Ongoing tiredness often comes from sleep, stress, mood, workload or a recent illness, and a blood test won't show those. If you have felt tired for more than a few weeks, blood tests can help check for common physical causes: low iron, anaemia, an underactive thyroid, high blood sugar, and low vitamin B12 or folate.
Feeling flat for a week after a busy stretch is normal. Waking up tired every day for a month or more is different, and it is one of the most common reasons Australians see a GP.
This guide covers the blood tests that check for the usual physical causes, what each one shows, the causes a blood test can't pick up, and the signs that mean you should see your GP soon. If you're concerned about how you're feeling, speak with your GP.
The Baseline Health Check covers 70+ markers, including iron studies, a full blood count, thyroid and blood sugar, the core tests for ongoing tiredness.
Women aged 18 to 49 who told us they were tired or low on energy. Low iron stores were the most common finding by far. A similar share of all women members under 50 had low ferritin (26%), so a low result is worth acting on, but it may not be the whole story.
| Women 18 to 49 who reported tiredness | |
|---|---|
| Ferritin under 30 µg/L | 26.7% (n=221) |
| Vitamin D under 50 nmol/L | 18.9% (n=159) |
| Haemoglobin under 120 g/L | 5.5% (n=399) |
| TSH above 4 mIU/L | 3.6% (n=276) |
| Vitamin B12 under 150 pmol/L | 2.1% (n=94) |
For many people, the reason lies in how they are living rather than in their blood. Poor or short sleep, stress, a heavy workload, low mood or anxiety, alcohol, and the tail end of a virus are common reasons for ongoing tiredness. A smaller group of people have a physical cause that a blood test can find, and many of those can be treated once you know about them. If your main problem is trouble thinking clearly, our guide to brain fog causes and blood tests goes into that.
That is why the usual approach in Australian general practice is a short, targeted set of blood tests, alongside questions about sleep, mood, periods, diet and medicines. Most people who are tested don't get an abnormal result. A normal result is still useful, because it makes the common treatable causes less likely and points you back to the things that may help more.
A lot of patients often normalise symptoms. So I’ll often say to them, “Come on, complain to me. That’s why you’re here. I want to hear all of the details of the issues that you’re experiencing.”
These tests check for the usual physical causes of tiredness.
| Test | What it looks for |
|---|---|
| Ferritin and iron studies | Low iron stores. Ferritin can fall well before you become anaemic, and low stores alone can leave you tired, breathless on stairs or sleeping badly |
| Full blood count, including haemoglobin | Anaemia (too few red blood cells or too little haemoglobin to carry oxygen), plus signs of infection or other blood problems |
| TSH | An underactive thyroid, a common and treatable cause of tiredness, feeling cold, constipation and weight gain |
| Fasting glucose and HbA1c | High blood sugar or type 2 diabetes, which can cause tiredness, thirst and passing more urine |
| Vitamin B12 and folate | Low levels can cause a type of anaemia and, for B12, tingling or numbness. More likely if you eat little or no animal food or take metformin or reflux medicine long term |
| Vitamin D | Low vitamin D is common in Australia, especially in winter and in people who spend little time outdoors. The link with tiredness is weaker than for iron or thyroid |
| Kidney and liver function | Problems with either can cause tiredness and are checked in a standard panel |
| hs-CRP | Inflammation in the body. A raised result doesn't name a cause, but it tells your doctor to look further |
Your GP may also suggest a coeliac blood test, because coeliac disease can cause tiredness and low iron even without gut symptoms. Keep eating gluten until that test is done, or the result can come back falsely normal.
Iron deficiency is one of the most common nutrient deficiencies in Australia, and tiredness is often one of the first signs. Women with heavy periods, people who are pregnant or have recently given birth, regular blood donors, endurance athletes and people who eat little red meat are most at risk.
Ferritin and iron studies can pick up low iron prior to a drop in haemoglobin: low iron stores are associated with fatigue, restless legs, altered cognition, poor sleep: even when Hb is still in the normal range.
