Query: thyroxine requirements during breastfeeding

[haggisplant]

I feel this is an unanswerable question! Partly as people don’t research women’s issues much.

I know low hormones can affect breastfeeding. I’m on thyroxine and never had this issue. In fact I can easily get oversupply.

However my thyroid results have been different to when I’m not. More specifically, I breastfeed on demand and so experience amenorrhea (first time for around 20 months), this time its so far 11 months.

As there’s no cycle so rises of oestrogen which I know can increase requirements, does the body need slightly less t4?

I can’t find any info on this. I probably need more info on what hormones are going on during amenorrhea. And this therefore may be a completely non question!!

(I’m going to reduce my thyroxine slightly to see if other symptoms are eased and wonder if I’ll need to go up again when they return. Bizarrely I’m heavier than in the past, though much of it is muscle, which is another thing I’m wondering about.)

[MaisieGray]

I've come across a number of studies looking at various aspects of post-partum/thyroid issues and in particular breastfeeding, but whether they're more about issues such as the transfer of the mother's hormones in the breast milk etc etc, I can't recall. However, I think there's much anecdotal evidence of women reporting that their milk supply is sensitive to their blood level of thyroid hormones, and that having their thyroid hormone levels just anywhere within the normal range was not enough to support full milk production, rather, that levels needed to be higher than their personal norm. Mary Shoman wrote that after childbirth, it is common for thyroid levels to change as a result of postpartum shifts in estrogen and progesterone. A current blood check might better inform your decision to reduce thyroxine or not, or even indicate if a temporary increase is warranted, if you don't have one. Regarding amenorrhea, both hyper- and hypothyroidism can be a cause, so not much use to you without the specifics of hormonal shifts, as you say; but I do know that stress of whatever sort and presumably including birth etc, can temporarily alter the functioning of your hypothalamus and thereby impact the hormones that regulate your menstrual cycle (and also presumably production of TFH and onwards to TSH); and that as the stress abates, normal function of both the gland and the menses returns.

[haggisplant in reply to MaisieGray]

Thank you for your reply.

My tsh is 0.22 and my t4 is 22.7. (Range 21) Though the blood test was sprung on me by the Gp so I’d taken my thyroxine that day. I’ve been having a lot of peripheral neuropathy over the last week and rashes in the last month.

In sept 4 mo post partum on same dose it was 0.12 and 19 (but not taken t4 that day. So go happy to let me continue) I guess however it’s vaguely possible I have very faint function, though I became hypo at age 20 so I find it odd. What’s been noticeable is that I’ve just started to loose a bit more weight naturally and now am possibly getting hyper symptoms. When I was heavier that dose seemed to work well. Before this pregnancy my tsh was around 0.4 on the same dose.

However I do think things have been off since I started taking Teva 25 a month ago. I’ve agreed to drop only 12.5 and I asked to go back to pharma mercury. He said I could go back up if needed and if the nerve issues didn’t return. But I’ve been having difficulty sleeping too.

Amenorrhea is normal if breastfeeding on demand day and night; many women in my local group have it for between 1-4 years and it’s weight linked. Some get frustrated as they want a second child and get told to try eating more cake! However not many people know that; an nhs consultant actually tested me for addisons on the basis of amenorrhea when I was bf my first. (I was referred to him for severe weight loss which Actually was was all problems with thyroid levels - too little then far too much for a while and stress.)

I’m guessing there’s a lot of variability in women as some get cycles back sooner.

one query I have is if oestrogen affects thyroxine in a similar way to how oestrogen in contraception pills do. I also suppose in a healthy woman the thyroid adjusts accordingly to need so we won’t know if the body needs more or less when lactational amenorrhea occurs.

But thanks again x