B12 testing

[Winniepoo15]

Can someone please advise. I’ve gone almost 4 months with no b12 supplement as need to be tested for deficiency & PA. my ferritin level is 31 & need to take ferrous fumarate. Is this going to interfere with my test? I’m under active & am feeling absolutely awful atm. I need to have full thyroid & all bloods done too but don’t know where to start.

[SeasideSusie Remembering]

Winniepoo15

Always advised here, when having thyroid tests:

* Blood draw no later than 9am. This is because TSH is highest early morning and lowers throughout the day. If looking for a diagnosis of hypothyroidism, an increase in dose of Levo or to avoid a reduction then we need the highest possible TSH

* Nothing to eat or drink except water before the blood draw. This is because eating can lower TSH and coffee can affect TSH.

* Last dose of Levo 24 hours before the test, take that day's dose after the blood draw. This is because if you take your Levo before the blood draw the test will measure the dose just taken and show a false high. If you leave longer than 24 hours the result will show a false low.

* If you take Biotin or a B Complex containing Biotin (B7), leave this off for 7 days before any blood test. This is because if Biotin is used in the testing procedure it can give false results (most labs use biotin).

These are patient to patient tips which we don't discuss with phlebotomists or doctors.

As you are taking ferrous fumerate, is this prescribed? Are you regularly monitored for your iron levels? This is essential when taking iron supplements.

Taking ferrous fumerate shouldn't interfere with your B12 results. Just don't take any supplements before any blood test on the day, take them afterwards, and, as mentioned above, B Complex or Biotin supplements need to be left off for 7 days before any blood test.

[Winniepoo15 in reply to SeasideSusie]

Thank you for the information. No the ferrous fumarate is not prescribed. GP told me to buy from boots & take for a few weeks. Didn’t mention anything about being monitored. My last test was at end of July, & my ferritin had dropped to 31. Previous to that, I’d been eating liver etc for six months. I’ll be back for more advice as I know there’s definitely something more going on.