Thyroid Flashcards
Reference range for TSH
0.5 to 4.5 mIU/L
Drugs that inhibit TRH
Somatostatin and its analogs
Drugs that can inhibit TSH
Dopamine
Dopamine agonists
High levels of glucocorticoid
T4 other name
Thyroxine
Free t4 reference range
0.7 to 1.9 ng/dL
Half life of thyroxine
7-10 days
T3 other name
Triiodothyronine
Half life of triiodothyronine
24 hours
Hyperthyroidism diagnosis with tsh and t4
Tsh low
T4 elevated
Primary causes of hyperthyroidism
Graves' disease Toxic multinodular goiter Toxic adenoma Thyroid cancer Iodine excess
Most common cause of hyperthyroidism
Graves’ disease
Secondary causes of hyperthyroidism
Tsh secreting pituitary tumors
Gestational thyrotoxicosis
Which sex is at greater risk for Graves’ disease
Female
Tshr-sab antibodies seen in what disease
Graves’ disease
Pathology of Graves’ disease
Antibodies increase tsh release causing increase t4 release
Visual findings with Graves’ disease
Opthalmopathy
Eye lid retraction
Skin signs and symptoms in Graves’ disease
Non pitting edema
Treatment options for Graves’ disease
Radioactive iodine
Ptu
Mmi
Surgery
Thyroid radiology scan also called
Radio iodine uptake RAIU
Thyroid radiology testing contraindicated in who
Pregnant or breastfeeding
Symptoms of hyperthyroidism
Nervousness Fatigue Weakness Increased perspiration Heat intolerance Tremor Hyperactivity, irritability Palpitations Increased appetite Weight loss Menstrual disturbance Diarrhea
Signs of hyperthyroidism
Hyperactivity Tachycardia Atrial fibrillation Hyperreflexia Warm skin Moist skin Goiter Muscle weakness Ophthalmopathy (graves disease) Dermopathy (Graves' disease )
Non pharm therapy for hyperthyroidism
Avoid strenuous exercise Avoid caffeine Avoid Otc decongestant Avoid iodine supplement and contrast media Smoking cessation
Who is indicated for thyroid surgery
Large goiters
Thyroid cancer
Unresponsive to therapy
Pharm treatment options for hyperthyroidism
Iodine
Radioactive iodine
Anti thyroid drugs
Beta blockers
Anti thyroid drugs used
Propylthiouracil
Methimazole
Beta blockers used for hyperthyroidism
Metoprolol Atenolol Propranolol Nadolol Esmolol
How do beta blockers help in hyperthyroidism
Alleviate symptoms such as palpitations
When is esmolol used
Thyroid storm
Why are non selective beta blockers and nadolol used for hyperthyroidism
Reduces the conversion of t4 to t3
Anti thyroid drugs also called
Thionamides
Anti thyroid drugs not recommended in who
Low RAIU hyperthyroidism
Which anti thyroid drug is usually preferred
Methimazole
When is methimazole not preferred
Thyroid storm
First trimester
Methimazole allergy
Methimazole duration of treatment
Ideally 12-18 months
If euthyroid discontinue
Initial dose of methimazole
10-20 mg daily
Propylthiouracil duration of treatment
Short time frame
Propylthiouracil initial dose
50-150 mg TID
Side effects of anti thyroid drugs
Hepatotoxic Agranulocytosis Arthralgia Skin rash GI upset
Boxed warning on propylthiouracil
Hepatotoxic
Define thyrotoxicosis
Any syndrome with increased thyroid hormones
Risk with hyperthyroidism in pregnancy
Increased risk of miscarriage
Pregnancy effect of hyperthyroidism
Worsens
Why use propylthiouracil in first trimester
Methimazole teratogenic in first trimester
Which anti thyroid drug to use while breastfeeding
Methimazole
Which hyperthyroidism treatment preferred in pediatric
Methimazole
Consider beta blockers
Avoid which two hyperthyroidism treatments during pregnancy
Radioactive iodine
Surgery if possible
What is thyroid storm
Severe form of thyrotoxicosis
Thyroid storm labs
Tsh undetectable
T4 and t3 elevated
Signs and symptoms of thyroid storm
High fever Tachycardia Tachypnea Dehydration delirium Coma GI disturbances
Causes of thyroid storm in a hyperthyroidism patient
Trauma
Surgery
Radioactive iodine treatment
Sudden withdrawal from anti thyroid meds
Treatment options for thyroid storm
Supportive care Steroids Short acting beta blockers Oral lodine Anti thyroid drugs
Iodide MOA
Inhibit thyroid hormone synthesis and release
Iodide recommended when
Prior to thyroid surgery (graves)
Thyroid storm
Non thyroid patients post nuclear attack
Name two iodide solutions
Potassium iodide
Lugols solution
Recommended dose of iodide
120-400 mg per day
Side effects of iodide treatment
Palpitations
Depression
Gynecomastia
Pustular skin pockets
MOA of radioactive iodine
Thyroid cell necrosis over a few weeks
When is radioactive iodine recommended
Graves’ disease
Toxic adenomas
Toxic multinodular goiters
When is radioactive iodine contraindicated
Pregnancy
Do you give radioactive iodine with high t4 levels
Pretreat with methimazole. Discontinue methimazole within 7 days of radioactive iodine
Side effects of radioactive iodine
Hypothyroidism
Sialadentis
Can worsen graves orbitopathy
What is sialadenitis
Salivary gland inflammation
