What is Jod-Basedow Syndrome?
Jod-Basedow syndrome, also known as iodine-induced hyperthyroidism, is a rare condition where a person has an overactive thyroid due to the intake of additional iodine. This often happens after iodine contrast media (ICM) – a type of dye used to make certain areas show up clearly on scans – is used in imaging tests like CT scans and angiographs (pictures of blood vessels). Many times, this syndrome goes unnoticed, so it’s important for all doctors, both general and specialists, to be more aware of it. This condition can appear in individuals of any age. And while it is thought it would always clear up completely, there are instances where some thyroid problems persist.
What Causes Jod-Basedow Syndrome?
If you have underlying thyroid issues like Hashimoto thyroiditis (a condition where your immune system attacks your thyroid), autoimmune thyroid disease, had previous thyroid surgery, or have hidden Graves disease (an autoimmune disease that leads to overactivity of the thyroid gland), and nontoxic goiter (enlarged thyroid that’s not due to cancer), you might be more likely to develop a condition called iodine-induced hyperthyroidism. This condition happens when your thyroid absorbs too much iodine and produces too much thyroid hormone.
Also, if you have long-term kidney disease or end-stage renal disease (the last stage of chronic kidney disease where the kidneys have nearly stopped working), you have a higher chance of developing iodine-induced hyperthyroidism. This is because your kidneys are responsible for removing excess iodine from your body.
It’s also important to know that a condition called Jod-Basedow syndrome, another term for iodine-induced hyperthyroidism, is usually associated with the use of contrast material used for medical imaging. But it can also occur if you’re exposed to too much iodine from other sources like iodinated antiseptic solutions and oral vitamins or nutritional supplements.
Furthermore, overactivity of the thyroid gland can be seen after taking a medication called amiodarone, which contains iodine. However, this is considered a separate condition, and the exact reasons for why this happens might be different.
Risk Factors and Frequency for Jod-Basedow Syndrome
Jod-Basedow syndrome is a seldom-seen condition, with only a limited number of reported cases. It’s worth noting that this syndrome is probably not reported as often as it occurs, due to misdiagnosis or failing to link it with exposure to iodine. If more people are aware of this condition, doctors may be able to identify it faster, treat it appropriately, and take steps to prevent it.
Signs and Symptoms of Jod-Basedow Syndrome
Jod-Basedow syndrome is a condition that shares many symptoms with an overactive thyroid. This is referred to as hyperthyroidism. Symptoms of this syndrome include:
- Increased sweating
- Feeling of rapid heartbeat (palpitations and tachycardia)
- Feeling restless and anxious
- Frequent bowel movements or diarrhea
- Intolerance to heat
- Difficulty sleeping (insomnia)
In severe cases, a dangerous condition known as a ‘thyroid storm’ can occur. When this happens, symptoms like fever, severe diarrhea, rapid heartbeat, and changes in consciousness can be seen. In rare instances, this syndrome can cause issues with heart rhythm, including a condition called atrial fibrillation.
Testing for Jod-Basedow Syndrome
If a doctor thinks you might have a condition called iodine-induced hyperthyroidism, they will use similar methods to diagnosing regular hyperthyroidism. It’s very important to give your doctor detailed information about your past health and recent experiences. This can help your doctor draw connections between exposure to something called iodinated contrast media (ICM), often used in medical imaging, and your symptoms.
You usually start to feel symptoms less than a month after being exposed to ICM, and sometimes as soon as a few hours or days later. Blood tests can confirm the diagnosis as they often show elevated levels of thyroid hormones (also called T3 and T4) and decreased levels of thyroid-stimulating hormone (TSH). Additionally, iodide levels in your urine can be up to three times higher than normal.
Medical imaging tests, which allow doctors to take pictures of the inside of your body, can also assist in diagnosing this condition. Specifically, they may do a nuclear imaging test of the thyroid. This test tracks how much radioactive iodine your thyroid absorbs. In cases of iodine-induced hyperthyroidism, your thyroid is likely to absorb low to no detectable amounts of radioactive iodine.
If doctors anticipate that you might develop this condition, they can perform thyroid hormone tests before and after giving you ICM. This can make it easier to track any changes in your thyroid function and provide a more accurate evaluation.
Treatment Options for Jod-Basedow Syndrome
For individuals who are at risk of developing an overactive thyroid caused by iodine (known as iodine-induced hyperthyroidism) and need an imaging procedure that uses iodine-containing dyes, doctors may propose the use of protective medications. These protective medications, known as anti-thyroid drugs (like methimazole or perchlorate), can help prevent the thyroid from being too active.
