To ask why a doctor would want a blood test repeated

[Thisismycon]

Had bloods on Thursday results were back that afternoon. Told to book a non urgent appointment I did. Appointment is the start of next month. I’ve since received another text saying I need to repeat the blood test in a couple of weeks and that a form has been sent set up. I’m confused as obviously I don’t know what the issue is.I’ve never had this issue before.

I’ve had this before. It was because one of the results was borderline and then wanted to double check it. The 2 weeks was to allow for any infections (or other anomalies to pass)

I’ve attempted to call the surgery at two different times today and the line just goes dead as the receptionist are busy with other calls.

Can you email them?
I found an email address for my doctor's on their website and was surprised to receive a response the same day.

Depends what you are testing for also. For example, if this is an antibody test and the results are borderline, then they might ask for a few weeks delay to see if the levels go up (or down!).

This happened to me earlier this year and I was asked for a repeat test two weeks later. It was because my platelets were elevated, but two weeks later they were back down to normal. The GP just wanted to double check it was a transient thing as it was out of the ordinary for me.

It’s probably to check that it wasn’t a one off result.

Sometimes a repeat could be that the sample wasn't to the full line.seen this several times in my line of work

My one liver function test came back saying I was at risk of or had fatty liver disease? my doctor had harsh words with me about my drinking until I pointed out I dont actually drink i can drink but I never really do so she repeated the test and all was well really no idea why it came back that way we assumed lab mix up but my thyroid tests were the same so 🤔

Just off the top of my head (I have a lot of blood tests), one of the things a full blood count can do is detect signs of infection or inflammation - whilst a single case of raised ESR could indicate an infection, a second set a couple of weeks later could show it's still raised, which is more indicative of inflammation, such as you get with various autoimmune disease like Rheumatoid Arthritis. They might add a couple of things on for the second bloods to double check, they might not.

In short, it could be something and it could be nothing - but testing two weeks apart gives a far better picture than a single snapshot.

I request lots of blood tests in my work. It's most likely that one of the tests has come back outwith the normal range and they want to double check it but it's not alarming enough to recheck urgently.

Any number of reasons. I have bloods regularly to monitor specific readings. Also if I’m going on new meds they may do two tests just to be certain about results. I’ve also had blood results lost, incomplete, borderline, Drs forgotten one off the list, contaminated. If your taking specific medications they can effect results sometimes and in addition to my usual bloods monitoring they may ask for additional monitoring while taking specific medications. There could be any number of reasons and unfortunately Drs are not always efficient when ordering them or letting the patient know why some are being done. Well in my experience anyway.

I work in a pathology lab so I'll try and give some examples of why this might be but I'm just guessing!

It's unlikely to be a lab problem, particularly if they want it done in 2 weeks rather than ASAP.

It's probably a borderline result that they want to recheck as a recent infection for example even a minor cold could have altered your results so checking again will rule that out. Or it could be that your sample heamolysed. Some blood is spun and we only test the serum not whole blood, if your sample has heamolysed it means the red blood cells were damaged when the blood was drawn, this could cause a falsely hight potassium for example as could not testing the blood the same day it was drawn.

It's highly unlikely the lab forgot to run a test as everything is booked though the pc systems and the software already knows what tests the GP has ordered, we just receive the sample into the lab. Or it could be that the GP wanted to add additional tests on after seeing your initial results but many tests have a time limit in which we can perform them in usually 1-2 days before the sample degrades to much and would give innacurate results so if your GP didn't request them until say this morning you blood would be 4 days old and over the cut off.

Other issues we get are samples sent in the incorrect tube. Some tubes have anticoagulants, some don't some have other preservatives and we need the blood to be in the correct tube to run the tests ordered. Mislabelling or unlabeled samples are also an unfortunate occurance in which case we would not run anything as we have no way of knowing if that is even your sample.

I hope this helps

There’s so many reasons.

Maybe it was a borderline result.

Maybe it was a deranged result on a test that is known be temporarily impacted by recent viral infections.

Maybe the original sample heamolysed because it sat around in the surgery for too long waiting to be taken to the hospital lab (a very common problem).

I had this for high white blood count (they didn't tell me why until later) they asked me to come back a week or so after a routine test for a blast test. Was all fine, the results were normal

@Thisismycon instead of trying to phone complete an econsult request.

I had them done at the hospital so would imagine they did get to the lab on time though obviously you never know!

Most likely to see if the level of something has changed between the two tests. For example, say an indicator of kidney function (estimated glomerular filtration rate, eGFR) is low at the first test. The clinical picture will be very different depending on whether the eGFR measured two weeks later is higher than, the same as or lower than the first measurement.

I have had this with borderline HbA1c of 50. Have to repeat after 2 weeks. If >49 on 2nd test diagnostic of diabetes

It's quite common that they ask for another test. Not enough blood taken to do the tests required is the usual reason.

I wouldn’t worry about this at all.
If there was anything wrong that was serious they would have definitely asked you to go to the hospital straight away for urgent treatment.
There are plenty of reasons why one might repeat blood tests most of them mentioned above.
It’s worth noting that if it’s a borderline result, they may not want to repeat it immediately to check if it’s normal for you or just an random abnormality.
If you don’t have any symptoms and nothing has changed since you had the tests done, I wouldn’t worry at all.