Energy and focus
ADHD Symptoms in Women: What to Rule Out First
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed October 20265 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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No blood test can show ADHD. But a few common, fixable problems cloud focus and memory in the same way. The NHS lists poor concentration under an underactive thyroid, and memory problems under low B12. Checking TSH, free T4, B12, ferritin and vitamin D first means an ADHD assessment starts from a clear baseline.
You lose your keys daily. You start five things and finish none. You have just watched a podcast on ADHD and recognised yourself in every minute of it.
That recognition is worth taking seriously. This guide covers the body’s own lookalikes, the ones a blood test can check, so you can go into an assessment knowing they are ruled out.
By the Helvy Medical Team · Reviewed by a qualified clinician · 5 min read
As of October 2026. The Diary of a CEO released its episode “What is ADHD?” on 7 October 2026, and the question of ADHD in women is everywhere again.
1. Why is ADHD missed in women?
Because it often looks quiet. Women more often have the inattentive type: drifting off, forgetting, losing track.
“ADHD is thought to be recognised less often in women than men. This may be because women with ADHD more commonly have inattentive symptoms.”
The NHS lists being easily distracted or forgetful, finding it hard to organise your time, and losing things often. Those are real signs. They are also signs a tired, depleted body can give.
2. What else can feel like ADHD?
Four common ones show up in a blood test. Most are more common in women, and they can sit unnoticed for years.
- A slow thyroid. The NHS lists “difficulty concentrating or thinking clearly” as a symptom. Hashimoto’s, the usual cause, is most common in women aged 30 to 50.
- Low B12 or folate. The NHS lists problems with memory, understanding and judgement.
- Low iron. Heavy periods and pregnancy are the most common causes, and tiredness is the main symptom.
- Perimenopause. The NHS names poor memory and brain fog among its symptoms.
None of these rules ADHD in or out. You can have both. But if your thyroid is slow, fixing it changes what an assessment sees. Our brain fog blood test guide covers the wider list.
3. Which blood markers should you check?
Five markers cover the main lookalikes.
- TSH is the signal your brain sends to push the thyroid. A high TSH usually means the thyroid is lagging.
- Free T4 is the main hormone the thyroid makes. Free T3 is the active form your cells use.
- Vitamin B12 keeps nerves and red blood cells healthy. Folate works alongside it.
- Ferritin is the protein that holds iron in reserve. It shows how much iron you have banked.
- Vitamin D is often low in UK winters. Its link to focus is less clear, but it is cheap to check.
A full blood count, which checks for anaemia directly, is a GP test and not on our panels. Our full blood count guide explains what it shows.
4. What do you do with the results?
Take them to your GP either way.
If something is out of range, that is the first thing to treat. Give it a few months, then see how your focus feels. If your results are normal, you walk into the ADHD conversation with the common physical causes already checked.
Only a specialist, such as a psychiatrist, can diagnose ADHD. The NHS says they look at your symptom history, especially whether it started in childhood.
The Helvy General Energy & Wellness panel (£149) covers TSH, free T4, B12, vitamin D and cortisol. Vitamins & Minerals (£159) adds ferritin, iron and folate. Thyroid & Vital Organs (£159) adds free T3. A blood test measures. It does not diagnose, and a qualified clinician reads the results together.
Frequently asked questions
Can a blood test diagnose ADHD?
No. ADHD is diagnosed by a specialist from your history and symptoms. A blood test can only check for other causes of poor focus.
Can an underactive thyroid feel like ADHD?
It can overlap. The NHS lists difficulty concentrating, tiredness and low mood as symptoms. A TSH and free T4 test shows whether your thyroid is keeping up.
Can low iron cause brain fog?
Low iron often causes tiredness and a lack of energy, which makes focus harder. Heavy periods are one of the most common causes. Ferritin shows your iron reserves.
Is it ADHD or perimenopause?
It can be both. Symptoms that appear for the first time in your forties point more towards perimenopause, since ADHD starts in childhood.
READY TO TEST?
Check the lookalikes before the assessment
Helvy's home finger-prick kits report your thyroid, B12, iron and vitamin D, with a written explanation of what each one shows. Samples are processed by UKAS-accredited UK laboratories.
Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Blood markers measure, they do not diagnose, and no blood test can diagnose or exclude ADHD. Consult your GP or a qualified healthcare professional. All Helvy blood tests are processed by UKAS-accredited UK laboratories to ISO 15189.
Last updated: October 2026 · By Helvy · Medically analysed at UKAS-accredited UK laboratories
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