SM155 Thyroid Pathophysiology

Question 1

Hypothyroidism vs. hyperthyroidism: activity level, heart rate, temperature perception, reflexes, weight change, bowel symptoms, skin/hair, edema

Answer 1

Hypothyroidism: low activity/lethargy/weakness/fatigue, bradycardia, cold intolerance, diminished reflexes, weight gain, constipation, dry/cool skin and coarse/brittle hair, myxedema (facial/periorbital)

Hyper: high activity, tachycardia, heat intolerance, increased reflexes, weight loss, diarrhea, warm/moist skin and fine hair, pretibial myxedema

Question 2

Lab findings (TSH and T4/T3): primary hypothyroidism

Answer 2

TSH: high T4/T3: low

Question 3

Lab findings (TSH and T4/T3): primary hyperthyroidism

Answer 3

TSH: low T4/T3: high

Question 4

Lab findings (TSH and T4/T3): secondary hypothyroidism

Answer 4

TSH: low T4/T3: low

Question 5

Lab findings (TSH and T4/T3): secondary hyperthyroidism

Answer 5

TSH: high T4/T3: high

Question 6

Grave’s disease: pathophysiology

Answer 6

Autoimmune etiology. Autoantibodies bind TSH receptors and stimulate the thyroid to produce more thyroid hormone

Question 7

Grave’s disease: antibody and associated HLA subtype

Answer 7

TSI (thyroid stimulating immunoglobulin)

HLA DR3

Question 8

Grave’s disease: clinical signs

Answer 8

Ophthalmopathy (proptosis, EOM swelling), pretibial myxedema, diffuse goiter, connective tissue deposition

Question 9

Grave’s disease: thyroid storm

Answer 9

Stress-induced catecholamine surge that can lead to death by arrhythmia

Question 10

Grave’s disease: beta-blockers

Answer 10

Lower HR, helps with trembling and irritability

Question 11

Grave’s disease: thionamides (when do you use one over the other?). Dangerous side effect?

Answer 11

Methimazole and Propylthiouracil (PTU) both block TPO. PTU also blocks 5’-deiodinase.

Only use PTU during first trimester of pregnancy.

Agranulocytosis.

Question 12

Other autoimmune disease associated with Grave’s

Answer 12

Vitiligo

Question 13

Endocrine ophthalmopathy

Answer 13

Seen in Grave’s disease.

Includes chemises, proptosis.

Question 14

Radiotherapy

Answer 14

131-I destroys thyroid follicular cells with beta-irradiation. Slow onset of effects (need to treat with thionamides in the meantime).

Question 15

Postpartum thyroiditis (PPT): definition, at risk groups

Answer 15

Occurrence of hyperthyroidism (or hypothyroidism) during the postpartum period

At risk: DI (type I), other autoimmune disease

Question 16

Subacute thyroiditis (de Quervain’s): course, path finding, clinical signs

Answer 16

Self-limited, follows flu-like illness
Granulomas
High ESR, jaw pain, tender thyroid

Question 17

Course of thyroiditis

Answer 17

Often hyper- initially (lots of hormone is pre-made and then released upon damage) and hypo- later in the course

Question 18

Toxic multinodular goiter: pathophysiology, Jod-Basedow phenomenon,

Answer 18

Focal patches of overactive follicular cells (working independently of TSH due to activating mutation to the TSH receptor) secrete more T4/T3

Jod-Basedow: thyrotoxicosis when an iodine deficient patient is given iodine

Question 19

Iodine deficiency: clinical sign, severe manifestation

Answer 19

Goiter
Cretinism (severe fetal deficiency)

Question 20

Congenital hypothyroidism: clinical signs (5 P’s)

Answer 20

Pot-bellied, pale, puffy-faced, protruding umbilicus, protuberant tongue

Question 21

Riedel’s thyroiditis: pathophysiology, clinical signs

Answer 21

Thyroid gets replaced by fibrous tissue

Fixed, hard (rock-like), painless goiter

Question 22

Hashimoto’s thyroiditis: antibodies, HLA subtype, associated cancer, histology, clinical signs

Answer 22

TPO and antithyroglobulin antibodies
HLA-DR5
non-Hodgkin's lymphoma
Hurthle cells, lymphocytes, germinal centers
Diffuse, non-tender thyroid