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EspañolLow TSH symptoms: What are the early signs of low TSH?
Overview: What does low TSH feel like?
Thyroid-stimulating hormone (TSH) tells the thyroid gland, a butterfly-shaped gland in the neck, to release thyroid hormones called T3 (triiodothyronine) and T4 (thyroxine). These two hormones control many bodily functions, including energy levels, metabolism, body temperature, and tissue growth. The relationship between TSH, released by the pituitary gland, and thyroid hormones, released by the thyroid gland, is a feedback loop. TSH increases when thyroid hormones decrease. TSH decreases when thyroid hormones increase. This feedback loop keeps thyroid hormone levels normal. In most cases, low TSH levels are due to high levels of thyroid hormones. This is usually caused by a thyroid disorder, which causes the thyroid to release too much thyroid hormone, a condition called overactive thyroid or hyperthyroidism. When thyroid hormones are too high, the whole body feels like it’s going faster. People feel energetic, restless, shaky, twitchy, and anxious. They have to poop more than usual. They get hungrier, eat more, and lose weight. The heart rate increases, which is a main side effect of low TSH. However, in rare cases, low TSH can be a problem with the pituitary gland. As a result, the thyroid doesn’t release enough thyroid hormone, causing low thyroid hormone levels. This experience is exactly the opposite of an overactive thyroid.
Key takeaways:
Low TSH is an uncommon health condition that can affect anyone, regardless of age, sex, race, or ethnicity.
Early signs of low TSH include high energy, restlessness, mood changes, and nervousness.
Serious symptoms of low TSH, such as high fever, racing heartbeat, confusion, severe agitation, jaundice, or unconsciousness, may require immediate medical attention.
Low TSH is usually caused by an overactive thyroid (hyperthyroidism) that can be caused by autoimmune disorders, thyroid enlargement, thyroid nodules, goiter, thyroid cancer, pregnancy, giving birth (postpartum thyroiditis), prescription medications, or certain types of supplements. You may be at risk for developing low TSH symptoms if you are a woman, have Type 1 diabetes, have a family history of autoimmune diseases, ingest too many iodine supplements, or take certain prescription drugs. People who smoke are also at risk.
Low TSH usually requires a medical diagnosis.
Low TSH generally requires treatment. Low TSH symptoms are typically controlled within a few days of treatment.
Treatment of low TSH may include symptom treatment, antithyroid drugs, radioactive iodine therapy, and surgery. Read more about hyperthyroidism treatments here.
Untreated low TSH could result in complications, such as thyroid storm, or an increased risk of cardiovascular events, atrial fibrillation, stroke, infertility, osteoporosis, and death.
Use coupons for low TSH treatments, like atenolol, methimazole, and propylthiouracil, to save up to 80%.
What are the early signs of low TSH?
The early signs of low TSH are typically changes in energy and mood. Low TSH is usually associated with an overactive thyroid, a condition that speeds up the body and the brain. Early signs of hyperthyroidism include:
Heightened energy
Mood swings
Restlessness
Jitteriness
Irritability
Anxiousness
Problems falling asleep
Other low TSH symptoms
Thyroid disorders that cause high thyroid hormone levels and low TSH may have symptoms, such as:
High energy
Restlessness
Shakiness
Irritability
Rapid talking or pressured speech
Difficulty sleeping
Weight loss
Frequent defecation
Racing heartbeats
Palpitations
Heat intolerance
Fast reflexes
“Thyroid stare” (bulging eyes and retracted eyelids occur in 1 out of 3 people with overactive thyroid)
Sweating
Tremor
Fatigue
Nail separation
Changes in the menstrual cycle
Low TSH vs. high TSH symptoms
Low TSH is usually associated with an overactive thyroid. On the other hand, high levels of TSH suppress thyroid function, so high TSH is typically caused by an underactive thyroid. Symptoms of hypothyroidism are the opposite of symptoms of hyperthyroidism. The causes, however, can be very similar. The most common cause of hyperthyroidism and low TSH is an autoimmune disorder, Grave’s disease. The most common cause of hypothyroidism and high TSH is also an autoimmune disorder, Hashimoto’s thyroiditis or Hashimoto’s disease. In both thyroid disorders, the immune system mistakes healthy thyroid tissues as intruders and attacks them.
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RELATED: Thyroid health 101: Common problems you should watch for
Types of low TSH: How can I tell which one I have?
Clinicians diagnose low TSH as either subclinical hyperthyroidism or overt hyperthyroidism. The distinction between the two involves the chemistry of the body. Subclinical hyperthyroidism is diagnosed when thyroid tests show TSH levels are low, but T3 and T4 levels are in the normal range. Overt hyperthyroidism has both low TSH levels and high T3 and T4 levels.
Can people tell the difference between subclinical and overt hyperthyroidism without a blood test? Probably not. People with subclinical hyperthyroidism usually don’t have symptoms; if symptoms are present, they are usually only mild. To confound matters further, overt hyperthyroidism doesn’t always cause symptoms; symptoms can also be mild if they are present. Therefore, the only way to know is through a blood test.
When to see a doctor for low TSH symptoms
See a doctor when any signs of low TSH are noticed. An overactive thyroid is treatable, but it can cause serious complications.
