Firecracker Endo II Flashcards
What binds to T3 and T4 in peripheral blood?
TBG (thyroxine-binding globulin)
Graves disease is characterized by a triad of which histologic findings?
1) Diffuse hypertrophy & hyperplasia of thyroid follicular epithelial cells
2) Pale colloid with scalloped (moth-eaten) margins
3) Lymphocytic infiltrate w/ germinal centers (!)
123I uptake results in a patient w/ Graves disease?
Diffusely ↑ 123I uptake in the whole thyroid gland.
123I uptake results in a patient w/ toxic multi nodular goiter?
Uneven 123I uptake with occasional autonomous “hot” nodules demonstrating ↑ 123I uptake.
123I uptake results in a patient w/ thyroiditis
↓ 123I uptake
123I uptake results in a patient w/ hypothyroidism taking too much levothyroxine
↓ 123I uptake
123I uptake results in euthyroid pt taking thyroid hormone for 2ndary gain?
↓ 123I uptake
In subacute lymphocytic thyroiditis, is the thyroid tender or nontender?
Nontender
What thyroid hormone is devoid of any biological activity?
Reverse T3
What are 5 common causes of hypothyroidism?
- Hashimoto thyroiditis (chronic autoimmune thyroiditis)
- Post ablation: Surgical or I-131 radiation
- Iodine deficiency
- Drugs: Lithium, Amiodarone, Sulfonamides
- Subacute lymphocytic thyroiditis (painless)
Hyperparathyroidism –> what electrolyte disturbance?
hypercalcemia
Can you describe some of the cardiac manifestations of hypothyroidism? What happens to HR, SV, PP, and CO?
Down
Down
Down
Down
A patient with a thyroid cancer is found to have increased calcitonin levels. Besides treatment of this patient’s thyroid cancer, you recommend evaluation of her:
Adrenal gland (think MEN IIa)
What is the typical presentation of subacute granulomatous (DeQuervain’s) thyroiditis?
Preceded by flu-like illness with sore throat and fever, jaw pain, tender thyroid, and a markedly elevated ESR. Causes can include mumps or coxsackievirus.
Describe the relationship between free serum Ca2+ levels and PTH secretion.
↓ Free serum Ca2+ causes ↑ PTH secretion and vice versa. Ca2+-sensing receptors on chief cells mediate these effects.
In patients with subacute granluomatous (DeQuervain’s) thyroiditis, what does histologic analysis of thyroid parenchyma typically reveal? (Try to name 2 characteristic findings)
- lymphocytic infiltrate
- multinucleate giant cells surrounding fragments of colloid
Treatment of hyperthyroidism
- Beta blocker
- Thioamide
- High-dose iodine
- High dose-radioactive iodine
The parathyroid gland contains which 2 types of cells?
Chief cells (water-clear appearance) & oxyphil cells.
Which cells secrete parathyroid hormone?
Chief cells
How does follicular thyroid carcinoma spread?
Hematagoneous
Treatment of DeQuervain
ASA
PTH –> Bone resorption of calcium and phosphate by binding the PTH receptor on osteoblasts → in response, osteoblasts secrete
M-CSF and RANK-L, which stimulate osteoclasts to break down bone and release calcium.
Medullary CA of thyroid is associated with which two MEN syndromes?
MEN 2a and 2b (2b is sometimes called 3)
- ↓ BMR (basal metabolic rate);
- Positive nitrogen balance (anabolic)
- ↓ Heat production
- Growth retardation
Metabolic changes in hypothyroidism
Cardiac effect of hyperthyroidism
Increased synthesis of beta1 receptors –> increased HR, contractility, and SV
What are the 2 dietary forms of vitamin D?
D2 or ergocalciferol from plants, and D3 or cholecalciferol from fish.
Dietary sources of vitamin D
egg yolk, fish oil, liver
Parathyroid hyperplasia is commonly associated with what 2 MEN syndromes?
MEN 1 and MEN 2A
- ↑ BMR (basal metabolic rate);
- Weight loss despite ↑ appetite
- Negative nitrogen balance (catabolic) → thyroid myopathy (proximal muscle weakness and ↓ muscle mass)
- ↑ Heat production and sweating
Metabolic manifestations of hyperthroidism
2 ways CKD –> hyperparathryoidism
- Decreased conversion of active vitamin D
2. Inadequate excretion of phosphate
What is the main GI side effect of hyperthyroidism?
diarrhea
What effect does thyroid hormone have on the autonomic nervous system? How does this occur?
increases sympathetic activity because it up-regulates β1-adrenergic receptors in the heart.
What is the only emergent hypothyroid condition?
Myxedema coma
What is the most common cause of hyperparathyroidism?
Single benign adenoma: 80% of cases
How does active vitamin D affect renal handling of calcium and phosphate?
- ↑ Reabsorption of Ca2+
- ↑ Reabsorption of phosphate
What is the Wolff-Chaikoff effect?
High levels of I- inhibit thyroid hormone synthesis by blocking the organification step.
which autoantibody is relatively specific for Graves?
TSI
- Lymphocyte infiltrate
- Prominent germinal follicles
- Hürthle cell metaplasia
histology of hashimoto
What effect does thyroid hormone have on bone growth?
bone growth, synergism with growth hormone and IGF-1 (insulin-like growth factor-1)
What anions inhibit the Na-I transporter of thyroid follicular cells?
thiocyanate and perchlorate
Clinical presentation of Hashimoto’s
Nontender thyroid, which often becomes diffusely enlarged → insidious development of hypothyroidism, most commonly in women age 30-50
Graves disease:
- more common in males or females?
- age range for peak incidence?
F > M (females are 10x more frequently affected than males); peak incidence between 20-40yo
In which patients does thyroid storm most commonly occur?
underlying Graves disease
- High fever (hyperpyrexia)
- Tachycardia out of proportion to fever
- Tachyarrhythmias
- Shock due to heart failure and/or vomiting-induced volume depletion
- Coma
Thyroid storm
Vitamin D causes resorption of bones in the setting of
hypocalcemia or too much vitamin D
What disorder of the peripheral nervous system can result from hypothyroidism?
Carpal tunnel
What are the signs and symptoms of acute thyroiditis? (Try to name 3)
- Fever
- Painful thyroid
- Painful cervical lymphadenopathy
What are 2 important histological findings associated with papillary thyroid carcinoma?
- orphan annie eye nuclei
2. psammoma bodies
Which thyroid carcinoma stains positive for amyloid?
Medullary
How many types of thyroid carcinoma are there?
4 - papillary, follicular, medullary, anaplastic
