The short answer: "normal" means the markers your GP checked fell inside the laboratory's reference range. It does not mean everything was checked, and a GP tiredness screen is deliberately short. A comprehensive panel adds the markers that are usually left out: free T3 and thyroid antibodies, full iron studies, B12 and folate, vitamin D, fasting insulin, cortisol, a coeliac screen and hormones. If you have red-flag symptoms (below), go back to your GP before buying anything.
Most laboratory reference ranges are defined as the interval that contains 95% of results from a healthy reference population. By design, about 2.5% of healthy people fall below the range and 2.5% above it, and ranges vary between laboratories (Bennett Institute, University of Oxford). Two things follow.
A result inside the range can still matter in context. A ferritin just above the lower limit in someone with heavy periods and tiredness, or a TSH in the upper part of the range alongside positive thyroid antibodies, will both be reported as normal. Neither is a diagnosis; both are worth a conversation with your GP.
"Normal" only covers what was ordered. If vitamin D, B12 or a coeliac test was not requested, there is no result to be abnormal. When your GP says your bloods are normal, it is reasonable to ask which tests were done and to see the numbers (you can usually see them in the NHS App).
A word of caution the other way: "optimal ranges" sold online are often not evidence-based. Being near one end of a range is a reason to look at the whole picture, not proof of a problem.
The NHS says that if you have been tired for a few weeks without knowing why, you may need blood tests "to check for anaemia, diabetes or hyperthyroidism" (NHS: tiredness and fatigue). NICE's primary care guidance lists the first-line tests for tiredness as the full blood count, kidney function, liver function, TSH, bone profile, an inflammation marker (CRP or plasma viscosity), ferritin, a coeliac antibody test (IgA tTG) and creatine kinase.
In practice, not all of those are always requested. A 2025 audit of 16,889 primary care tiredness requests found the full blood count was requested in 89% and TSH in 80%, but ferritin in only 9.4% and the coeliac test in 3.2%. Where ferritin was tested, 26% of results were abnormal (Murphy et al., Annals of Clinical Biochemistry, 2025).
NICE also advises offering coeliac testing to people with prolonged fatigue, and to people with unexplained iron, B12 or folate deficiency or autoimmune thyroid disease (NICE NG20). If you have prolonged tiredness and were not tested, ask. Keep eating gluten before the test: NICE advises gluten in more than one meal a day for at least 6 weeks beforehand.
| Marker | Why it's relevant to tiredness | What to know |
|---|---|---|
| Full thyroid: TSH, free T4, free T3, TPO and thyroglobulin antibodies | The NHS lists extreme tiredness, weight gain, low mood and difficulty concentrating among the symptoms of an underactive thyroid (NHS). | A GP screen usually measures TSH only. Antibodies show whether the thyroid is under autoimmune attack, even when TSH is in range. |
| Full iron studies incl. ferritin | Iron deficiency can cause tiredness before haemoglobin falls. | Ferritin is recommended for tiredness but often not requested (audit above). Inflammation can raise ferritin, so read it with CRP and transferrin saturation. |
| B12 (total or active) and folate | Deficiency is a recognised cause of tiredness and of anaemia. | Active B12 measures the fraction cells can use. Not every panel includes it: see the provider table. |
| Vitamin D | Low levels are common in UK winters. | Not on the NICE first-line tiredness list. Results are seasonal, so note the month you tested. |
| Fasting insulin and HbA1c | HbA1c picks up diabetes and prediabetes; fasting insulin shows how hard the body is working to keep glucose normal. | Fasting insulin needs a fasted sample and is not used to diagnose anything on its own. |
| Cortisol | Very low or very high cortisol causes tiredness, but both are uncommon. | A single morning sample is a screen only, and timing matters. Stress does not reliably show up in one cortisol result. |
| Coeliac screen (tTG) | NICE lists prolonged fatigue as a reason to test (NG20). | Only valid if you have been eating gluten. A positive result needs your GP and usually a referral. |
| Hormones: testosterone, oestradiol, FSH, LH, SHBG, prolactin | Perimenopause and low testosterone can both cause tiredness and low mood. | Timing in the cycle matters for women. Hormones are rarely part of a GP tiredness screen. |
Related: thyroid blood test · ferritin · B12 · vitamin D · cortisol
Each provider's most comprehensive standard panel, checked on its own website on 15 October 2026. All four use a venous sample for these panels.
