Low ft3, normal tsh

[Yvesme]

Hi. Can anyone help me to understand why my ft3 went on the low side after increasing my levo to 50mg? I’m 16 pregnant and I also have low iron .

Thank you

[jimh111]

Your fT4 has fallen so there is less T4 to convert to T3. It may be that your thyroid has recently started to fail and is gradually secreting less and less. It's best to keep your TSH below 2.5 (or 3.0 later in pregnancy) so I think it would be better to increase your levothyroxine in view of the fact that your fT4 is likely to fall further. It may be that this is a temporary attack on your thyroid ('acute thyroiditis') whilst you are pregnant and will resolve six to twelve months after the baby is born.

It's important to keep your thyroid hormone levels good during the pregnancy so you will need more levothyroxine and to be monitored. A low fT3 can sometimes cause depression so keep this in mind if you should feel down.

I am a fellow patient not a doctor.

[shaws Administrator]

If you are pregnant and you have now been diagnosed as hypothyroid, you will need to look after you and baby's health by making sure your doctor looks after you and that your baby is also getting sufficient.

The usual replacement is called levothyroxine (or T4). This is an inactive hormone and it has to convert to T3. T3 being the active thyroid hormone and brain and heart have the most T3 receptor cells.

Some of us are poor convertors of T4 (levothyroxine) and I think your GP will have to add T3 so that you have a T4/T3 combination. The baby will have to get the thyroid hormones through you. I will give you some further links that may be helpful.

hormone.org/diseases-and-co...

[SlowDragon Administrator]

You urgently need dose increase in levothyroxine

The aim of levothyroxine is to have Ft4 result in top third of range

50mcg levothyroxine is only a starter dose

Dose should be increased in 25mcg steps up. Possibly GP might increase more rapidly as you are pregnant

Retest thyroid levels 6-8 weeks after each dose increase

All thyroid tests should be done as early as possible in morning before eating or drinking anything other than water and last dose levothyroxine 24 hours before test

Also insist on testing vitamin D, folate and B12

High thyroid antibodies confirms autoimmune thyroid disease

Pregnancy guidelines

thyroiduk.org/having-a-baby-2/

gp-update.co.uk/files/docs/...

See pages 7&8

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

thyroidpharmacist.com/artic...