete 2026 Guide for UK Businesses

Check the range on your own report, ask your clinician what the result means for you and avoid self-diagnosing. Guidance and ranges change, so use reliable sources such as the NHS for the latest information. free androgen index normal range women.

FAQs

What is a normal free androgen index for a woman?

It depends on the lab and age. One NHS lab lists 0.7 to 10.9% for ages 18 to 46, while other UK guides quote a range of about 0.18 to 7.07 for ages 20 to 50. Use the range on your own report.

How is the free androgen index calculated?

It’s total testosterone divided by SHBG, multiplied by 100, with both measured in nmol/L. Labs often calculate it automatically when testosterone and SHBG are requested together.

Does a high FAI mean I have PCOS?

Not necessarily. A high FAI can be linked to conditions such as PCOS, but it doesn’t diagnose anything. Doctors consider symptoms, periods and other tests. free androgen index normal range women.

Why does my FAI range differ from a website?

Labs use different methods, age bands and populations, and websites often quote a single generic range. Always compare your result with the range printed on your own report.

Is FAI the same as free testosterone?

No. FAI is a calculated estimate based on total testosterone and SHBG. Directly measured free testosterone is more accurate but less widely available.

Can birth control affect the result?

Some medicines, including hormonal contraception, can affect SHBG and therefore the FAI. Tell your clinician what you take before the test. free androgen index normal range women.

For more updates visit: medvisibility.co.uk