What Is Postprocedural Hypothyroidism?

Postprocedural hypothyroidism, also known as postoperative hypothyroidism, is a condition characterized by low thyroid levels after thyroid surgery, including thyroidectomy (full or partial removal of the thyroid).

This article discusses the symptoms, causes, diagnosis, and treatment of postprocedural hypothyroidism.

Symptoms of Postprocedural Hypothyroidism

Inform your healthcare provider about any of the following symptoms after thyroid surgery, since they are a sign of abnormal thyroid levels:

• A change in energy levels
• Menstrual cycle changes
• Skin, hair, and nail changes
• Appetite changes
• Changes in bowel habits
• Mood changes
  

Causes of Postprocedural Hypothyroidism

The thyroid gland is a hormone-producing organ located at the base of the neck. It is responsible for making the thyroid hormones, thyroxine and triiodothyronine, which are involved in important metabolic processes throughout the body. Problems with the thyroid gland, such as cancer, goiter (enlarged thyroid), or nodules, may require surgery to remove all or part of the thyroid gland.

Postprocedural hypothyroidism is expected after the removal of the entire thyroid gland (a total thyroidectomy) since it is the only organ that can produce thyroid hormones. People who have had their entire thyroid gland removed must take medication to replace thyroid hormones.

Thyroid hormone levels may also be low after the removal of just part of the gland (known as hemithyroidectomy or lobectomy). Low thyroid levels in this setting can be temporary or permanent. In one study of people undergoing hemithyroidectomy in South Korea, thyroid function normalized after an average of one year in 2 of 3 people with hypothyroidism.

Thyroid ablation with radioactive iodine is another therapy that causes postprocedural hypothyroidism. It is sometimes used to treat an overactive thyroid, goiter, and thyroid cancer. When used to treat thyroid cancer, postprocedural hypothyroidism is always expected.

Rates and Risk Factors for Postprocedural Hypothyroidism

The rate of postprocedural hypothyroidism after thyroidectomy depends on how much of the thyroid gland is removed. In a total thyroidectomy, the rate is 100%. In hemithyroidectomy, 20% to 30% of people will require thyroid hormone replacement medication.

Risk factors for postprocedural hypothyroidism after hemithyroidectomy include the following:

• Presence of antithyroid antibodies
• Lymphocytic thyroiditis
• High thyroid stimulating hormone (TSH) and low thyroxine (T4) levels prior to surgery
• Low amount of thyroid tissue remaining
  

How Is Postprocedural Hypothyroidism Diagnosed?

Hypothyroidism does not always cause symptoms, which is referred to as subclinical hypothyroidism. Thankfully, simple blood tests can reveal a diagnosis of hypothyroidism regardless of the presence of symptoms. Thyroid stimulating hormone and thyroxine blood levels are measured routinely after thyroid surgery to determine if thyroid supplementation is needed and to guide the dosing of the medication.

Treatment of Postprocedural Hypothyroidism

It is important that postprocedural hypothyroidism is diagnosed early to prevent complications of low thyroid levels. Fortunately, treatment of hypothyroidism is possible with medication.

Thyroid hormone replacement is available as an oral medication in pill or liquid form, and the dose is adjusted based on levels of thyroid hormones.

Complications of Postprocedural Hypothyoridism

Thyroid hormones are involved in many metabolic processes, and low thyroid hormone levels can cause many symptoms:

• Low energy levels
• Constipation
• Feeling cold all of the time
• Skin, hair, and nail changes
• Mood changes
• Menstrual changes

Prolonged or severe hypothyroidism can be the life-threatening condition called myxedema coma, characterized by confusion, low body temperature, low heart rate, and swelling.

After thyroid surgery, thyroid hormone levels are routinely monitored for timely treatment, and longstanding or severe hypothyroidism can be avoided.

Preventing Postprocedural Hypothyroidism

It is not always possible to prevent postprocedural hypothyroidism, since you cannot control how much of the thyroid gland needs to be removed.

However, you can prevent the serious complications of hypothyroidism after surgery. Following up with your healthcare providers, getting all recommended lab tests, and taking medications as prescribed can help you ensure that thyroid levels are in a healthy range.

Summary

Postprocedural hypothyroidism is a condition of low thyroid hormone that is not uncommon—it oftentimes is an expected consequence—of thyroid surgery. In some cases, postprocedural hypothyroidism may be temporary.

Hypothyroidism is diagnosed with blood tests. Treatment involves taking thyroid hormone replacement medication and getting occasional blood tests to monitor thyroid hormone levels.

A Word From Verywell

If you are prescribed thyroid replacement therapy, it's important to take your medication as prescribed by your healthcare provider.

Try to take it at the same time each day on an empty stomach. Always tell your healthcare provider about any other medications or supplements you are on and if you have been prescribed any new medications, since thyroid medication may not be absorbed as well when given with other medication.

If you become pregnant, your medication dose will likely need to be increased and monitored carefully.