Updated December 16, 2014.
The American Association of Clinical Endocrinologists (AACE) and the American Thyroid Association (ATA) convened a task force on hypothyroidism in adults. The result was jointly published in 2012 in the journals Thyroid and Endocrine Practice as Clinical Practice Guidelines for Hypothyroidism in Adults (The "Guidelines.")
The Guidelines present "evidence-based recommendations" that, according to the report, "were developed to aid in the care of patients with hypothyroidism and to share what the authors believe is current, rational and optimal medical practice for the diagnosis and care of hypothyroidism."

(Note: For the purposes of their guidelines, the task force defined overt hypothyroidism as a Thyroid Stimulating Hormone (TSH) level above 10 mIU/L, and subclinical hypothyroidism as a TSH less than 10 mIU/L, with lower Free Thyroxine (Free T4) levels.)

The following are highlights of some of the Guidelines' key recommendations. The full list of guidelines can be read online at in the journal Thyroid.

Diagnosis-Related Guidelines

The Guidelines include a number of recommendations related to the diagnosis of hypothyroidism. The most notable include the following.

• Thyroid peroxidase antibody (TPOAb) measurements -- which when elevated, can confirm Hashimoto's thyroiditis -- should be considered when evaluating patients with subclinical hypothyroidism.
• When a patient has thyroid nodules, and autoimmune thyroiditis is suspected, measuring TPOAb should be considered.
• Measurement of total triiodothyronine (T3) or Free T3 should not be used to diagnose hypothyroidism.

Treatment-Related Guidelines
The Guidelines feature a number of recommendations that have implications for hypothyroidism treatment.

• Monitoring of Free T4, in addition to TSH, should be considered for patients being treated with levothyroxine.
• Patients being treated for hypothyroidism should have TSH bloodwork done four to eight weeks after starting treatment or changing the dose. Once the TSH levels are stabilized, TSH tests should be done after six months, and then every 12 months, or more often if needed.
• Treatment for patients with TSH levels between the upper limit of a lab's reference range (usually around 4.0 mIU/L) and 10 mIU/L should be considered if the patient has symptoms of hypothyroidism, positive TPO antibodies, evidence of cardiovascular disease, or risk factors for cardiovascular disease.
• Patients with hypothyroidism should be treated only with levothyroxine drugs.
• The evidence does not support using levothyroxine-plus-T3 combinations to treat hypothyroidism.
• There is no evidence to support using natural desiccated thyroid hormone -- i.e., Armour, Nature-Throid -- in preference to levothyroxine in treating hypothyroidism. The Guidelines conclude that "therefore desiccated thyroid hormone should not be used for the treatment of hypothyroidism."
• In patients receiving levothyroxine, TSH should be retested within four to eight weeks of starting or stopping any drugs that impact absorption of levothyroxine.
• Except for pregnant women, the evidence does not support specific TSH target values within the normal reference range.

Screening
The Guidelines state that screening for hypothyroidism should be considered only in patients over the age of 60, and "aggressive case-finding" -- basically, looking for hypothyroidism in people who have risk factors, family history and/or symptoms -- should be considered in those at increased risk for hypothyroidism. The issue of thyroid screening raised by the Guidelines is discussed at greater length in Why Do Experts Disagree on Thyroid Screening?

When Hypothyroid Patients Should See an Endocrinologist

According to the Guidelines, "most physicians can diagnose and treat hypothyroidism." They recommend consultation with an endocrinologist in the following situations:

• Children and infants with hypothyroidism
• Patients in whom it is difficult to render and maintain a euthyroid (TSH normal range) state
• Women planning conception
• Cardiac disease
• Presence of goiter, nodule, or other structural changes in the thyroid gland
• Presence of other endocrine disease such as adrenal and pituitary disorders
• Unusual constellation of thyroid function test results
• Unusual causes of hypothyroidism

When to Take Your Thyroid Medications
The Guidelines point out studies that have found that absorption of thyroid medication is best when levothyroxine medication is takenwith water on an empty stomach, and the patient waits consistently 30 minutes to an hour before eating breakfast, or, when the thyroid medication is taken at night, at least four hours after the last meal.