Low TSH is diagnosed by a blood test that measures TSH levels and thyroid hormone levels. That’s enough for a diagnosis of hyperthyroidism, but the clinician will also want to discover the cause. That will mean a physical examination, a thorough medical history, and blood tests for thyroid auto-antibodies or thyroid-stimulating antibodies. The clinician may also need to take scans, usually a radioactive iodine uptake scan called thyroid scintigraphy. The clinician may take an ultrasound scan of the thyroid gland.
RELATED: How to understand thyroid panel test results
Complications of low TSH
Depending on the cause, untreated hyperthyroidism can have serious complications:
Thyroid storm, is a life-threatening condition in which the thyroid gland produces large amounts of thyroid hormone
Abnormal heart rhythms
Heart problems, including heart failure
Stroke
Osteoporosis
Fertility problems
According to a 2012 study, high cholesterol may also be a complication of low TSH, further increasing the risk of heart disease and stroke.
How to treat low TSH symptoms
A hormone specialist, an endocrinologist, usually treats low TSH and overactive thyroid. Depending on the cause, treatments include:
Adjustments to hypothyroidism treatment: Normally, low TSH is caused by an overactive thyroid. However, it may indicate a medication problem in someone with an underactive thyroid. In that case, it usually means that the thyroid hormone dose is too high. To fix this, healthcare professionals will reduce the dose of the thyroid hormone, usually a drug called levothyroxine.
Drug side effects: If hyperthyroidism is caused by prescription drugs, the healthcare provider will discontinue those drugs if possible.
Beta blockers: Drugs like atenolol or propranolol can relieve symptoms of hyperthyroidism, such as racing heartbeats, high blood pressure, tremors, and anxiousness, but they do not affect thyroid hormone levels.
Antithyroid drugs: Methimazole and propylthiouracil block the ability of the thyroid to produce thyroid hormones.
Radioiodine therapy: Radioactive iodine taken as a capsule kills thyroid gland tissues, compromising the thyroid’s ability to produce thyroid hormone.
Thyroidectomy: Less commonly, surgeons may remove part or all of the thyroid gland in order to reduce thyroid hormone levels.
Both radioiodine therapy and surgery will result in permanent hypothyroidism. After treatment, people will be placed on lifelong thyroid hormone replacement treatment.
RELATED: Hyperthyroidism treatments and medications
Living with low TSH
Most people with low TSH have subclinical hyperthyroidism. They have low levels of TSH, but thyroid hormone levels are in the normal range. There should be no symptoms, but some people will experience mild symptoms. Additionally, the “normal range” may not be normal for everyone, so healthcare professionals may treat subclinical hyperthyroidism depending on the cause, the severity of the symptoms, and the person’s risk for complications. However, healthcare providers usually don’t think treatment is necessary. If that is the case, here are a few tips for living with low TSH:
Don’t worry—only a few cases of subclinical hyperthyroidism get worse
Follow all the instructions and advice given by a healthcare provider
Keep a symptom diary and share it with the clinician
Tell the doctor about any new medical conditions
Tell the doctor about any new drugs being taken
Most importantly, see a doctor
If any of the symptoms of low TSH are experienced, see a doctor. Some of the complications of low TSH are very severe. Some can be deadly. The only way to identify low TSH is through a blood test. Once confirmed, low TSH can be fixed, but only with the appropriate treatment under the guidance of a healthcare professional.
FAQs about low TSH symptoms
Can low TSH cause weight gain?
Low TSH is typically a sign of an overactive thyroid. People with an overactive thyroid are more likely to lose weight than gain weight.
Can low TSH cause anxiety?
Low TSH is typically a sign of an overactive thyroid. Excess thyroid hormone typically speeds up the brain, causing anxiety, restlessness, agitation, and sleeplessness.
Can low TSH cause brain fog?
Low TSH means there’s a thyroid problem, usually an overactive thyroid. When thyroid hormones fall out of balance, cognitive problems are very commonly experienced. People with underactive or overactive thyroid typically complain of problems with concentration, memory, and “brain fog.” Fortunately, these are temporary problems. The brain fog and cognitive deficits usually clear up when thyroid hormone levels return to normal.
What’s next? Additional resources for people with low TSH symptoms
Test and diagnostics
How to understand thyroid panel test results, SingleCare
Hyperthyroidism, StatPearls
Hyperthyroidism: diagnosis and treatment, American Family Physician
Hyperthyroidism in children and adults, American Thyroid Association
Subclinical thyroid disease, American Family Physician
Treatments
Hyperthyroidism, NIH National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Hyperthyroidism in children and adults, American Thyroid Association
Hyperthyroidism treatments and medications, SingleCare
Management of subclinical hyperthyroidism, International Journal of Endocrinology and Metabolism
Radioiodine (radioactive iodine) therapy, Cleveland Clinic
Scientific studies and clinical trials
Thyroid-stimulating hormone levels within the reference range are associated with serum lipid profiles independent of thyroid hormones, The Journal of Clinical Endocrinology & Metabolism
Update on the prevalence and pathogenesis of central hyperthyroidism, Journal of the Endocrine Society