21.3 Thyroid and Parathyroid Disorders

Dietary Iodine

Dietary iodine is required for the synthesis of T3 and T4. But for much of the world’s population, foods do not provide adequate levels of this mineral. The amount in crops varies according to the level in the soil in which the food was grown, as well as the irrigation and fertilizers used. Marine fish and shrimp tend to have high levels because they concentrate iodine from seawater, but many people in landlocked regions lack access to seafood. Thus, the primary source of dietary iodine in many countries is iodized salt. Fortification of salt with iodine began in the United States in 1924, and international efforts to iodize salt in the world’s low-income nations continue today (Cavanaugh, 2024).

Dietary iodine deficiency can result in the impaired ability to synthesize T3 and T4, leading to a variety of severe disorders. Normally, the body controls T3 and T4 levels through a feedback loop. The hypothalamus releases thyrotropin-releasing hormone (TRH) which stimulates the pituitary gland to release TSH, which stimulates the thyroid to release T3 and T4. When T3 and T4 cannot be produced, the loop becomes broken and TSH is secreted in increasing amounts. As a result of this hyperstimulation, thyroglobulin accumulates in the thyroid gland follicles, increasing their deposits of colloid. The accumulation of colloid increases the overall size of the thyroid gland, causing a condition called a goiter (Figure 21.8). Iodine deficiency can also cause impaired growth and development, decreased fertility, and prenatal and infant death. Moreover, iodine deficiency is the primary cause of preventable intellectual disabilities worldwide.

Figure 21.8 A visible goiter on a person’s neck is caused by an accumulation of colloid. (credit: “Goiter” by Jerry Kirkhart/Flickr, CC BY 2.0)

Hyperthyroidism

The overproduction of thyroid hormones, hyperthyroidism can lead to an increased metabolic rate and its effects: weight loss, excess heat production, sweating, and an increased heart rate. Graves’ disease is the most common cause of hyperthyroidism. In Graves’ disease, the hyperthyroid state results from an autoimmune reaction in which antibodies overstimulate the follicle cells of the thyroid gland. The person’s eyes may bulge (exophthalmos) as antibodies produce inflammation in the soft tissues of the orbits. The person may also develop a goiter. Complications of Graves’ disease include heart arrhythmias, heart failure, miscarriage, preterm birth, preeclampsia, maternal heart failure, osteoporosis, and thyroid storm.

Thyroid Storm

Also known as thyroid crisis or thyrotoxic crisis, thyroid storm is when the thyroid gland releases a large amount of thyroid hormone in a short period of time. It can be caused by sudden events such as infection, trauma, abrupt discontinuation of antithyroid medication, acute illness, stroke, or giving birth. Symptoms include:

• confusion/delirium
• fever
• nausea/vomiting/diarrhea
• agitation
• anxiety
• tachycardia
• shakiness
• jaundice
• loss of consciousness

Thyroid storm is a medical emergency and requires immediate care. Complications include blood clots, heart failure, seizures, delirium, and coma. If not promptly treated, death from heart failure, cardiac arrhythmias, or multiple organ failure can occur. Up to 30 percent of thyroid storm cases are fatal. Management involves providing antithyroid medications to decrease the creation and release of thyroid hormone and supportive care to treat the body systems affected. It is also important to treat the underlying cause of the thyroid storm (Cleveland Clinic, 2022b).

Hypothyroidism

Inflammation of the thyroid gland, known as hypothyroidism, is the more common cause of low blood levels of thyroid hormones and is characterized by a low metabolic rate, weight gain, cold extremities, constipation, reduced libido, menstrual irregularities, and reduced mental activity. Females are more likely than men to develop hypothyroidism, and it occurs in approximately 5 out of 100 Americans over the age of 12 (NIDDK, 2021). The condition of congenital hypothyroidism is characterized by cognitive deficits, short stature, and sometimes deafness and muteness in children and adults born to mothers who were iodine-deficient during pregnancy.

Thyroid Cancer

Thyroid cancer affects approximately 44,000 Americans yearly, and most types have an overall 5-year survival rate of at least 90 percent (American Cancer Society, 2023). It is three times more common in females and 70 percent more common in White people than Black people (American Cancer Society, 2023). Risk factors for thyroid cancer include radiation exposure, low iodine diet, obesity, family history, and certain hereditary conditions. While thyroid cancer is a treatable cancer with a high survival rate, some patients develop hypothyroidism as a result from thyroidectomy or radiation treatment.

