ENDO-HYPOThy Flashcards
Describe Hypothyroidism
Hypometabolic state resulting from insufficient production of thyroid hormones
Describe Primary hypothyroidism
high TSH with low T4 = thyroid gland etiology
Describe Secondary hypothyroidism
low TSH with low T4 = pituitary or hypothalamic etiology (less common); referred to endocrine
Who is more affected by thyroid disease
3 times more likely in women than in men
What is the most common cause of Hypothyroidism
1] dietary iodine deficiency (developing countries), 2] In the US, Autoimmune destruction of the thyroid (Hashimoto’s thyroiditis), 3] Iatrogenic, 4] Drug induced
What antibodies are invovled in Hashimoto’s thyroiditis
Anti-thyroid peroxidase antibodies; Anti-thyroglobulin antibodies
Describe the Iatrogenic cause of Hypothyroidism
resulting from hyperthyroid or thyroid cancer treatment (RAI, thyroidectomy)
Describe the drug induced cause of Hypothyroidism
lithium, amiodarone, thalidomide
Describe the onset of Hypothyroidism
insidious
What are the clinical features of Hypothyroidism
Fatigue, lethargy, increased sleep requirement, impaired mental function, depression, cold intolerance, weakness, myalgias ,weight gain, hair loss, skin & nail changes (dry, brittle, scaling), constipation, hoarseness, dysphagia, edema, menstrual irregularities (increased risk of miscarriage, infertility)
What are the physical exam findings of Hypothyroidism
palpable goiter, bradycardia, decreased tendon reflexes, macroglossia
Describe a goiter
enlarged thyroid gland; most common thyroid abnormality
Describe what an Endemic goiter indicates
iodine deficiency goiter
Describe what an Goiter + hyperthyroidism indicates
1] Graves disease, 2] toxic multinodular goiter; hot nodule
Describe what an Goiter + hypothyroidism indicates
Hashimoto’s thyroiditis
Describe the treatment of Goiters
1] Goiters often decrease in size with thyroid treatment (hyper/hypothyroid medication, RAI), 2] sometimes surgery indicated due to goiter affecting swallowing or causing airway obstruction
Describe the diagnostic values of Primary hypothyroidism
high TSH with low/low normal free T4
Describe the diagnostic values of Secondary hypothyroidism
low TSH with low free T4
What are additonal tests that confirm hypothyroidism?
1] Positive TPOAb or TgAb in autoimmune disease, 2] Decreased uptake on thyroid scan, 3] Additional lab findings can include anemia, elevated LDL, hyponatremia
What is the other name for Hashimoto’s Thyroiditis and why
Chronic Lymphocytic Thyroiditis because lymphocytic infiltration and destruction of thyroid tissue
What is the most common cause of hypothyroidism
Hashimoto’s Thyroiditis
Describe who is commonly affected by hypothyroidism
Most commonly affects women age 30-60, often family history present
List the findings of Hashimoto’s Thyroiditis
1] Associated with high titers of autoantibodies (TPOAb and/or TgAb), 2] Goiter is common finding
What is the treatment for Hashimoto’s Thyroiditis
lifelong replacement therapy due to autoimmune thyroid gland failure
Describe Thyroid hormone replacement
levothyroxine (Synthroid, Levoxyl, Levothroid, Tirosint)
What is the dosing for levothyroxine
1.7mcg/kg po qd (once daily dose, best taken on empty stomach in the morning)
Describe the approach to levothyroxine intiation
1] Conservative initial therapy: incremental increase to slowly achieve restoration of normal metabolic rate 50 mcg; 2] Children, elderly or cardiac pts. start tx at low dosage
Describe the clinical response of levothyroxine
Full clinical response usually takes several months, ideally repeat labs 4-6 weeks after starting therapy and adjust dose prn
Describe the target response of levothyroxine
TSH and T4 both within normal range- euthyroid
What is a complication of hypothyroidism
Myxedema Coma
Describe a Myxedema Coma
Severe hypothyroidism, often fatal, Medical emergency with high mortality rate as Respiratory failure is a major concern
Who is more at risk for Myxedema Coma
More typically seen in the elderly with long-standing, untreated hypothyroidism; Often precipitated by acute event: infection (pneumonia, peritonitis), MI, CVA, trauma
Define Myxedema
generalized skin and soft tissue swelling due to abnormal deposits of mucin
Describe the clinical findings of Myxedema Coma
1] Skin: extensive scaling, dry, cold; appears thickened or “doughy”; yellow-orange discoloration; periorbital edema and nonpitting edema throughout, 2] Sinus bradycardia, hypotension, hypoventilation, pericardial effusion, pleural effusion, ascites, 3] Decreased mental status, slowed speech, ataxia
