If you’re like me, you were probably told that you have hypothyroidism or thyroid disease as a diagnosis. But there’s much more to that – in order to effectively treat your hypothyroidism you need to know what type it is and what caused it. In this article you’ll learn what tests you need to determine whether you have Hashimoto’s disease since it’s the most common cause of hypothyroidism.

If you were diagnosed with hypothyroidism, there’s a 90% chance that it was caused by Hashimoto’s Thyroiditis – an auto-immune disease, that destroys thyroid cells and impairs the production of thyroid hormones.

The Difference Between Hypothyroidism and Hashimoto’s

thyrofix-ad-3Hypothyroidism is a state of impaired thyroid function while Hashimoto’s is an autoimmune disease that can result in symptoms of hypothyroidism. In other words: In hypothyroidism the problem lies within the thyroid gland itself; in Hashimoto’s patients the problem is with your immune system creating antibodies against proteins in your thyroid gland, causing gradual destruction of your gland, and making it unable to produce sufficient thyroid hormones.

You may need to undergo several tests before being diagnosed with hypothyroidism or Hashimoto’s Thyroiditis. These may include clinical assessment and evaluation, various blood tests, biopsies, imaging tests, etc.

Hypothyroidism and Hashimoto’s affect millions of people worldwide. The problem may be mild to severe, with women above the age of 50 being at higher risk. The symptoms may begin as mild at first, but may pose bigger challenges at a later time. Hypothyroidism may lead to other problems like heart disease, joint pains, obesity, and infertility. Early diagnosis is therefore necessary to avoid further complications.

Hashimoto’s Disease Explained

Chronic lymphocytic thyroiditis, or Hashimoto’s thyroiditis, was first described by the Japanese physician Hashimoto in 1912. The disease shows a marked hereditary pattern but it is up to 20 times more common in women than in men. It occurs most frequently between the ages of 30 and 50 but may arise at any age, even in young children.

Development of goiter is common – a gradual painless enlargement of the thyroid gland, usually asymptomatic, but sometimes patients complain of dysphagia (difficulty in swallowing) and a feeling of local pressure.

Most commonly, the inflammation takes the form of a chronic, progressive disease known as chronic lymphocytic thyroiditis or Hashimoto’s disease. This condition may be so mild that it may go unnoticed for many years, but eventually it may destroy so much thyroid tissue that hypothyroidism develops as a result. We’ll discuss risk factors, causes and symptoms in more detail in the next article.

How is Hashimoto’s diagnosed?

In addition to a clinical evaluation, the diagnosis is made by measuring blood levels of thyroid hormones T4 and T3 and thyroid-stimulating hormone (TSH) to determine how the gland is functioning as well as TPO antibodies and Tg antibodies.

Required Lab Tests

Normal Ranges at a Glance

TSH……………………………0.3-3.0 mIU/L
Free T4……………………….0.7–1.9 ng/dl
Free T3……………………….230– 619 pg/d
TPO-ab……………………..<34.9 iU/ml
Tg-ab………………………..<4.0 IU/mL


TSH is secreted by the pituitary gland. If a decrease of thyroid hormone occurs, the pituitary gland reacts by TSH Normal Range
producing more TSH and the blood TSH level increases in an attempt to encourage thyroid hormone production. This increase in TSH can actually precede the fall in thyroid hormones by months or years. Thus, the measurement of TSH is elevated in cases of hypothyroidism.

There’s a lot of controversy surrounding the TSH  normal range. In the past it used to be between 0.5 and 5.0.

In the fall of 2002, the American Association of Clinical Endocrinologists (AACE) announced the new guidelines which narrowed the TSH reference range to 0.3 – 3.0. According to AACE the new guidelines double the number of people who have abnormal thyroid function, bringing the total to around 27 million, up from 13 million thought to have the condition under the old guidelines. These new estimates make thyroid disease the most common endocrine disorder in the US, far outnumbering diabetes sufferers.

