Hyperthyroidism vs. Hypothyroidism

Learning about the Thyroid

One of the most important endocrine subjects is hypothyroidism versus hyperthyroidism. Once the clinician understands the etiology, pathophysiology, and unique signs and symptoms of either hypothyroidism or hyperthyroidism, they will understand the other because they are opposites. 

The most common etiology of hyperthyroidism is  Grave’s disease. The most common etiology of hypothyroidism is Hashimoto’s disease. Both conditions are autoimmune issues where the immune system starts attacking the thyroid in different ways  This article will first review hyperthyroidism.

The thyroid gland is located in the neck area.

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Grave’s Disease

Graves’ disease causes hyperthyroidism. This condition can cause significant and severe complications resulting from a thyroid emergency. 

Immune systems produce autoantibodies that make the thyroid respond or over-respond to stimulation from TSH — the thyroid-stimulating hormone produced by the pituitary gland. The auto-antibodies make the thyroid overreact to TSH stimulation, so the thyroid produces too much T3 and T4, the primary thyroid hormones.

T3 and T4 play a huge role in metabolism, making the body respond more efficiently to catecholamines. They increase metabolic rate and play a role in metabolism. They also make the body more responsive to fight or flight hormones. 

By understanding T3 and T4, the clinician learns what goes on in the body when these hormones are overproduced. An increased metabolism caused by increased T3 and T4 presents symptoms such as weight loss, diarrhea, anxiousness, anxiety, tremors, and tachycardia.

The thyroid system involves a pathway of hormones, leading to the production of T3 and T4 by the thyroid.

Relating Pathophysiology to the Signs and Symptoms

Understanding pathophysiology is critical to mastering endocrine disorders by learning the signs and symptoms. Their unique signs and symptoms separate the two disorders.

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Signs and Symptoms of Grave’s Disease

One of the prominent symptoms of Graves’ disease is exophthalmos. The word “-opthalmos” references the eyes. A sign of Grave’s disease is the eyes bulging out. The protuberance is due to little deposits of connective tissue which collect behind the eyes or in the orbital cavity. 

Clinicians may also see a goiter due to the overworked thyroid. The thyroid begins to expand, becoming large. A goiter may also present in hypothyroidism, but for a different reason.

Thyroid Storm Emergency in Hyperthyroidism and Management

Clinicians must watch for a potentially fatal thyroid storm. For this to happen, a patient must have underlying hyperthyroidism. It doesn’t happen immediately or spontaneously. For example, a patient with underlying hyperthyroidism, or one who’s on thyroid medication or replacement, may experience a stressful event, sending them into a thyroid storm. 

Vigorous palpation of the thyroid may also send a patient with existing hyperthyroidism into a thyroid storm. They include the symptoms earlier discussed, but in this case, they’re “extra hyper.” 

A patient may exhibit an extremely high heart rate, a dysrhythmia like atrial fibrillation with a rapid ventricular response (RVR), extremely high blood pressure, or hyperpyrexia (extremely hot, dangerous temperature). Treatment includes:

• Keeping the patient stable until they can receive medical treatment and reverse the underlying cause.
• Maintaining a quiet, low stimulus environment.
• Applying a cooling blanket to keep the patient’s temperature normalized.
• Administering antiarrhythmics to control the heart.
• Treating with antihypertensives to decrease blood pressure.

Supportive care is paramount until the clinician reverses the underlying cause of the thyroid storm. 

Clustering care is also important. Stimulate the patient as little as possible while simultaneously administering as many treatments as the situation requires. Allow the patient rest periods in between care, medication administration, procedures, and diagnostics.

Lab Values in Hyperthyroidism

The lab values will present elevated T3 and T4. The clinician will also observe abnormally low TSH levels due to negative feedback. The pituitary gland senses the elevated T3 and T4 and dials back the TSH. Thus, hyperthyroidism will display elevated T3 and T4 and a low TSH.

Treatment of Hyperthyroidism

Iodine is essential in the production of T3 and T4. Therefore, a treatment for hyperthyroidism is radioactive iodine. Without iodine, the production of T3 and T4 is stalled. Iodine is readily taken up by the thyroid. 

The clinician injects the patient with radioactive iodine. It is taken up by the thyroid, killing it off. Remember, patients who receive this treatment will need to take thyroid replacement for the rest of their lives.

Hypothyroidism, the Opposite of Hyperthyroidism

Hypothyroidism is most often an autoimmune issue where a patient’s immune system attacks the thyroid tissue. The condition is called Hashimoto’s thyroiditis — when the immune system produces antibodies that attack the thyroid gland. Patients will exhibit an underproduction of T3 and T4, exhibited by a slower metabolic rate.

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Signs and Symptoms of Hashimoto’s Thyroiditis

With Hashimoto’s thyroiditis, a patient will display the opposite signs and symptoms of hyperthyroidism. A clinician will observe a slow heart rate, slow metabolism, lower body temperature, and decreased blood pressure. There may be some edema, the patient may gain weight, and they may be constipated. Everything is “hypo” and slow. 

Unique to hypothyroidism is myxedema. Unlike hyperthyroidism’s exophthalmos, or bulging eyes, the eyes of patients with hypothyroidism will be edematous, or puffy. 

With this condition, small accumulations of edematous connective tissue are deposited underneath the eyes. These patients will have pronounced, puffy-looking edematous under their eyes, making them look very tired.

A hallmark sign of Hashimoto’s disease is myxedema, which often manifests as puffiness under the eyes.

Myxedema Coma Emergency in Hypothyroidism and Management

If a patient’s hypothyroidism presents as an emergency, it’s called a myxedema coma. The patient will have a very low blood pressure, heart rate, and temperature. They may display altered levels of consciousness as their brain isn’t receiving enough stimuli due to the low blood pressure. The patient may further progress to lethargy and coma. 

Steps to support the patient:

• Support blood pressure and give fluids and vasopressin.
• Administer atropine to elevate the heart rate.
• Increase body temperature and keep the patient warm.
• Support the patient’s airways due to the decreased level of consciousness to prevent aspiration.

Lab Values in Hypothyroidism

A clinician will observe decreased T3 and T4 because the autoantibodies have attacked the thyroid. The pituitary gland senses the attack and overproduces thyroid stimulating hormone (TSH), so clinicians will note increased TSH levels.

Treatment of Hypothyroidism and Precautions

Patients with hypothyroidism must take a thyroid replacement, such as levothyroxine and Synthroid®. 

Patients with Hashimoto’s thyroiditis will need to wear a medical alert bracelet. If they pass out in public, a rescuer will know how to treat them. Without the bracelet, clinicians might assume the patient collapsed due to diabetic ketoacidosis (DKA) or another similar condition.

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Summary

Endocrine system disorders include hyperthyroidism and hypothyroidism. Clinicians can easily remember the differences because the conditions are total opposites. 

Hyperthyroidism causes elevated T3, T4, and reduced TSH levels. Patients exhibit a high heart rate, high blood pressure, elevated temperature, and exophthalmos. 

Hypothyroidism causes decreased T3, T4, and increased TSH levels. Patients exhibit  a low heart rate, low blood pressure, low temperature, and myxedema. 

Grave’s disease is a common cause of hyperthyroidism, and Hashimoto’s disease is a common cause of hypothyroidism.