management of thyroid gland disorders (see DM)

Question 1

why is weight gain seen in hypothyroidism

Answer 1

decreased heart rate and basal metabolisms leads to less energy requirement -> less fat stores burnt -> weight gain

Question 2

what is the most common cause of hypothyroidism in the developed world vs developing

Answer 2

developed: hashimoto’s disease
developing: iodine deficency

Question 3

in an acutely sick pt who can’t swallow, how should TH levels be corrected

Answer 3

liothyronine (T3) via NG tube - don’t give IV

Question 4

why should T3 not be given IV

Answer 4

high risk of arrhythmias

Question 5

when should subclinical hypothyroidism be treated (3)

Answer 5

1. if pt is pregnant
2. TSH>10
3. symptomatic pts w TSH 4-10 (start levothyroxine on trial basis)

Question 6

what is subclinical hypothyroidism

Answer 6

mild thyroid failure - TSH levels are high but fT3/T4 levels are normal

Question 7

when should a pt w subclinical hypothyroidism be checked annually

Answer 7

if TSH 4-10 and anti-TPO +ve

Question 8

what test can be done if hypothyroid treatment is not working

Answer 8

thyroxine absorption test

Question 9

what can over treating hypothyroidism result in (3)

Answer 9

1. arrhythmias
2. osteoporosis
3. menstrual irregularities

Question 10

thyrotoxicosis vs hyperthyroidism

Answer 10

thyrotoxicosis - an excess of thyroid hormone, having an overactive thyroid gland is not a prerequisite (e.g. ingestion of excess thyroid hormone);
hyperthyroidism - overactive thyroid gland (i.e. increased thyroid hormone production) causing an excess of thyroid hormone and thyrotoxicosis

Question 11

what will Grave’s disease look like on a thyroid uptake scan

Answer 11

symmetrical uniform swelling

Question 12

examples of causes of hyperthyroidism (7)

Answer 12

1. grave’s disease
2. toxic multinodular goitre (most common in older people)
3. toxic adenoma
4. iodine and iodine containing drugs e.g. amiodarone
5. post partum painless thyroiditis
6. subacute thyroiditis
7. TSH secreting pituitary adenoma (ademona in the pit gland causing increased TSH release)

Question 13

what is a thyroid storm

Answer 13

an acute life threatening complication of untreated hyperthyroidism

Question 14

thyroid storm presentation (8)

Answer 14

1. acute onset
2. hyperthermia
3. tachycardia
4. arrhythmia
5. dehydration
6. shock
7. delerium
8. coma

Question 15

Carbimazole MOA

Answer 15

decreases the uptake and concentration of inorganic iodine by thyroid, it also reduces the formation of di-iodotyrosine and thyroxine -> Once converted to its active form of methimazole, it prevents the thyroid peroxidase enzyme (TPO) from coupling and iodinating the tyrosine residues on thyroglobulin, hence reducing the production of the thyroid hormones T3 and T4

Question 16

mgx for thyroid storm (4)

Answer 16

1. Beta-blockers
2. Thionamides: typically propylthiouracil, which in addition to its anti-thyroid effect also reduces the conversion of T4 to T3
3. Corticosteroids: reduce the conversion of T4 to T3
4. Lugol’s iodine