Testing choices
Do you need advanced testing?When more tests help, and when they do not.
More tests are useful when they answer a clear question and can change care. A larger panel can also create cost, false alarms and uncertainty.
More testing helps when it can answer a useful question.
“Advanced testing” is not one medical category and it is not automatically the next step when routine results are normal. A useful test should have a clear purpose, a method that is fit for that purpose, and a result that can change what happens next.
If the test cannot change diagnosis, treatment, monitoring or referral, more information may add cost and uncertainty without improving care.
Start with the question, not the size of the panel.
Before any test, ask what problem the clinician is trying to solve. Is the test checking a suspected diagnosis? Monitoring a known condition? Looking for a medicine effect? Helping decide whether a referral is needed?
NHS blood-test guidance makes clear that different blood tests are used for different purposes. No one set of “normal bloods” answers every clinical question. [1]
A long panel can feel thorough, but the number of markers is not a measure of quality. The useful test is the one that fits the clinical question and has a plan for interpreting the result.
The strongest reason to test is that a result has a realistic chance of changing the plan.
What diagnosis becomes less likely, and what happens then?
What follow-up confirms the finding, and would treatment or referral change?
How can more tests create false positives?
Every test has limits. When many measurements are taken, some results can fall outside a reference range even when they are not the cause of a person’s symptoms. That can lead to repeat testing, worry and follow-up.
The UK National Screening Committee explains this clearly in the screening setting: tests can produce false positives, false negatives and uncertain findings, and false-positive results can lead to unnecessary worry and further procedures. [2]
Diagnostic testing in a person with symptoms is not the same as population screening. However, the general lesson still matters: adding tests adds opportunities for unclear or misleading results. The chance of a finding needs to be weighed against whether that finding is likely to be useful in this clinical context.
What is an incidental finding?
An incidental finding is a result discovered while looking for something else. It may be important, harmless, uncertain or unrelated to the symptom that prompted testing.
The more broadly you test, the more likely you are to find something that needs interpretation. That is not always a reason to avoid a test. It is a reason to ask in advance what kind of unexpected findings can occur and who will deal with them.
A result should not be turned into a diagnosis just because it is unusual. It may need confirmation, a different test, clinical examination or specialist advice.
Does a specialist test mean a better test?
No. A specialist test may be the right tool for a narrow question that routine tests cannot answer. But “specialist”, “advanced” and “comprehensive” are not evidence grades.
Ask whether the method has been validated for the intended use, whether the laboratory has suitable quality systems, how the reference range was derived and whether professional guidance supports using the result for the decision being proposed.
UKAS highlights validation and verification as key parts of showing that a medical laboratory method is fit for purpose. [3] A technically sound test can still be clinically unhelpful if it is used for the wrong question.
Two standards, not one
A test needs both technical credibility and clinical usefulness. Good laboratory performance does not prove that testing a particular person will improve their care.
What if previous tests were normal?
Normal previous results can be useful. They may reduce concern about the conditions those tests were designed to assess. They do not mean every possible cause has been excluded.
Before adding more tests, review what was already done, when it was done and what question it answered. Then ask whether the symptom pattern has changed. Sometimes reassessment, examination, medicine review or referral is more useful than a broader panel.
The aim is not to keep testing until something becomes abnormal. It is to choose the next step that has the best chance of explaining the problem or changing care.
What should you know before paying for a private test?
- What exact condition, risk or decision is the test meant to address?
- Why is this test more useful than standard assessment for that question?
- What does a normal result change?
- What does an abnormal result change?
- How often are results unclear or need confirmation?
- Who interprets the result in your medical context?
- What follow-up may be needed, and what might it cost?
- Could the result affect insurance, treatment decisions or create a new medical label?
UK NSC guidance for commercial screening recommends asking about benefits, harms, unclear results, follow-up and fees. Those questions are also sensible when considering any optional private test, even though symptomatic diagnostic care is not the same as screening. [2]
How should risks and alternatives be discussed?
NICE shared decision-making guidance recommends discussing benefits, risks and consequences of options, including the option of making no change when relevant. [4]
For testing, that means you should be able to compare doing the test now, using a standard alternative, monitoring first, or not testing. The best choice depends on the clinical question and how much the result could change an important decision.
If the test has little chance of changing care, waiting or using a simpler route can be a rational choice.
How does this fit with Dr Stavy’s testing service?
The Functional Medicine Testing and Diagnostics page explains the practice’s testing approach and the role of previous results. It does not mean every patient needs advanced testing.
This guide is deliberately more cautious than a test catalogue. It does not claim that a broad panel will find a hidden cause, and it does not treat normal standard tests as useless. Any test should be interpreted alongside symptoms, history, medicines and prior investigations.
A decision can be good even when the answer is “not yet”.
Testing is one tool in clinical care. Sometimes the best next step is a test. Sometimes it is to repeat a standard test at the right time, examine a symptom more closely, review a medicine, refer to another service or watch how the pattern changes.
A clear decision explains why the chosen step is likely to help. It also sets a review point so that “no test now” does not become “ignore the problem forever”.
Bring the question back to your main goal. If the aim is to feel better, reduce risk or make a treatment choice, ask how the proposed test connects to that goal. Data that cannot guide a useful action may be interesting without being useful care.
What patients say about the consultation experience.
Patient reviews can help you understand how a consultation feels. They do not prove that a particular diagnosis will be found or that a treatment will work.
Individual reviews reflect personal experiences and do not predict diagnosis, treatment response or outcome.
“takes incredible care to get to know her patients”
Google reviewer
“patient, understanding and kind”
Google reviewer
“warm and compassionate bedside manner”
Google reviewer
Common questions
Do I need advanced functional medicine tests?
Not automatically. Start with the clinical question, previous results and what a new result could change. A specialist test may be useful for a defined problem, but a broad panel is not automatically better than standard assessment. Ask why the test is needed and what happens with either result.
How can extra tests lead to false positives?
Tests can produce results outside a reference range even when the finding is not the cause of symptoms. The more measurements taken, the more chances there are for unexpected or unclear results. Some findings need repeat or confirmatory testing before they should influence diagnosis or treatment.
What should a test change before I pay for it?
A useful result should have a plausible effect on the next step. Ask what a normal result would change, what an abnormal result would change, and what follow-up would be needed. If neither result changes diagnosis, treatment, monitoring or referral, the value of testing may be limited.
Do more tests help when previous results are normal?
Sometimes, but not simply because the earlier results were normal. Review what the previous tests were designed to assess and whether your symptoms have changed. Another targeted test, examination, medicine review, referral or monitoring may be more useful than a larger panel.
Are specialist tests more accurate than routine tests?
Not as a general rule. Accuracy depends on the test, method, condition and intended use. A specialist test can be excellent for a narrow question and unhelpful for another. Ask about validation, reference ranges and whether the result is clinically actionable in your situation.
Can I decide not to have a test?
Yes. Shared decision making includes discussing benefits, risks, alternatives and, where relevant, the option of making no change. If you defer a test, agree what symptoms, time period or new information should trigger review so the problem is not simply forgotten.
Medical sources and further reading
- NHS: Blood tests. Explains that different blood tests are used for different clinical purposes.
- UK NSC: NHS and commercial health screening tests. Explains false positives, false negatives, uncertain findings, follow-up and important questions before private screening.
- UKAS: Validation and verification in medical laboratories. Highlights validation, verification and fitness for purpose of laboratory methods under ISO 15189.
- NICE NG197: Shared decision making. Recommends discussion of benefits, risks, alternatives and the option of making no change where relevant.
A test should earn its place in the plan.
Ask what it measures, what each result changes and who will act on it.