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I would like a blood test to check I am well…

This is not an uncommon request and, in busy primary care, it may sometimes seem easiest just to say yes! But there is potential risk to this approach, including missing undisclosed symptoms or risking over-investigation in a healthy, asymptomatic person. How can we navigate this request in primary care?

This article was last updated in November 2024.

We all understand the sentiment here. But, as clinicians, we also recognise that tests are probably not going to give us the reassurance the patient is seeking, particularly if they have no symptoms. But we also don’t want to get into a battle with the patient, who may interpret our reluctance to do any tests as a sign that we don’t care.

We will need to use the bread-and-butter primary care concept of eliciting our patient’s ideas, concern and expectations (BMJ 2023;382:e075728):

Do they have a specific worry? (e.g. “My aunt has just been diagnosed with brain cancer…”)
Do they actually have symptoms?
Do they have any risk factors for an underlying condition?
Are any tests indicated to assess for common conditions, e.g. diabetes or to assess cardiovascular risk?

Following this, we will need to utilise our primary care super-skill of communication.

In this article, we consider each of these concepts. But, first, let’s consider the risks of a blood test fishing trip…

The risks of a fishing trip

Let’s take the example of inflammatory markers. A UK-based cohort study looked at inflammatory marker testing. Due to the study design, we do not have details as to why each test was done. The researchers used the CPRD to identify 160 000 patients who had had inflammatory markers tested, and compared them with 40 000 controls (BJGP 2019;69(684):e470):

The aim of the study was to look for disease (infection, cancer or autoimmune disease) in those with raised inflammatory markers compared with those with normal inflammatory markers or no testing.
Overall incidence of disease following raised inflammatory markers was 15% (so 85% of individuals had no significant illness despite raised levels).
- Inflammatory markers had a sensitivity of <50% for any relevant disease.
- For 1000 inflammatory marker tests performed, we can anticipate 236 false positive results, generating an additional 710 GP appointments, 229 phlebotomy appointments and 24 referrals in the next 6 months (as well as any accompanying patient, or clinician, anxiety).
In those with a normal inflammatory marker level, there was a false negative rate of 4%, meaning the tests missed significant disease 4% of the time.

A Canadian paper asked, “should a FBC be used as a screening tool in asymptomatic, non-pregnant adults?”. The answer? No! (Canadian Family Physician 2017;63:772):

Up to 11% of the results were abnormal.
<1% of results resulted in a change in management.
There was no impact on mortality.

Other considerations (BMJ 2023;382:e075728):

The reference range at the laboratory is often set up to identify 95% of normal results, so 5% of healthy people will fall outside of ‘normal range’.
Some tests also have significant variation on repeated measurement.

See the article A test result has changed but is the change significant? for more information.

In summary, investigations should answer a specific clinical query, rather than testing ‘just in case’.

Why this test?...and why now?

It is important to ascertain why this person wants a blood test in the first place. Why this test? Why now? This information helps us have effective conversations about the appropriateness of a test (BMJ 2023;382:e075728).

Explore underlying thoughts and fears about what may be wrong (BMJ 2023;382:e075728):

Take a focused history of important symptoms and consider risk factors for important underlying conditions:

In practice, this framework may help navigate such a consultation:

Communication skills

If the patient doesn’t seem to need any tests, we should be thinking about reaching a shared understanding that tests are not indicated. This is much more likely to be achieved if the patient really feels listened to and has had their worries addressed, and this is a challenge in time-limited consultations. What should we cover? The table below gives some suggested concepts and conversation starters (BMJ 2023;382:e075728):

What are we trying to achieve?	What could we say?
Offer empathy and compassion, listen actively and validate their experiences, even if you do not share the patient’s concerns or believe that they need a blood test.	It sounds like you are quite concerned about this… Being worried about your health can have a big impact on your life…
Discuss the pros and cons of the test.	A negative result doesn’t necessarily rule out a health problem, and many people only feel reassured for a short time. Around 1 in 20 results can come back just outside the normal range, but are not necessarily a sign of illness. It can be hard to interpret these results, and they can trigger anxiety and stress… How might this scenario affect you? Repeating tests too often can generate complicated variable results that are not always straightforward to interpret. Tests can also reveal a subclinical condition that may need regular monitoring and can affect your health insurance. Discovering this can make some people feel less healthy or ‘well’.
Carry out tests if there is reasonable clinical doubt. Highlight explicitly if you are expecting a test result to be negative.	I’m going to carry out a test to look at… I’m doing this because I’d like to rule out… I’m expecting the result to be normal, and we won’t need to repeat the test if it’s negative.
Many people may not need a test. Try to avoid over-investigation or carrying out tests ‘for reassurance’, which can ultimately increase health anxiety. Acknowledge the existence of uncertainty, and share risk with the patient.	It’s important to only carry out tests when we really need them, otherwise they are less helpful and can make people unnecessarily anxious. I’m happy to review this if things change in the future. Living with uncertainty is a real challenge. It’s not always possible to be totally ‘sure’ that you are well, no matter how many tests we do.
Use a ‘twin-tracks’ approach to broaden the agenda to include both physical health and emotional wellbeing.	I take your health concerns very seriously and I’m always willing to review the physical aspects of your health. You seem very worried about your health. We can help with this, and this will not affect any other treatment that you are receiving. I’m wondering if worries about your health are also having an impact on your wellbeing. Could we explore this alongside your physical health?
Consider comorbid mental health conditions such as depression or anxiety. Explore possible emotional symptoms and their functional impact on behaviour.	How anxious are you about this problem? How much time do you spend thinking about it? Do you often worry about your health? Have you asked for this test before? Do you often find yourself checking your health, looking up symptoms on the internet or seeking reassurance? How is your mood? Have you been feeling low or finding it hard to enjoy things? Have there been changes in your work, relationships or social life because of feeling low or anxious about your health?
Focus on lifestyle and improving quality of life.	It is often more helpful to focus on changing lifestyle to maximise health rather carrying out tests without a clear indication. Could we discuss some ways to improve your quality of life that may also benefit your physical health? Could we explore whether making changes in your physical activity, social activity or relaxation might help?

What does success look like?

This depends on each individual patient’s concerns and expectations, as well as findings on history and examination:

It may be that a blood test was entirely appropriate, e.g. due to underlying symptoms or risk factors.
Perhaps the conversation highlighted underlying anxiety, health anxiety or depression, giving an opportunity to offer support and ongoing management.
Perhaps the patient was appropriately reassured, deciding they didn’t need any tests and are instead keen to explore lifestyle options to maximise their health.

I would like a blood test to check I am well…

Resist the temptation to just say ‘yes’!

Elicit and explore any underlying worries and expectations.

Assess for undisclosed symptoms.

Assess for risk factors for underlying conditions.

Consider whether their needs would be met by an NHS health check or an NHS screening programme.

Consider using the conversation starters provided to facilitate an effective discussion.

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