Thyroid problems: tests and diagnosis

There are many distinct problems that may be associated with the thyroid gland. These include issues relating to thyroid growth, hormone production, thyroid nodules, and thyroid cancer. All of these conditions require an accurate diagnosis.

Thyroid tests and what they mean

– A complete blood count (CBC) plus metabolic profile are important thyroid tests, helping to determine that there is no anemia, liver malfunction, excess blood calcium, and other possible causes.

– Total and free thyroxine (T4). These two thyroid tests are measured separately from each other. Total T4 testing measures all thyroxine circulating in blood; free T4 testing measures only the biologically active thyroxine (those not bound to serum-binding proteins and can attach to the hormone receptors in cells). Total triiodothyronine (T3). This thyroid test measures the T3 levels circulating in the blood. The normal reference range is 0.4 to 4.2 micro IU/ml. This blood test is usually conducted when your doctor needs more information about the function of your thyroid.

– Thyroid antibody blood tests. These thyroid tests detect antibodies to thyroid cell components, such as antibodies to thyroglobulin and thyroperoxidase. High levels of these various antibodies can help confirm Graves’ disease. A timely diagnosis of this disease in children will help to avoid severe developmental pathologies.

– Needle aspiration biopsy. A biopsy may be taken from suspicious nodules. In this thyroid test, a needle withdraws some fluid or cells for analysis. Detecting cancers up to 90 percent of accuracy is possible with this thyroid test.

– Iodine level test.

What the iodine test measures and what is normal

– The iodine test from FFP Labs measures iodine loading and saturation.

– The loading test looks at how many mg (milligrams) of iodine you excrete in 24 hours after taking a known loading dose = 50 mg.

– The saturation value is a percentage equal to the amount of iodine that you urinated out over 24 hours divided by the amount of iodine that you took = 50 mg.

– The normal range for the loading test given by the lab is that you should urinate out greater than 44 mg of iodine of the 50 mg that you took orally. This gives a normal range for the saturation of

Interpret your thyroid test results

These are basic guidelines for interpreting your thyroid test results. Where it is possible to be sure of what is going on from your test results you will be able to interpret your own test results.

– If your iodine test results show that the iodine loading value is below 30 mg you are low in iodine and should supplement iodine.

– If your iodine loading value is above 40 mg you do not need to supplement iodine.

– If your iodine loading value is between 30-40 mg then you are in a gray area and should consult with a practitioner who is experienced in interpreting these tests.

The uses of thyroid scan

The thyroid scan is useful in showing where the nodules have less (”cold”) or greater (”hot”) absorption of radioactive iodine in comparison with normal paranodular tissue. The data helps in classifying nodules as “cold” (hypofunctional), “warm” (functioning normally), or “hot” (hyperfunctional). The thyroid scan produces an image that illustrates the basic shape of your thyroid gland, and the pattern of the relative concentration of the radioactive imaging agent that has been introduced.

A “cold” nodule usually occurs in the isthmus (the central stalk) or at the fringes of the thyroid. The contours of the gland thus remain normal with little distortion. It may indicate that the patient has thyroid cancer, and a thyroid lobectomy (a procedure where the surgeon removes a single lobe of your thyroid) is often recommended by doctors.

However, it must be noted that thyroid nodules such as cysts, benign follicular lesions, colloid nodules, and hyperplastic nodules are all cold when scanned, so the doctor approaches the diagnosis carefully. “Hot” nodules (which happen because RAI uptake in surrounding tissue is unimpeded) can also indicate a malignancy.

The thyroid scan is, in fact, not a cost-effective method for all patients who show symptoms of the thyroid nodule. In the following situations, however, a thyroid scan may be useful:

– To determine how a nodule in a Graves’ disease patient is functioning, since a cold nodule usually becomes a candidate for biopsy and partial thyroidectomy (rather than iodine ablation or drug therapy for hyperthyroidism);

– To establish the status of a nodule’s functioning, where it has been shown to be a follicular neoplasm through the fine needle aspiration method;

– To differentiate the functional status of each separate nodule in instances of multinodular goiter; and,

– To help describe the presence of nodules, especially when there are indications of multinodularity or substernal extension.