A ferritin result below 30 µg/L usually means your iron stores are low, even if your haemoglobin is normal. Ferritin also rises with inflammation, so a "normal" ferritin during an infection can hide low stores. That is why it is read with iron, transferrin saturation and CRP. Our guide to iron deficiency signs and ferritin results covers this in detail, and the ferritin levels for women by age guide shows where most women sit.
Don't start iron tablets before you test. Iron supplements are a common treatment for low iron, but too much iron can cause its own problems, and taking it first can make the cause harder to find.
If your blood tests come back normal, these are the next things to look at with your GP:
Adrenal fatigue isn't a recognised medical condition. A systematic review of 58 studies found no consistent evidence that tiredness comes from "worn out" adrenal glands. Cortisol does change with stress and sleep, and a cortisol test can show your daily pattern, but it can't diagnose adrenal fatigue.
True adrenal insufficiency (Addison's disease) is rare and serious. It can cause weight loss, dizziness when you stand, nausea, salt craving and darker skin, and needs a doctor straight away.
See your GP soon if your tiredness comes with any of these:
If you are feeling very low or having thoughts of harming yourself, talk to your GP today or call Lifeline on 13 11 14.
Start with the Baseline Health Check. It covers iron studies and ferritin, a full blood count, TSH, fasting glucose, HbA1c, fasting insulin, vitamin D, hs-CRP, and liver and kidney markers, which takes in most of the tests above. Vitamin B12 and folate are add-ons. You can add them on their own or as part of the Core Nutrients Test.
You don't need a referral from your own GP. A GP from our network signs your request after a short telehealth consult. You have one blood draw at one of our 3,700+ partner collection centres, with no appointment needed, and results arrive in the Vively app, usually within a few days. A Vively practitioner talks you through them, including what to raise with your GP about a low or borderline result, and you have a targeted re-test after 3 months to see if things have changed.
The Baseline Health Check is included in the $99 a month membership, with no minimum term. Add-on tests are priced individually. Vively does not diagnose, manage or treat chronic conditions, and doesn't replace your GP. If you're concerned about your symptoms, speak with your GP. Start with your Baseline.
Start with ferritin and iron studies, a full blood count, TSH, fasting glucose or HbA1c, and kidney and liver function. Add vitamin B12 and folate if you eat little animal food or take metformin or reflux medicine. Your GP may add a coeliac test. These check for the common physical causes of ongoing tiredness.
Yes. Ferritin, your iron store, can drop well before haemoglobin does. Low ferritin on its own can cause tiredness, poor exercise tolerance and restless sleep. That is why ferritin is checked alongside the full blood count rather than relying on haemoglobin alone. A result below 30 µg/L usually means low stores.
Yes. An underactive thyroid is a common, treatable cause of tiredness, especially in women. It often comes with feeling cold, constipation, dry skin and weight gain. TSH is the first test. If it is high, your doctor may check free T4 and repeat the test, because one borderline result can settle on its own.
A normal result makes the common physical causes less likely, and your tiredness is still real. The next step is to look at sleep, including a check for sleep apnoea, mood, stress, alcohol, medicines and recovery from a recent illness. See your GP if it lasts more than a month or is getting worse.
No. ME/CFS is diagnosed on symptoms, mainly a crash in energy after small amounts of activity that lasts a day or more, plus unrefreshing sleep, once other causes are ruled out. Blood tests are still done first, because they can help rule out conditions that look similar, like anaemia and thyroid disease.
You don't need a referral from your own GP with Vively. A GP from our network signs your request after a short telehealth consult, because standard blood tests need a doctor's request. Medicare covers the Baseline lab tests; your membership pays for the analysis, your report, the app and your practitioner.
It is better to test first. Supplements can lift a result for a while without addressing the cause, and iron taken without a need can build up. Tell us or your doctor about anything you take. If you take a hair, skin and nail supplement with biotin, stop it 2 to 3 days before testing, because biotin can upset some blood test results.
Vively supports preventative health and health optimisation. It does not replace your GP, emergency care or specialist medical advice.
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