Hypothyroidism is characterized by an underactive thyroid gland, which results in insufficient production of thyroid hormones. The thyroid gland plays a crucial role in regulating various metabolic processes in the body by producing hormones, primarily thyroxine (T4) and triiodothyronine (T3). The most common cause of hypothyroidism is an autoimmune condition called Hashimoto’s thyroiditis, where the immune system attacks and damages the thyroid gland.
Other causes include certain medications, radiation therapy, surgical removal of the thyroid gland, congenital hypothyroidism, and dysfunction of the pituitary gland or hypothalamus. If left untreated, hypothyroidism can lead to more severe health problems, including cardiovascular issues, infertility, joint pain, and, in extreme cases, a life-threatening condition known as myxedema coma.
Epidemiology
Hypothyroidism is a relatively common endocrine disorder. Hypothyroidism can occur at any age but is more common in older adults. Women are more likely to develop hypothyroidism than men. The condition often affects women, especially as they age. Hashimoto’s thyroiditis is a leading cause of hypothyroidism, tends to be more prevalent in women, and often presents during middle age.
Iodine deficiency can be a significant factor in the prevalence of hypothyroidism. Regions with insufficient iodine levels in the diet may experience higher rates of hypothyroidism. Some cases of hypothyroidism are iatrogenic, meaning they result from medical treatments such as surgery or radiation therapy to the thyroid gland.
Anatomy
Pathophysiology
Hypothyroidism results from an insufficient production of thyroid hormones by the thyroid gland. The primary thyroid hormones involved are thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body’s metabolism. The pathophysiology of hypothyroidism can be understood through various causes, with most cases stemming from an underactive thyroid gland.
Iodine is an essential component for the synthesis of thyroid hormones. In areas with insufficient dietary iodine, the thyroid gland cannot produce adequate thyroid hormones, leading to hypothyroidism. Iodine deficiency can be a significant factor, especially in regions where iodine is not naturally present in the soil or adequately supplemented.
Certain medications like lithium and amiodarone can interfere with thyroid hormone production and contribute to hypothyroidism. The pituitary gland and hypothalamus play a role in regulating thyroid hormone production. Dysfunction in these areas can lead to decreased stimulation of the thyroid gland, resulting in hypothyroidism.
Without intervention, hypothyroidism poses a significant risk of elevated morbidity and mortality. It can progress to the point of inducing coma or even proving fatal. In children, neglecting the treatment of hypothyroidism may lead to profound mental retardation.
Among adults, heart failure stands out as a prominent cause of mortality. Fortunately, with proper treatment, the prognosis for most patients is favorable, and symptoms typically show improvement within a few weeks or months.
Clinical History
Hypothyroidism can gradually onset, and symptoms may develop over an extended period. The duration of symptoms before seeking medical attention can vary among individuals. Hypothyroidism may have an acute onset in some cases, especially if it results from factors like viral thyroiditis or certain medications.
Patients with hypothyroidism often experience persistent fatigue and weakness. Unexplained weight gain or difficulty losing weight despite no significant changes in diet or exercise. Heightened sensitivity to cold, with patients feeling cold even in moderate temperatures. Slowed metabolism can lead to constipation.
Skin may become dry and hair brittle due to reduced production of oils. Generalized muscle aches and joint pain may be present. Women may experience changes in menstrual cycles, including irregular periods. Changes in the voice, including hoarseness, can be present.
Physical Examination
A characteristic facial expression with a dull, puffy appearance is sometimes observed, known as myxedema facies. Many individuals with hypothyroidism may experience unexplained weight gain. Puffiness and swelling of the face, especially around the eyes. Hypothyroidism can lead to dry and coarse skin.
Brittle, dry hair, and hair loss are common. In a few individuals, bradycardia and hypotension are observed. Some individuals may experience abdominal discomfort and bloating. Hypothyroidism can affect fertility in both men and women.
In some cases, a visible or palpable enlargement of the thyroid gland (goiter) may be present. Some individuals may experience memory problems and difficulty concentrating. Patients may experience tingling or numbness in the hands and fingers.
