Disorders of the Thyroid Flashcards
What is thyroid storm? How do we deal with it?
A life threatening form of thyrotoxicosis characterized by high fever, tachyarrhythmia, psychosis, confusion, diarrhea, and liver dysfunction.
Needs antithyroid medications and B-adrenergic blockers
What does hyperthyroidism lead to and what causes it?
Hyperhyroidism causes thyrotoxicosis, elevated thyroid hormones in the blood. Graves Disease causes the majority of cases.
What is the etiology behind hyperthyroidism caused by Graves Disease?
Thyroid stimulating immunoglobulin (TSI) binds TSH receptor on the thyroid gland, leading to an increase in T3/T4. This is a type II hypersensitivity.
Can also be associated with other autoimmune conditions
How does hyperthyroidism secondary to Graves Disease present?
Diffuse, nontender Goiter with or without bruit.
Infiltrative opthalmopathy (exopthalmos, extraocular muscle dysfunction)
Pretibial myxedema
What is the etiology behind hyperthyroidism caused by Plummer disease? How does it present?
Also known as Toxic Multinodular goiter, this is where you get hyperfunctioning areas of the thyroid that dish out a lot more T3/T4 (shows a patchy uptake on thyroid scan, vs a diffuse one as we see with Graves).
This is all due to a TSH receptor mutation, and is most commonly seen in the elderly. It presents similarly as Graves, but not as severe.
What is the etiology of hyperthyroidism caused by subacute thyroiditis?
Also called de Quervain thyroiditis, this is an inflammation of he thyroid gland, leading to a spilling of preformed thyroid hormones, which leads to transient hyperthyroidism. Pituitary inhibition causes transient hypothyroidism before returning to a normal thyroid state.
High yield, this is usually preceeded by an upper respiratory infection.
Clinical manifestation of Subacute thyroiditis?
Thyroid gland firm and tender, fever, increased ESR with pain radiating to ears, neck, and arm
What is struma ovarii?
This is a very rare condition in which ectopic thyroid tissue develops as part of an ovarian tumor, causing hyperthyroidism.
What is the general presentation of someone with hyperthyroidism?
General Symptoms: Tremor, weight loss with a robust appetite, irritable, restless, sweaty, increased bowel movements, tachycardia.
Classic: Warm and moist skin due to peripheral vasodilation and excessive sweating
Hyperthyroidism can cause an increased risk for:
Atrial fibrillation, isolated systolic hypertension, high-output cardiac failure
How do we diagnose hyperthyroidism?
- Increase levels of T3 and T4 (big leap here, I know)
- Decreased TSH (except with TSH secreting tumors)
- Anti-TSH receptor antibodies for Graves Disease
- Radioactive iodine uptake scan (diffuse for Graves, localized for toxic adenoma and multinodular thyroid and no uptake for thyroiditis and struma ovarii)
What are our treatment options for hyperthyroidism?
Propylthiouracil (PTU) and methimazole - Inhibit thyroid hormone synthesis by inhibiting the organification of iodine. Also inhibits the peripheral conversion of T4 to T3
Radioactive iodine ablation - Destroy thyroid follicular cells. Radioiodine is contraindicated for treatment of hyperthyroidism during pregnancy because it can cross the placenta and destroy the infants thyroid
B-blockers - Like propanolol; Control of adrenergic symptoms like sweating, tachycardia, tremor
What is primary hypothyroidism?
Failure of the thyroid gland itself, leading to hypothyroidism
What is Hashimoto Thyroiditis?
Autoimmune (HLA-DR5) condition of the thyroid.
How do we confirm Hashimoto Thyroiditis?
Histo - Lymphocytic infiltrate with germinal centers AND Hurthle cells ( a Hurthle cell is a kind of thyroid cell that has a distinctive look: Under the microscope it is bigger than a follicular cell and has pink-staining cellular material)
Labs - Antithyroid peroxidase antibodies confirm the diagnosis.
What is subacute (de Quervain) thyroiditis?
Self-limited hypothyroidism following a flu-like illness with hyperthyroid symptoms seen early on.
How do we confirm subacute (de Quervain) thyroidits?
Histology - Granulomatous inflammation
Labs - Elevated ESR
PE - Tender thyroid and jaw
Most common cause of hypothyroidism?
Iodine deficiency. We can also see it with lithium toxicity
What is Riedel thyroiditis?
Rare disease in which the thyroid is chronically replaced by fibrosis. We see rock hard, fixed, but painless goiter.
Sheehan Syndrome? How do we recognize it?
This is a secondary cause of hypothyroidism. This is postpartum pituitary necrosis secondary to postpartum hemorrhage. We see low levels of TSH
What is a goiter? What is the most common cause?
An enlarged thyroid gland due to any cause such as inflammation, tumor, or autoimmune disease. Endemic goiter, caused by iodine deficiency, is the most common cause of goiter worldwide.
What is the general presentation of goiter?
Lethargy, fatigue, muscle weakness, cold intolerance (remember, heat intolerance for hyperthyroidism), weight gain, slow mentation
What is myxedema coma?
A symptom of hypothyroidism, we see stupor, a coma, and hypoventilation coupled with hypothermia, bradycardia, and hypotension
How do we diagnose hypothyroidism?
Chemistries: Mild normocytic anemia, hyponatremia, and hypoglycemia
Immunology: Antithyroid peroxidase antibody test for hashimoto thyroiditis
Risk factors for thyroid neoplasms?
Childhood head and neck radiation exposure, male gender, young age, and a positive family history
Hypothyroidism in newborns causes what condition? Describe it.
Cretinism - Mental retardation, short stature, coarse features, umbilical hernia.
What is the typical presentation for a thyroid neoplasm?
Typically presents as a solitary nodule. Dyspnea, coughing/choking spells. dysphagia and hoarseness due to compression of the trachea and esophagus.
How do we diagnose the different neoplasms of the thyroid?
Fine needle aspiration - Provides diagnostics for four different types of the neoplasms
How do we treat thyroid neoplasms?
Thyroidectomy unless its an anaplastic carcinoma
What are MEN?
Just think Don Rees
What are multiple endocrine neoplasias (MEN)? How do we categorize them?
Autosomal Dominant inherited syndromes divided into three categories:
MEN 1 (Wermer Syndrome) - Tumors of the 3 P’s (Pancreas, Pituitary, Parathyroid). May present with kidney stones secondary to hyperparathyroidism and GI ulcers secondary to gastrin-producing pancreatic adenomas which cause Zollinger-Ellison Syndrome
MEN 2A (Sipple Syndrome) - Medullary thyroid carcinoma, pheochromocytoma and parathyroid adenoma
MEN 2B - Medullary thyroid carcinoma, pheochromocytoma, and oral/GI ganglioneuromatosis (associated with marfanoid habitus)
Mutations that cause the MEN
MEN 1 arises from mutations in the self-named men1 oncogene. MEN 2A and 2B stem from mutations in the ret oncogene.
