Hypothyroidism: Diagnosis and Treatment

These range from simple formulae based only on body weight or BMI to more complex formulae that also incorporate other factors such as patient sex 10, 14. Generally, both a TSH-based estimate and a body weight-based estimate yield similar initial estimates of dose requirement (Fig.1). With respect to age, for patients who are elderly, have concomitant cardiac disease, or may have had long-standing untreated hypothyroidism, it is wise to initiate levothyroxine therapy with smaller doses such as 25–50 μg levothyroxine and incrementally increase the dose to full replacement to avoid precipitating cardiac ischaemia 8. Conventionally, hypothyroid patients are advised to take levothyroxine on an empty stomach half an hour before breakfast to prevent impairment of absorption by food. Several recent studies have looked at whether a bedtime dosage of levothyroxine is preferable. Taking levothyroxine at bedtime resulted in a decrease in mean TSH of 1.25 mIU/L (95% confidence interval CI 0.60–1.89), and an increase in free T4 of 0.07 ng/dL (95% CI 0.02–0.13) and total T3 of 6.5 ng/dL (95% CI 0.9–12.1).34 However, there were no improvements in quality of life scores, blood pressure, or lipid profile.

• So, as a reminder, SYNTHROID is indicated for the treatment of hypothyroidism.
• Patients older than 60 years or with known or suspected ischemic heart disease should start at a lower dosage of levothyroxine (12.5 to 50 mcg per day).
• Triiodothyronine, the active form of thyroid hormone, is secreted in small amounts by the thyroid but is mainly generated via extrathyroidal conversion of the prohormone thyroxine.
• Diagnosis and treatment of hypothyroidism is often considered simple and is mostly carried out in a primary care setting.
• The “optimal dose” was determined for each patient as that dosage of thyroxine being taken when the thyrotropin releasing hormone (TRH) response was normal (ie, an increase in TSH of between 4.7 and 25 mIU/L).

DOSE ADJUSTMENTS AND TSH MONITORING

However, studies continue to show problems in the management of this condition. When initiating levothyroxine therapy, serum TSH should be measured to monitor for adequate replacement. TSH can take up to 4 months to normalize, even when starting on a full dose replacement regimen, due to thyrotroph hyperplasia. It is recommended that the TSH is measured 6–8 weeks after initiation of, or a change in levothyroxine dose. Once the patient is on a stable dose of levothyroxine, annual monitoring of TSH is recommended, although a retrospective study suggests that the monitoring interval could be safely increased to 18 months.38 Common causes of persistently elevated TSH in patients on levothyroxine replacement are shown in Table 1.

• However, the study was not designed to investigate whether this was due to physician-patient interaction, specific education following the meetings, the influence of pharmaceutical companies, or media exposure, or a combination of these.
• In summary, it is necessary in all cases to periodically verify the need for dose adjustment and/or continuation of treatment.
• Mistaken generic users defined as those who reported taking SYNTHROID but did not have “SYNTHROID” embossed on the pill in a national online survey conducted in 2021 of 1908 adults diagnosed with hypothyroidism and currently taking LT4  products.
• But also specific medical changes that may indicate there may be a need for a dose change or something that could have affected their thyroid hormone levels.
• The medication most used to treat hypothyroidism is levothyroxine, a compound that acts as a replacement for a person’s thyroid hormone.

Common drugs that can affect levothyroxine absorption include iron, calcium, cholestyramine, and aluminum and levothyroxine must be taken at least 4 hours apart from these drugs. Enzyme inducers, such as phenytoin, carbamazepine, phenobarbital, and rifampicin can increase the clearance of levothyroxine, necessitating an increased dose. For example, initiation of levothyroxine in a hypothyroid patient may enhance the effect of warfarin, which may need dose adjustment. Diagnosis and treatment of hypothyroidism is often considered simple and is mostly carried out in a primary care setting.

