Hormone replacement Most people with<unk>  symptoms and confirmed thyroxine deficiency are treated with a synthetic long-acting form of thyroxine, known as levothyroxine (L-thyroxine). In young and otherwise healthy people with overt<unk> , a full replacement dose (adjusted by weight) can be started immediately; in the elderly and people with heart disease a lower starting dose is recommended to prevent over supplementation and risk of complications. Lower doses may be sufficient in those with subclinical<unk> , while people with central<unk>  may require a higher than average dose. Blood free thyroxine and TSH levels are monitored to help determine whether the dose is adequate. This is done 4–8 weeks after the start of treatment or a change in levothyroxine dose. Once the adequate replacement dose has been established, the tests can be repeated after 6 and then 12 months, unless there is a change in symptoms. Normalization of TSH does not mean that other abnormalities associated with<unk>  improve entirely, such as elevated cholesterol levels. In people with central/secondary<unk> , TSH is not a reliable marker of hormone replacement and decisions are based mainly on the free T4 level. Levothyroxine is best taken 30–60 minutes before breakfast, or four hours after food, as certain substances such as food and calcium can inhibit the absorption of levothyroxine. There is no direct way of increasing thyroid hormone secretion by the thyroid gland. Liothyronine Treatment with liothyronine alone has not received enough study to make a recommendation as to its use; due to its shorter half-life it would need to be taken more often than levothyroxine. Adding liothyronine (synthetic T3) to levothyroxine has been suggested as a measure to provide better symptom control, but this has not been confirmed by studies. In 2007, the British Thyroid Association stated that combined T4 and T3 therapy carried a higher rate of side effects and no benefit over T4 alone. Similarly, American guidelines discourage combination therapy due to a lack of evidence, although they acknowledge that some people feel better when receiving combination treatment. Guidelines by NICE for England and Wales discourage liothyronine. People with<unk>  who do not feel well despite optimal levothyroxine dosing may request adjunctive treatment with liothyronine. A 2012 guideline from the European Thyroid Association recommends that support should be offered with regards to the chronic nature of the disease and that other causes of the symptoms should be excluded. Addition of liothyronine should be regarded as experimental, initially only for a trial period of 3 months, and in a set ratio to the current dose of levothyroxine. The guideline explicitly aims to enhance the safety of this approach and to counter its indiscriminate use. Desiccated animal thyroid Desiccated thyroid extract is an animal-based thyroid gland extract, most commonly from pigs. It is a combination therapy, containing forms of T4 and T3. It also contains calcitonin (a hormone produced in the thyroid gland involved in the regulation of calcium levels), T1 and T2; these are not present in synthetic hormone medication. This extract was once a mainstream<unk>  treatment, but its use today is unsupported by evidence; British Thyroid Association and American professional guidelines discourage its use, as does NICE. Subclinical<unk>  There is no evidence of a benefit from treating subclinical<unk>  in those who are not pregnant, and there are potential risks of overtreatment. Untreated subclinical<unk>  may be associated with a modest increase in the risk of coronary artery disease when the TSH is over 10 mIU/l. A 2007 review found no benefit of thyroid hormone replacement except for "some parameters of lipid profiles and left ventricular function". There is no association between subclinical<unk>  and an increased risk of bone fractures, nor is there a link with cognitive decline. Since 2008, consensus American opinion has been that in general people with TSH under 10 to 20 mIU/l do not require treatment. American guidelines recommend that treatment should be considered in people with symptoms of<unk> , detectable antibodies against thyroid peroxidase, a history of heart disease or are at an increased risk for heart disease, if the TSH is elevated but below 10 mIU/l. NICE recommends that those with a TSH above 10 mIU/l should be treated in the same way as overt<unk> . Those with an elevated TSH but below 10 mIU/l who have symptoms suggestive of<unk>  should have a trial of treatment but with the aim to stopping this if the symptoms persist despite normalisation of the TSH. Myxedema coma Myxedema coma or severe decompensated<unk>  usually requires admission to the intensive care, close observation and treatment of abnormalities in breathing, temperature control, blood pressure, and sodium levels. Mechanical ventilation may be required, as well as fluid replacement, vasopressor agents, careful rewarming, and corticosteroids (for possible adrenal insufficiency which can occur together with<unk> . Careful correction of low sodium levels may be achieved with hypertonic saline solutions or vasopressin receptor antagonists. For rapid treatment of the<unk> , levothyroxine or liothyronine may be administered intravenously, particularly if the level of consciousness is too low to be able to safely swallow medication. While administration through a nasogastric tube is possible, this may be unsafe and is discouraged. Pregnancy In women with known<unk>  who become pregnant, it is recommended that serum TSH levels are closely monitored. Levothyroxine should be used to keep TSH levels within the normal range for that trimester. The first trimester normal range is below 2.5 mIU/L and the second and third trimesters normal range is below 3.0 mIU/L. Treatment should be guided by total (rather than free) thyroxine or by the free T4 index. Similarly to TSH, the thyroxine results should be interpreted according to the appropriate reference range for that stage of pregnancy. The levothyroxine dose often needs to be increased after pregnancy is confirmed, although this is based on limited evidence and some recommend that it is not always required; decisions may need to based on TSH levels. Women with anti-TPO antibodies who are trying to become pregnant (naturally or by assisted means) may require thyroid hormone supplementation even if the TSH level is normal. This is particularly true if they have had previous miscarriages or have been hypothyroid in the past. Supplementary levothyroxine may reduce the risk of preterm birth and possibly miscarriage. The recommendation is stronger in pregnant women with subclinical<unk>  (defined as TSH 2.5–10 mIU/l) who are anti-TPO positive, in view of the risk of overt<unk> . If a decision is made not to treat, close monitoring of the thyroid function (every 4 weeks in the first 20 weeks of pregnancy) is recommended. If anti-TPO is not positive, treatment for subclinical<unk>  is not currently recommended. It has been suggested that many of the aforementioned recommendations could lead to unnecessary treatment, in the sense that the TSH cutoff levels may be too restrictive in some ethnic groups; there may be little benefit from treatment of subclinical<unk>  in certain cases. Alternative medicine The effectiveness and safety of using Chinese herbal medicines to treat<unk>  is not known.
Hypothyroidism
Heart failure
Late onset congenital adrenal hyperplasia
Dementia
Autoimmune thyroiditis
Depression (mood)
Acromegaly
Chronic fatigue syndrome