Iodine-123 (I-123), Iodine-131 (I-131), and Technetium pertechnetate (Tc-99) are the most commonly used radioactive probes for thyroid scanning. I-123 is usually the preferred isotope, but some specialists would like to use Tc-99. Both I-123 and Tc-99 are effective imaging agents, though there may be occasions when they yield contrary results. Tc-99 may show a nodule to be functioning normally, while I-123 may show it as cold. For this reason, it is not an uncommon practice to conduct a thyroid scan with I-123 if a nodule appears hot with Tc-99.

Thyroid hormone tests: Who decides which levels are normal and which are not?

Many, many doctors, probably most, use only the TSH test in order to assess your thyroid situation. If your TSH levels are low, the doctor will say that you are not hypothyroid. If they are high he will say that you are.

What is a normal TSH level?

With the TSH test, laboratories simply decide what is a “normal” TSH level. They do this by testing a certain number of individuals from the general population and defining that a certain percentage of this group is normal.

It is simply a decision that the laboratories make.

Simply deciding what is normal using statistical “logic” can never correctly diagnose anyone.

In terms of numbers, most laboratories decide that 95% of all test results from a given test group is normal. That leaves 5% for the “abnormal” group. So they look at all the results and put the top 2.5% and the bottom 2.5% to one side and call these numbers “abnormal”.

So only 2.5% are “reserved’ for abnormally low TSH results.

This practice, of course, has many issues. What happens if a disease begins to show with a higher frequency in a large group of people? For comical purposes let’s take the plague that killed millions in the 1300s. Well, if a plague patient happened to take a plague test at a doctor’s office in 1350, he would probably be sent home with a pat on the back confirming that his test results are completely normal.

Simply deciding what is normal using statistical “logic” can never correctly diagnose anyone.

For most laboratories, a TSH level of 4.00 to 4.50 is defined as normal. Most hypothyroid researchers and doctors with plenty of hypothyroid experience will tell you that this number is too high.

In fact, many studies now show that the “normal” TSH levels should be much closer to 1.00 than to 4.00.

Do not make the mistake thinking that the TSH test’s reference values are anything to go by, do your research. The logical way of deciding on these levels and thresholds should be perfectly normal doctors observing the symptoms of patients with hypothyroidism.

Not a laboratory statistically deciding what is normal and what is not.

The problem with the statistical method

What are the consequences of this? Well, if you have a doctor who relies blindly on what laboratories define as a “normal” TSH range of a TSH test he will probably give you less medication than you need if any medication at all.

A TSH level of 4.00 on a TSH test will be interpreted as being normal, while in fact, you are way above what most hypothyroid specialists consider normal for the TSH test. You may continue to have many of your hypothyroid symptoms. If your doctor is ignorant enough he will attribute your hypothyroid symptoms as being other diseases with the “logic” that your TSH levels are “normal”.

Do not rely on what most laboratories tell you are a “normal” test level, but confer with experienced doctors.

The other problem has to do with the TSH test in itself.

It is not a good indicator of hypothyroidism.

Why? Simple. TSH is a hormone that has nothing directly to do with the thyroid.

It is a pituitary hormone that gets its “orders” from various biofeedback systems, most notably the hypothalamus that is supposed to “sense” how your thyroid hormone levels are in the blood. When some thyroid levels are on the low side the hypothalamus will poke the pituitary, which will poke the thyroid (with TSH).

The only scenario that really works with the TSH is when your hypothyroidism is caused by a faulty thyroid gland. A “classic” hypothyroidism case that doctors love because it’s so easy to diagnose.

TSH will mask many real hypothyroid situations, so a normal level – even if we decide to agree on what a “normal’ TSH level is – is not a guarantee that you are not hypothyroid.

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