A high TSH level indicates an underactive thyroid gland or hypothyroidism. TSH stands for thyroid stimulating hormone, which is produced by the pituitary gland in the brain. When thyroid hormone levels are low, the pituitary releases more TSH to stimulate the thyroid to produce more hormones. This causes TSH levels to rise. A TSH level above the normal range is an indication that the thyroid is underactive and not producing enough hormones on its own. However, in some cases, a high TSH can resolve on its own without requiring lifelong thyroid hormone replacement. There are a few key factors that determine whether high TSH will go away or require treatment.
What is Considered a High TSH Level?
TSH levels are measured through a simple blood test and levels are expressed in units of mIU/L (milliunits per liter). Normal TSH levels can vary slightly between labs but generally fall into this range:
- 0.5 to 4.5-5 mIU/L for adults
- 0.7 to 5.7 mIU/L for children/teens
- 0.4 to 4 mIU/L for newborns
A TSH above the normal range indicates hypothyroidism:
- Mild hypothyroidism: TSH levels between 5-10 mIU/L
- Moderate hypothyroidism: TSH levels between 10-15 mIU/L
- Severe hypothyroidism: TSH higher than 15-20 mIU/L
The higher above the normal range the TSH level is, the more severe the hypothyroidism.
What Causes High TSH?
There are a few possible causes of an elevated TSH, including:
- Hashimoto’s disease – This autoimmune disorder damages the thyroid gland causing decreased hormone production. It is the most common cause of persistent high TSH levels.
- Thyroiditis – Inflammation of the thyroid gland from an autoimmune attack or viral infection can temporarily impair hormone production.
- Congenital hypothyroidism – Some babies are born with an underactive thyroid gland due to defects at birth.
- Pituitary gland tumors – Tumors on the pituitary can interfere with TSH production causing high levels.
- Medications – Certain medications like lithium, amiodarone, interferon-alpha, and interleukin-2 can impact thyroid function.
- Iodine deficiency – Lack of sufficient iodine in the diet inhibits hormone synthesis leading to hypothyroidism.
Getting to the root cause of the high TSH through further testing can help determine if the cause is permanent or temporary.
Key Factors That Determine If High TSH Will Resolve
There are a few key factors that play a role in whether a high TSH level will return to normal or remain persistently elevated:
1. The Degree of Elevation
The higher the TSH level, the less likely it is to resolve on its own.
- Mild TSH elevations (5-10 mIU/L) are more likely to normalize over time than moderate or severe elevations.
- In cases of mild subclinical hypothyroidism, periodic monitoring of TSH is recommended vs immediate treatment.
- TSH levels above 10 mIU/L often indicate an underlying thyroid disorder requiring treatment.
2. The Cause and Duration
The underlying cause and duration of the high TSH also determines its likelihood of resolving.
- Hashimoto’s thyroiditis often leads to progressive thyroid failure and persistent high TSH.
- Postpartum thyroiditis, painless thyroiditis or subacute thyroiditis may cause temporary TSH elevations that later resolve.
- High TSH resulting from certain medications may resolve with dosage changes or stopping the medication.
If the high TSH has been present for many months to years, it less commonly normalizes vs a recent onset.
3. Age of Patient
The patient’s age influences whether TSH abnormalities will self-correct:
- In infants and children, congenital hypothyroidism requires immediate treatment and lifelong thyroid hormone replacement.
- In adults over 60, high TSH levels are less likely to resolve and more often require treatment.
- In middle-aged adults, periodic monitoring of mild TSH elevations is sometimes reasonable.
4. Symptoms
If a high TSH is accompanied by symptomatic hypothyroidism such as fatigue, weight gain, feeling cold, dry skin, or hair loss, it is less likely to resolve on its own without treatment. Lack of symptoms increases the chance it may normalize.
Can High TSH Resolve Without Treatment?
In some situations, a mildly elevated TSH level can temporarily resolve and return to normal without requiring thyroid hormone replacement treatment. Some examples include:
- Subacute thyroiditis – Caused by a viral infection, subacute thyroiditis inflames the thyroid gland transiently impairing thyroid function. TSH may remain elevated for several months after the infection then normalize.