Hyperparathyroidism

Abnormally high activity of the parathyroid gland can cause hyperparathyroidism, a disorder caused by an overproduction of PTH, which results in excessive calcium reabsorption from bone. The two main causes of hyperparathyroidism are an abnormality or tumor on the parathyroid gland or a secondary condition, such as chronic kidney disease or vitamin D deficiency, that affects the function of the parathyroid gland. Hyperparathyroidism can significantly decrease bone density, leading to spontaneous fractures or deformities. As blood calcium levels rise, cell membrane permeability to sodium is decreased, reducing the responsiveness of the nervous system. At the same time, calcium deposits may collect in the body’s tissues and organs, impairing their functioning.

Hypoparathyroidism

Abnormally low blood calcium levels may be caused by parathyroid hormone deficiency, also known as hypoparathyroidism, which may develop following injury or surgery involving the thyroid gland, certain autoimmune disorders, abnormal development of the parathyroid tissues, mutation of calcium-sensing receptors, or PTH resistance (Hans & Levine, 2022). Low blood calcium increases membrane permeability to sodium, resulting in muscle twitching, cramping, spasms, or convulsions. Severe deficits can paralyze muscles, including those involved in breathing, and can be fatal.

Clinical Manifestations of Thyroid and Parathyroid Disorders

The thyroid controls metabolism, heart rate, and body temperature. Clinical signs and symptoms of thyroid disorders typically involve either hyperactivity (hyperthyroidism) or hypoactivity (hypothyroidism) of the thyroid gland. Table 21.9 lists signs of symptoms of hyperthyroidism and hypothyroidism.

Clinical manifestations of parathyroid disease are unusual in the early stages. Signs and symptoms vary and are dependent on the type of disorder present. A patient with hyperparathyroidism may present with muscle weakness, fatigue, depression, chronic thirst, frequent urination, loss of appetite, abdominal pain, trouble concentrating, and mild confusion. If hypercalcemia is present, the patient may have muscle spasms, bone/joint pain, drowsiness, confusion, cardiac arrhythmias, hypertension, osteoporosis, kidney stones, gastric ulcers, or pancreatitis. Patients with hypoparathyroidism may present with muscle cramps, spasms, or numbness or tingling in their toes, fingers, or lips.

Recognizing Cues and Analyzing Cues

Begin a subjective assessment by asking the patient focused questions to determine if the patient is experiencing any symptoms or has a previous medical history of neck issues. Some questions to ask may include:

• Have you ever been diagnosed with a medical condition related to your neck, such as a thyroid or swallowing issue? Please describe.
• Are you currently taking any medications, herbs, or supplements for your thyroid?
• Have you ever had any radiation exposure? Please describe.
• Do you have a family history of thyroid problems? Please describe.
• Are you experiencing any joint/muscle pain, weakness, anxiety, insomnia, cold/heat intolerance, weight loss/gain, change in bowel habits, or mood swings? Please describe.

Utilize the information gathered from your subjective assessment to guide your physical assessment, as follows:

• Inspect the face and neck. The face should not be overly rounded, eyes should be normally set and not bulging, the trachea should be midline, and there should not be any noticeable enlargement of the thyroid gland.
• Note the patient’s speech. They should be able to speak clearly with no slurring or garbled words.
• Assess the patient’s skin, hair, and nails for dryness, brittleness, or thinness.

Prioritizing Hypotheses, Generating Solutions, and Taking Action

Prevention of complications, such as thyroid storm and myxedema coma, are a high priority during treatment. To monitor for thyroid storm, the nurse should monitor the patient for signs of hyperthermia, tachycardia, and hypertension; thyroid storm is a medical emergency that requires ICU level of care. Supplemental therapies include cooling blankets, telemetry, and pharmacological therapies (such as methimazole or PTU) to both treat hemodynamic instability and excessive production of thyroid (Pokhrel et al., 2022).