Dr. Gharib says, “The new TSH range from the AACE guidelines gives physicians the information they need to diagnose mild thyroid disease before it can lead to more serious effects on a patient’s health – such as elevated cholesterol, heart disease, osteoporosis, infertility, and depression.”

Although these new guidelines have been in effect for almost a decade now, many doctors refuse to treat patients with TSH below 5.0. Most labs still use the old range of 0.5-5.0, so when a doctor looks at the results, it says “normal” and they don’t bother to look into the issue any further. At the same time the patient still has symptoms but they are told they are normal and there’s nothing else that could be done. Even worse, they might be misdiagnosed with something like anxiety or depression and put on antidepressants or other drugs.

A research done by the National Academy of Clinical Biochemistry, part of the Academy of the American Association for Clinical Chemistry (AACC) in 2002 revealed that, “In the future, it is likely that the upper limit of the serum TSH euthyroid reference range will be reduced to 2.5 mIU/L because more than 95% of rigorously screened normal euthyroid volunteers have serum TSH values between 0.4 and 2.5 mIU/L.” Another study revealed that using a TSH upper normal range of 5.0, nearly 5% of the population is hypothyroid. But if the normal range was lowered to 3.0 per the AACE recommendations, approximately 20% of the population would be considered hypothyroid.

T4/Free T4

When the body releases thyroid hormones, it releases both thyroxine (T4) and triiodothyronine (T3) in a ratio of around 80:20. Thyroxine (T4) is then converted to the active hormone (T3), mainly by the liver. The lab blood tests reflect the amount of these hormones in the blood.

The T4 test also called Total T4, Total Thyroxine, or Serum Thyroxine test, has a normal range of approximately 4.6–12 ug/dl.

Today doctors often measure Thyroxine in its free form – Free T4, because some T4 is bound to proteins and unavailable to the body; Free T4 is able to enter the various target tissues in the body to exert its effects. The normal range of Free T4 is approximately 0.7–1.9 ng/dl.

T3/Free T3

Sometimes the impaired thyroid gland will start producing very high levels of T3 but still produce normal levels of T4. Therefore measurement of both T4 and T3 in addition to TSH provides an even more accurate evaluation of thyroid function.

Doctors measure T3 particularly in cases where hyperthyroidism is suspected, as the T3 level will be obviously raised in these cases. A T3 blood test is not very useful in cases of hypothyroidism, as the T3 levels are the last to be affected – it’s possible to be severely hypothyroid, with a low T4, high TSH but utterly normal T3 level.

As with T4, T3 may be tested for levels of the Free form (Free T3, FT3, or Free Triiodothyronine l), for which the normal range is approximately 230– 619 pg/d. A level of less than 230 may indicate hypothyroidism.

Note also that certain drugs, such as birth control pills and large doses of aspirin can interfere with T3 test results. The hormone is also affected by illness; serious illness will reduce levels of T3 significantly.

TPO-ab (Thyroid peroxidase antibodies)

Thyroid peroxidase (TPO) is an enzyme made in the thyroid gland that is important in the production of thyroid hormone. TPO is found in thyroid follicle cells where it converts the thyroid hormone T4 to T3. The presence of TPO-Ab in the blood reflects an attack on the thyroid tissue by the body’s immune system.

TPO-Ab is the most sensitive test for detecting autoimmune thyroid disease. Autoimmune thyroid disease or Hashimoto’s, accounts for 90 percent of all hypothyroidism cases in countries where iodine deficiency is not an issue so if you were diagnosed with hypothyroidism you should have your TPO-ab levels checked and see if your case is auto-immune as well. The normal level of TPO-ab is <34.9 iU/ml.

