Question
Compare Radioactive Iodine and Carbimazole.
Q6 8 marks Short Essays ★ ✓
Answer
Compare Radioactive Iodine and Carbimazole
Feature Radioactive Iodine (I-131) Carbimazole Class Radioisotope Thioamide Mechanism Concentrates in thyroid via Na-I symporter, beta-emission destroys tissue Inhibits thyroid peroxidase, blocking hormone synthesis Onset Slow (weeks) Slow (weeks, since it blocks new synthesis, not release of stored hormone) Outcome Definitive — often causes hypothyroidism Reversible — normal function can resume on stopping Use in pregnancy Absolutely contraindicated Used with caution (PTU preferred in first trimester) Relapse after stopping Not applicable (permanent effect) Common, especially after a short course Suitability Definitive treatment for Graves’/toxic nodular goitre, especially where surgery is contraindicated or medical therapy has failed First-line medical therapy, particularly for a first episode or in younger patients wishing to avoid permanent treatment Key adverse effect Hypothyroidism (expected long-term outcome) Agranulocytosis, hepatotoxicity
Shared feature : both ultimately reduce circulating thyroid hormone levels, but by fundamentally different mechanisms (tissue destruction versus synthesis blockade), giving different onset, reversibility, and long-term outcome profiles.
1 Thyroid Hormones and Antithyroid Drugs
Other Years Asked
1 T4 and very low TSH
levels. A diagnosis of hyperthyroidism was made.
( 2022 July (Supplementary) (2019 Scheme) Essay · 10 marks 2 Classify Thyroid inhibitor drugs. Describe the mechanism of action, and adverse
effects of carbimazole. Explain the role of iodides in hyperthyroidism. (2+2+2) 2022 May (Supplementary) (2010 Scheme) Essay · 6 marks 3 ( 2023 July (Supplementary) (2019 Scheme) Essay · 6 marks 4 A 32years old woman, presented with complaints of weight loss, palpitations,
sweating, irregular menses and occasional tremors of hands since 2-3 months.
Clinical examination revealed a diffusely enlarged thyroid gland and blood tests
showed decreased TSH. She was started on medication for Grave’s disease. 2025 March (Supplementary) (2010 Scheme) Essay · 6 marks 5 Classify antithyroid drugs. Write the advantages and disadvantages of using
radioactive Iodine. (2+2+2) 2021 February (Supplementary) (2010 Scheme) Essay · 6 marks 6 A 35 years old woman came with complaints of heat intolerance, retraction of upper eyelid
and menstrual irregularities. Her T3 , T4 , FT4 & FT3 are elevated while TSH is suppressed.
Answer the following: 2015 February (2010 Scheme) Essay · 6 marks 7 Treatment of thyrotoxic crisis. 2023 January (Supplementary) (2019 Scheme) Short Answer · 4 marks 8 Pharmacotherapy of Thyrotoxic crisis (thyroid storm) 2024 June (Supplementary) (2019 Scheme) Short Answer · 4 marks 9 Mechanism of action, uses and adverse effects of Radio active iodine. 2025 March (Supplementary (SAY)) (2019 Scheme) Short Answer · 4 marks 10 Carbimazole 2022 October (Supplementary) (2010 Scheme) Short Note · 3 marks 11 Radioactive Iodine 2024 March (Supplementary) (2010 Scheme) Short Note · 3 marks 12 Anti thyroid drugs 2014 September (Supplementary) (2010 Scheme) Short Note · 3 marks 13 Radioactive Iodine 2021 May (Supplementary) (2010 Scheme) Short Note · 3 marks 14 Lugol’s Iodine is given for 10 days prior to thyroidectomy surgery for Grave’s
disease. 2023 July (Supplementary) (2010 Scheme) Short Answer · 1 mark 15 Anti-thyroid drugs 2018 July (Supplementary) (2010 Scheme) Short Answer · 1 mark 16 Explain the use of propranolol in thyrotoxicosis. 2018 February (2010 Scheme) Short Answer · 1 mark 17 Methimazole acts by: 2024 December (Supplementary) (2019 Scheme) MCQ · 1 mark 18 Antithyroid drugs 2013 April (2010 Scheme) Short Answer · 1 mark 19 Drug used in thyrotoxic crisis 2014 March (2010 Scheme) Short Answer · 1 mark 20 Propylthiouracil 2025 August (Supplementary) (2010 Scheme) Short Answer · 1 mark 21 Anti- thyroid drugs safe during pregnancy 2017 August (Supplementary) (2010 Scheme) Short Answer · 1 mark 22 Thyrotoxic crisis. 2015 September (Supplementary) (2010 Scheme) Short Answer · 1 mark 23 Anti thyroid drugs 2016 October (Supplementary) (2010 Scheme) Short Answer · 1 mark 24 Radioactive iodine 2020 February (Supplementary) (2010 Scheme) Short Answer · 1 mark 25 Use of Propranolol in Thyrotoxic crisis. 2024 March (Supplementary) (2010 Scheme) Short Answer · 1 mark 26 The preferred drug for her is: 2024 December (Supplementary) (2019 Scheme) MCQ · 1 mark 27 Carbimazole for treatment of Thyroid storm 2024 August (Supplementary) (2010 Scheme) Short Answer · 0.3 marks 28 Antithyroid drugs 2019 February (2010 Scheme) Short Answer · 0.3 marks 
