interpreting tsh and t4 values post pregnancy

[Habibi87]

I have given birth almost 4 weeks ago and my gp has re-run my TSH and T4 tests to see if my levothyroxine levels need to be adjusted post pregnancy ( during pregnancy my dosage was established by the consultant obstetrician ). I am currently on 50 mcg a day following on subacute thyroditis during pregnancy. The result that came back today show a low TSH at 0.28 (normal range 0.35 to 4.94) and a T4 of 11.4 (normal range 9 - 19.1). I am bit lost on why my TSH is low if my T4 is not high and I’d like to know what I should ask my GP? Should T3 also have been checked? I don’t have any obvious symptoms. Thank you in advance for the help

[SlowDragon Administrator]

Was this test done early morning and last dose levothyroxine 24 hours before test

How long at this dose levothyroxine

Do you always get same brand levothyroxine at each prescription

Are you currently taking any vitamin supplements

Ft4 is low

For full Thyroid evaluation you need TSH, FT4 and FT3 tested 

Also both TPO and TG thyroid antibodies tested at least once 

Very important to test vitamin D, folate, ferritin and B12 at least once year minimum

About 90% of primary hypothyroidism is autoimmune thyroid disease, usually diagnosed by high thyroid antibodies 

Autoimmune thyroid disease with goitre is Hashimoto’s

Autoimmune thyroid disease without goitre is Ord’s thyroiditis. 

Both are autoimmune and generally called Hashimoto’s.

Low vitamin levels are extremely common when hypothyroid, especially with autoimmune thyroid disease 

20% of autoimmune thyroid patients never have high thyroid antibodies and ultrasound scan of thyroid can get diagnosis 

In U.K. medics hardly ever refer to autoimmune thyroid disease as Hashimoto’s (or Ord’s thyroiditis)

Recommended that all thyroid blood tests early morning, ideally just before 9am and last dose levothyroxine 24 hours before test 

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)

Private tests are available as NHS currently rarely tests Ft3 or all relevant vitamins

List of private testing options and money off codes

thyroiduk.org/getting-a-dia...

Medichecks Thyroid plus antibodies and vitamins

medichecks.com/products/adv...

Blue Horizon Thyroid Premium Gold includes antibodies, cortisol and vitamins

bluehorizonbloodtests.co.uk...

If you can get GP to test vitamins then cheapest option for just TSH, FT4 and FT3 and includes BOTH TPO and TG antibodies -£29 

randoxhealth.com/at-home/Th...

Only do private testing early Monday or Tuesday morning. 

Link about thyroid blood tests

thyroiduk.org/getting-a-dia...

Link about Hashimoto’s

thyroiduk.org/hypothyroid-b...

Symptoms of hypothyroidism 

thyroiduk.org/wp-content/up...

Tips on how to do DIY finger prick test 

healthunlocked.com/thyroidu...

[Habibi87 in reply to SlowDragon]

Hi SlowDragon, thanks got the info.

The last test for TSH and T4 was done in the morning, only after a few hours from taking levothyroxine (I wasn’t told about the 24h!). I had been in 50 mcg of levo for 7weeks.

I tested in September 22 for Vitamin D (value 99 nmol/l range 50-200), folate (value >20), B12 active (value 151 pmol/l m range 25.1-165). Ferritin was at 339 ug/l versus range of 13-151. I was told that the high ferritin was related to the high CRP value I had which in turn was caused by subacute thyroiditis. Hospital checked 4 different antibodies and they were all okk do autoimmune thyroid issues were ruled out. I also had an ultrasound scan which confirmed subacute thyroiditis. How can Ft4 be too low if TSH is also low ? Really confused

[SlowDragon Administrator in reply to Habibi87]

Suggest you retest again in another 6-8 weeks

Recommended that all thyroid blood tests early morning, ideally just before 9am and last dose levothyroxine 24 hours before test 

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)

Private tests are available as NHS currently rarely tests Ft3 or all relevant vitamins

List of private testing options and money off codes

thyroiduk.org/getting-a-dia...

cheapest option for just TSH, FT4 and FT3 and includes BOTH TPO and TG antibodies -£29 

randoxhealth.com/at-home/Th...

Monitor My Health also now offer thyroid and vitamin testing, plus cholesterol and HBA1C for £65 

(Doesn’t include thyroid antibodies) 

monitormyhealth.org.uk/full...

10% off code here 

thyroiduk.org/getting-a-dia...

Only do private testing early Monday or Tuesday morning. 

Link about thyroid blood tests

thyroiduk.org/getting-a-dia...

Symptoms of hypothyroidism 

thyroiduk.org/wp-content/up...

Tips on how to do DIY finger prick test 

healthunlocked.com/thyroidu...