Thyroid

Question 1

Levothyroxine

1. Drug class
2. Indication
3. Dosage range, Frequency and best admin time
4. Monitoring
5. Counselling

Answer 1

1. Thyroid hormone
2. 1 and 2 hypothyroidism, block replacement in hyperthyroidism(w/antithyroid drugs), suppressive tx in thyroid cancer to suppress TSH below normal range, euthyroid goitre
3. 25microg(elderly/frail/ischaemic Hdisease)-200microg. Morning, empty stomach.
4. TFTs - TSH, T4, T3.
   Signs of hyperthyroidism (palpitations, excitability, insomnia, sweating, weight loss). If it occurs stop for a week and restart at lower dosage.
   Worsening of ischaemic smx, in ischaemic heart disease.
   BMD - decreased bone density and fractures can occur.
   Benign intracranial hypertension

BRANDS not bioequivalent - if changing to or from Eltroxin monitor thyroid function and adjust dose if necessary.
Monitor thyroid fn in each trimester of PREG.

5. LABELs: 4a (delete dairy products), 6*, C
   Lifelong tx
   Pref before breakfast on empty stomach 30 mins.
   Tell Dr if smx of hyperthyroidism (achycardia, arrhythmia, excitability, insomnia, flushing, sweating, diarrhoea and excessive weight loss.)
   Tell Dr if headache or papilloedema(eyes) (h/ache, N&V, etc)
   KEEP IN THE FRIDGE. Eltroxin NO FRIDGE and no interchangable
   Otherwise 2 weeks in room temp

Question 2

Propylthiouracil

1. Drug class
2. Indication
3. Dosage range, Frequency and best admin time
4. Monitoring
5. Counselling

Answer 2

1. Antithyroid Drugs
2. Graves’ disease, short-term tx before thyroid surgery or before & after radioactive iodine tx, thyroid storm.
3. • Initially 200-400mg in 2-4 doses for 3-4 weeks.
     Maintenance
   • Adjusted regimen= 25-300mg d in divded doses.
   • Block regimen= continue initial dose then add 100-150microg of levothyroxine when T4 normal range.
     Thyroid storm 600-1200mg d in divided doses, gradually reduced.
4. LFTs at baseline and when clinically indicated (hepatotoxicity).
   Stop if abnormalities occur.
   Agranulocytosis (most likely in first 3 months)
   Vasculitis
   Monitor full blood count, and liver and thyroid function.

5. labels: 21, A
SMURFBB
Tell Dr if you develop fever, mouth ulcers, rash, sore throat, severe fatigue, nausea, abdo pain, or jaundice.
Preferred in 1st trimester of PREG.
Gastric discomfort (N&V)
Joint pain common

Question 3

Carbimazole

1. Drug class
2. Indication
3. Dosage range, Frequency and best admin time
4. Monitoring
5. Counselling

Answer 3

1. Antithyroid Drugs
2. Graves’ disease, short-term tx before thyroid surgery or before & after radioactive iodine tx, thyroid storm.
3. Initially 10-45mg(up to 60mg) in 2-3 doses for 3-4 weeks.
   Adjusted regimen= 5-15mg D (but highly variable)
   Block regimen= continue initial dose then add 100-150microg of levothyroxine when T4 normal range.
   Thyroid storm= 60-80mg d in divided doses, gradually reduced.
4. LFTs at baseline and when clinically indicated (hepatotoxicity more common with Propylthiouracil).
   Stop if abnormalities occur.
   Agranulocytosis (most likely in first 3 months)
   Vasculitis (more common with Propylthiouracil)
   Monitor full blood count, and liver and thyroid function.

5. Tell Dr if you develop fever, mouth ulcers, rash, sore throat, severe fatigue, nausea, abdo pain, or jaundice.
Preferred in PREG except 1st trimester.
Gastric discomfort (N&V)
Joint pain common

Question 4

Iodine

1. Drug class
2. Indication
3. Dosage range, Frequency and best admin time
4. Monitoring
5. Counselling

Answer 4

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