You may have received a text from us referring you to this page

This page covers

  • Repeated tests
  • Out of range readings
  • Inconclusive results
  • Unlabelled samples
  • Sampling errors
  • Need for more/different tests



Please try not to be too worried if you have received a text or letter asking you to repeat blood tests. This page is to explain why we may ask for tests to be repeated.

Please always bear in mind, if your results could indicate serious disease that needs urgent action, we will always call you urgently to either assess you further by telephone or to see you face-to-face, so please do try not to worry if we ask you to repeat a test.

Dear Patient

Needing a repeat test does not automatically mean that something serious is going on. This page is intended to explain some of the background to why your doctor may wish you to have repeat tests, so that you don't need to worry too much.


Blood test results always come with what is called a reference range (also known as a normal range) within which the majority of results lie. However on occasion, sometimes results lie slightly outside the reference range.

In general this is not too concerning, however the doctor who assesses your result may ask for the test to be repeated in order to see how the trend is. Often we find results have reverted back to normal.

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Or the repeat test results show that the readings are stable, leading us to conclude that the results are likely to be normal for that individual and/or their medical conditions or medications taken.

To help explain reference ranges a little further, if we were to look at heights of adults, we would find most adults' heights would be clumped around a rough average range of heights. This would equate to the 'normal range', which, for those interested in statistical terms, is usually the values that lie between two standard deviations from the average.

However, there will be some adults who are slightly shorter than the 'normal range' and some who would be slightly taller than the 'normal range'. These adults are not 'abnormal' and their height is 'normal' for them.

Clearly if they are very wide off the normal range then something might be amiss. The same thing applies to many other human physiological measurements, including blood results.


Tests are not always 100% accurate. Sometimes, test results come back inconclusive. A common example of this is urine testing, where no one single bacteria is identified as being the cause of the problem. In these cases, if you still have symptoms, we may repeat the test and see if it comes back showing a definite result. On rare occasions, tests may need to be repeated several times to see the underlying trend. Please do not be alarmed if this is the case.


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This is an extremely common and very frustrating reason for having to repeat tests, yet completely avoidable. If any sample does not carry as a minimum, name and date of birth, then the lab simply will not touch it. Therefore when dropping back samples to us, such as urine or stool bottles, please make sure that you have labelled all sample bottles with your name, date of birth, type of sample, date of sample and if there is space for it, the first line of your address.

We now have facilities to print labels for sample bottles and/or swabs, therefore if you have collected or dropped off a bottle or swab from the front desk, but it does not yet have a label, please ask our receptionist to print off a label for you to attach to the bottle.


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Sometimes, test results indicate there were problems with the actual testing of the sample or other sampling problems, such as too small a urine sample provided, problems with laboratory equipment, or wrong bottle being used for the type of blood test. This means that the test will need to be repeated.


Sometimes, results bring up something that requires some new or different tests in order to shed some further light on what could be happening with you. Again, please try not to worry if this is the case. The doctor will have decided that such testing is appropriate, based on the result and their prior assessment of your condition.


Hopefully this page will have come some way to explaining things for you so that you do not worry unnecessarily. As indicated in the red message box above, if something urgently serious is going on, we will always get in touch with you directly.

Yours sincerely

Ivy Grove Surgery


This page including all linked content is © 2019- Dr Michael Wong and may not be reproduced without permission. Practices wishing to adapt or use any of our information should get in touch first