In cases where a person has developed an overactive thyroid from iodine, doctors often recommend corticosteroids, which are a type of medication that can quickly lower the levels of thyroid hormones back to normal. Symptoms of an overactive thyroid can also be brought under control with temporary use of medications called beta-blockers and more anti-thyroid drugs, like methimazole.
On some occasions, if these anti-thyroid drugs don’t work well enough to slow down thyroid hormone production, doctors might suggest a medication called lithium. Lithium has the ability to slow down the activity of the thyroid.
What else can Jod-Basedow Syndrome be?
When the symptoms indicate overactive thyroid, it’s important to check for underlying thyroid diseases. Some of the possible causes doctors might investigate include:
- Graves disease: This can be identified by running a test for thyroid-stimulating immunoglobulin (TSI) levels.
- Hyper-functioning thyroid nodules: When they are the problem, they show high levels of radioiodine uptake during an imaging test of the thyroid.
It’s important to note that having an existing thyroid disease doesn’t rule out the possibility of Jod Basedow syndrome, a type of hyperthyroidism caused by excessive iodine in the body. Sometimes, an existing thyroid condition can increase the risk of developing this iodine-induced hyperthyroidism. Knowing the patient’s full medical history is incredibly useful in connecting the symptoms to exposure to ICM (iodine-containing contrast media) or other substances that contain iodine.
What to expect with Jod-Basedow Syndrome
The outlook for iodine-induced hyperthyroidism, a condition where the thyroid gland becomes overactive due to too much iodine, is generally positive. Most patients will return to their normal thyroid function after a variable recovery period, which may be weeks or months. Doctors usually recommend these patients for regular check-ups.
However, a small number of patients may face long-lasting effects from this condition. For this reason, close monitoring and ongoing thyroid function tests are recommended to ensure the condition is managed effectively.
Possible Complications When Diagnosed with Jod-Basedow Syndrome
Iodine-induced hyperthyroidism can have serious complications such as an extreme and life-threatening form of hyperthyroidism called thyroid storm, permanent hyperthyroidism, and an irregular heartbeat known as atrial fibrillation. Persistent hyperthyroidism can add extra stress to the heart and blood vessels, worsening conditions like heart disease and heart failure.
When using iodine contrast materials in pregnant women, extra care is needed. This is because iodine can cross the placenta and reach the baby. This exposure can result in the unborn baby having reduced thyroid activity, also known as fetal hypothyroidism, and the growth of an enlarged thyroid, or goiter. Fetal hypothyroidism occurs when the baby can’t bypass the normal response to high iodine levels, which is to reduce thyroid activity, known as the Wolff-Chaikoff effect. Even though fetal hypothyroidism after the mother is given iodine contrast materials is usually short-term, it can negatively impact the baby’s development. If the baby continues to be exposed to iodine in the first few weeks of life, it could lead to permanent hypothyroidism.
Dangers of Iodine-induced Hyperthyroidism:
- Thyroid storm
- Permanent hyperthyroidism
- Atrial fibrillation
- Increased strain on the cardiovascular system
- Worsening of existing heart conditions
- Fetal hypothyroidism with in utero exposure
- Goiter development in the fetus
- Potential developmental issues in the fetus
- Potential permanent hypothyroidism in the baby
Recently, there have been unique cases reported in which patients experienced muscle weakness and temporary paralysis after using iodine-containing substances, which triggered hyperthyroidism. There was also a report of a patient with fluid build-up in the heart sac, a condition known as pericardial tamponade, which is rare in hyperthyroid states and is typically seen in hypothyroid states.
Preventing Jod-Basedow Syndrome
If you have a known thyroid condition, it’s important that you understand the connection between something called the “Jod-Basedow syndrome” and a medical substance called “intravenous contrast media” (ICM). If at any point in the future you need an imaging test that requires contrast (a special dye to make certain areas stand out), you should let your doctor know about your previous thyroid issues. This is because there’s a chance that the iodine in the contrast could overstimulate your thyroid (a condition called “iodine-induced hyperthyroidism”).
You and your doctor will need to decide together if this test is really necessary. If it’s important for your health to have the test, your doctor might give you a preventive medication to protect your thyroid. This could be an “anti-thyroid medication” like methimazole, or a type of heart medication known as a “beta-blocker”.
Also, before you receive the ICM, your doctor should check all the medications and supplements you’re currently taking. This is because some of them can have a lot of iodine in them. If you take any supplements or medications with extra iodine, it might be necessary to change your medication routine before you receive ICM, in order to lower your risk of iodine-induced hyperthyroidism.