Hypothyroidism

Hypothyroidism is a condition in which the thyroid gland does not make enough thyroid hormone. The thyroid makes two hormones, T4 (storage hormone) and T3 (active hormone). These hormones regulate our metabolism in every cell of our body. It affects how many calories we burn, heat production, body weight, and controls our body through energy metabolism. For example, the thyroid hormones have direct effects on the heart rate, which beats faster and harder under the influence of thyroid hormones. Every cell in the body will respond to decreases in thyroid hormone with a decrease in the rate at which they use energy. So it is understandable that people with this condition will have symptoms associated with a slow metabolism. The estimates vary, but approximately 10 million Americans have this common medical condition. In fact, as many as 10% of women may have some degree of thyroid hormone deficiency. Hypothyroidism is more common than you would believe, and millions of people are currently hypothyroid and don't know it.

Causes of Hypothyroidism

There are two common causes of hypothyroidism. The most common cause of thyroid gland failure is called autoimmune thyroiditis (also called Hashimoto’s thyroiditis), which is a form of thyroid destruction caused by the patient’s own immune system. The body makes a protein or antibody which specifically kills the thyroid cells. The second major cause is the broad category of treatments of thyroid conditions which warrants surgical removal or planned destruction of the thyroid gland, such as surgery for thyroid cancer or treatment of hyperthyroidism where radiation is planned to destroy the thyroid.
But at other times, the surgery will be done to remove a worrisome nodule, leaving half of the thyroid in the neck undisturbed. Sometimes, this remaining thyroid lobe and isthmus will produce enough hormone to meet the demands of the body. For other patients, however, it may become apparent years later that the remaining thyroid just can't quite keep up with demand.
Similarly, goiters and some other thyroid conditions can be treated with radioactive iodine therapy. The only place in the body which iodine goes is to the thyroid cells. The aim of the radioactive iodine therapy (for benign conditions) is to kill a portion of the thyroid to prevent goiters from growing larger or producing too much hormone (hyperthyroidism). The result of radioactive iodine treatment will be to destroy thyroid cells so the patient often becomes hypothyroid within a year or two. However, this is usually greatly preferred over the original problem.
There are several other rare causes of hypothyroidism, one of them being a completely "normal" thyroid gland that is not making enough hormone because of a problem in the pituitary gland. If the pituitary does not produce enough thyroid stimulating hormone (TSH) then the thyroid simply does not have the "signal" to make hormone. Rarely, people are born without a thyroid and this is the reason why every child is checked at birth for an absent thyroid gland.

Symptoms of Hypothyroidism:
• Fatigue
• Weakness
• Weight gain or increased difficulty losing weight
• Coarse, dry hair
• Dry, rough pale skin
• Hair loss
• Cold intolerance (you can't tolerate cold temperatures like those around you)
• Muscle cramps and frequent muscle aches
• Constipation
• Depression
• Irritability
• Memory loss
• Abnormal menstrual cycles
• Decreased libido

Each individual patient may have any number of these symptoms, and they will vary with the severity of the thyroid hormone deficiency and the length of time the body has been deprived of the proper amount of hormone. Usually the failure or destruction of the thyroid happens so slowly that one does not notice the symptoms. You may have one of these symptoms as your main complaint, while another will not have that problem at all and will be suffering from an entirely different symptom. Most people will have a combination of these symptoms. Occasionally, some patients with hypothyroidism have no symptoms at all, or they are just so subtle that they go unnoticed.
Other possible symptoms can be due to goiter or enlarged thyroid. Difficulty in swallowing liquids or solids or difficulty in breathing may occur because the thyroid grows and pushes on the esophagus or trachea. When the thyroid hormone is low, the pituitary will make additional thyroid stimulation hormone (TSH) in an attempt to force the thyroid to produce more hormone. This constant bombardment with high levels of TSH may cause the thyroid gland to grow and form a goiter (termed a “compensatory goiter”). When the thyroid gets too big, it pushes on the esophagus (tube that food passes to the stomach). When the thyroid gets very large, it can also compress on the trachea which is the tube that air passes from the mouth to the lungs. Left untreated, severe hypothyroidism can progress to life-threatening depression, edema, heart failure, or coma.

Diagnosis of Hypothyroidism

The symptoms of Hypothyroidism are not specific to the thyroid. Hypothyroidism is diagnosed with simple blood tests, such as a TSH or thyroid hormone levels in the blood (T4 and T3). Often blood samples are also checked to see if there are antibodies present which destroy the thryoid (TPO). In the typical person with an under-active thyroid gland, the blood level of T4 (the main thyroid hormone) will be low, the T3 will be low or normal, while the TSH level will be high. The pituitary recognizes that the thyroid levels in the blood are low and responds appropriately by making more Thyroid Stimulating Hormone (TSH) in attempt to force more hormone production out of the thyroid. In the very rare case of hypothyroidism due to pituitary failure, the thryoid hormone T4 will be low, but the TSH level will also be low. The thyroid is behaving “appropriately” under these conditions because it can only make hormone in response to TSH signals from the pituitary. Since the pituitary is not making enough TSH, then the thyroid will never make enough T4 and T3. If the pituitary is not working, additional pituitary testing will need to be performed.
Hypothyroidism is completely treatable in most patients simply by taking a T4 hormone once a day (see thyroid therapy). However, this is a simplified statement, and it's not always so easy. There are several types of thyroid hormone preparations and one type of medicine will not be the best therapy for all patients. Many factors will go into the treatment of hypothyroidism and it is different for everybody. Rarely (<1% of the time), people need both thyroid hormones T4 and T3 which can be quite complex to manage, and a specialist is needed to “fine tune” both thyroid hormones.
For the majority of patients with hypothyroidism, taking some form of purified thyroid hormone replacement will make the “thyroid function tests” return to the normal range, AND, this is accompanied by a general improvement in symptoms making the patient feel better. This does not happen to all individuals, however, and for these patients it is very important to find an endocrinologist who is trained in thyroid diseases and treatment. Because most patients will be improved (or made completely better) when sufficient thyroid hormone is provided daily to make the hormone levels in the blood come into the normal range, physicians will often rely on test results to determine when a patient is on the appropriate dose and therefore doing well. Remember, these tests have a wide normal range. There is more than one drug and there is more than one lab test so the therapy may be simple or complex. Occasionally, hypothyroid treatment does not relieve a patient’s symptoms and other causes of their symptoms need to be addressed by additional testing.

