In short: A private blood test can check things such as blood count, iron, vitamins, thyroid, cholesterol, blood sugar, liver and kidney function and hormones, without needing a GP referral. Blood tests are most useful when chosen to answer a specific question about your symptoms or risk. They cannot rule out every condition, and results should always be interpreted by a clinician alongside your history.

This guide, written by a Ready Health prescribing pharmacist, explains what common blood tests can and cannot tell you, and how private blood testing works for people near Wigan, Chorley, Horwich and Bolton.

Why do people book a private blood test?

ongoing tiredness, low energy or feeling "not right"
unexplained weight change
checking cholesterol and blood sugar as part of a health check
hormone questions, for example around menopause or male health
monitoring a known condition between NHS reviews
convenience: booking at a time that suits you

What can common blood tests tell you?

Test	What it can show	What it cannot show on its own
Full blood count (FBC)	Anaemia, signs of infection or inflammation, platelet levels	The cause of an abnormal result
Ferritin	Iron stores	Can be raised by inflammation, masking low iron
Thyroid function (TSH, free T4)	Underactive or overactive thyroid	Results can be temporarily off during illness
Vitamin D, B12 and folate	Deficiency	Whether symptoms are caused by a borderline result
Cholesterol (lipid profile)	Cholesterol levels, used to estimate heart and stroke risk	Your overall risk without other factors like blood pressure and smoking
HbA1c	Average blood sugar over 2 to 3 months; diabetes and prediabetes	Reliable results in some conditions affecting red blood cells
Liver and kidney function	How these organs are working	The cause of a change without further assessment
Hormones	For example testosterone, FSH, LH, oestradiol or prolactin	Menopause diagnosis in most women over 45 (usually based on symptoms)

What are the limits of blood tests?

Normal ranges are based on most healthy people, so a small number of healthy people will have a result just outside the range.
Normal results do not rule out every condition.
Timing matters: testosterone is usually tested in the morning, and some hormone tests depend on the day of your cycle.
Supplements and medicines can affect results. For example, biotin can interfere with some hormone and thyroid tests.
More is not always better: testing for lots of things without a reason can lead to borderline results, worry and repeat testing.

How does a private blood test work at Ready Health?

Book online or by phone and choose the test or package.
Follow any preparation instructions (for example whether to fast or test in the morning).
Visit our clinic in Standish, between Wigan and Chorley, where a trained phlebotomist takes a small blood sample.
Your sample is sent to a laboratory for analysis, and a clinician can explain your results and next steps, including sharing them with your NHS GP if you wish.

When should I see a doctor rather than just book a test?

If you have symptoms such as unexplained weight loss, persistent fever or night sweats, blood in your poo or pee, a new lump, or severe or worsening symptoms, see a doctor so you are assessed properly. A blood test alone is not a substitute for a consultation.

Frequently asked questions

Do I need to fast before a blood test?

Many tests, including cholesterol in most cases, do not need fasting. You will be told if your chosen test requires it.

Do I need a GP referral for a private blood test?

No. You can book directly, and we recommend sharing significant results with your GP.

Can a blood test check my fertility?

Hormone tests can give some information, but they cannot reliably predict whether you will conceive naturally. Speak to a clinician about your situation.

What happens if a result is abnormal?

A clinician will explain what it means, whether a repeat test is needed, and whether you should see your GP or a specialist.

Key takeaways

Private blood tests are convenient and do not need a referral.
Choose tests to answer a specific question.
Results need clinical interpretation and may need repeating.
See a doctor for worrying symptoms rather than relying on a test.

Sources and further reading

Last reviewed: October 2026 by Shamir Patel, Independent Prescribing Pharmacist, Ready Health. This article is general information and does not replace advice from your own clinician.

Ready Health in Standish offers private blood tests and blood test packages for people across Wigan, Chorley, Horwich and Bolton, with clinician support to explain your results.