32, diagnosed with hypothyroidism, period now 12 days late

[AbsW2018]

In May 2021 I was diagnosed with underactive thyroid. This month would have been my first period since I started on levothyroxine. But it has still not made an appearance and I feel like I have pregnancy symptoms but the tests say I'm negative. I'm on my 12th day of it being late and I've had 4 negative pregnancy tests since last Wednesday. Can anyone help?

[SlowDragon Administrator]

Very common for menstrual cycle to alter while adjusting to starting on levothyroxine

How much levothyroxine are you currently taking

Which brand of levothyroxine are you currently taking

Many people find different brands are not interchangeable

Do you have thyroid test results from before starting on levothyroxine

Bloods should be retested 6-8 weeks after each dose change or brand change in levothyroxine

EXTREMELY important to regularly retest vitamin D, folate, ferritin and B12…..plus thyroid antibodies tested too to confirm autoimmune thyroid disease (vast majority of primary hypothyroidism is autoimmune thyroid disease diagnosed by high thyroid antibodies)

[radd]

AbsW2018,

Welcome to our forum. Hypothryoidism & introducing Levothyroxine commonly causes abnormal menstrual patterns.

Hypothyroidism will increase the TSH (trying to encourage further thyroid hormone) that also encourages increased prolactin. This inhibits the production of LH & FSH that activate the ovaries to produce oestrogen regulating menstrual/ovarian cycles.

SHGB (sex hormone-binding globulin) is a protein transporter produced in the liver which reduces with inadequate thyroid hormone. This results in a reduction in total circulating steroid levels & an increase in the free fraction. Introducing Levothyroxine has just caused further imbalance but one that should rectify all imbalances once thyroid hormones are optimal.

No hormone works in isolation but within many feed back loops all of which eventually interconnect with each other. For further reading investigate the hypothalamus-pituitary-gonadal axis (HPG).

[HashisKate]

Hi there, Have you by any chance had your first Pfizer vaccine recently? I’m a similar age to you. When I started Levo, my cycle length did increase slightly, but not significantly. My periods were a lot lighter once medicated.

However, the reason I’ve asked about Pfizer is because it’s quite well documented that this IS significantly effecting menstrual cycles. Mine is now 1 week late, later than it has ever been I believe (and I’m definitely not pregnant). Just something to consider x

[AbsW2018 in reply to HashisKate]

Hi yes I had my 1st Pfizer jag on 6th June and my period is 14 days late. My doctor today has ordered a blood test to check for pregnancy at the same time I get my bloods taken tomorrow to check my thyroid levels. Its just weird cos for the last week I've had what I thought were pregnancy symptoms but I've had 6 negative tests on the home pregnancy tests so I don't know what's going on.

[HashisKate in reply to AbsW2018]

I had mine end of May and mine is 7 days late so far. I too keep feeling as if it’s on it’s way but it never arrives. I know I can’t be pregnant so I’m putting it mainly down to my vaccine. It’s quite widely reported as a known side effect so you could Google if you’d like to read more.

Great your doctor has ordered a blood test though to check things as we mustn’t assume ☺️ hopefully you’ll get it soon so you can get back on track x