Treatment of Hypothyroidism

Hypothyroidism is usually quite easy to treat (for most people). The easiest and most effective treatment is simply taking a thyroid hormone pill (T4 or Levothyroxine) once a day, preferably in the morning on an empty stomach for best absorption of the medication. The patient should wait about 40 minutes before eating or taking other medications for the best absorption of the medication. This hormone is a purified T4 which is an exact replacement for the T4 that the human thyroid gland normally secretes. It comes in multiple strengths, which means that an appropriate dosage can almost always be found for each patient. The dosage should be re-evaluated and adjusted until the proper level is established. Once at the goal determined by the doctor for each patient, the dose should then be re-evaluated at least annually. If you are on this medication, make sure your physician knows it so he/she can check the levels at least yearly. This simple approach does not hold true for everybody. Occasionally, the correct dosage is a bit difficult to pin-point and therefore you may need an exam and blood tests more frequently. Also, some patients just don’t do well on some thyroid medications and will be quite happy on another. There are a number of situations which affect the thyroid hormone level and require adjustments. For these reasons you should not be shy in discussing with your doctor your blood hormone tests, symptoms, how you feel, and the type of medicine you are taking. The goal is to make you feel better and avoid risks of too much or too little therapy. Sometimes that’s easy. When it’s not, you need a specialist to explore different dosages or other types of medications (or alternative diagnoses). There is another thyroid hormone (T3 or Liothyronine) which is rarely needed and added to the Levothyroxine.
Some patients will notice a slight reduction in symptoms within 1 to 2 weeks, but the full metabolic response to thyroid hormone therapy is often delayed for a month or two before the patient feels completely normal. It is important that the correct amount of thyroid hormone is used. Not enough and the patient may have continued fatigue or some of the other symptoms of hypothyroidism. Too high a dose could cause symptoms of nervousness, palpitations or insomnia typical of hyperthyroidism. Some recent studies have suggested that too much thyroid hormone may cause increased calcium loss from bone increasing the patient's risk for osteoporosis. For patients with heart conditions or diseases, an optimal thyroid dose is particularly important. Even a slight excess may increase the patient's risk for heart attack or worsen angina or chest pains or cause abnormal heart rhythms. Frequent dose checks and blood hormone levels are appropriate in these patients to prevent possible complications of therapy.
After about 6-8 weeks of treatment, hormone levels are measured in the blood to establish whether the dose of thyroid hormone which the patient is taking is appropriate. We don't want too much given or subtle symptoms of hyperthyroidism could ensue, and too little would not alleviate the symptoms completely. Once treatment of hypothyroidism has been started, it typically will continue for the patient’s life. The T4 dose may have to be adjusted frequently during pregnancy (usually more hormone is needed to meet the increased demands during pregnancy) and reduced after delivery. Therefore, it is of great importance that the diagnosis be firmly established and lifelong follow up is arranged. Patients should always ask their physician about their thyroid hormone and other drugs or over-the-counter medications that could adversely interact with thyroid hormone replacement. There are other potential problems with other drugs including iron-containing vitamins, calcium supplements, as well as other prescription drugs which bond the T4 and do not allow drug absorption. The brand name T4 tablets are the preferred thyroid hormone replacement (Synthroid or Levoxyl) therapies preferred by most experts because they are more accurate in dosing compared to the generic preparations.

How to take the medication

Take this medication at the same time each day whenever possible. If you miss a dose, take it as soon as you remember it. For best absorption of the thyroid hormone, take it first thing in the morning with water and wait at least 40 minutes before other medications or food intake.
Other drugs may bind to thyroid hormone and reduce the amount that is available in your body, making it less effective. Separate doses from the following medicines: Antacids containing aluminum, ferrous sulfate (a type of iron supplement) and if your diet is high in fiber take your thyroid hormone 1 hour before eating. Calcium (such as Tums) should be taken with meals for best absorption but separated from thyroid hormone by 3-4 hours. Please tell your doctor: if you are allergic to any foods or medicines, are pregnant or intend to become pregnant, are breastfeeding, are diabetic, are taking any other prescription or non-prescription medication, or have any other medical problems, especially cardiovascular disorders, including angina, coronary artery disease and hypertension. Please tell your doctor if you initiate estrogen replacement therapy or if you change your current form of estrogen replacement therapy.
Levothyroxine is in the FDA pregnancy category A. This means that Levothyroxine is safe for use during pregnancy. It is also safe to take thyroid hormones if you are breastfeeding a baby. This drug does pass into breast milk but will not harm a nursing infant.

A special medication called Ryebelsus has to be taken first thing in the morning without other medication for at least 30 minutes. In this situation, timing of thyroid hormone therapy can be safely taken at bedtime but will require more monitoring by your doctor.