Age group
Associated comorbidity
Associated activity
Acuity of presentation
Differential Diagnoses
Laboratory Studies
Imaging Studies
Procedures
Histologic Findings
Staging
Treatment Paradigm
The treatment paradigm for hypothyroidism involves the administration of levothyroxine. Patients are diagnosed based on clinical symptoms and laboratory tests, including TSH and free T4 levels. The medication is typically taken on an empty stomach, preferably in the morning, with precautions against substances that may interfere with absorption.
Regular monitoring of thyroid function guides individualized dosage adjustments, aiming to maintain optimal hormone levels and alleviate symptoms. Lifestyle considerations are emphasized, such as consistent medication administration and dietary habits. Special considerations exist for pregnant women, those with autoimmune causes, and individuals with coexisting conditions.
The levothyroxine absorption test may be conducted to assess a patient’s ability to absorb the medication. Overall, patient education, follow-up appointments, and a collaborative approach between healthcare providers and patients are essential for the successful long-term management of hypothyroidism.
by Stage
by Modality
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Stem Cell Transplant
Targeted Therapy
Palliative Care
lifestyle-modifications
Certain substances, such as calcium supplements, iron, and high-fiber foods, can interfere with levothyroxine absorption. These should be taken at a different time than the thyroid medication. Consistent dietary habits and medication administration are essential for optimal treatment outcomes.Â
Administration of a pharmaceutical agent
Levothyroxine, a synthetic form of the thyroid hormone T4, is the standard and most commonly prescribed medication for hypothyroidism. The goal of treatment is to normalize thyroid hormone levels and relieve symptoms. Levothyroxine is usually taken on an empty stomach, preferably in the morning, to maximize absorption.
It is recommended to wait at least 30 minutes to an hour before eating or taking other medications that may interfere with absorption. To enhance absorption, it is advisable to administer levothyroxine 30-45 minutes before breakfast or at least 3 hours after consuming a meal, making these times convenient for the majority of patients. Furthermore, elemental supplements like calcium and magnesium can impede levothyroxine absorption.
Commonly prescribed medications such as proton pump inhibitors also negatively affect levothyroxine absorption. Consistency in the formulation or brand of levothyroxine is crucial. Slight variations in dosage among generic formulations may impact a small subset of highly sensitive hypothyroid patients, underscoring the importance of maintaining uniformity.Â
Gel formulations of thyroid hormone replacements, such as Triocent, are employed in malabsorption syndromes. Agents like sucralfate, calcium preparations, and bile acid sequestrants can impede the absorption of levothyroxine. Notably, the levothyroxine absorption test is conducted to demonstrate a patient’s inability to absorb levothyroxine.Â
Age: >50 years old or less than 50 years with CV disease 
25-50 mcg orally once a day
Or 12.5-25 mcg every 6-8Week 
Age: >50 years with CV disease 
12.5-25 mcg orally once a day
Or 12.5-25 mcg for every 4-6weeks until the patient becomes euthyroid 
Severe Hypothyroidism 
12.5-25 mcg orally once a day
Subclinical Hypothyroidism 
1 mcg/kg orally once a day
Initially, 25-75 mcg orally each day
It increases by 25 mcg every 1-2 weeks, do not exceed 100 mcg/day
Maintenance dose- 25-75 mcg orally each day
May also use 10-12.5 mcg triiodothyronine (T3) combined with tetraiodothyronine (T4)
Decrease the T4 dose by 50 mcg
Initially, 25-75 mcg orally each day
It increases by 25 mcg every 1-2 weeks, do not exceed 100 mcg/day
Maintenance dose- 25-75 mcg orally each day
May also use 10-12.5 mcg triiodothyronine (T3) combined with tetraiodothyronine (T4)
Decrease the T4 dose by 50 mcg
1 tablet Thyrolar 1/2 daily, followed by 1 tablet Thyrolar 1/4 every 2 to 3 weeks
In long-standing myxedema, a lower initial dose of 1 tab is recommended, especially if cardiovascular damage is suspected, in which further caution is advised
Maintenance: one tablet of Thyrolar 1 to 1 tablet Thyrolar 2 daily; failure to respond to tab Thyrolar 3 can suggest a lack of compliance and malabsorption.
