One abnormal number in a test: how worried should you be?

You have your test result, and there is a star or an arrow next to one number

The first reaction of most of us is to search for the result on the internet right then. Here are a few points so that you do not lose a night’s sleep over it.

What does “outside the range” mean?

Next to each number, a reference range is printed. This range comes from the results of a large group of healthy people. So:

• A healthy person also sometimes has a number outside the range.
• Laboratories do not all have the same range. Compare the number with the range on the same sheet.
• Look at the unit.
• Likewise, a number inside the range does not prove that everything is fine, especially if you have symptoms.

Why is one number not a diagnosis?

A test result depends on many things: recent food and drink, medicines and supplements, heavy exercise before the test, your monthly period, and not keeping to the fasting instructions. The test itself is not perfect either, and sometimes gives a false positive or false negative. For this reason the doctor usually reads one number alongside the symptoms, the examination, the patient’s and family’s history, and sometimes imaging, and repeats the test if the result does not fit the rest of the picture.

A few examples:

• Blood count (CBC). A haemoglobin or red cell count outside the range may be anaemia or iron deficiency, but dehydration or heart disease can also have an effect. A change in white cells may be related to an infection or a reaction to a medicine. A change does not only mean illness: diet, activity, medicines, periods and fluids all have an effect.
• Liver enzymes. The doctor looks at the pattern of all the numbers. A change in these numbers is not always from the liver, and a recent illness can also change them temporarily.
• Creatinine. It also depends on muscle mass, diet, dehydration and exercise. One high or low number cannot be interpreted on its own, and the usual next step is a repeat test or other tests.
• TSH. Being abnormal tells you the thyroid may have a problem, not its cause. Severe non-thyroid illness can also change it temporarily, and in people over 80 without a thyroid problem it is also higher.
• Blood sugar. Several limits are used to diagnose diabetes or prediabetes (for example, a fasting blood sugar of 100 to 125 mg/dL is prediabetes and 126 or more is in the diabetes range), and the limit alone is not a “diagnosis”; the details are in the patient guide, and the diagnosis is the doctor’s.

What should I do until the visit?

• Keep the result and take it to the visit, even if it is only one abnormal number.
• Do not start, stop or change any medicine because of that number.
• Do not take a supplement or tablet yourself just because “such and such a number was low”.
• The internet and messaging apps are not suitable for interpretation. A number that meant something for someone else does not necessarily mean the same for you.
• Ask: “How important is this number in my case? Do we need to repeat the test? When is the next test? What should I watch until then?”
• If you take a particular medicine, or ate something unusual before the test, tell the doctor.

When not to wait

If the abnormal result comes with a serious symptom, do not wait for the visit: chest pain, shortness of breath, vomiting blood (even if it has stopped), black or bloody stool with weakness, dizziness, paleness or feeling unwell, confusion, sudden weakness on one side of the body, or a very high or very low blood sugar with feeling unwell. In these situations call 115 (Iran’s emergency number) immediately. Black or bloody stool without these signs should also be seen the same day. The full list is in the section “When should I call urgently?”.