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The manufacture of sodium thyroxine (levothyroxine) thus resulted in a major pharmacological achievement in endocrinology, giving a more stable and effective thyroid hormone compound that, over the last few decades, has considerably improved the lives of millions of patients with various forms of hypothyroidism. Although the diagnosis and treatment of hypothyroidism is often considered simple, there are large numbers of people with this condition who are suboptimally treated. Even in those people with hypothyroidism who are biochemically euthyroid on levothyroxine replacement there is a significant proportion who report poorer quality of life. This review explores the historical and current treatment options for hypothyroidism, reasons for and potential solutions to suboptimal treatment, and future possibilities in the treatment of hypothyroidism. For healthy adults with hypothyroidism, thyroid hormone replacement should begin at a full replacement dose of 1.6 micrograms per kilogram per day and the doses adjusted or titrated up by 12 ½ to 25 micrograms every 4-6 weeks until the patient is clinically euthyroid and the TSH is normalized.

DISCUSS THE FOLLOWING WITH PATIENTS

The “optimal dose” was determined for each patient as that dosage of thyroxine being taken when the thyrotropin-releasing hormone (TRH) response was normal (ie, an increase in TSH of between 4.7 and 25 mIU/L). Pituitary Thyrotropin (Thyroid Stimulating Hormone, TSH) SuppressionSYNTHROID is indicated in adult and pediatric patients, including neonates, as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer. These medications are those where small changes in the dose or blood concentration may lead to serious therapeutic failures and/or adverse drug reactions. Monitor serum free-T4 levels and maintain in the upper half of the normal range in these patients. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Clinical Guidance additional Links

Nevertheless, these studies suggest that bedtime dosing of levothyroxine could be tried as an alternative strategy in those patients who have problems in taking morning levothyroxine on an empty stomach. After more than 120 years since Murray first successfully treated hypothyroidism with sheep thyroid extract29 and numerous subsequent advances in the field, there remain many uncertainties surrounding the management of this common disease. What is the target thyroid function for hypothyroid patients on levothyroxine replacement?

Levothyroxine is the standard therapy for patients with hypothyroidism, a condition that affects up to 5% of people worldwide. While levothyroxine therapy has substantially improved the lives of millions of hypothyroid patients since its introduction in 1949, the complexity of maintaining biochemical and clinical euthyroidism in patients undergoing treatment with levothyroxine cannot be underestimated. Initial dosing of levothyroxine can vary greatly and may be based on the amount of residual thyroid function retained by the patient, the body weight or lean body mass of the patient, and thyroid-stimulating hormone levels. As levothyroxine is usually administered over a patient’s lifetime, physiological changes throughout life will affect the dose of levothyroxine required to maintain euthyroidism. Furthermore, dose adjustments may need to be made in patients with concomitant medical conditions, in patients taking certain medications, as well as in elderly patients. Patients who have undergone any weight or hormonal changes may require dose adjustments, and the majority of pregnant women require increased doses of levothyroxine.

Women with hypothyroidism who become pregnant should increase their weekly dosage by 30% up to nine doses per week (i.e., take one extra dose twice per week), followed by monthly evaluation and management. Patients with persistent symptoms after adequate levothyroxine dosing should be reassessed for other causes or the need for referral. Most patients with subclinical hypothyroidism do not benefit from treatment unless the thyroid-stimulating hormone level is greater than 10 mIU per L or the thyroid peroxidase antibody is elevated.

4 Monitoring TSH and/or Thyroxine (T Levels

As a person progresses through life, their dose may need to be adjusted because other diseases or medications can affect the dose needed for effective treatment. Pregnancy or weight gain can also affect the dose of levothyroxine needed by the patient, so patients and physicians need to work in partnership to ensure that the treatment is working as well as it can. The goal of this partnership is to maintain normal thyroid hormone levels without the patient experiencing any side effects or synthroid production negative health consequences of taking too much or too little levothyroxine.

Factors Potentially Contributing to the Need for Levothyroxine Dose Adjustments Throughout a Patient’s Life Span

It’s very important to make sure that you write “Dispense as written,” or whatever state-specific language, on the prescription when you prescribe the medication. I go over with the patient there are treatment goals that are very important in the process. And the other is to improve the clinical symptoms that they’ve been experiencing. Because the long-acting nature of the medication, I do indicate that it may take several months to see an improvement in both of these levels.