Thyroid – hyperthyroidism

Question 1

Hyperthyroidism

Answer 1

Thyroid making too much thyroid hormone

Question 2

Thyrotoxicosis

Answer 2

Too much thyroid hormone for any reason

Exogenous hormone
Thyroid inflammation

Question 3

S/s of thyrotoxicosis

Answer 3

Tachycardia
Palpitations
Anxiety
Wt loss
Heat intolerance
Hyperactivity
Warm skin

Low TSH

Question 4

Toxic adenoma/multinodular goiter

Answer 4

Focal patches of hyper-functioning follicular cells

Mutation in TSH receptor

Hyperthyroidism w/o exophthalamos and pretibial myxedema

Radioactive iodine study – increased uptake – hot nodule

Question 5

Graves Disease

Answer 5

MC
Autoimmune
TSI (IgG Ab) binds TSH receptor -> secretion of T3, T4

Assoc w/ HLA-DR3, HLA-B8
4:1 female predominance

radioactive iodine study: increased uptake – diffusely

Features:
Exophthalmos
Pretibial myxedema
Warm, dry skin, thin hair
Tachycardia, palpitations
Muscle atrophy
Wt loss
Bowel hypermotility
Decreased or absent menstrual flow

Tx:
Methimazole (preferred) propulthiouracil (PTU) – inhibit thyroid production
b-blockers – tachycardia and anxiety
Radioactive iodine over months
Surgical removal

Question 6

Methimazole

Answer 6

Inhibits peroxidase in thyroid

Se:
AGRANULOCYTOSIS
Cause severe pharyngitis, pharyngeal abscesses

Cross placenta

• > fetal goiter and hypothyroidism
• > fetal aplasia cutis in first trimester

safe in pregnancy 2nd and 3rd trimesters – preferred

Question 7

Propylthiouracil (PTU)

Answer 7

Inhibits peroxidase in thyroid
Inhibits peripheral conversion of T4 -> T3

SE:
AGRANULOCYTOSIS
Liver dysfunction

Question 8

Struma ovarii teratoma

Answer 8

Contains functional thyroid tissue -> hyperthyroidism

Question 9

Thyroid storm (Thyrotoxic crisis)

Answer 9

Rare

Increased body temperature
Altered metnal status
Tachycardia, arrhythmias
V/D, dehydration
Coma
Death 20%

Tx:
Beta-blocker
Methimazole or PTU

Question 10

Causes of thyroiditis

Answer 10

Hashimoto
Subacute thyroiditis
Pregnancy and post partum – self limited, low uptake on scan

Overdose of thyroid medication – prescribed, factitious, accidental
-low uptake on scan

transient hyperthyroid – release d/t inflammation
-> normal or hypothyroid depending on damage

Question 11

Suspected thyrotoxicosis w/ normal TSH and T3/T4 ddx

Answer 11

Consider menopause, panic attack, anxiety, pheochromocytoma

Question 12

Suspected thyrotoxicosis w/ low TSH and high T3/T4 with low iodine uptake thyroid scan

Answer 12

Subacute thyroiditis:
Hx of URI
Painful tender thyroid gland

Excess T3/T4 dosing -> exogenous thyrotoxicosis

Question 13

Suspected thyrotoxicosis w/ low TSH and high T3/T4 with single hot nodule on iodine uptake thyroid scan

Answer 13

Thyroid adenoma

Question 14

Suspected thyrotoxicosis w/ low TSH and high T3/T4 with multiple hot and cold nodules on iodine uptake thyroid scan

Answer 14

Toxic multinodular goiter

Question 15

Suspected thyrotoxicosis w/ low TSH and high T3/T4 with diffuse uptake on iodine uptake thyroid scan

Answer 15

Grave’s disease

• TSI
• Exophthalmos
• Thyroid bruit