After necessary clinical laboratory analyses of T4 bound and free TSH blood levels, adjust the dosage within the first four weeks of therapy
Palopegteriparatide (FDA approval pending) is an investigational drug, and the new drug application (NDA) is submitted to FDA
Now waiting for approval of Prescription Drug User Fee Act (PDUFA)
First: medication in the ratio of 25 mcg/6.25 mcg once a day; in patients with chronic myxedema, a lower starting dose (12.5 mcg/3.1 mcg) is advised, mainly if concomitant cardiovascular impairment is present (if angina ensues, reduce dose) 12.5 mcg/ 3.1 mcg dose increases may be made every two to three weeks
The usual maintenance dose is 50–100 mcg/ 12.5–25 mcg once daily An insufficient response, even with sufficient dosage replacement, could be a sign of the preparation's inactivity, poor absorption, excessive excretion, or nonadherence
Age1-3 months
10-15 mcg/kg orally once a day
5-7.5 mcg/kg IV/IM once a day
For patients' risk of heart failure: 25 mcg/day
start a higher dose (50 mcg/day) as initial if serum T4 is lower than five mcg/dL
Age 3-6 months
8-10 mcg/kg orally OR 25-50 mcg orally once a day
4-7.5 mcg/kg IV/IM once a day
Age: 6-12 months
6-8 mcg/kg orally OR 50-75 mcg orally once a day
3-6 mcg/kg IV/IM once a day
Age: 1-5 years
5-6 mcg/kg orally, OR 75-100 mcg orally once a day
2.5-4.5 mcg/kg IV/IM once a day
Age: 6-12 years
4-5 mcg/kg orally OR 100-125 mcg orally once a day
2-3.75 mcg/kg IV/IM once a day
Age: >12 years
2-3 mcg/kg orally, OR 150 mcg orally once a day
1-2.25 mcg/kg IV/IM once a day
Indicated for Congenital hypothyroidism
Initially 5 mcg orally each day
May increase the dose by 5 mcg every 3-4 days
Maintenance dose
For <1 year: 20 mcg orally each day
For 1-3 years: 50 mcg orally each day
For >3 years: 25-75 mcg orally each day
0 to 6 months: 3.1/12.5 to 6.25/25 orally;
6 to 12 months: 6.25/25 to 9.35/37.5 orally;
1 to 5 yrs: 9.35/37.5 to 12.5/50 mcg orally;
6- to 12 yrs: 12.5/50 to 18.75/75 mcg orally;
Above 12 yrs: more than 18.75/75 mcg orally;
Six months or less: 12.5 mcg / 3.1 mcg Oral dosage of 25 mcg-25 mcg/6.25 mcg daily
for 6 to 12 months: 25 mcg/6.25 mcg Orally administered daily
for one to five years: 37.5 mcg/9.35 mcg Orally administered daily
Six to twelve years old: 50 mcg/ 12.5 mcg – 75 mcg/18.75 mcg Orally administered daily
Over 12 years: 75 mcg/18.75 mcg dosages are to be taken orally each day
Hypothyroidism is characterized by an underactive thyroid gland, which results in insufficient production of thyroid hormones. The thyroid gland plays a crucial role in regulating various metabolic processes in the body by producing hormones, primarily thyroxine (T4) and triiodothyronine (T3). The most common cause of hypothyroidism is an autoimmune condition called Hashimoto’s thyroiditis, where the immune system attacks and damages the thyroid gland.
Other causes include certain medications, radiation therapy, surgical removal of the thyroid gland, congenital hypothyroidism, and dysfunction of the pituitary gland or hypothalamus. If left untreated, hypothyroidism can lead to more severe health problems, including cardiovascular issues, infertility, joint pain, and, in extreme cases, a life-threatening condition known as myxedema coma.
