The Attitude Toward Hypothyroidism During Early Gestation: Time for a Change of Mind?

I posted a study about universal screening the other day, this is another area of controversy. Professor Wiersinga weighs in with a positive outlook. The study is a free download from Liebert, they charge $51.00 for most of their studies. Note that here in the US the current standard is a TSH of 2.5 or less for pre-conception and the first trimester and 3.0 or less for the second and third trimester. I doubt most doctors are aware of this standard. PR

online.liebertpub.com/doi/f...

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  • PR4NOW, in the UK pre-conception and first trimester TSH is recommended in the low normal range 0.4-2.0. As universal screening isn't done this is likely only to be useful to women who already know they are borderline or diagnosed subclinically/overtly hypothyroid. It's recommended the dose of those on Levothyroxine is increased by 25mcg-50mcg during the first trimester to ensure good foetal development.

    cks.nice.org.uk/hypothyroid...

  • Clutter, I didn't know the range for TSH was slightly less in the UK, thanks for the info. The link won't let me in, you have to be in the UK to gain access. It seems to be difficult to get universal screening in any part of the population. This paper is in favor of it as part of the normal testing at 8-12 weeks gestation. I think it would be even better as part of pre-conception planning. PR

  • PR4NOW, I agree with you, 8/12 weeks is too late, preconception planning and confirmation of pregnancy would be better.

    This is the info in the link, sorry about formatting:

    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):

    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.

    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.

    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].

    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].

    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.

    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).

    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.

    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.

    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].

    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].

    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:

    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.

    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:

    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.

    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].

    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].

    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].

    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].

    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:

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

    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:

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

    Refer for further management.

    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].

    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].

    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].

    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].

  • Thanks Clutter, I have added this to my library of information. These seem to be pretty reasonable guidelines to me, other than no option for NDT or T3 and no checking for all the other factors like B12, Folate and so on and so forth. PR

  • This is a very interesting read. I'm in the uk with Hashi and untreated. Incidentally I had my TSH tested 3 weeks before I got pregnant with the reading of 4.89 and noted as high by the lab. I moved at that time and registered with a new surgery. I asked them to test my thyroid as soon as I knew I was pregnant and the result was 'fine' but I wasn't told the value. It was never tested again during my pregnancy. My experience was nothing like the guidelines and it was 3 years ago. My baby was born 5 weeks early, the labour started prematurely.

  • I think this is true on both sides of the pond. The actual treatment is quite often completely different from the suggested standard. PR

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