Levothyroxine dose in pregnancy. New advice?

I have a 17m old conceived via icsi ivf. Hypothyroidism was diagnosed during fertility investigations in 2011. During pregnancy I was told my tsh levels were normal when it later transpired they were not, according to reference values for each trimester. 2w ago I took a pregnancy test which was positive to our absolute amazement. (Daughter was born following 3 rounds of ivf and we've since had another round which was unsuccessful.) I had to delay the last ivf because tsh was 3.8 and needs to be <2.5 for conception / to prevent miscarriage. I increased my dose from 75 to 100mcg and tsh level was 0.66 within a few weeks. I asked for levels to be checked again when I was 4.5 weeks (unknowingly) pregnant and levels were 0.76. Today I asked for repeat prescription and confirmation I am on the correct dose. My gp said there are new guidelines and that I should increase my dose from 100 to 150mcg. However 0.76 is within the range for the first trimester. I'm worried I will be taking too much. GP said I only need further checks at 20 and 30-something weeks which she admitted after first saying I wouldn't require further tests while pregnant. I pushed her on this point as I was advised incorrectly prior to conception and during my last pregnancy by GPs at two different surgeries. SO my questions are:

Can anyone send me a link to the most recent advice?

Should ft3 and ft4 be tested as well as tsh?

What are the symptoms I should watch for if I am taking too much levothyroxine?

Thank you for your expertise.

Ally

6 Replies

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  • AllyR,

    Congratulations :)

    NICE CKS revamped their guidance on treating pregnant women in April 2016 and it is less comprehensive than the previous advice. cks.nice.org.uk/hypothyroid...

    I copied the previous guidance cks.nice.org.uk/hypothyroid... before it was changed and have pasted it below:

    I had copied the previous guidance and have pasted it below:

    Scenario: Preconception or pregnant

    Scenario: Subclinical or overt hypothyroidism in the prenatal or antenatal period

    Age from 16 years onwards (Female)

    Pre-existing subclinical hypothyroidism

    How should I manage a woman with pre-existing subclinical hypothyroidism who is pregnant or planning a pregnancy?

    • Check thyroid function tests before conception if they have not been done in the past 6 months.

    • Advise women planning a pregnancy to consult their GP as soon as they think they may be pregnant.

    • For women with known subclinical hypothyroidism who are already receiving levothyroxine treatment (perhaps because their thyroid-stimulating hormone [TSH] concentration was greater than 10 mU/L):

    o At confirmation of pregnancy, immediately increase the levothyroxine dose, and perform thyroid function tests while awaiting referral to a specialist:

     The dose should be increased usually by adding at least 25–50 micrograms levothyroxine; the size of the initial increase in dose will depend on the dose the woman is already taking and the TSH and free thyroxine (FT4) concentrations.

     Aim for a TSH concentration in the low-normal range (0.4 mU/L to 2.0 mU/L) and an FT4 concentration in the upper reference range.

     If there is any uncertainty about what dose to prescribe, seek immediate specialist advice so that there is no delay in the woman receiving an adequate dose of levothyroxine.

    o Monitor TSH and FT4 levels:

     Every 4 weeks during titration of levothyroxine.

     Every 4 weeks during the first trimester, and again at 16 weeks and at 28 weeks of gestation, in a woman who is on a stable dose of levothyroxine.

     More frequent tests may be appropriate on specialist advice.

    • All women with subclinical hypothyroidism who are pregnant or planning a pregnancy and are not receiving levothyroxine treatment should be started on levothyroxine therapy while waiting for referral to a specialist. Management is the same as for women with a new diagnosis of subclinical hypothyroidism who are pregnant or planning a pregnancy.

    Basis for recommendation

    • These recommendations are based on information from a consensus guideline produced by the Association for Clinical Biochemistry, the British Thyroid Association, and the British Thyroid Foundation [BTA et al, 2006]; expert opinion in a guideline produced by the Endocrine Society [Abalovich et al, 2007]; expert opinion in a learning module [Edwards and Vanderpump, 2007]; and the opinion of CKS expert reviewers. Some of the evidence to support these recommendations is based on observational studies.

    o In women with hypothyroidism, the need for levothyroxine is increased in pregnancy by 30–50% above the preconception dosage, and absorption of levothyroxine may be diminished, therefore it is important to increase the dose quickly in women already on levothyroxine [BTA et al, 2006; Abalovich et al, 2007; Reid et al, 2010].

    o There is evidence of increased fetal loss, and psychomotor and IQ deficits, in infants born to mothers with undiagnosed or inadequately treated hypothyroidism (including subclinical hypothyroidism) [Casey et al, 2005].

    o The increase in the levothyroxine dose is necessary to maintain normal serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels for the gestational age [BTA et al, 2006].

