A basic blood count can look fine while your iron stores quietly run out. Here's what a fuller panel shows, and why answers based on your own numbers beat answers written for everyone.
Months of "just tired"
It's most common in women who have periods, since monthly blood loss is the leading cause of low iron before menopause.
The 3pm wall
You're 34. You sleep eight hours and wake up feeling like you got four. By mid-afternoon you're reading the same email for the third time. You blame work, then winter, then turning 34.
"Your bloods are fine"
Eventually you see your GP. They run a full blood count, and a week later a text arrives: results normal, no further action. The relief lasts about a day, then the tiredness is back, now with a nagging sense that you're imagining it.
One line out of range
A month later, still exhausted, you search "always tired but blood test normal" and learn that a full blood count doesn't measure your iron stores. You order a home test with a wider panel, do the finger prick before work, and a few days later the results arrive in WhatsApp.
Nearly everything is in range except ferritin: 12 µg/L, flagged low. Haemoglobin is still normal, which is why the first test had nothing to report.
Your resultsMicronutrients & blood countHaemoglobinOxygen-carrying protein132 g/LIn rangeMCVAverage red cell size81 fLLow endFerritinIron stores · flagged12 µg/LBelow rangeIllustrative values. Reference ranges vary by lab.
A better question
You've asked ChatGPT "why am I always tired" before and got a list of everything. This time you ask Hea about your ferritin, and instead of a list it asks a few questions back.
hHeaWhatsApp · your results attachedWhy would my ferritin be low? I eat pretty well.Your ferritin is 12 µg/L with normal haemoglobin, which points to low iron stores without anaemia. To narrow down why, can I ask a few things?- Do you eat red meat, fish or poultry most weeks?
- What do you usually drink with meals?
- Have your periods changed recently?
Mostly plant-based since last year. Tea with everything. And my periods got heavier after I stopped the pill.Each of those can lower iron, and together they could explain your result. I can't diagnose this, so it's worth seeing your GP, especially about the heavier periods. I've put your results, likely causes and questions into a summary you can show them.GP summary
Ferritin 12 µg/L (low) · Hb normal · MCV low-normal · fatigue 6+ months · heavier periods since stopping the pillBack to the GP, and three months later
This time the appointment starts with the numbers. The GP confirms iron deficiency, prescribes iron tablets and books a follow-up about the heavier periods. Three months on, you test again: ferritin has more than doubled, and you no longer fight to stay awake at 3pm.
Ferritin over time, µg/L. Illustrative values. The medicineWhy a normal blood test can miss low iron
Haemoglobin is the last thing to fall. Your body uses up its iron stores first, so ferritin drops well before haemoglobin does. An NHS guide for GPs calls this stage, iron deficiency without anaemia, relatively common, with fatigue, poor concentration, hair loss and restless legs among its symptoms.
Schematic, not to scale. Ferritin drops months before haemoglobin moves. Many GPs do check ferritin when someone says they're exhausted. When the first round is a blood count alone, low stores come back as "normal".
<30 µg/LMany UK guidelines treat ferritin below this as iron deficiency. Each lab sets its own cut-off.
+ CRPFerritin rises with inflammation, which can hide a real shortfall, so it's best read next to CRP.
Hea in WhatsAppSame question, better answer
Ask ChatGPT why you're tired and it answers for the average person, because it has nothing else to go on. Hea works from UK clinical guidelines and your own results, and it remembers your past tests and symptoms, so you don't start from scratch each time.
"Why am I so tired all the time?"Without your results
A list of 12 possible causes, from sleep hygiene to diabetes, and a suggestion to get a blood test.With your results
"Your ferritin is below range while your haemoglobin is normal. That pattern fits low iron stores without anaemia, which commonly causes fatigue. Your thyroid and B12 are in range, so they're less likely to be the cause. Here's what to raise with your GP.""I'm seeing my GP on Thursday. What should I bring up?"Without your results
Generic advice to write your symptoms down.With your results
A one-page GP-ready summary: markers out of range, changes since your last test, your symptoms and the questions worth asking.Illustrative conversations. Hea doesn't diagnose. It helps you understand your results and walk into your GP appointment prepared.
One sample · 10 areas of healthWhat Hea's home blood test checks
One finger-prick sample covers 37 markers for men and 39 for women. Iron is one of 10 areas, because tiredness rarely has a single cause and most early changes come without symptoms.
