Hashimotos/underactive thyroid and recurrent miscarriage

[Bananacake1]

Hi all, I'm currently going through my third early miscarriage. I would be grateful for thoughts on my latest blood results and treatment options going forward.

27/02/2025:

CRP HS: 0.44 mg/L (Range < 3)

Ferritin: 73 ug/L

Vitamin B12 - Active: 149.0 pmol/L (Range > 37.5)*

Vitamin D: 89 nmol/L (50-250nmol, I believe optimal for TTC is 100-150?)

TSH: 2.550 mlU/L (Range: 0.27 - 4.2)

Free T3: 3.9 pmol/L (Range: 3.1 - 6.8)

Free Thyroxine: 18.5 pmol/L (Range: 12 - 22)

Thyroglobulin Antibodies: 297.0 kIU/L (0 - 115)

Thyroid Peroxidase Antibodies: 97.2 KIU/L (0 - 34)

Homocystein (fasting) via TDL: 5.81 umol/L (4.4-13.6)

*I'm confused about ranges relating to B12 and would be grateful for advice.

Hormone profile has been tested and no abnormal results. Thrombophila / APLS screen also came back as normal. Karyotype (chromosomes) for me and my partner came back as normal.

Up until today, I was taking 75mg Levothyroxine (after positive pregnancy test I did increase this to 100mg until I realised I was miscarrying). I have seen a fertility specialist who has recommended alternate daily dose of 75/100mg to reduce TSH, without hopefully going above 20pmol/L for Free thyroxine (T4). I have also seen a Thyroid specialist GP who had advised considering T3 or NDT in the future as it is likely my body is poor at converting T4 into T3, however she was cautious change anything now while I am actively TTC.

I was also taking 150mg Aspirin from day 14 of cycle for the last pregnancy, as well as Cyclogest (Progesterone) from the positive pregnancy test. I am also taking supplements, which include Zinc, Selenium 200mg, Iron, Vitamin D, Methylfolate 5mg (due to MTHFR). I am now doubling my Vitamin D dose to increase into optimal fertility range. I follow a Gluten free diet.

The plan going forward is that I will have a uterine scan. I am also considering whether it would be helpful for my partner to have a sperm analysis, DNA fragmentation analysis, despite not having difficulty conceiving up until now. Once I am TTC again, I will be taking Aspirin 150mg, Heparin, and Cyclogest (Progesterone) from day 14 of cycle.

I would be grateful for your thoughts generally, and in particular on:

- T3

- Supplements

- Investigations done and any others I can consider

- Medication plan for when we are TTC again.

Thank you all x

[SlowDragon Administrator]

welcome to the forum

Very sorry for your losses

75mcg Levo is quite a low dose unless you’re very petite

What were thyroid levels before pregnancy

Which brand of levothyroxine are you taking

[Bananacake1 in reply to SlowDragon]

Thank you SlowDragon.

The above were the latest thyroid levels I had before pregnancy. I had a positive pregnancy test on 12/03/2025, however this week I had a negative pregnancy test and bleeding therefore appears to be a chemical pregnancy/very early miscarriage.

The brand of levothyroxine is Wockhardt UK Ltd (for 25mg) and Accord (for 50mg), although I think I have had other brands at times also.

[SlowDragon Administrator in reply to Bananacake1]

So levels were a bit low before pregnancy was confirmed

Approx how much do you weigh in kilo

Generally with hashimoto’s looking for TSH around or below 1

And TSH always below 2-2.5 before TTC

Vitamin levels look good

Active B12 is private test

What was Serum B12 on NHS test

No folate test ?

Ferritin aim to always maintain over 70

[Bananacake1 in reply to SlowDragon]

Yes I think T3 was low, unfortunately I have had difficulty with GPs prescribing adequate Levothyroxine, with my levels being up to TSH 3.8 in December, until they agreed to increase my dose from 50 to 75mg. I am now taking 75/100mg alternate days and will have another blood test in a few weeks. I don't have any recent folate results due to a failing to get the results (using medichecks finger prick), however I have NHS blood test for folate, B12, and Thyroid panel in a few weeks.

Latest folate serum results: 36.4nmol/L (range: 7-37.8nmol/L) on 14/03/2024

I am around 55.5kg, and 165cm

Serum B12 NHS test: 712 ng/L (range: 180-900ng/L) on 19/05/23, unfortunately this is the only one I have currently.

Thank you, yes I have also increased my iron supplement dose as I was told it was a little on the low side.

[SlowDragon Administrator in reply to Bananacake1]

So 55.5kg x 1.6mcg is approximately what you have now been increased to

Retest in 6-8 weeks

Pregnancy guidelines

thyroiduk.org/having-a-baby/

NICE guidelines that if hypothyroid or subclinical you should see endocrinologist BEFORE TTC

cks.nice.org.uk/topics/hypo...

Important See pages 7&8

btf-thyroid.org/Handlers/Do...

Also here - dose increase in levothyroxine as soon as pregnancy test confirms conception

cuh.nhs.uk/patient-informat...

thyroidpharmacist.com/artic...

Low ferritin, low thyroid levels and miscarriage

preventmiscarriage.com/iron...

Folate and B12 and Neural tube defects and autism

healthunlocked.com/thyroidu...

ec.bioscientifica.com/view/...

Cardiff research and pregnancy

healthunlocked.com/thyroidu...