Will a virus affect my blood test results?

[Caroline888]

Hi all,

I wonder if anyone can help me. I have had a bad cough for about a fortnight. I think I caught a virus from my daughter - no cold just the cough. I have spoken to Medichecks as I have a blood test kit which expires on 28/09 and wondered if a virus would affect my blood test results. The advice they gave me was to wait until the cough had abated before doing the test. They kindly said they would extend the validity of my blood test kit for a “reasonable length of time”. I am still coughing but am definitely on the mend. Do you know how long I should wait after I have stopped coughing before going ahead with the test? The kit is for the Thyroid Check Ultra.

I would be so grateful for any advice.

Best wishes

Caroline

[Poniesrfun]

Infection will affect testing because it affects how the body processes thyroid hormone.

During infection/inflammation the body wants to slow down metabolism so you may convert T4 less to the active hormone T3 and more to inactive rT3 (reverse T3).

How much it affects testing would depend on if you have a thyroid producing T4 or are taking T4 or if you have no thyroid and are taking T4 or taking T3 only.

Patti in AZ

[Caroline888 in reply to Poniesrfun]

Thank you so much Patti for taking the trouble to reply to my post.

I was diagnosed with Hashimoto’s two years ago and I take 75 mcg levothyroxine only. The test kit I have is the Thyroid Check Ultra which checks levels of TSH, FT4, FT3, thyroid antibodies, ferritin, B12 and folate and CRP-hs.

I have had the cough for a fortnight but am nearly over it now. Do you think all the above results will be affected then? I am hoping to do the test on the 25/09 but could delay until the 1/10 if you think that would be wiser.

Thanks again for your reply.

Best wishes

Caroline

[Poniesrfun in reply to Caroline888]

If you're no longer showing signs of infection you should be OK.

Interesting - infection/inflammation also increases iron storage; as excess iron can "feed" inflammation the body tries to lower circulating iron - so ferritin (which measures iron storage) levels might also be increased.

Patti in AZ

[Caroline888 in reply to Poniesrfun]

That’s really interesting about iron and inflammation!

Unfortunately I can’t delay doing the test too long as, although Medichecks have kindly said they’ll extend the validity of the kit by a reasonable amount of time, it should actually expire on the 28/09 and I have no idea what kind of delay would make the results more valid.

I guess I’ll just have to do the test and hope for the best.

Thanks again for your input.

Best wishes

Caroline

[Poniesrfun in reply to Caroline888]

As long as you aren't running a fever and any secretions coughed up are clear (not yellow, green or pink) it should be fine.

[Caroline888 in reply to Poniesrfun]

Thanks Patti😊. All secretions are clear. Never had a fever with it, no cold, just the cough. Never made me feel ill, it’s just been very tiresome😟.

Thanks so much for your help and advice. I’ll aim to do the test on the 25th September, assuming I’ve fully recovered by then. Otherwise I’ll delay one week.

Thanks so much for your help - I’m really grateful.

Best wishes

Caroline

[vocalEK in reply to Poniesrfun]

Yes. My ferritin came in at 185.5 (10.0 - 150 ng/mL) during the time I had an infection. All the other iron measures were normal, though.

[Caroline888 in reply to vocalEK]

Thanks for that - very interesting! Certainly seems wise then to delay the test.

All the best

Caroline