Hypothyroidism Questions & Answers

Updated: Mar 03, 2021
  • Author: Philip R Orlander, MD, FACP; Chief Editor: George T Griffing, MD  more...
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Questions & Answers

Overview

What is hypothyroidism?

What are the symptoms of hypothyroidism?

What symptoms of hypothyroidism are specific to Hashimoto thyroiditis?

What are physical signs of hypothyroidism?

What is myxedema coma?

What is the role of third-generation thyroid-stimulating hormone (TSH) assays in the diagnosis of hypothyroidism, and how might biotin interfere with screening?

Which abnormalities on CBC count are associated with hypothyroidism?

Which patients are candidates for hypothyroidism screening?

Which medication is the drug of choice for hypothyroidism treatment, and what are the key aspects of initiating therapy?

What are the symptoms and signs of levothyroxine (LT4) overtreatment in hypothyroidism?

What action should be taken if hypothyroidism symptoms continue to occur after treatment?

What are the ATA guidelines on the use of levothyroxine (LT4) as the drug of choice for the treatment of hypothyroidism?

What are the recommendations on treating hypothyroidism in pregnant women?

How is myxedema coma treated?

Which classic signs and symptoms are commonly observed in hypothyroidism?

What causes hypothyroidism?

What are the causes of secondary and tertiary hypothyroidism?

What are the most common causes of hypothyroidism, and is there a link between vitamin D levels and autoimmune thyroid disease?

Which assay is commonly used to screen for hypothyroidism, and what is the normal reference range of TSH?

How is thyroid hormone supplemented or replaced in hypothyroidism treatment?

What causes congenital hypothyroidism and is it treatable?

What is cretinism, and what causes it?

What is the pathophysiology of hypothyroidism?

What are the effects of thyroid hormone deficiency?

What is central hypothyroidism, and what are the potential causes?

What is the most common cause of hypothyroidism in areas of adequate iodine intake?

What are the types of primary hypothyroidism?

What is chronic lymphocytic (autoimmune) thyroiditis (Hashimoto thyroiditis), and which antibodies are most commonly associated with it?

What is postpartum thyroiditis, and how is it treated?

What is subacute granulomatous thyroiditis (de Quervain disease)?

Which medications may cause hypothyroidism?

Can radioactive iodine (I-131) cause hypothyroidism?

Can external neck irradiation cause hypothyroidism?

Can thyroidectomy or thyroid lobectomy result in hypothyroidism?

Which genes are associated with a risk of developing hypothyroidism?

Which genetic mutations are most commonly associated with congenital hypothyroidism?

What is Pendred syndrome?

What is autoimmune polyendocrinopathy?

What is the role of iodine in hypothyroidism?

How do tumors in or around the pituitary affect TRH and TSH?

What is congenital nongoiterous hypothyroidism type 4, and what causes it?

Which genetic mutation causes TRH resistance?

Which genetic mutation causes TRH deficiency?

What is the prevalence of hypothyroidism in the US?

What is the most common cause of hypothyroidism in developing countries, and what has been done to decrease the incidence?

What are the WHO recommendations for urinary iodine concentrations?

Which age group has the highest prevalence of hypothyroidism?

Is hypothyroidism more common in males or females?

Does hypothyroidism have racial predilection?

What is the prognosis of hypothyroidism?

What educational information should be provided to patients with hypothyroidism?

Presentation

What are the manifestations of hypothyroidism?

What is myxedema coma, and what signs and symptoms are associated with it?

What are the symptoms of hypothyroidism?

Which symptoms of hypothyroidism are more specific to Hashimoto thyroiditis?

What are the physical signs of hypothyroidism?

What is the role of hypothyroidism in masked hypertension?

DDX

Which conditions should be considered in the differential diagnoses of hypothyroidism?

What are the differential diagnoses for Hypothyroidism?

Workup

Which screening assay is the recommended test for hypothyroidism?

Other than hypothyroidism, which physiologic conditions can cause variations in TSH levels?

What steps should be taken in screening for hypothyroidism if TSH levels are above the reference range?

What factors can contribute to variation in free thyroxine (T4) levels?

How is free T4 measured, and how is the free T4 index (FTI) calculated?

How is free T4 measured and monitored in pregnancy?

What do TSH levels and free hormone levels indicate in hypothyroidism diagnoses?

What are the roles of anti-thyroid peroxidase (anti-TPO) and antithyroglobulin (anti-Tg) assays in the diagnosis of hypothyroidism?

Which TSH, T3, and T4 levels are characteristic of nonthyroidal disease (euthyroid sick syndrome)?

