In brief: NHS guidance says blood tests may be used to check health, investigate symptoms, assess risk or monitor a condition, and that the type of blood test depends on symptoms, existing conditions and medicines.[1] This guide is not a self-order list. It explains how to think about test choice, when symptoms should be assessed urgently, and why every result needs clinical context.
When blood tests are not the first step
Call 999 or seek emergency care for life-threatening symptoms such as severe chest pain, collapse, severe breathing difficulty, stroke symptoms, severe bleeding or sudden severe illness. Use NHS 111 when you think you need medical help now and are unsure where to go.[3] A routine blood test should not delay urgent assessment.
How clinicians choose tests by symptom
NICE CKS describes fatigue as a common, non-specific symptom and recommends assessment of the onset, severity, triggers, sleep, activity, associated symptoms, medicines, diet, mental-health context and examination findings before deciding whether blood tests are useful.[2] The same principle applies to most symptoms: a test is useful when it changes the next decision.
| Symptom or question | What should be assessed first | Blood tests that may be discussed |
|---|---|---|
| Persistent tiredness or fatigue | How long it has been present, sleep, mood, medicines, weight change, bleeding, infection symptoms, pregnancy possibility and impact on daily life. | A clinician may consider a full blood count, ferritin or iron studies, thyroid function, glucose or HbA1c, kidney or liver tests, B12, folate, vitamin D, pregnancy testing or urinalysis, depending on the history and examination. |
| Palpitations, breathlessness or reduced exercise tolerance | Whether symptoms are sudden, severe, associated with chest pain, fainting, pregnancy, infection, anaemia symptoms, thyroid symptoms or known heart disease. | Blood tests may help check anaemia, thyroid function, electrolytes, diabetes risk or selected cardiac markers, but rhythm tests such as an ECG or monitor may be more relevant than blood tests alone. |
| Hair loss, weight change or temperature intolerance | Pattern and speed of change, diet, recent illness, medicines, menstrual pattern, pregnancy, stress, family history and physical examination findings. | Thyroid function, ferritin or full blood count may be considered in context. Hormone panels are not automatically useful for every person with these symptoms. |
| Irregular periods, heavy bleeding or menopause questions | Age, pregnancy possibility, bleeding pattern, contraception, pain, anaemia symptoms, risk factors and whether symptoms are new, heavy or postmenopausal. | Pregnancy testing, full blood count or ferritin, thyroid function or selected reproductive hormones may be considered. Hormone blood tests are not routinely needed to diagnose menopause in otherwise healthy women aged 45 or over. |
| Joint or muscle pain | Location, swelling, weakness, fever, rash, stiffness pattern, injury, medicines, infection risk, neurological symptoms and impact on movement. | Inflammatory markers, full blood count, kidney or liver tests, vitamin D or selected autoimmune tests may be considered only when the clinical picture supports them. |
| Health-risk review without specific symptoms | Age, blood pressure, smoking, family history, existing conditions, medicines, weight, ethnicity, previous results and what question the test is meant to answer. | Cholesterol and glucose or HbA1c may support cardiovascular and diabetes risk assessment in selected people. Broad tumour-marker screening is not a substitute for recognised screening or symptom-led assessment. |
Age can guide risk, but it should not create a fixed panel
Age changes the likelihood of some conditions, but it does not make one universal panel right for everyone. A person in their 30s with heavy periods, fatigue and breathlessness may need a different route from a person in their 50s asking about cardiovascular risk, and a person with new severe symptoms may need urgent assessment rather than screening.
Start with the symptom or health question rather than a shopping list of markers.
Check whether the symptom needs urgent assessment before routine testing.
Choose tests only if the result is likely to change advice, treatment, monitoring or referral.
Plan who will explain the result, what abnormal results mean and when further assessment is needed.
Preparing for a useful blood-test appointment
Bring a short symptom timeline, a medicines and supplement list, relevant past results, details of pregnancy possibility where relevant, and the question you want the test to answer. The NHS says the GP, nurse or specialist should tell you whether preparation is needed; fasting or medicine changes apply only to some tests.[1]
Evidence-only information
This page summarises NHS, NICE and NICE CKS guidance for patient education. It does not claim a named clinician review, provide a personal diagnosis, or state that a fixed blood-test panel is appropriate for every symptom or age group.
Frequently asked questions
Can I choose my own blood tests?
You can ask about a test, but the safer route is to confirm whether it is appropriate for your symptoms, history, medicines and timing. Some results are difficult to interpret without a clear clinical question.
Do normal blood tests mean nothing is wrong?
No. Normal results may be reassuring for the specific question tested, but they do not rule out every cause of symptoms. Ongoing, severe or changing symptoms still need clinical review.
Do I need to fast before a blood test?
Preparation depends on the exact test. The NHS says a healthcare professional should tell you if you need to fast or adjust medicines before a blood test. Victoria Medical confirms preparation at booking.
How quickly will I get results?
Reporting and follow-up depend on the test and laboratory pathway. The clinic explains when and how results will be reported and how follow-up will be arranged at booking.
Should I request hormone tests for menopause?
Hormone blood tests are not routinely needed to diagnose menopause in otherwise healthy women aged 45 or over; testing may be appropriate in younger women, atypical presentations, or where another diagnosis is being considered.
Related guides and services
References
- [1]NHS. Blood tests. Page last reviewed 2 November 2023. Accessed 30 August 2026. View source
- [2]NICE Clinical Knowledge Summaries. Tiredness/fatigue in adults. Last revised June 2025. Accessed 30 August 2026. View source
- [3]NHS. When to use NHS 111 online or call 111. Page last reviewed 14 November 2022. Accessed 30 August 2026. View source
- [4]NICE. Menopause: identification and management. NICE guideline NG23. Accessed 30 August 2026. View source