    • The recommendations on monitoring of thyroid function (TSH and FT4 levels) are based on expert opinion in guidelines [BTA et al, 2006].

    New diagnosis of subclinical hypothyroidism

    How should I manage a woman with a new diagnosis of subclinical hypothyroidism who is pregnant or planning a pregnancy?

    • All women with a new diagnosis of subclinical hypothyroidism who are pregnant or planning a pregnancy should be started on levothyroxine therapy while waiting for referral to a specialist.

    o Follow local specialist advice regarding the dose, as experts recommend different starting doses (varying from 25 micrograms to 100 micrograms to be taken each morning).

    o Monitor thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels:

     Every 4 weeks during titration of levothyroxine.

     Every 4 weeks during the first trimester, and again at 16 weeks and at 28 weeks of gestation, in a woman who is on a stable dose of levothyroxine.

     More frequent tests may be appropriate on specialist advice.

    o Aim for a TSH concentration in the low-normal range (0.4–2.0 mU/L) and an FT4 concentration in the upper reference range.

    Basis for recommendation

    • These recommendations are based on information from a consensus guideline produced by the Association for Clinical Biochemistry, the British Thyroid Association, and the British Thyroid Foundation [BTA et al, 2006]; expert opinion in a guideline produced by the Endocrine Society [Abalovich et al, 2007]; expert opinion in a learning module [Edwards and Vanderpump, 2007]; and the opinion of CKS expert reviewers. Some of the evidence to support these recommendations is based on observational studies.

    o In women with hypothyroidism, the need for levothyroxine is increased in pregnancy by 30–50% above the preconception dosage, and absorption of levothyroxine may be diminished; therefore, it is important to increase the dose quickly in women already on levothyroxine [BTA et al, 2006; Abalovich et al, 2007; Reid et al, 2010].

    o There is evidence of increased fetal loss, and psychomotor and IQ deficits, in infants born to mothers with undiagnosed or inadequately treated hypothyroidism (including subclinical hypothyroidism) [Casey et al, 2005].

    o The increase in the levothyroxine dose is necessary to maintain normal serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels for the gestational age [BTA et al, 2006].

    • The recommendations on monitoring of thyroid function (TSH and FT4 levels) are based on expert opinion in guidelines [BTA et al, 2006].

    Pre-existing overt hypothyroidism

    How should I manage a woman with pre-existing overt hypothyroidism who is pregnant or planning a pregnancy?

    • Check thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels before conception if possible, to check adequacy of treatment and to make sure the woman is stable and understands the importance of adherence to levothyroxine.

    • If the woman has a history of Graves' disease, refer her to an endocrinologist for evaluation.

    • Advise the woman to consult her GP as soon as she thinks she may be pregnant.

    • At diagnosis of pregnancy, immediately increase the levothyroxine dose and check TSH and FT4 levels while waiting for referral to a specialist:

    o The dose should be increased usually by adding at least 25–50 micrograms levothyroxine; the size of the initial increase in dose will depend on the dose the woman is already taking and the TSH and FT4 concentrations. A 30–50% increase in dosage may be required. If there is any uncertainty about what dose to prescribe, seek immediate specialist advice so that there is no delay in the woman receiving an adequate dose of levothyroxine.

    o Check TSH and FT4 levels every 4 weeks until stabilized, aiming for a TSH concentration in the low-normal range (0.4–2.0 mU/L) and an FT4 concentration in the upper reference range.

    • Monitor TSH and FT4 levels:

    o Every 4 weeks during titration of levothyroxine.

    o Every 4 weeks during the first trimester, and again at 16 weeks and at 28 weeks of gestation, in a woman who is on a stable dose of levothyroxine.

     More frequent tests may be appropriate on specialist advice.