What is the role of thyroid evaluations in a critically ill person?

What is the role of testing T4 levels in hypothalamic or pituitary dysfunction in the evaluation of hypothyroidism?

What is the TRH stimulation test?

Which CBC count and metabolic profile results suggest hypothyroidism?

How does primary hypothyroidism affect TRH and prolactin levels?

What is the role of ultrasonography in the workup for hypothyroidism?

What is the role of color flow Doppler scanning in the workup for hypothyroidism?

Should thyroid nodules noted on imaging studies be evaluated?

What is the role of radioactive iodine uptake (RAIU) and thyroid scanning in the workup for hypothyroidism?

What is the role of whole-body F18- FDG-PET scanning in the workup for hypothyroidism?

Who should be screened for hypothyroidism?

How are thyroid nodules typically identified?

Which procedures are used to evaluate thyroid nodules?

Which risk factors are associated with thyroid nodules?

What percentage of thyroid nodules are malignant, and which sonographic features should raise suspicion?

How does autoimmune thyroiditis cause functional tissue destruction?

Other than autoimmune thyroiditis, which conditions can cause functional tissue destruction and infiltration?

Treatment

How is hypothyroidism treated, and what are the treatment goals?

How is thyroid hormone replacement therapy initiated in the treatment of hypothyroidism?

How soon do hypothyroidism signs and symptoms improve after treatment begins?

Should T4 or TSH levels be used to guide treatment of central hypothyroidism?

What is the standard surveillance of patients with hypothyroidism once hormone levels have stabilized, and what are the signs and symptoms of overtreatment?

What are the ATA guidelines on the use of levothyroxine (LT4) as the treatment of choice for hypothyroidism?

What is the difference in side effects of T4-triiodothyronine (T3) combination therapy versus T4 monotherapy in the treatment of clinical hypothyroidism?

Does levothyroxine (LT4) normalize free T4 or T3 levels in athyrotic patients?

What factors may contribute to ongoing symptoms of hypothyroidism despite normalization of the TSH level?

What is the approach for treating patients with hypothyroidism who are on long-term continuous tube feeding?

How is severe hypothyroidism, such as myxedema, treated?

When is surgery indicated in hypothyroidism?

What are the ATA guidelines for the treatment of hypothyroidism in pregnant women?

What are the potential obstetric complications of hypothyroidism in pregnancy?

What is the role of routine screening for thyroid dysfunction in pregnant women?

What medication adjustments should be made in the management of hypothyroidism in pregnant and lactating women, and how often should serum TSH levels be measured?

What are the potential effects of autoimmune thyroid disease on pregnancy?

Should levothyroxine (LT4) be used in women with subclinical hypothyroidism or thyroid autoimmunity who undergo fertility treatment?

What are the recommended dosages of levothyroxine (LT4) for pregnant women newly diagnosed with subclinical or overt hypothyroidism?

What is the recommended treatment of mild (subclinical) hypothyroidism?

What is the recommended treatment of mild (subclinical) hypothyroidism in pregnant women?

What is the role of ultrasonography in subclinical hypothyroidism?

What is the recommended treatment of subclinical hypothyroidism in nonpregnant patients?

According to the AACE, what TSH levels indicate the need for hypothyroidism treatment?

How does levothyroxine (LT4) therapy protect against coronary artery disease (CAD) in patients with subclinical hypothyroidism?

What is the treatment for myxedema coma?

How is adrenal insufficiency treated in cases of myxedema coma?

What is the role of IV LT3 in the treatment of myxedema coma?

Which risk factors have the highest associations with mortality in myxedema coma?

What is the role of thyroid hormone replacement in hypothyroidism and adrenal crisis?

When might thyroid hormone replacement compromise cardiac function in hypothyroidism?

Can thyroid hormone replacement cause subclinical hyperthyroidism?

What is the relationship between levothyroxine (LT4) treatment for hypothyroidism and osteoporosis in elderly patients?

Which patients should be closely monitored for overtreatment of hypothyroidism?

Is hypothyroidism treatment associated with vision loss?

Is hypothyroidism treatment associated with pseudotumor cerebri?

Which complications of hypothyroidism treatment can develop in patients with depression or severe psychological illness?

Which complications of hypothyroidism may occur in untreated infants?

Are there specific dietary restrictions or recommendations for patients with hypothyroidism?

Which kinds of physical activity should be avoided by patients with hypothyroidism?

When is consultation with an endocrinologist indicated for patients with hypothyroidism?

What is the role of long-term monitoring in hypothyroidism, and what should be included?

Medications

Which medications in the drug class Thyroid Products are used in the treatment of Hypothyroidism?