Hypothyroidism is a relatively common endocrine disorder. Hypothyroidism can occur at any age but is more common in older adults. Women are more likely to develop hypothyroidism than men. The condition often affects women, especially as they age. Hashimoto’s thyroiditis is a leading cause of hypothyroidism, tends to be more prevalent in women, and often presents during middle age.
Iodine deficiency can be a significant factor in the prevalence of hypothyroidism. Regions with insufficient iodine levels in the diet may experience higher rates of hypothyroidism. Some cases of hypothyroidism are iatrogenic, meaning they result from medical treatments such as surgery or radiation therapy to the thyroid gland.
Hypothyroidism results from an insufficient production of thyroid hormones by the thyroid gland. The primary thyroid hormones involved are thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body’s metabolism. The pathophysiology of hypothyroidism can be understood through various causes, with most cases stemming from an underactive thyroid gland.
Iodine is an essential component for the synthesis of thyroid hormones. In areas with insufficient dietary iodine, the thyroid gland cannot produce adequate thyroid hormones, leading to hypothyroidism. Iodine deficiency can be a significant factor, especially in regions where iodine is not naturally present in the soil or adequately supplemented.
Certain medications like lithium and amiodarone can interfere with thyroid hormone production and contribute to hypothyroidism. The pituitary gland and hypothalamus play a role in regulating thyroid hormone production. Dysfunction in these areas can lead to decreased stimulation of the thyroid gland, resulting in hypothyroidism.
Without intervention, hypothyroidism poses a significant risk of elevated morbidity and mortality. It can progress to the point of inducing coma or even proving fatal. In children, neglecting the treatment of hypothyroidism may lead to profound mental retardation.
Among adults, heart failure stands out as a prominent cause of mortality. Fortunately, with proper treatment, the prognosis for most patients is favorable, and symptoms typically show improvement within a few weeks or months.
Hypothyroidism can gradually onset, and symptoms may develop over an extended period. The duration of symptoms before seeking medical attention can vary among individuals. Hypothyroidism may have an acute onset in some cases, especially if it results from factors like viral thyroiditis or certain medications.
Patients with hypothyroidism often experience persistent fatigue and weakness. Unexplained weight gain or difficulty losing weight despite no significant changes in diet or exercise. Heightened sensitivity to cold, with patients feeling cold even in moderate temperatures. Slowed metabolism can lead to constipation.
Skin may become dry and hair brittle due to reduced production of oils. Generalized muscle aches and joint pain may be present. Women may experience changes in menstrual cycles, including irregular periods. Changes in the voice, including hoarseness, can be present.
A characteristic facial expression with a dull, puffy appearance is sometimes observed, known as myxedema facies. Many individuals with hypothyroidism may experience unexplained weight gain. Puffiness and swelling of the face, especially around the eyes. Hypothyroidism can lead to dry and coarse skin.
Brittle, dry hair, and hair loss are common. In a few individuals, bradycardia and hypotension are observed. Some individuals may experience abdominal discomfort and bloating. Hypothyroidism can affect fertility in both men and women.
In some cases, a visible or palpable enlargement of the thyroid gland (goiter) may be present. Some individuals may experience memory problems and difficulty concentrating. Patients may experience tingling or numbness in the hands and fingers.
The treatment paradigm for hypothyroidism involves the administration of levothyroxine. Patients are diagnosed based on clinical symptoms and laboratory tests, including TSH and free T4 levels. The medication is typically taken on an empty stomach, preferably in the morning, with precautions against substances that may interfere with absorption.
Regular monitoring of thyroid function guides individualized dosage adjustments, aiming to maintain optimal hormone levels and alleviate symptoms. Lifestyle considerations are emphasized, such as consistent medication administration and dietary habits. Special considerations exist for pregnant women, those with autoimmune causes, and individuals with coexisting conditions.
The levothyroxine absorption test may be conducted to assess a patient’s ability to absorb the medication. Overall, patient education, follow-up appointments, and a collaborative approach between healthcare providers and patients are essential for the successful long-term management of hypothyroidism.
