Hypothyroidism

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Hypothyroidism Main page
Patient Information
Overview
Classification Primary hypothyroidism Hashimoto's thyroiditis Secondary hypothyroidism Tertiary hypothyroidism
Differentiating different causes of hypothyroidism
Screening
Diagnosis
History and symptoms

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mahshid Mir, M.D. [2]

Synonyms and keywords: Myxedema; myxoedema; thyroid activity decreased; hypothyroid

Classification

	Endagenous causes	Exagenous causes
		Surgery or radiation	Other causes
Primary hypothyroidism	Congenital hypothyroidism Autoimmune (Hashimoto's) thyroiditis	Thyroidectomy Radioiodine therapy of thyroid gland	Iodine deficeincy Drug induced thyroiditis Amiodarone Lithium Thionamide Iodine Iterferon Sunitinib Rifampicin Thalidomide
Transient hypothyroidism	Subacute (de Quervain’s) thyroiditis Postpartum thyroiditis
Secondary hypothyroidism	Pituitary mass lesions, especially pituitary adenomas Brain cysts and abscesses meningiomas dysgerminomas metastatic tumors craniopharyngiomas pituitary apoplexy Sheehan syndrome (postpartum pituitary necrosis) Idiopathic isolated TSH deficiency	surgery of pituitary adenomas radiation therapy of pituitary adenomas or other mass lesions near pituitary gland	head trauma with injury of the stalk
Tertiary hypothyroidism	hemochromatosis histiocytosis autoimmune lymphocytic hypophysitis Developmental abnormalities internal carotid aneurysms Other central nervous system (CNS) tumors Idiopathic isolated TRH deficiency	Radiation in high doses to the brain infratemporal nasopharyngeal oropharyngeal	Infections tuberculosis syphilis toxoplasmosis sarcoidosis

• Primary hypothyroidism
  • Congenital hypothyroidism 17512233
  • Autoimmune (Hashimoto's) thyroiditis
  • Iodine deficeincy
  • Drug induced thyroiditis
    • Amiodarone
    • Lithium
    • Thionamide
    • Iodine
    • Iterferon
    • Sunitinib
    • Rifampicin
    • Thalidomide
  • Thyroidectomy
  • Radioiodine therapy
• Transient hypothyroidism 9294788
  • Subacute (de Quervain’s) thyroiditis
  • Postpartum thyroiditis

• Secondary hypothyroidism (due to decreased levels of TSH) 8772595 1486881 18941435
  • Pituitary mass lesions, especially pituitary adenomas
  • cysts and abscesses
  • meningiomas
  • dysgerminomas
  • metastatic tumors
  • craniopharyngiomas
  • surgery or radiation therapy for pituitary adenomas or other mass lesions near pituitary gland
  • head trauma with injury of the stalk 15144914
  • pituitary apoplexy
  • Sheehan syndrome (postpartum pituitary necrosis)
  • Idiopathic isolated TSH deficiency

• Tertiary hypothyroidism
  • Infiltrative disorders affecting the pituitary or the hypothalamus include hemochromatosis, and histiocytosis
  • autoimmune lymphocytic hypophysitis
  • Developmental abnormalities
  • internal carotid aneurysms
  • Other central nervous system (CNS) tumors
  • Idiopathic isolated TRH deficiency

Differential diagnosis

Disease	History and symptoms					Laboratory findings								Additional findings
	Fever	Goiter				Serum glucose	Urinary Glucose	Urine PH	Serum Sodium	Urinary Glucose	24 hrs cortisol level	C-peptide level	Serum glucagon
Primary hypothyroidism	+	+	+	+	-	↑	↑	Normal	Normal	N/↑	Normal	↓	Normal	Auto antibodies present (Anti GAD-65 and anti insulin anti bodies)
Transient hypothyroidism	+	+	+	+	-	↑	↑	Normal	Normal	↑	Normal	Normal	↑	Acanthosis nigricans
Subclinical hypothyroidism	+	+	+	-	+	↑	↑	Normal	Normal	↑	Normal	Normal	N	-
	+	+	-	-	-	Normal	Normal	Normal	↓	Normal	Normal	Normal	Normal	-
	+	+	-	-	-	Normal	Normal	Normal	↑	Normal	Normal	Normal	Normal	-
Transient hyperglycemia	-	-	-	-	-	↑	↑	Normal	Normal	↑	Normal	Normal	N/↑	In hospitalized patients especially in ICU and CCU
Steroid therapy	+	-	-	-	+	↑	↑	Normal	Normal	↑	↑	N/↑	N/↑	Acanthosis nigricans,
RTA 1	-	-	-	+	-	Normal	Normal	↑	Normal	↑	Normal	Normal	Normal	Hypokalemia, nephrolithiasis
Glucagonoma	-	-	-	-	-	↑	Normal	Normal	Normal	-	Normal	Normal	↑	Necrolytic migratory erythema
Cushing syndrome	-	-	-	-	+	↑	-	Normal	↓	N/↑	↑	Normal	Normal	Moon face, obesity, buffalo hump, easy bruisibility

General feature

Symptoms

	Constituitional	Local	Reproductive	Neuropsysiological	Others	Physical exam
	cold intolerance puffiness decreased sweating coarse skin hypothermia Fever if accompanied by thyroiditis weight gain coarse, brittle, straw like hair with hair loss	obstructive sleep apnea (secondary to macroglossia)	Females can present with galactorrhea and menstrual disturbances	depression	paresthesia and nerve entrapment syndromes	decreased systolic blood pressure increased diastolic blood pressure bradycardia pericardial effusion abdominal distension ascites (uncommon) non-pitting edema (myxedema) pitting edema of lower extremities hyporeflexia with delayed relaxation ataxia
		fullness and pain in the throat and neck	infertility	emotional lability	constipation
		hoarseness sore throat		blurred vision	macroglossia
		goiter		Attention deficit	periorbital puffiness
				slowed speech and movements

• Metabolic abnormalities associated with hypothyroidism include:
  • anemia,
  • dilutional hyponatremia,
  • hyperlipidemia,
  • reversible increase in creatinine

Complications

Myxedema coma

Rare, severe form of hypothyroidism, a life-threatening condition

• Altered mental status,
• hypothermia,
• bradycardia,
• hypercarbia, and
• hyponatremia.
• Cardiomegaly,
• pericardial effusion,
• cardiogenic shock, and
• ascites
• commonly occurs in individuals with undiagnosed or untreated hypothyroidism who is subjected to an external stress, such as low temperature, infection, or medical intervention (e.g., surgery or hypnotic drugs)