Area Markers What it can show Full blood count WBC, RBC, HGB, HCT, MCV, MCH, MCHC, RDW Anaemia, signs of infection, red cell changes that hint at low iron or B12 Micronutrients Ferritin, iron, transferrin, vitamin B12, folate Low iron stores before anaemia, B12 or folate shortfall Thyroid TSH, free T4, free T3 An underactive or overactive thyroid Hormones Men: testosterone
Women: oestradiol, LH, FSHLow testosterone, cycle and perimenopause changes Cholesterol Total, LDL, HDL, non-HDL, triglycerides, total/HDL ratio Heart and circulation risk Liver ALT, GGT, ALP, bilirubin, albumin, total protein, globulin Early signs of fatty liver and other liver strain Kidneys Creatinine, eGFR, urea, uric acid How well your kidneys filter, gout risk Inflammation C-reactive protein (CRP) Inflammation in the body, and context for reading ferritin Immunity IgA Low IgA, which affects infection risk and how coeliac tests are read Electrolytes Magnesium Low magnesium, linked to cramps and fatigue How it works
- Order the kitIt arrives by post with lancets, a collection tube and a prepaid return envelope.
- Sample at homeA finger prick, ideally in the morning, then post it back.
- The lab runs itSamples go to a UKAS-accredited partner lab.
- Results in WhatsAppEvery marker explained, with a Personal Risk Report, action plan and GP-ready summary.
- Ask anythingHea keeps your results, so each new test is compared with the last.
Free check vs fuller panelHea and the NHS Health Check
The free NHS Health Check looks at heart and circulation risk for adults aged 40 to 74 every five years. Hea covers a wider set of markers, whenever you want to test. If you're eligible for the NHS check, it's worth having both.
NHS Health Check Hea Who Ages 40–74 without certain existing conditions Adults How often Invited every 5 years Whenever you choose Lab tests Cholesterol, sometimes blood sugar 37–39 markers across 10 areas Also covers Blood pressure, BMI, lifestyle questions Iron, B12, folate, thyroid, hormones, liver, kidneys, CRP After the results A chat with a nurse or healthcare assistant Explanations, action plan, GP-ready summary, questions answered in WhatsApp Cost Free £135, one-off Find out what's behind your tiredness
If you've been told you're fine and you don't feel fine, the next step is a fuller picture. One finger prick, 37–39 markers, and answers built on your own numbers.
£135one-off- 37–39 lab tests from one home sample
- UKAS-accredited partner lab
- Every result explained, with a Personal Risk Report
- Personalised action plan and GP-ready summary
- Ask Hea anything in WhatsApp, no app to download
FAQQuestions people ask
What blood tests should I get if I'm tired all the time?
The usual starting set is a full blood count, ferritin, thyroid function, vitamin B12 and folate, which covers the most common treatable causes. Depending on your symptoms, a GP may add blood sugar, kidney and liver tests, inflammation markers or a coeliac screen. Hea's panel covers most of these. It doesn't include blood sugar (HbA1c) or coeliac antibodies.
Why am I always tired if my blood test came back normal?
It depends what was tested. A full blood count can be normal while iron stores are low, and thyroid, B12 or folate may not have been checked. Fatigue can also come from poor sleep, stress or low mood, which no blood test shows, so raise those with your GP too.
What does low ferritin mean?
Ferritin reflects how much iron your body has stored. A low result usually means those stores are running down, and it can cause tiredness even while haemoglobin is still normal. Labs set their own ranges, and many UK guidelines treat under 30 µg/L as iron deficiency. The cause matters as much as the number, so take a low result to your GP.
Is a finger-prick test as reliable as a blood draw?
For the markers in this panel, finger-prick samples analysed in an accredited lab give clinically useful results. Hea's partner lab is UKAS-accredited.
Does Hea replace my GP?
No. Hea doesn't diagnose or prescribe. It explains your results, flags what needs attention and prepares a summary so your GP appointment starts from the facts.
How often should I test?
Once gives you a baseline. After a change, such as starting iron or changing your diet, retesting in about three months shows whether it's working.
Hea doesn't diagnose. It helps you understand your results, catch problems early and walk into your GP appointment prepared. If you have symptoms that worry you, such as unexplained weight loss, blood in your stool or very heavy bleeding, see your GP without waiting for a test.
Sources- Royal United Hospitals Bath NHS Foundation Trust. Ferritin interpretation: a guide for GPs. 2025.
- NHS Shetland. Anaemia: iron deficiency pathway.
- NHS Highland. Iron deficiency guidelines.
- NICE CKS. Anaemia: iron deficiency.
- NHS. NHS Health Check.
- NHS. Tiredness and fatigue.