Emergency Medicine
Certain substances, such as calcium supplements, iron, and high-fiber foods, can interfere with levothyroxine absorption. These should be taken at a different time than the thyroid medication. Consistent dietary habits and medication administration are essential for optimal treatment outcomes.Â
Emergency Medicine
Levothyroxine, a synthetic form of the thyroid hormone T4, is the standard and most commonly prescribed medication for hypothyroidism. The goal of treatment is to normalize thyroid hormone levels and relieve symptoms. Levothyroxine is usually taken on an empty stomach, preferably in the morning, to maximize absorption.
It is recommended to wait at least 30 minutes to an hour before eating or taking other medications that may interfere with absorption. To enhance absorption, it is advisable to administer levothyroxine 30-45 minutes before breakfast or at least 3 hours after consuming a meal, making these times convenient for the majority of patients. Furthermore, elemental supplements like calcium and magnesium can impede levothyroxine absorption.
Commonly prescribed medications such as proton pump inhibitors also negatively affect levothyroxine absorption. Consistency in the formulation or brand of levothyroxine is crucial. Slight variations in dosage among generic formulations may impact a small subset of highly sensitive hypothyroid patients, underscoring the importance of maintaining uniformity.Â
Gel formulations of thyroid hormone replacements, such as Triocent, are employed in malabsorption syndromes. Agents like sucralfate, calcium preparations, and bile acid sequestrants can impede the absorption of levothyroxine. Notably, the levothyroxine absorption test is conducted to demonstrate a patient’s inability to absorb levothyroxine.Â
medtigo
Hypothyroidism
Updated :
May 20, 2024
Hypothyroidism is characterized by an underactive thyroid gland, which results in insufficient production of thyroid hormones. The thyroid gland plays a crucial role in regulating various metabolic processes in the body by producing hormones, primarily thyroxine (T4) and triiodothyronine (T3). The most common cause of hypothyroidism is an autoimmune condition called Hashimoto’s thyroiditis, where the immune system attacks and damages the thyroid gland.
Other causes include certain medications, radiation therapy, surgical removal of the thyroid gland, congenital hypothyroidism, and dysfunction of the pituitary gland or hypothalamus. If left untreated, hypothyroidism can lead to more severe health problems, including cardiovascular issues, infertility, joint pain, and, in extreme cases, a life-threatening condition known as myxedema coma.
Hypothyroidism is a relatively common endocrine disorder. Hypothyroidism can occur at any age but is more common in older adults. Women are more likely to develop hypothyroidism than men. The condition often affects women, especially as they age. Hashimoto’s thyroiditis is a leading cause of hypothyroidism, tends to be more prevalent in women, and often presents during middle age.
Iodine deficiency can be a significant factor in the prevalence of hypothyroidism. Regions with insufficient iodine levels in the diet may experience higher rates of hypothyroidism. Some cases of hypothyroidism are iatrogenic, meaning they result from medical treatments such as surgery or radiation therapy to the thyroid gland.
Hypothyroidism results from an insufficient production of thyroid hormones by the thyroid gland. The primary thyroid hormones involved are thyroxine (T4) and triiodothyronine (T3), which play a crucial role in regulating the body’s metabolism. The pathophysiology of hypothyroidism can be understood through various causes, with most cases stemming from an underactive thyroid gland.
Iodine is an essential component for the synthesis of thyroid hormones. In areas with insufficient dietary iodine, the thyroid gland cannot produce adequate thyroid hormones, leading to hypothyroidism. Iodine deficiency can be a significant factor, especially in regions where iodine is not naturally present in the soil or adequately supplemented.
Certain medications like lithium and amiodarone can interfere with thyroid hormone production and contribute to hypothyroidism. The pituitary gland and hypothalamus play a role in regulating thyroid hormone production. Dysfunction in these areas can lead to decreased stimulation of the thyroid gland, resulting in hypothyroidism.
Without intervention, hypothyroidism poses a significant risk of elevated morbidity and mortality. It can progress to the point of inducing coma or even proving fatal. In children, neglecting the treatment of hypothyroidism may lead to profound mental retardation.
