Endocrine #2 (Thyroid Disorders) Flashcards
Explain the hypothalamus-pituitary-thyroid axis.
Describe a primary thyroid disorder. How about a secondary disorder?
Hypothalamus secretes TRH –> Pituitary secretes TSH –> Thyroid secretes T3 and T4
Primary: Disease in the thyroid
secondary: Disease in hypothalamus or pituitary
MCC of Hyperthyroidism. Explain the pathophysiology of this.
Graves Disease
Autoimmune disease: TSH receptor antibodies target and stimulate TSH receptor leading to thyroid gland enlargement and hyperthyroidism (t3 and T4 production)
Symptoms of hyperthyroidism
-Palpitations
-Heat Intolerance
-Tremors, weight gain
-Atrial fibrillation
-Ophthalmopathy: proptosis, exophthalmos, lid lag, diplopia, vision changes
-Pretibial Myxedema: swollen red patches on legs with non-pitting edema
-Warm, moist skin
-Fine Hair
-Diffusely enlarged non-tender goiter
-Hyperreflexia
-Insomnia
-Diarrhea
-Fine Tremors, Anxiety, Nervousness
What labs are done for hyperthyroidism? What is specific for Graves Disease?
What is shown on radioactive iodine uptake scan?
-Decreased TSH + Increased Free T4 and T3
- Thyroid Stimulating Immunoglobulins (TSH receptor antibodies) for Graves
-Diffuse, increased iodine uptake (active and hyper)
Treatment for Hyperthyroidism
_____ for Symptoms
______first line for thyroid hormone synthesis
______ for ophthalmopathy
Beta Blockers for symptoms
Methimazole or Propylthiouracil (PTU)
Glucocorticoids
What treatment is preferred in the first trimester and for thyroid storm?
PTU
What is thyroid storm/thyrotoxicosis?
Potentially fatal if untreated, thyrotoxicosis after a precipitating event (surgery, trauma, infection, pregnancy, preeclampsia)
-Hyperthyroid with an event that makes it much worse
Symptoms of thyroid storm
-Hyperthyroid storm + CV Dysfunction (palpitations, tachycardia, A-fib, CHF)
-High fever, Tremors
-CNS Dysfunction: delirium, psychosis, stupor, coma
Management for thyroid storm
-IVF + Propanolol + IV Glucocorticoids + PTU
-Then oral or IV sodium iodide
-Cooling blankets
-Antipyretics (not Aspirin)
What is the MCC of Hypothyroidism in the US?
What is the pathophysiology of this?
Hashimoto Thyroiditis
Autoimmune thyroid cell destruction by anti-thyroid peroxidase and anti-thyroglobulin
What are other etiologies of hypothyroidism?
What is the MCC in the WORLD?
Amiodarone, Lithium, Alpha-Interferon
Hashimoto’s
Iodine Deficiency MCC in world
Symptoms of hypothyroidism
-Decreased metabolic rate
-Cold intolerance
-Weight gain
-Dry, thick rough skin
-Loss of outer 1/3 of eyebrow
-Nonpitting edema (Myxedema)
-Fatigue, memory loss, depression
-Constipation
-Anorexia
-Bradycardia
-Galactorrhea (increased prolactin)
What is the normal lab values for hypothyroidism?
What is specific to Hashimoto?
What is seen on radioactive iodine uptake scan?
Increased TSH + Decreased free T3/T4
+ Antithyroid peroxidase and/or anti-thyroglobulin antibodies
Decreased iodine uptake (inactive and slow)
Treatment for hypothyroidism
-Levothyroxine (Synthetic T4)
AKA Synthroid
Explain what myxedema coma is.
Who should you think about when thinking about this condition?
What are some other “precipitating events”
Extreme form of hypothyroidism with a high mortality rate
Elderly women with a long-standing history of hypothyroidism in the winter
Discontinuation of Levothyroxine, infection, CHF, etc.
Symptoms of Myxedema Coma
-Severe signs of hypothyroidism + bradycardia + hypothermia + hypotension + hypoglycemia + hyponatremia
Treatment for Myxedema Coma
-IV Levothyroxine + Supportive (ICU, passive warming), IV Glucocorticoids
What are some etiologies of iatrogenic hypothyroidism?
-Surgery without subsequent thyroid hormone replacement
-Amiodarone
-Lithium
-Alpha-Interferon
What is Cretinism?
What is the MCC in developing counties?
What is the MCC in developed countries?
Untreated congenital hypothyroidism
-Developing: lack of maternal iodine intake
-Developed: Dysgenesis of thyroid gland
Symptoms of cretinism
-Mental developmental delays
-Symptoms of hypothyroidism
-Goiter symptoms: hoarseness and dyspnea
-Coarse facial features: Macroglossia, umbilical hernia, hypotonia, feeding problems, prolonged jaundice
Treatment for Cretinism
Levothyroxine
What is subclinical hypothyroidism?
Isolated increased TSH in patients with little or no symptoms
What do labs show for subclinical hypothyroidism?
what is the treatment?
Isolated increased TSH + Normal T3/T4
Levothyroxine if TSH 10 or higher to prevent cardiovascular problems
Euthyroid Sick Syndrome is …..
It is MC seen in those with …..
Abnormal thyroid function tests in patients with normal thyroid function
Sepsis, malignancies, etc.
What unique thing is seen on diagnostics for Euthyroid Sick Syndrome?
Low T3 Syndrome: decreased free T3 and increased reverse T3 (inactive form of T3)
Risk factors for a thyroid nodule
-Extremes of age (very young or > 60)
-History of head and neck radiation
What is the MC type of thyroid nodule?
-Follicular adenoma (colloid)
Although most thyroid nodules are asymptomatic, what symptoms CAN the patient have?
-Compressive symptoms: swallowing or breathing difficulty, neck/jaw/ear pain, hoarseness (recurrent laryngeal nerve impingement)
What nerve can be compressed by a thyroid nodule?
Recurrent laryngeal nerve
On physical exam, explain what a benign thyroid nodule feels/appears like?
How about a malignant nodule?
Benign: varied, smooth, firm, irregular, sharply outlined, discrete, painless
Malignant: rapid growth, fixed in place, no movement with swallowing, hypoechoic on US
What is the initial test done to evaluate the nodule?
-Thyroid function testing
If TSH is normal, what is indicated to further evaluate the nodule?
FNA with biopsy
What test is done after thyroid function tests to determine if a FNA is needed?
Thyroid US
A FNA with biopsy is performed on a thyroid nodule if it is > _____________________ or in highly suspicious nodules
if > 1.5 cm with normal TSH
What can be performed if the FNA is indeterminate or low or subnormal TSH?
What results can you get with this and what does it mean?
Radioactive iodine uptake scan
Cold nodules (no or low iodine uptake) should be biopsied to rule out malignancy
Functioning (normal) or hot nodules have low malignancy potential
What is the treatment for a cold nodule, if thyroid cancer suspected, or an indeterminate FNA?
Surgical excision
If surgery is NOT performed for a thyroid nodule, when should you get an US?
Observation + follow up US every 6-12 months to observe for growth or changes
