What can cause falsely low TSH?

Understanding Falsely Low TSH Levels
Thyroid-stimulating hormone (TSH) plays a crucial role in regulating thyroid function, and its levels can provide significant insights into a person’s thyroid health. However, there are several factors that can lead to falsely low TSH readings, which may mislead healthcare providers and patients alike.
Causes of Falsely Low TSH Levels
1. High Thyroid Hormone Levels: One of the most common reasons for low TSH levels is the presence of elevated thyroid hormones in the bloodstream. Conditions such as hyperthyroidism, where the thyroid gland is overactive, can suppress TSH production. This occurs because the pituitary gland reduces TSH secretion in response to high levels of thyroid hormones, which are responsible for regulating metabolism and energy levels.
2. Non-Thyroidal Illness Syndrome: Serious illnesses that are not directly related to thyroid function can also cause low TSH levels. This phenomenon, often referred to as euthyroid sick syndrome, occurs during periods of systemic inflammation, severe injury, or infection. In such cases, both TSH and thyroid hormone levels may decrease, leading to misleading test results.
3. Medications: Certain medications can interfere with TSH levels. For instance, drugs such as steroids, dopamine, and opioid painkillers (like morphine) can lower TSH readings. Additionally, high doses of biotin, a common B vitamin supplement, have been known to cause falsely low TSH levels by interfering with the assay used to measure TSH.
4. Physiological Factors: Factors such as pregnancy and fasting can also impact TSH levels. During pregnancy, hormonal changes can lead to lower TSH levels, particularly in the first trimester. Similarly, fasting can alter metabolic processes and affect hormone levels, potentially resulting in a temporary decrease in TSH.
5. Pituitary Disorders: In rare cases, disorders affecting the pituitary gland itself can lead to low TSH levels. Conditions such as pituitary adenomas or other forms of pituitary dysfunction may impair the gland’s ability to produce TSH, resulting in low readings despite normal or elevated thyroid hormone levels.
Conclusion
Falsely low TSH levels can arise from a variety of factors, including elevated thyroid hormones, non-thyroidal illnesses, certain medications, physiological changes, and pituitary disorders. Understanding these causes is essential for accurate diagnosis and treatment of thyroid-related conditions. Healthcare providers must consider these factors when interpreting TSH test results to avoid misdiagnosis and ensure appropriate patient care.

Can TSH be falsely low?

Biotin supplements, for example, can interfere with thyroid function tests by showing falsely low TSH levels. The ATA recommends you stop taking biotin for at least two days before a thyroid test to avoid misleading results. You get sick. “If you become very sick, your TSH can be suppressed,” Davies says.

Can TSH be temporarily low?

It’s common for TSH to be slightly lower than normal during the first trimester, then slowly increase. Severe illness: People who are very sick with conditions that aren’t related to the thyroid may have a low TSH level temporarily.

Can stress affect TSH levels?

In addition, stress exacerbates autoimmune thyroid diseases, such as Graves’ disease and Hashimoto’s thyroiditis, leading to elevated thyroid hormone and decreased TSH levels [10]. Despite being exposed to a similar stressor, autoimmune thyroid disease can make it difficult to interpret the response of the HPT axis.

Can you have a false low TSH level?

High amounts of biotin in the sample will prevent the formation of the solid phase complex, yielding a low or absent signal. This will produce a falsely low TSH result. The combination of low TSH and high FT4 gives a false impression of hyperthyroid results on the ruthenium chemiluminescence assay system.

What would cause TSH to drop suddenly?

Summary. For people with thyroid disease, certain things can cause fluctuations in TSH levels. These include disease progression, medication changes, pregnancy, inadequate dosing, changes in weight, seasonal variations, and age.

Why is my TSH low and everything else is normal?

If you had thyroid blood tests and the results indicate that your TSH levels are low or undetectable (0.1 to 0.4 mIU/L) and your thyroxine (T4) and triiodothyronine (T3) levels are in the normal range, it means you have subclinical hyperthyroidism.

What can throw off a TSH test?

What can affect thyroid test results?

• Certain medications and supplements.
• The time between the last time you took your thyroid medication and when a provider draws your blood.
• Whether you ate before your test (only a factor with thyroid scans).
• Stress, including the effects on a non-thyroidal illness.

Can TSH lab results be wrong?

Outside factors may affect the results of your thyroid test. This can include whether or not you ate before your test, what time of day you take the test, and things like stress, diet, and sleep. Some medications and supplements may also affect your results. This may be because they change your thyroid function.

What is the root cause of low TSH?

Most of the time, low TSH levels indicate hyperthyroidism. This is also known as an overactive thyroid. Much more rarely, low TSH can be due to a problem with the pituitary gland. If a person’s thyroid gland is secreting levels of hormones that are too high, the pituitary gland produces less TSH.

What can alter TSH results?

Smoking mainly led to a decrease in TSH levels and an increase in triiodothyronine (T3) and thyroxine (T4) levels, while BMI levels were positively correlated with TSH and free T3 levels. Excess iodine led to an increase in TSH levels and a decrease in thyroid hormone levels.