| Panel | Price | Thyroid + antibodies | Iron studies | B12 | Folate | Vit D | Fasting insulin | Cortisol | Coeliac (tTG) | Sex hormones |
|---|---|---|---|---|---|---|---|---|---|---|
| Typical GP tiredness screen | Free | TSH only, usually | Ferritin recommended, often not requested | Not first-line | Not first-line | No | No | No | Recommended, often not requested | No |
| Medichecks Ultimate Performance (56 markers) | £199 + draw | Yes | Ferritin, iron, TIBC, saturation | Active | Yes | Yes | No | Yes | No | Yes |
| Lola Health Peak Insights 70 | £200 self-arranged, £235 with draw | Yes | Ferritin, iron, TIBC, saturation | Active | Yes | Yes | No | Yes | No | Yes |
| Forth Ultimate Health Check (52 listed) | £399 + draw | Yes | Ferritin only | Active | Yes | Yes | No | Yes (9am) | No | Yes |
| TrueVitals Ultimate (140) | £349 + £19 / £39 draw | Yes | Ferritin, iron, transferrin, saturation | Total | Yes | Yes | Yes | Yes | Yes | Yes |
Prices checked October 2026, from Medichecks (price shown as an offer; clinic draw +£35, nurse +£59), Lola Health (home or clinic draw +£35) and Forth (clinic +£45, home nurse +£59). GP screen per NICE first-line list and the 2025 audit above. Check the provider before you buy.
TrueVitals facts: Ultimate: 140 biomarkers (139 for women), £349 + £19 clinic draw or £39 home visit, venous sample, Nationwide Pathology (UKAS-accredited), clinician-reviewed report within 4 working days, 103 partner clinics.
Where TrueVitals fits: if you want the gaps filled in one draw, including fasting insulin and a coeliac screen that the other panels above leave out, and a written report that reads the results together. Weaknesses to know: booking is by phone after payment rather than online, it is a newer brand than Medichecks or Forth, and the Ultimate measures total rather than active B12 (active B12 is on the Signature panel: 230 biomarkers, £799 including the draw at Randox Health clinics, up to 12 working days).
The NHS advises seeing a GP if you have been tired for a few weeks and don't know why, if tiredness affects your daily life, or if you are tired and have other symptoms such as weight loss or mood changes (NHS). Go back to your GP, or call 111, rather than buying a test if you have:
A private blood test is information, not a diagnosis. TrueVitals reports say clearly when a result needs your GP, and many customers take the report to their appointment. NHS vs private blood tests: what each is for.
Usually for one of three reasons. The cause may not show in a blood test at all (sleep, stress, low mood, medicines, recovery from an infection). The relevant marker may not have been tested: a GP fatigue screen is deliberately short. Or a result may sit inside the reference range but towards one end of it, which a range cannot flag. Keep talking to your GP, and if symptoms continue ask which tests were done and whether any were not.
It means the result fell inside the laboratory's reference range, which is usually the interval containing 95% of results from a healthy reference population (Bennett Institute, University of Oxford). That means about 1 in 20 healthy people fall outside it, and a result inside it does not prove nothing is wrong. It also only covers the tests that were run.
The first-line tests NICE's guidance suggests for tiredness are the full blood count, kidney and liver function, TSH, bone profile, an inflammation marker, ferritin, a coeliac antibody test and creatine kinase. Free T3, thyroid antibodies, active B12, vitamin D, fasting insulin, cortisol and sex hormones are not on that first-line list, and a 2025 audit found ferritin was requested in only 9.4% of tiredness requests and the coeliac test in 3.2%.
It can help if you want to see the markers that were not checked, or the exact numbers behind "normal". It does not replace your GP: a private report is information to take back to them, not a diagnosis. If you have red-flag symptoms such as unexplained weight loss, see your GP first rather than buying a test.
Not always, and be wary of anyone who sells optimal ranges as rules. Some in-range results are worth a closer look in context, for example a ferritin near the bottom of the range in someone with heavy periods and tiredness. That is a judgement made with your symptoms and history, which is why a written interpretation and your GP matter more than a colour-coded range.
The Ultimate panel measures total serum B12, folate, ferritin and full iron studies. Active B12 is on the Signature panel. If B12 is your main question, Medichecks, Lola Health and Forth all include active B12 on the panels compared on this page.
Ultimate: 140 biomarkers including full thyroid, iron, B12, folate, vitamin D, fasting insulin, cortisol, coeliac screen and hormones. £349 plus your draw. Clinician-reviewed report within 4 working days. Klarna and Clearpay at checkout.
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