Hypothyroidism, also known as underactive thyroid, is a condition where the thyroid gland does not produce enough thyroid hormone. It can develop gradually over time, but some people may experience a sudden onset of hypothyroidism symptoms. There are several potential causes for suddenly developing this condition.
What is hypothyroidism?
The thyroid gland is a small, butterfly-shaped gland located at the base of the neck. It produces two main hormones – triiodothyronine (T3) and thyroxine (T4). These hormones regulate metabolism, heart rate, mood, and many other important body functions.
Hypothyroidism occurs when the thyroid gland does not produce enough T3 and T4. This causes metabolism to slow down. Common symptoms include:
- Fatigue
- Weakness
- Weight gain
- Dry skin
- Hair loss
- Difficulty concentrating
- Depression
- Irregular menstrual cycles
Hypothyroidism often develops slowly over months and years. However, some people may experience a abrupt onset of symptoms.
What causes sudden hypothyroidism?
There are several possible causes for suddenly developing hypothyroidism:
Thyroiditis
Thyroiditis refers to inflammation of the thyroid gland. Different types of thyroiditis can cause thyroid hormone levels to suddenly plummet. The main types include:
- Postpartum thyroiditis – Occurs in up to 10% of women after pregnancy. It causes temporary hypothyroidism followed by temporary hyperthyroidism as the thyroid recovers.
- Subacute thyroiditis – Caused by a viral infection, this causes painful thyroid inflammation followed by temporary hypothyroidism before the gland recovers.
- Hashimoto’s thyroiditis – An autoimmune disease that damages the thyroid over time leading to hypothyroidism. But thyroid hormone levels can drop suddenly during a severe flare-up.
- Silent thyroiditis – A painless autoimmune inflammation of the thyroid that can cause abrupt onset of hypothyroidism.
Medications
Certain medications can affect thyroid function and may trigger sudden hypothyroidism. These include:
- Lithium
- Interferon-alpha
- Interleukin-2
- Amiodarone
- Immune checkpoint inhibitors like pembrolizumab and nivolumab
These medications can disrupt thyroid hormone synthesis and release, leading to abrupt hypothyroidism within a few weeks or months of starting treatment.
Radiation therapy
Radiation treatment to the neck area, such as for lymphomas and head/neck cancers, can damage the thyroid gland. This may result in sudden hypothyroidism a few months after therapy.
Thyroid surgery
Surgical removal of the thyroid gland causes hypothyroidism since the body can no longer produce thyroid hormones. Sometimes thyroid hormone levels can drop precipitously if there is damage to the remaining thyroid tissue after a partial thyroidectomy.
Iodine excess
Consuming very high amounts of iodine can temporarily inhibit thyroid hormone production and cause hypothyroidism. Sources of excess iodine include:
- Kelp supplements
- Some heart medications
- Contrast dyes used in imaging studies
- Amiodarone
Iodine deficiency
On the flip side, iodine deficiency impairs the thyroid’s ability to make hormones. Populations with chronic iodine deficiency tend to have high rates of hypothyroidism. But iodine levels can suddenly drop in some circumstances like after weight loss surgery or adopting a restrictive diet, triggering hypothyroidism.
Thyroid injury
Any injury to the thyroid gland can abruptly affect its hormone production. For example, this may occur due to:
- Whiplash injury
- Neck trauma
- Surgery in the neck area
Pituitary gland dysfunction
The pituitary gland at the base of the brain produces thyroid stimulating hormone (TSH) that controls thyroid activity. High levels of TSH normally stimulate the thyroid gland to produce more hormones. But pituitary dysfunction can prevent this response. Tumors, inflammation, surgery or radiation therapy in the pituitary gland area may cause levels of TSH to suddenly decrease or stop completely, leading to hypothyroidism.
Who is at risk for developing sudden hypothyroidism?
Some people are at a higher risk of experiencing an abrupt onset of hypothyroidism. These high risk groups include:
- Women – especially in the postpartum period or over 50 years old
- People with autoimmune disorders like type 1 diabetes and celiac disease
- Those with a family history of thyroid disease
- Patients taking lithium, amiodarone, interferon-alpha or interleukin-2
- People who have had radiation therapy to the neck/chest area
- Those who have had thyroid surgery or injury to the gland
However, sudden hypothyroidism can really occur in anyone – regardless of risk factors – especially if the thyroid gland sustains acute damage from severe inflammation, radiation exposure or medications.
