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- 1 What is the highly toxic drug they give for intractable afib
- 2 How long does it take to workWhat is the highly toxic drug they give for intractable a fib
- 3 If it hasnt worked after a week or two is it best to stop?How long does it take to workWhat is the highly toxic drug they give for intractable a fib
- 4 Why percent of patients had thyroid issues
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Why percent of patients had thyroid issues
Roughly 1 in 6 patients on long-term amiodarone develops a thyroid problem, and hypothyroidism is the more common one.
The best single number here comes from a Taiwanese cohort of 527 patients on amiodarone for about 410 days: 13.1% developed hypothyroidism, 4.0% developed thyrotoxicosis (overactive), and 82.9% stayed normal [1]. That is about 17 in 100 with any thyroid dysfunction. A separate 354-patient cohort found 73 with hypothyroidism and 57 with thyrotoxicosis, roughly 37 in 100 combined [2].
| Study | Patients | Hypothyroid | Overactive | Normal |
|---|---|---|---|---|
| Taiwan cohort [1] | 527 | 13.1% | 4.0% | 82.9% |
| 2009 cohort [2] | 354 | 73 patients | 57 patients | 224 patients |
Geography matters. In iodine-rich Worcester, hypothyroidism ran about 22% and overactive about 2%; in iodine-deficient Tuscany it flipped, with overactive at 9.6% and hypothyroidism at 5% [3]. Older age and a high starting TSH raise your risk [1]. Women and people with thyroid antibodies are hit harder [3].
Short courses are gentler. In a randomized trial of 8 weeks of amiodarone, 3 of 108 had a biochemical thyroid abnormality versus 1 of 104 on placebo, and none had clinical thyroid disease [4]. The damage scales with duration and cumulative dose.
My call: expect roughly a 1 in 6 chance of a thyroid problem on long-term therapy, higher if you are older, female, antibody-positive, or in an iodine-rich region, and get TSH checked every 3 to 6 months [3]. Confidence: moderate, since these are mostly retrospective cohorts from single regions.
Sources used 4
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Amiodarone-induced thyroid dysfunction in Taiwan: a retrospective cohort study
This retrospective cohort study investigates the incidence and risk factors of amiodarone-induced thyroid dysfunction in Taiwan, revealing a higher prevalence of amiodarone-induced hypothyroidism compared to thyrotoxicosis, particularly among older patients with elevated baselin…
DOI: 10.1007/s11096-013-9910-9 -
Amiodarone-Induced Thyrotoxicosis Is a Predictor of Adverse Cardiovascular Outcome
This study investigates the incidence of amiodarone-induced thyrotoxicosis (AIT) and its association with major adverse cardiovascular events (MACE) in patients undergoing long-term amiodarone therapy, revealing that AIT significantly increases the risk of MACE compared to euthy…
DOI: 10.1210/jc.2008-1907 -
Amiodarone and the thyroid
This article reviews amiodarone’s effects on the thyroid, detailing the mechanisms, epidemiology, clinical manifestations (AIH and AIT), management strategies, screening, and considerations for pregnancy/lactation, with guidance on follow-up of patients on amiodarone.
DOI: 10.1016/j.amjmed.2004.11.028 -
Short-term amiodarone treatment for atrial fibrillation after catheter ablation induces a transient thyroid dysfunction: Results from the placebo-controlled, randomized AMIO-CAT trial
In a double-blind, placebo-controlled randomized trial of 212 AF patients undergoing catheter ablation, short-term amiodarone (8 weeks) caused rapid but transient thyroid dysfunction (changes in TSH and thyroid hormones at 1–3 months) with full recovery after withdrawal and no c…
DOI: 10.1016/j.ejim.2016.04.012