Some people without symptoms of thyroid disease may have TPO antibodies. However, the presence of thyroid peroxidase antibodies increases the risk of future thyroid disorders. This is because the immune system keeps producing antibodies that slowly destroy your thyroid. It may take years for symptoms to appear. In such cases it’s important to address the cause of auto-immunity as soon as possible. If you have normal thyroid function with TPO antibodies, you need to have blood tests done periodically to monitor thyroid function.

Tg-ab (Thyroglobulin antibodies)

Thyroglobulin antibodies are proteins produced by the body’s immune system to attack thyroglobulin (Tg). Tg is used by the thyroid gland to produce the thyroid hormones thyroxine (T4) and triiodothyronine (T3). Thyroglobulin antibodies are positive in about 60 percent of Hashimoto’s patients and 30 percent of Graves’ patients.

Tb-ab (Blocking TSH Receptor Antibodies)

Blocking TSH receptor antibodies (TB-Ab or TSB-Ab) are antibodies that prevent TSH from binding to the cell receptor, and cause hypothyroidism. Patients with Hashimoto’s disease usually test positive for these antibodies.

Clinical Assessment and Evaluation

The first and most basic tool used to test for thyroid disorders is a clinical assessment. If you feel any of the symptoms of the thyroid disorders, you have to be seen by a physician immediately. Here are the clinical tests that should be done by your health care provider:

  • neck palpation
  • auscultation of the thyroid gland through the use of a stethoscope
  • reflex testing
  • vital signs measurement
  • height and weight measurement
  • temperature measurement
  • facial examination especially on the eyes
  • observation on the quality or quantity of your hair
  • skin examination
  • nails and hands examination
  • clinical signs review

Thyroid Imaging Studies

Imaging studies are done to visualize the affected part of the body. If the doctor suspects abnormality in the thyroid gland upon clinical assessment, he may suggest further studies such as imaging tests. Examples include the following:

–        Computed Tomography Scan – detects and diagnoses Goiter or enlargement of the nodules.

–        Thyroid Ultrasound – ultrasounds are done to detect nodules that are filled with cyst or tissue. This test also evaluates the lumps, nodules, and size of your thyroid gland.

–        Magnetic Resonance Imaging Studies – evaluates the shape and size of the thyroid gland

Morning Temperature and Pulse

One of the easiest ways to check whether you suffer from hypothyroidism is to take your temperature and pulse in the morning, right after you wake up. For the most accurate results when taking your morning temperature, keep a thermometer by your bedside and take your temperature before getting out of bed or even moving much.

According to recent studies 98.2 °F is now considered to be the correct average human body temperature, but it’s worth mentioning that if you took your temperature right now, it almost certainly won’t be that number. Your body’s temperature fluctuates throughout the day, from roughly 97.6 °F at 6AM to 98.5 °F at 6PM.

A morning temperature below 97.6°F is highly indicative of hypothyroidism. However, your morning temperature is not always the best indicator of hypothyroidism; when the air around you is warm, your thyroid doesn’t have to work that hard to maintain normal body temperature, that’s why the results would be more accurate if you take your pulse into consideration as well.

Having very low pulse rates is common for patients suffering from hypothyroidism. But when patients take a thyroid supplement, their pulse rates generally return to normal. The average resting heart rate of a healthy person is around 85 beats per minute. 70 beats per minute or less could be a sign of hypothyroidism. So, by taking into account your morning temperature and pulse rate together, you get more accurate results than with morning temperature alone.

More Tests

Your doctor may order additional tests including:

  • Thyroid-Stimulating Immunoglobulins (TSI)
  • Thyroid Receptor Antibodies (TRAb)
  • Thyroglobulin Antibodies or Antithyroglobulin Antibodies
  • Antimicrosomal Antibodies or Antithyroid Microsomal Antibodies
  • Reverse T3
  • Thyroid Binding Globulin or Thyroglobulin
  • T3 Resin Uptake

Now that you know what tests you need, speak with your doctor and request the necessary testing if it wasn’t performed already.

Next: Understanding Hashimoto’s and Hypothyroidism

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