Thyroid Guidelines Related to Fertility, Pregnancy, and Miscarriage

The Guidelines specify a number of recommendations related to hypothyroidism's effect on fertility, pregnancy, and in the case of miscarriage. These recommendations are generally consistent with the Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum, and include:

• TPOAb measurement should be considered in women who suffer from recurrent miscarriage -- with or without infertility.
• In a woman who is hypothyroid, who has a history of Graves' disease (and had radioactive iodine treatment or thyroidectomy prior to pregnancy), TSH-receptor antibody (TSHRAb) should be measured either at 20-26 weeks of gestation or during the first trimester, and again at 20-26 weeks if they were elevated upon first measurement.
• In pregnancy, total T4 should be measured in addition to TSH.
• In pregnancy, the upper limit of the normal range should be based on trimester-specific ranges for that laboratory. If trimester-specific reference ranges for TSH are not available in the laboratory, the following are the recommended upper limits: first trimester, 2.5 mIU/L; second trimester, 3.0 mIU/L; third trimester, 3.5 mIU/L
  (Note: the Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum recommend that the upper limits be 2.5 mIU/L in the first trimester, 3.0 in the second trimester, and 3.0 mIU/L in the third trimester, which is .5 less than the new Guidelines.)
• Treatment with levothyroxine should be considered in women of child bearing age with TSH levels between 2.5 mIU/L and the upper limit of normal if they are in the first trimester of pregnancy or planning an upcoming pregnancy using assisted reproduction techniques.
• Treatment with levothyroxine should be considered in women in the second and third trimester of pregnancy who have TSH levels between 3.0 mIU/L and the upper limit of normal for a lab's reference range.
• Treatment with levothyroxine should be considered for women who have normal TSH levels who are planning a pregnancy or assisted reproduction if they have or have in the past tested positive for TPOAb. This is considered particularly important if the woman has a history of miscarriage or a past history of hypothyroidism.
• Women who are pregnant or planning a pregnancy, including assisted reproduction in the immediate future, should be treated with levothyroxine if they currently or in the past have had positive levels of TPOAb and their TSH level is greater than 2.5 mIU/L.
• Women who have positive levels of TPOAb with a TSH greater than 2.5 mIU/L who are not being treated with levothyroxine should be tested every four weeks during the first 20 weeks of pregnancy to monitor the development of hypothyroidism.
• In women with hypothyroidism who are being treated with levothyroxine, TSH should be promptly measured after conception, and the levothyroxine dosage adjusted, with a goal of maintaining a TSH of less than 2.5 mIU/L during the first trimester.
• In pregnant women with hypothyroidism who are being treated with levothyroxine, the goal should be to maintain a TSH less than 3 mIU/L during the second trimester, and less than 3.5 mIU/L during the third trimester. (Again, note that the third trimester goal of a TSH less than 3.5 mIU/L differs from the Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum, which recommend a TSH no higher than 3.0 mIU/L in the third trimester.
• A pregnant woman's TSH and total T4 should be tested every four weeks during the first 20 weeks of pregnancy, and at least once between 26 and 32 weeks of pregnancy, and the levothyroxine dosage adjusted as necessary.
• Universal screening is not recommended for patients who are pregnant or are planning pregnancy, including assisted reproduction.
• "Aggressive case finding" for patients who are planning pregnancy should be considered.
• Iodine supplementation in the form of kelp or other seaweed-based products should not be used to treat iodine-deficiency in pregnant women.
• Levothyroxine and T3 combinations should not be given to pregnant women or women planning pregnancy.

Controversial Recommendations
Some of these recommendations are controversial, based on other Guidelines and research findings, and are in direct contradiction to the practices of many integrative practitioners. The controversies in these 2012 Guidelines are explored in the article 2012 Hypothyroidism Guidelines Are Controversial for Some Patients and Practitioners.

<sub>Source:

Clinical Practice Guidelines for Hypothyroidism in Adults: Co-sponsored by the American Association of Clinical Endocrinologists and the American Thyroid AssociationOnline</sub>