Ferritin blood test (finger prick)

[sip1]

I want to double check my ferritin levels - is there any particular time of day I should do this, and medication I should avoid before doing it?

[humanbean]

Iron related tests like ferritin should be done first thing in the morning, and fasting (except for water). In other words, the same conditions as Thyroid Function Tests.

There are different opinions on this, but some sources say iron supplements should be stopped for 5 days before testing, others say 24 hours is enough. See the following two links and search for the word iron on each page :

nhs.uk/chq/Pages/1018.aspx?...

stopthethyroidmadness.com/l...

I've tried to find the source of the STTM quote but have never succeeded, sadly.

[sip1 in reply to humanbean]

Thank you for this. Do you know if taking my thyroid medication beforehand would be OK? I'm taking it about 4 am when I tend to wake up.

[humanbean in reply to sip1]

I forgot to say, Biotin supplements might affect the result of a ferritin test. Check any supplement ingredients to see if any of them contain biotin, and any that do, stop taking them for a couple of days before the test.

From this link : ddtjournal.com/action/downl...

Biotin also interferes with the measurement of testosterone, oestradiol,

dehydroepiandrosterone-sulfate (DHEAS), parathyroid hormone, ferritin and thyroglobulin, testosterone, thyroglobulin, leutinizing hormone (LH), follicle stimulating hormone (FSH), sex hormone binding globulin (SHBG), vitamin B12 and folate (4)

[My emphasis in the quote]

I don't think thyroid meds affect ferritin tests, so take them as normal.

For more on the subject of biotin affecting tests :

healthunlocked.com/thyroidu...

Note that link specifically refers to thyroid function tests being affected by biotin. But I would just stop biotin for 48 hours before any test, given how many warnings there are on the problem.

[sip1 in reply to humanbean]

Thank you, you've been immensely helpful