    Basis for recommendation

    • These recommendations are based on a UK consensus guideline produced by the Association for Clinical Biochemistry, British Thyroid Association, and the British Thyroid Foundation [BTA et al, 2006], and expert opinion in a guideline produced by the Endocrine Society [Abalovich et al, 2007].

    o In women with hypothyroidism, the need for levothyroxine is increased in pregnancy by 30–50% above the preconception dosage, and absorption of levothyroxine may be diminished; therefore, it is important to increase the dose quickly in women already on levothyroxine [BTA et al, 2006; Abalovich et al, 2007; Reid et al, 2010].

    o There is evidence of increased fetal loss and IQ and psychomotor deficits in infants born to mothers with undiagnosed or inadequately treated hypothyroidism [Haddow et al, 1999; Pop et al, 1999; Casey et al, 2005].

    o The increase in the levothyroxine dose is necessary to maintain normal serum TSH and FT4 for the gestational age. A TSH concentration of 0.4 mU/L to 2.0 mU/L is normal for pregnancy [BTA et al, 2006].

    o Monitoring of thyroid function tests at least once in each trimester aims to detect inadequately treated hypothyroidism, thereby reducing the risk of long-term adverse effects on the psychomotor and auditory systems of the neonate.

    • The recommendation to refer women with a history of Graves' disease to an endocrinologist for evaluation is based on guidelines developed by the European Thyroid Association [Laurberg et al, 1998]; expert opinion in a clinical practice guideline on the investigation and management of primary thyroid dysfunction produced by the Thyroid Working Group, a multidisciplinary team composed of family physicians, laboratory specialists, and endocrinologists [Alberta Medical Association, 2008]; and expert opinion in a review article [Brent, 2008].

    New diagnosis of overt hypothyroidism

    How should I manage a woman with a new diagnosis of overt hypothyroidism who is pregnant or planning a pregnancy?

    • If the woman is planning a pregnancy and is newly diagnosed with overt hypothyroidism:

    o Start treatment (see prescribing information for information on how to do this), and advise delaying conception until she is stabilized on thyroxine replacement therapy.

    o Advise her to consult her GP as soon as she thinks she may be pregnant, because her thyroid-stimulating hormone (TSH) levels will need to be checked and her levothyroxine dose increased.

    • If the woman is pregnant and is newly diagnosed with overt hypothyroidism:

    o Start treatment with levothyroxine immediately; see prescribing information. There should be no delay in starting treatment.

    o Refer for further management.

    o The target TSH concentration in pregnancy is 0.4 mU/L to 2.0 mU/L, depending on trimester-specific normal TSH ranges.

    Basis for recommendation

    • These recommendations are based on a UK consensus guideline produced by the Association for Clinical Biochemistry, the British Thyroid Association, and the British Thyroid Foundation [BTA et al, 2006], and expert opinion in a guideline produced by the Endocrine Society [Abalovich et al, 2007].

    o The need for levothyroxine is increased in pregnancy in women with hypothyroidism, and absorption of levothyroxine may be diminished. It is therefore important to intervene quickly [BTA et al, 2006].

    o There is evidence of increased fetal loss and IQ deficits in infants born to mothers with undiagnosed or inadequately treated hypothyroidism [Haddow et al, 1999; Pop et al, 1999; Casey et al, 2005].

    o The increase in the levothyroxine dose is necessary to maintain normal serum thyroid-stimulating hormone and free thyroxine levels for the gestational age [BTA et al, 2006].

  • Well done for copying this Clutter. It's beggars belief that they made the cks less comprehensive when doctors don't educate themselves on this subject as it is.🙈

  • Goodlife1,

    Luckily an American member was interested in the NICE recommendations and the links can't be accessed outside of UK so I copied them for him.

    I understand that recommendations evolve and change but I think the April 2016 revamp lacks clarity.

  • AllyR make sure you get monthly blood tests to see how that dose is working for you. Also request/demand free t3 as well as free t4 to get a bigger picture along with TSH. I think it's a good thing the doc knows to increase your dose, they usually go 25% initially but then have to go up again later. Maybe the doc is referring to the 30-50% dose increase overall during pregnancy and increasing by 50mcg immediately. The symptoms of being overmedicated would be things like racing heart , jittery and sweats.

  • Also, TSH can go up quickly at the beginning of pregnancy so the 0.76 at 4.5 weeks will probably not stay there. Hence a hike in meds for us hypothyroid ladies immediately is best practice.

  • Thank you, both. Really helpful. I'm having a viability scan tomorrow at my fertility clinic and have asked for advice from my consultant. She's on leave so I won't see her tomorrow but hope that she will also know up to date info and suggest ft3 and ft4 when she does respond to me. Meanwhile I'll make sure midwife is on side when I meet her next week. Thanks again.

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