What is subclinical hyperthyroidism
Low tsh
Normal t4
Maybe symptoms
How often to monitor tsh for subclinical hyperthyroidism without treatment
Every 6 months
Treat which patients with subclinical hyperthyroidism
Tsh less than 0.1 mIU/L
Post menopausal women
Cardiovascular disease
Why treat subclinical hyperthyroidism
Increase risk of bone density loss
Increase risk of cardiovascular events
Screen who for hyperthyroidism
High risk
Women over 50
Which individuals are at high risk for hyperthyroidism
Presence of nodular goiters
Concurrent endocrine disorders
Concurrent medications
Concurrent medical conditions
Which medications cause high risk of hyperthyroidism
Amiodarone Alpha interferon Lithium Interleukin 2 Iodide contrast
Which medical conditions cause high risk of hyperthyroidism
Osteoporosis
Atrial fibrillation
Supra ventricular tachycardia
Hypothyroidism lab findings
High tsh
Low t4
Causes of hypothyroidism
Primary gland failure Insufficient gland stimulation by hypothalamus Autoimmune thyroid disease Iatrogenic causes Drug causes Disorder causes
What causes primary gland failure
Hashimoto disease
Iodine deficiency
Congenital abnormalities
What are iatrogenic causes of hypothyroidism
Post thyroid surgery
Radioactive iodine treatment
Which drugs cause hypothyroidism
Lithium Amiodarone Interferon alpha Interleukin 2 Ethionamide Sulfonylurea Valproic acid Tyrosine kinase inhibitors
Name a disorder that can cause hypothyroidism
Postpartum thyroiditis
Who gets screened for hypothyroidism
Only high risk patients
Who is high risk for hypothyroidism
History or first degree relative with autoimmune Radioactive iodine therapy Head and neck radiation Presence of a goiter Family history of a goiter Drugs that affect thyroid Psych disorders
Who is at higher risk of hypothyroidism wig interferon alpha
Asians
Thyroid antibodies
How does lithium cause hypothyroidism
Inhibits thyroid hormone secretion and synthesis
How does amiodarone cause hypothyroidism
Blocks conversion of t4 to t3
Decreases t3 receptor binding
Effects of amiodarone on thyroid labs
Decrease t3
Increase t4
Increase tsh
Symptoms of hypothyroidism
Fatigue Lethargy Mental impairment Depression Cold intolerance Dry skin Weight gain Decreased perspiration Menstrual disturbances Hair thinning or loss Muscle weakness Constipation
Signs of hypothyroidism
Slow speech Hoarseness Bradycardia Delayed reflexes Nonpitting edema Diastolic hypertension Elevated c reactive protein Increased creatinine kinase Increased triglycerides Increased ldl Hypothermia
Treatment options for hypothyroidism
Levothyroxine
Liothyronine
Dessicated thyroid
Liotrix
Levothyroxine brand name
Synthroid
Levoxyl
Levothyroxine contains which thyroid hormones
T4
Gold standard for hypothyroidism
Levothyroxine
Levothyroxine typical dose
1-1.6 mcg/kg/day
Liothyronine brand name
Cytomel
Liothyronine thyroid hormones
T3
Dessicated thyroid brand name
Armour thyroid
Desiccated thyroid contains what thyroid hormones
T4 and t3
Liotrix brand name
Thyrolar
Liotrix thyroid hormones
T4 and t3 in a 4:1 ratio
When to check thyroid labs if brand and generic are switched
6 weeks
Dose of levothyroxine in patients less than 65 with no cardiovascular disease
1.6 mcg/kg/day
Levothyroxine dose in persons over 75
1mcg/kg/day
Typical starting dose 25-50mcg
When to check tsh after starting levothyroxine
4-8 weeks
Separate levothyroxine how with calcium, iron, or prenatals
2 hours before or 6 hours after
Monitoring for levothyroxine
Tsh every 6-12 months with evaluations of symptoms
Hypothyroidism to euthyroid warfarin effects
Decrease dose as become euthyroid
Starting dose of levothyroxine in elderly with ischemic heart disease
12.5-50 mcg
After what age do pediatrics get adult doses of levothyroxine
12 years
Pregnancys effect on thyroid hormone
Increase demand
Give what to patients on levothyroxine with normal labs but symptoms
T3/t4 combination
Possible cause of symptoms of hypothyroidism on treatment with normal labs
Type 2 deiodinase polymorphism
Triggers of myxedema coma in long standing hypothyroidism
Trauma
Infection
Stroke
Hypnotics or opiates
Signs or symptoms of myxedema coma
Cns depression
Respiratory depression
Cardiac complications
Treatment options for myxedema coma
Levothyroxine bolus Iv
Glucocorticoid
Combination t4/t3
Lab findings of subclinical hypothyroid
Elevated tsh (4.5-10)
Normal t4
Maybe symptoms
Treat who with subclinical hypothyroidism
Tsh greater than 10 Elevated antibody levels Signs and symptoms Pregnant Tsh 5-10
Dangers of subclinical hypothyroidism
Increased cardiac mortality
Increased ldl
Neuropsychiatric signs
Decreased exercise tolerance
Hypothyroidism is linked to what other diseases
High cholesterol Increased vascular resistance Decreased cardiac output Increased diastolic blood pressure Dementia like state Increased risk of miscarriage