What are the symptoms of sudden hypothyroidism?
The symptoms of abruptly developing hypothyroidism are the same as gradual onset hypothyroidism. But they tend to come on very quickly over days or weeks. Symptoms may include:
- Fatigue and weakness
- Weight gain
- Feeling cold
- Constipation
- Dry skin and puffy face
- Muscle cramps
- Hair loss
- Depression
- Impaired memory and concentration
- Abnormal menstrual cycles
- Slowed heart rate
Goitrogens are substances that may cause thyroid enlargement by interfering with iodine uptake in the thyroid gland. Below are some common goitrogenic foods:
| Food | Substances |
|---|---|
| Soybeans | Isoflavones |
| Cruciferous vegetables | Thiocyanates |
| Millet | Thiocyanates |
| Cassava | Linamarin |
These symptoms tend to worsen over time if hypothyroidism is left untreated. Prompt medical attention is important for anyone who experiences an abrupt onset of these symptoms.
How is sudden hypothyroidism diagnosed?
Sudden hypothyroidism is diagnosed with blood tests that measure levels of TSH and thyroid hormones (T3 and T4). Typical findings that indicate hypothyroidism include:
- High TSH levels
- Low free T4 levels
- Low or normal T3 levels
Antibody testing may help determine if an autoimmune thyroid disorder like Hashimoto’s is responsible. The doctor will also perform a physical exam looking for an enlarged thyroid gland, dry skin, hair loss and slowed reflexes – which are all signs of hypothyroidism.
The medical history provides important clues about potential causes such as postpartum status, neck radiation or recent thyroid surgery. Let your doctor know if you have started any new medications recently as well.
How is sudden hypothyroidism treated?
Treatment involves taking a daily oral thyroid hormone replacement medication like levothyroxine (Synthroid, Levoxyl). This is usually needed for life. The dose is adjusted based on symptoms and TSH levels, which are monitored with regular blood tests.
It may take some trial and error to determine the optimal dose that relieves symptoms without causing side effects. It can also take several months for thyroid hormone levels to stabilize.
Treatment leads to complete relief of symptoms when managed properly. Close monitoring and follow-up care with a doctor knowledgeable in managing hypothyroidism can help optimize outcomes.
Can sudden hypothyroidism be prevented?
It is not always possible to prevent sudden hypothyroidism, particularly when it is caused by things like postpartum thyroiditis, Hashimoto’s disease or thyroid injury. However, the following measures may help reduce risk in some cases:
- Avoid very high iodine intake from supplements like kelp
- Ensure adequate iodine intake through diet and multivitamins
- Discuss medication options carefully with your doctor if you have thyroid issues
- Use thyroid guard during neck imaging or radiation treatments
- Be alert for symptoms during high risk periods like postpartum
What is the outlook for sudden hypothyroidism?
With early diagnosis and proper treatment, most people with sudden onset hypothyroidism can expect an excellent outcome. They are able to lead normal, healthy lives with thyroid hormone replacement medication and monitoring.
In some cases, the condition may be temporary such as with postpartum thyroiditis or subacute thyroiditis after a viral infection. However, in many instances lifelong treatment is necessary.
Rarely, severe untreated hypothyroidism can lead to a life-threatening condition called myxedema coma. But this happens extremely infrequently with today’s testing and treatment capabilities.
Key Points
- Sudden hypothyroidism can occur due to thyroiditis, medications, radiation, surgery or acute thyroid injury.
- Symptoms like fatigue, weight gain and feeling cold come on abruptly over weeks/months.
- Blood tests confirm the diagnosis by detecting high TSH and low thyroid hormone levels.
- Taking daily thyroid hormone replacement medication relieves symptoms and prevents complications.
- With proper treatment, most people with sudden onset hypothyroidism can expect excellent outcomes.
Conclusion
Sudden hypothyroidism may catch some people by surprise, but it can be managed effectively in most cases. While the exact cause is not always identifiable, plausible explanations include postpartum thyroiditis, Hashimoto’s flare-ups, certain medications or treatments, and acute thyroid injury. Blood tests make the diagnosis straightforward. Daily levothyroxine treatment restores thyroid hormone levels and provides complete symptom relief in the majority of patients. With conscientious monitoring and medication adjustments as needed, most people who develop hypothyroidism abruptly can anticipate living full, healthy lives.