Hypothyroidism Management in Patients with Atrial Fibrillation

Hypothyroidism Consultation

Hello Dr.
Hsiao, my mother is 65 years old and has a history of atrial fibrillation.
From March 2014 to July 2015, she was treated with Dronedarone (Multaq).
During the treatment, she developed hypothyroidism, and her attending physician prescribed Levothyroxine.
From July to December 2015, she took one 100 mcg Levothyroxine tablet every morning after breakfast.
In December 2015, her lab results showed T3: 0.8 (reference range: 0.6-1.81), T4: 11 (reference range: 4.5-12), and TSH: 7.551 (reference range: 0.55-4.78).
After reviewing these results, her physician reduced her Levothyroxine dosage to half a tablet daily.
Recently, her lab results indicated FREE T4: 0.85 (reference range: 0.71-1.85) and TSH: 52.913 (reference range: 0.55-4.78).
Since her follow-up appointment is not yet due, I would like to ask you, Dr.
Hsiao, if her latest lab results indicate that her Levothyroxine supplementation is insufficient (suggesting her thyroid function is still low)? How should we manage her supplementation or treatment moving forward?
I have read that stopping Dronedarone may allow thyroid function to return to normal.
My mother discontinued Dronedarone in mid-July 2015, but she used some Dronedarone again in November 2015 due to treatment needs.
Is there still a chance for her thyroid function to normalize? Generally, how long does it take for thyroid function to potentially return to normal?
Thank you for your assistance with these questions.
I appreciate your help.

Additionally, after stopping Dronedarone, she has been switched to Sotalol for treatment, and her condition is currently stable.
Her attending physician mentioned that to avoid excessive effects from Levothyroxine, it was scheduled to be taken after breakfast.

JJ, 30~39 year old female. Ask Date: 2016/03/25

Dr. Xiao Yongxun reply Internal Medicine

Dear JJ,
Based on the information you provided, the medications and units may be as follows: Cordarone® 200 mg (Amiodarone), Eltroxin® Tablets 100 mcg (synthetic Thyroxine), Rytmonorm® 150 mg Film-coated tablets.
The lab results are as follows: T3: 0.8 ng/ml (reference range: 0.6-1.81 ng/ml), T4: 11 μg/dl (reference range: 4.5-12 μg/dl), TSH: 7.551 (reference range: 0.55-4.78 μIU/ml).
Regarding the pharmacological effects:
1.
Cordarone® (Amiodarone) contains iodine and has a structure similar to Thyroxine.
It is a commonly used antiarrhythmic medication that also has antianginal properties.
Some common side effects include pulmonary interstitial fibrosis, gastrointestinal discomfort, tremors, ataxia, dizziness, hyperthyroidism or hypothyroidism, hepatotoxicity, photosensitivity, neuropathy, muscle weakness, and in rare cases, blue skin symptoms due to iodine accumulation in the skin.
2.
Eltroxin® (synthetic Thyroxine) is primarily absorbed orally.
Food, calcium-containing medications, and aluminum-containing antacids can reduce absorption.
For hypothyroidism, Thyroxine is used for treatment, and due to its long half-life, it is taken once daily.
It may take 6-8 weeks to achieve stable drug levels in the body.
3.
Rytmonorm® slows down the conduction speed of the cardiac electrical circuit and is considered a broad-spectrum antiarrhythmic medication.
Regarding your mother's test results:
1.
Thyroid function should show improvement; however, clinical symptoms must also be considered.
2.
Cordarone® can sometimes lead to hyperthyroidism or hypothyroidism due to its iodine content, so prescribing physicians are very cautious and monitor for side effects.
During the course of Thyroxine supplementation, once treatment is stable, it is understandable to consider reducing the dosage to prevent tachycardia or arrhythmias due to cardiovascular side effects.
Thyroxine should be taken in the morning to avoid insomnia, as taking it after meals can diminish its effectiveness.
3.
Can thyroid function recover? In addition to medication effects, the patient’s condition, age, and physiological function should also be considered.
According to the blood test report, your mother's Thyroxine secretion is relatively good; however, continuous monitoring is necessary, and adjustments should be made if needed.
The time required for recovery varies from person to person and cannot be precisely predicted.
4.
Your attending physician is very competent and careful.
It is advisable to discuss further with them to better understand the overall situation.

Reply Date: 2016/03/25

More Info

Managing hypothyroidism in patients with atrial fibrillation (AF) can be complex, particularly when considering the interplay between thyroid hormone levels and the medications used to manage AF. In your mother's case, it appears that she has been experiencing challenges with her thyroid function while being treated for AF, which is not uncommon.
Hypothyroidism can significantly affect heart health, potentially exacerbating conditions like AF. The thyroid hormones, primarily T3 and T4, play a crucial role in regulating heart rate and rhythm. When thyroid hormone levels are low, as indicated by elevated TSH (Thyroid Stimulating Hormone) levels and low Free T4 levels, it can lead to bradycardia (slow heart rate) and other cardiac issues. Conversely, excessive thyroid hormone can lead to tachycardia (rapid heart rate) and may worsen AF.

In your mother's case, the recent lab results show a TSH level of 52.913, which is significantly elevated, indicating that her hypothyroidism is not adequately controlled. The Free T4 level of 0.85 is also on the lower side of the reference range, suggesting that the current dose of levothyroxine (昂特欣) is insufficient. The adjustment from 100 mcg to 50 mcg may have been made to prevent overtreatment, but it seems that her thyroid function has not improved with this lower dose.

Regarding the potential for her thyroid function to normalize after discontinuing the AF medication (臟得樂), it is possible but not guaranteed. Some patients may experience a return to normal thyroid function after stopping certain medications, but this can vary widely based on individual circumstances, including the underlying cause of the hypothyroidism. The timeline for recovery can also differ; some patients may see improvements within weeks, while others may take months.

To address your questions about the next steps in her treatment:
1. Medication Adjustment: It is crucial for her healthcare provider to reassess her levothyroxine dosage. Given her elevated TSH and low Free T4, an increase in her levothyroxine dose may be necessary to bring her thyroid levels back into the normal range. Regular monitoring of her thyroid function tests (TFTs) will be essential to ensure that the dosage is appropriate.

2. Follow-Up Testing: It is advisable to schedule a follow-up appointment sooner rather than later, especially given the significant changes in her thyroid levels. Regular monitoring (every 6-8 weeks) is recommended until her levels stabilize.

3. Monitoring Symptoms: Keep an eye on any symptoms that may arise, such as fatigue, weight changes, or changes in heart rhythm. If she experiences any concerning symptoms, it is important to contact her healthcare provider promptly.

4. Lifestyle Considerations: Encourage a balanced diet and regular exercise, as these can help manage both thyroid function and overall cardiovascular health. However, any exercise regimen should be discussed with her healthcare provider, especially given her history of AF.

5. Collaboration with Specialists: If her thyroid levels do not improve with medication adjustments, it may be beneficial to consult an endocrinologist for further evaluation and management of her hypothyroidism.

In summary, your mother's recent lab results indicate that her hypothyroidism is not adequately managed, and adjustments to her levothyroxine dosage are likely necessary. Regular follow-up and monitoring will be key to ensuring her thyroid function stabilizes while managing her atrial fibrillation effectively. It is important to maintain open communication with her healthcare team to navigate these complexities.

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