Hypothyroidism resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Overview

This section provides a short and straight to the point overview of the disease or symptom. The first sentence of the overview must contain the name of the disease.

Causes

Hypothyroidism can be classified based on the location of the pathology or based on etiology as shown in the table below.

Causes of hypothyroidism
Primary hypothyroidim					Central hypothyroidism ( Secondary and Tertiary )							Congenital hypothyroidism
Auto immune	Drug induced	Iatrogenic	Transient Hypothyroidism	Infiltrative disorders	Genetic causes	Iatrogenic	Tumors	Vascular	Infiltrative	Infectious	Miscellaneous
Hashimotos thyroiditis Atrophic thyroiditis	Thionamides Lithium Amiodarone Iodine containing contrast agents Interferon - alfa Tyrosine kinase inhibitor	Subtotal or Total thyroidectomy Radioiodine therapy External radiation of neck Iodine deficiency	.Subacute granulomatous thyroiditis Postpartum thyroiditis Painless (silent, lymphocytic) thyroiditis	Amyloidosis Sarcoidosis Hemochromatosis Scleroderma Cystinosis Reidel's thyroiditis( fibrous thyroiditis )	TRH deficiency Isolated CeH Inactive TSH Inactive TRH receptor	Post pituitary surgery Post external radiation Drugs : GH therapy, Glucocorticoids, RXR agonists, Salicylates, Dopamine	Pituitary macro adenoma Craniopharyngioma Meningioma Glioma Rathke cleft cyst Metastatic	Hemorrhage: Pituitary apoplexy, Subarachnoid hemorrhage Ischemic: Postpartum pituitary necrosis Aneurysm	Hemochromatosis Histiocytosis Sarcoidosis	Syphilis Bacterial abscess Tuberculosis Toxoplasmosis	Transient: over replacement of T4 in primary hypothyroidism, Sick euthyroid state Trauma: head injury	Thyroid dysgenesis Thyroid agenesis Thyroid dyshormonogenesis

Common cause 1

• Common cause 2
• Common cause 3
• Common cause 4
• Common cause 5

Diagnosis

Shown below is an algorithm summarizing the diagnosis of hypothyroidism

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Signs and Symptoms of hypothyroidism present

TSH,freeT4 (FT4)

TSH >5.5mU/L

TSH 0.5-5mU/L

TSH <0.5mU/L

FT4 low

FT4 Normal

FT4 elevated

FT4 low

FT4 low

TPOAb (Thyroid peroxidase antibody)

Subclinical hypothyroidism

1. T4 to T3 conversion defect (5' deiodinase deficiency, amiodarone use), 2. Thyroid hormone resistance

1. Central hypothyroidism, 2. T3 replacement therapy

1. Following excess levothyroxine withdrawal, 2. "Post hyperthyroid" hypothyroidism ( I131 or surgery), 3. T3 replacement therapy, 4.Central hypothyroidism

Positive

Negative

Central hypothyroidism

Autoimmune thyroid disease

1. Euthyroid sick syndrome 2. External radiation 3. Drug induced 4. Iodine deficiency 5. Congenital hypothyroidism 6. Seronegative autoimmune thyroid disease

Measure TRH

Depressed

Normal or Elevated

Tertiary hypothyroidism (hypothalamic cause)

Secondary hypothyroidism (pituitary cause)

Treatment

Shown below is an algorithm summarizing the treatment of [[disease name]] according the the [...] guidelines.

Do's

• The content in this section is in bullet points.

Don'ts

• The content in this section is in bullet points.

References

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