For patients with hypothyroidism, nursing management includes:

• Monitoring of the patient’s weight, appetite, intake, and output
• Dietary consult and constipation management
• Providing skin moisturizer for dry skin
• Encouraging exercise
• Mental health consultation and support
• A bowel regimen to treat constipation
• Low-fat diet to prevent or manage hyperlipidemia

Severe cases of hypothyroidism, known as myxedema coma, require vigilant monitoring for hypothermia, bradycardia, and respiratory depression. Patients with myxedema coma also need continuous cardiac monitoring due to the risk of bradycardia. Medical management typically involves intravenous thyroid hormone replacement to quickly restore thyroid levels. Additionally, careful assessment of neurological status is crucial, as symptoms may include altered mental status, lethargy, and potential confusion. Similar to thyroid storm, patients with myxedema coma require ICU-level care to address these critical needs effectively. In chronic management of thyroid disorders, the nurse should be sure to report any symptoms of overtreatment to the provider. Older adults beginning thyroid replacement therapy should be educated to report any chest pain, as this could be an adverse effect. Routine blood work should be completed six to eight weeks after initiation of hormone adjustment therapy to evaluate the response.

Educate the patient and family about any diagnostic testing or procedures being completed, why they’re being done, and what the results can mean. Teach about the therapies and treatments being done and why it’s important for the patient to stick to prescribed regimens. For patients with hyperthyroidism, nursing management includes:

• Monitoring vital signs, cardiac rhythm, intake and output, and daily weights
• Teaching the patient relaxation techniques
• Providing oxygen as ordered and appropriate
• Providing a cooling blanket for fevers
• Utilization of eye lubricant to keep mucous membranes intact in the eyes
• High-calorie meals to meet metabolic demands.

Evaluating Outcomes

The primary outcome of disease management in thyroid disorders is symptom resolution and restoration of hormone levels to a normal range. The nurse evaluates the patient for symptom improvement throughout treatment. Laboratory values, such as TSH, T3, and T4 will be monitored to see if there is improvement in response to treatment. Vital signs, cardiac rhythm, fluid intake and output, and daily weight are monitored for fluctuations or abnormalities.

Recognizing Cues and Analyzing Cues

The nurse utilizes subjective and objective data to optimize care in patients with parathyroid disorders. Subjective data may include weakness, depression or forgetfulness, anxiety, bone and joint pain, severe muscle cramps, abdominal pain, insomnia, increased thirst, loss of appetite, constipation, or tingling in the mouth, hands, or feet. Vital signs are evaluated with a focus on heart rhythm, blood pressure, and lung sounds. A positive Chvostek’s sign (facial muscle twitching when the facial nerve is tapped) or Trousseau’s sign (hand and wrist spasm when a blood pressure cuff is inflated) is an indicator of hypocalcemia.

Prioritizing Hypotheses, Generating Solutions, and Taking Action

For patients being treated for hyperparathyroidism, targeted nursing care includes:

• Monitoring vital signs, calcium levels, intake, and output
• Obtaining baseline bloodwork, such as serum calcium, potassium, magnesium, and phosphate levels before treatment and as ordered
• Ensuring the patient receives information about all treatments for hyperparathyroidism
• Monitoring for bone pain, fractures, and gastrointestinal symptoms
• Providing emotional support and collaborate with psychology, as appropriate

Nurses should also monitor for signs and symptoms of hungry bone syndrome, a complication that occurs from prolonged hypocalcemia following surgical correction for hyperparathyroidism. This hypocalcemia is due to the sudden drop in PTH production and serum calcium being quickly incorporated into new bone. It is often accompanied by hypophosphatemia, hypomagnesemia, and elevated alkaline phosphatase (Pokhrel et al., 2022). Symptoms include:

• Seizures
• Paresthesia
• Arrhythmias
• Numbness
• Cardiomyopathy
• Laryngospasms

Treatment includes high levels of oral calcium and vitamin D supplementation, but intravenous calcium may be given in severe cases (Pokhrel et al., 2022).

For patients with hypoparathyroidism, targeted nursing care includes:

• Administering prescribed drugs, such as calcium
• Obtaining bloodwork as ordered, such as serum calcium and phosphorous levels
• Monitoring cardiac rhythm
• Instituting safety precautions and monitoring the patient for seizure activity
• Providing airway management by preparing for possible interventions like tracheostomy, oxygen administration, and suctioning if the patient develops severe respiratory issues or requires airway support

Evaluating Outcomes

For a patient with a parathyroid disorder, one outcome should be the patient’s serum calcium returning to normal levels. If not, the nurse should determine whether the patient followed the interventions that were chosen. Monitoring laboratory trends may reveal improvement in calcium levels, indicating that the treatment is working.