Among adults, heart failure stands out as a prominent cause of mortality. Fortunately, with proper treatment, the prognosis for most patients is favorable, and symptoms typically show improvement within a few weeks or months.
Hypothyroidism can gradually onset, and symptoms may develop over an extended period. The duration of symptoms before seeking medical attention can vary among individuals. Hypothyroidism may have an acute onset in some cases, especially if it results from factors like viral thyroiditis or certain medications.
Patients with hypothyroidism often experience persistent fatigue and weakness. Unexplained weight gain or difficulty losing weight despite no significant changes in diet or exercise. Heightened sensitivity to cold, with patients feeling cold even in moderate temperatures. Slowed metabolism can lead to constipation.
Skin may become dry and hair brittle due to reduced production of oils. Generalized muscle aches and joint pain may be present. Women may experience changes in menstrual cycles, including irregular periods. Changes in the voice, including hoarseness, can be present.
A characteristic facial expression with a dull, puffy appearance is sometimes observed, known as myxedema facies. Many individuals with hypothyroidism may experience unexplained weight gain. Puffiness and swelling of the face, especially around the eyes. Hypothyroidism can lead to dry and coarse skin.
Brittle, dry hair, and hair loss are common. In a few individuals, bradycardia and hypotension are observed. Some individuals may experience abdominal discomfort and bloating. Hypothyroidism can affect fertility in both men and women.
In some cases, a visible or palpable enlargement of the thyroid gland (goiter) may be present. Some individuals may experience memory problems and difficulty concentrating. Patients may experience tingling or numbness in the hands and fingers.
The treatment paradigm for hypothyroidism involves the administration of levothyroxine. Patients are diagnosed based on clinical symptoms and laboratory tests, including TSH and free T4 levels. The medication is typically taken on an empty stomach, preferably in the morning, with precautions against substances that may interfere with absorption.
Regular monitoring of thyroid function guides individualized dosage adjustments, aiming to maintain optimal hormone levels and alleviate symptoms. Lifestyle considerations are emphasized, such as consistent medication administration and dietary habits. Special considerations exist for pregnant women, those with autoimmune causes, and individuals with coexisting conditions.
The levothyroxine absorption test may be conducted to assess a patient’s ability to absorb the medication. Overall, patient education, follow-up appointments, and a collaborative approach between healthcare providers and patients are essential for the successful long-term management of hypothyroidism.
Emergency Medicine
Certain substances, such as calcium supplements, iron, and high-fiber foods, can interfere with levothyroxine absorption. These should be taken at a different time than the thyroid medication. Consistent dietary habits and medication administration are essential for optimal treatment outcomes.Â
Emergency Medicine
Levothyroxine, a synthetic form of the thyroid hormone T4, is the standard and most commonly prescribed medication for hypothyroidism. The goal of treatment is to normalize thyroid hormone levels and relieve symptoms. Levothyroxine is usually taken on an empty stomach, preferably in the morning, to maximize absorption.
It is recommended to wait at least 30 minutes to an hour before eating or taking other medications that may interfere with absorption. To enhance absorption, it is advisable to administer levothyroxine 30-45 minutes before breakfast or at least 3 hours after consuming a meal, making these times convenient for the majority of patients. Furthermore, elemental supplements like calcium and magnesium can impede levothyroxine absorption.
Commonly prescribed medications such as proton pump inhibitors also negatively affect levothyroxine absorption. Consistency in the formulation or brand of levothyroxine is crucial. Slight variations in dosage among generic formulations may impact a small subset of highly sensitive hypothyroid patients, underscoring the importance of maintaining uniformity.Â
Gel formulations of thyroid hormone replacements, such as Triocent, are employed in malabsorption syndromes. Agents like sucralfate, calcium preparations, and bile acid sequestrants can impede the absorption of levothyroxine. Notably, the levothyroxine absorption test is conducted to demonstrate a patient’s inability to absorb levothyroxine.Â
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