High MCV

[Hashissurvivor]

Hi,

I'm new to the forum. I was diagnosed with hashimotos last April after a slightly raised thyroid test (TSH 4.5). I have been on thyroxine for well over a year now and my tsh is at 1.7, my T4 has increased to 22 (12-22) and my T3 is 4.1 (3.1-6.8). My active B12 is good150 and my vitamin D is high, ferritin slightly low at 45 and folate top of the range. I was wondering if anyone has expirienced high MCV even after taking thyroid hormone, mine is at 99 which is above the range. This has increased from 98 last year. Should i be concerned?

[Hillwoman]

Your active B12 may look good, but there can still be difficulties with cellular uptake or metabolism of cobalamin, AKA functional deficiency. As far as I know, that is the most likely explanation of over-range MCV. Hopefully others can step with info on how thyroid function affects this marker.

I would consider finding a private lab to test for methylmalonic acid (MMA), which is an indirect way of gauging cobalamin uptake and metabolism. Homocysteine would be a good idea too. Viapath is the cheapest in my experience.

Your FT3 doesn't look very good, even though your FT4 has risen to the top of the range. This points to a possible conversion problem.

Your ferritin is too low for optimal thyroid function. Usually, we suggest getting to at least 70.

[NWA6]

Mine is 104.3 (75- 105) so still ‘in range. But I suspect this is where my blue lips come from. It’s just that no one cares 🤷‍♀️

[Hashissurvivor in reply to NWA6]

How's your b12? I'm trying not to worry to much and hoping it's down to thyroid

[NWA6 in reply to Hashissurvivor]

B12 is 124. I am seeing a pattern that all of my Vits/minerals need to be much higher in range to be optimal for me. I’ve been to relaxed about taking my supplements and my recent blood tests have given me a kick up the butt.

[SlowDragon Administrator]

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .

Last dose of Levothyroxine 24 hours prior to blood test. (taking delayed dose immediately after blood draw).

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

Is this how you do your tests?

Ft3 is on low side

What vitamin supplements are you currently taking?

High MCV

en.wikipedia.org/wiki/Mean_...

[Pixie1995 in reply to SlowDragon]

Hi: Should I delay my morning dose if I’m on t3 only?

[SeasideSusie Remembering in reply to Pixie1995]

Pixie1995

Last dose of T3 should be 8-12 hours before blood draw even if it means splitting dose and adjusting time the day before.

[Pixie1995 in reply to SeasideSusie]

Thank you! I don’t know why the doctor wants me to take it before the draw.

[SeasideSusie Remembering in reply to Pixie1995]

Pixie1995

Did he tell you why?

Sometimes they want to measure your FT3 at it's peak, which is wrong, it gives a false high level rather than the normal circulating level. They can then say you're taking too much and lower your dose or take you off it.

Unless there is a particular reason to take it before the blood draw, take last dose 8-12 hours before and don't say that you changed the time that he suggested.

[Pixie1995]

Ah! So if my last lab showed my t3 in the optimal range, it really isn’t because I took my dose. Thanks for explaining and for the advice. If I want to be optimal, I need to not take it. Thanks!