What an abnormal test result means and what happens next

What abnormal means on a report

A result is flagged abnormal when it falls outside the laboratory’s reference range. That range is usually set from healthy people, with the lower limit at the 2.5th percentile and the upper limit at the 97.5th, so it covers the middle 95% of their results [1] [2].

By design, then, 5% of results from healthy people fall outside the range and are flagged, about 1 in 20 [1]. If you have many tests at once, the chance that at least one is flagged rises with each test, even when you are well.

For cholesterol and some other tests, the line on the report is a decision limit, a threshold set from clinical studies above or below which a particular decision is recommended, rather than the spread of healthy results [1].

What the doctor looks at

A doctor reads the number in context, and these questions usually decide what happens next.

Common causes are checked first. Before referring someone with high cholesterol to a specialist, NICE advises excluding secondary causes such as uncontrolled diabetes, an underactive thyroid, liver disease and nephrotic syndrome [3].

• How far the value is from the range, and in which direction
• Whether it fits with your symptoms, the examination or your other results
• Whether something simple could explain it, such as a recent illness, hard exercise, a missed fast or a new medicine
• Whether it has changed since an earlier test

What usually happens next

Most abnormal results lead first to a repeat test or a short period of monitoring. Many values vary from day to day, and a second result shows whether the first was a passing change.

Blood pressure shows how this works. NICE advises that a clinic reading between 140/90 and 180/120 mmHg is confirmed with ambulatory or home monitoring before high blood pressure is diagnosed [4].

If a result stays outside the range, the doctor explains what it suggests and whether further tests or a specialist opinion would help.

An unexpected finding on a scan

Scans have their own version of this. In a review of MRI in adults without symptoms, potentially serious incidental findings were reported in 3.9% of people having brain and body scans [5]. In the limited data on final diagnoses, 20.5% of those findings proved serious [5].

A radiologist’s report usually suggests the next step, often a repeat scan after an interval or a specialist opinion. Your doctor will explain the report in plain words and agree that step with you.

When it is urgent

Most abnormal results are not emergencies, and a doctor will contact you promptly about any that need fast action. Some thresholds call for quick referral. NICE advises urgent specialist review for a triglyceride level above 20 mmol per litre that is not caused by alcohol or poorly controlled diabetes [3], and same day specialist assessment for a blood pressure of 180/120 mmHg or higher with new confusion, chest pain, signs of heart failure or acute kidney injury [4].

Whatever the result, symptoms come first. If you have chest pain, sudden breathlessness, severe bleeding, signs of a stroke or a sudden severe headache, call 999 in the UK or the local emergency number.

When a specialist is needed

A specialist opinion helps when a result stays abnormal, points to a condition that needs specialist tests, crosses a threshold set in guidance, or still worries you after a doctor has explained it.

NICE, for example, advises specialist assessment for a total cholesterol above 9.0 mmol per litre or a non-HDL cholesterol above 7.5 mmol per litre, even without a family history of early heart disease [3]. A good referral carries the question with it, so ask your doctor to send your results and the specific question the specialist should answer.

Questions to ask about an abnormal result

Choosing Wisely UK suggests asking about the benefits, the risks, the alternatives and what happens if you do nothing, and the same questions work for any next step after a result [6].

• How far outside the range is it, and does that matter for me?
• Could something simple explain it?
• Should it be repeated, and when?
• What would change if it is confirmed?
• What happens if we wait and watch?

How The Wellness can help

A GP appointment at The Wellness gives you time with a GMC registered doctor to go through your result, whether the test was done with us, at work or in another country. The doctor explains what it means for you and arranges any repeat test.

If you need a specialist, navigation finds the right one and offers a first appointment within 48 hours when it is urgent, with your results sent ahead. Our clinics are on Baker Street in Marylebone and Eccleston Street in Belgravia, and regulated services are delivered through registered partner clinics and accredited laboratories.