- Postpartum thyroiditis – Up to 10% of women develop inflammation of the thyroid in the first year after giving birth. This autoimmune flare causes temporary hypothyroidism. High TSH often resolves in 4-8 months.
- Painless thyroiditis – Also called silent thyroiditis, this autoimmune flare can increase TSH levels for a few months before thyroid function improves.
- Lithium use – Lithium therapy for bipolar disorder can affect thyroid function and raise TSH. Levels may return to normal when lithium is stopped.
- Iodine deficiency – Consuming adequate iodine allows the thyroid to resume normal hormone production, lowering TSH.
- Post-radiation – Radioactive iodine treatment and external beam radiation therapy for Graves disease and thyroid cancer can initially lead to elevated TSH that later resolves.
In these situations, the high TSH is temporary and returns to normal once the trigger is removed and the thyroid recovers. Periodic TSH monitoring without treatment may be reasonable.
When Does High TSH Require Treatment?
While temporary causes can sometimes resolve TSH elevations, high TSH levels often require thyroid hormone replacement treatment. Treatment is recommended in these cases:
- TSH remains elevated longer than 6 months
- TSH is above 10 mIU/L
- Patient has hypothyroid symptoms like fatigue, weight gain, dry skin
- Cause is Hashimoto’s thyroiditis or congenital hypothyroidism
- Patient is elderly
Levothyroxine is the typical thyroid hormone replacement medication used to treat high TSH. The levothyroxine dosage is gradually titrated until the patient’s TSH level is restored to the normal range. Treatment is then continued to maintain normal thyroid function.
What If High TSH Is Left Untreated?
Untreated hypothyroidism from elevated TSH can lead to complications:
- Goiter – enlarged thyroid gland
- Increased cholesterol levels
- Depression and other mood disorders
- Peripheral neuropathy
- Impaired fertility
- Cognitive dysfunction
- Fluid accumulation and heart failure
In infants and children, untreated congenital hypothyroidism can result in growth failure and permanent intellectual disability.
That’s why treatment is often recommended for persistent high TSH levels outside the normal range.
Monitoring High TSH
If the decision is made to monitor a mildly elevated TSH level before starting treatment, the TSH level should be rechecked periodically, such as every 4-6 weeks initially. This allows the tracking of any upward or downward trend in the TSH level.
TSH monitoring is also necessary in patients once levothyroxine treatment is initiated to ensure the medication dosage achieves a normal TSH level without going too low. Frequent TSH testing when first starting thyroid hormone allows for titration of the levothyroxine dose. Once the target TSH is reached and stabilized, testing may decrease to annually.
Natural Treatments
While thyroid hormone replacement is usually necessary for sustained high TSH levels, some patients may try natural therapies to potentially help lower TSH levels in mild subclinical hypothyroidism. These include:
- Selenium supplementation – Selenium is required for thyroid hormone synthesis and may help normalize TSH, especially in cases of Hashimoto’s disease.
- Vitamin D – Optimizing vitamin D levels may support thyroid function.
- Zinc supplementation – Zinc deficiency can impair thyroid hormone metabolism. Zinc supplementation may assist thyroid function.
- Ashwagandha – This herb may help lower TSH levels, improve hypothyroid symptoms, and reduce thyroid peroxidase antibody levels in autoimmune thyroiditis.
However, these natural remedies cannot treat severe hypothyroidism or fully replace thyroid hormone replacement medication.
Conclusion
In summary, mild high TSH levels (5-10 mIU/L) may temporarily resolve and return to the reference range without treatment in some cases. However, sustained TSH elevations usually indicate persistent hypothyroidism requiring thyroid hormone replacement medication. The degree of TSH elevation, underlying cause, patient age, and presence of hypothyroid symptoms provide insight into whether high TSH will resolve spontaneously or require levothyroxine treatment. Careful monitoring of TSH levels is important in determining the need for medication. With appropriate treatment, thyroid function can be restored and maintained long-term for patients with hypothyroidism and elevated TSH levels.