8.5 Thyroid Hormones

Question 1

Thyroid Hormone Functions

Answer 1

Regulates
- Cellular Metabolism
- Temperature control
- Cholesterol control
- RBC production
- Appetite
- Utilization of glucose
- Protein synthesis
- Calcium mobilization
- Cholesterol

• Regulated by TSH (Thyroid Stimulating Hormone) - Broken down into T3 or T4
• Thyroid also regulates calcitonin which helps maintain bone calcium levels (opposite of parathyroid hormone which promotes calcium in the blood)
• Calcitonin lowers serum calcium levels by taking it from the blood and putting it into the bones (helps with bone density)
• Controlled by TSH from the anterior pituitary through negative feedback
• Synthesis of thyroid hormone is DEPENDENT ON IODINE LEVELS
• Thyroid gland gives you energy and regulates metabolism

Question 2

Hypothyroidism

Answer 2

• Impacts growth more than GH

Congenital Hypothyroidism (Cretinism)
- Born with hypothyroidism
- Major issue because during infancy if growth is not able to occur (brain growth)
- This can cause mental retardation later in life.
- We need to recognize as quickly as possible for treatment

Juvenile Hypothyroidism
- Developed sometime during childhood
- Not associated with mental retardation because brain growth is COMPLETED BY 3 YEARS OLD.

ADOLESCENTS
- Memory/Attention Issues
- Visuospatial processing

MANIFESTATIONS (can mimic depression)
- Everything slows down
- Dry skin
- Constipation
- Sleepiness
- Lethargy
- Growth Failure
- Delayed puberty
- Weight gain

TREATMENT
- Supplemental thyroid hormones (Synthroid or Levothyroxine)
- This is a lifelong treatment (CANNOT STOP ABRUPTLY)

Question 3

Goiter

Answer 3

• Complication of hypothyroidism
• IT IS AN EMERGENCY FOR INFANTS
• It is irregular growth of thyroid gland due to airway obstruction

Interventions
- Intubation (prepare tracheostomy and supplemental oxygen)
- Hyperextension of the neck may help them breath
- May need surgery

Question 4

Hashimoto’s Disease (Acquired Hypothyroidism)

Answer 4

• Lymphocytic Thyroiditis
• Autoimmune condition that is the most common cause of thyroid disease in children and adolescents
• Usually develops after 6 but usually peaks during adolescents

Characterized
- Goiter
- Elevated Thyroglobulin Antibody with Rising TSH and Thyroid Peroxidase Antibody
- Thyroid cells are destroyed by T-cells and Cytokines (cells are replaced by fibrous tissue)
- Parents will notice goiter on their children (when they are swallowing or fullness feeling in neck and trouble swallowing or hoarseness)

• Most children start out as euthyroid (only slight increase in TSH) but as disease progresses T3 and T4 start to decrease dramatically.
• Can spontaneously resolve in a year or 2 or continue and linger where they may need oral thyroid replacement

Treatment
- Oral Thyroid Replacement helps decrease TSH levels and decrease size of thyroid gland

Question 5

Hyperthyroidism

Answer 5

• Graves Disease (MOST COMMON CAUSE)
• Autoimmune disorder (genetic)
• Occurs in adolescents
• Everything Speeds Up

S/S (can mimic mania)
- Develop over 6-12 months
- Hyperactivity
- Irritability
- Short attention span
- Tremors
- Increased appetite
- Weight loss
- Rapid pulse
- Flush skin
- Diaphoresis
- Heat intolerance

HALLMARK - Exophthalmos
- Protruding eyes

Question 6

Graves Disease

Answer 6

Diagnosis
- Elevated T3 and T4 but LOW TSH

Management
- Limited to school work only
- Vigorous exercise is restricted until hormone levels normalize due to cardiac implications of being sped up. We do not want them to overexert themselves

Therapy
- Antithyroid drugs (carbimazole)
- Radioactive Iodine (destroy some thyroid cells to decrease T3 and T4)
- Thyroidectomy (take out portions of the thyroid) - Oral iodine should be taken for several weeks before the procedure.

EDUCATION FOR THYROIDECTOMY
- Children should be prepared for bandages and possible endotracheal tube after surgery
- Need to support neck when sitting up

COMPLICATIONS OF THYROIDECTOMY
- Laryngospasm CAN BE LIFE THREATENING
- Signs include stridor, hoarseness, and tight feeling in the throat

• Right next to the thyroid is the parathyroid gland (which helps regulate calcium). Watch out for low calcium levels after surgery due to risk of damaging parathyroid during surgery.

Question 7

Thyroid Storm

Answer 7

• Thyrotoxicosis
• SUDDEN RELEASE OF THYROID HORMONE
• Usually brought on by stressful events, infection, or abruptly stopping medication
• DO NOT STOP TAKING MEDICATIONS OR SKIPPING DOSES

LIFE THREATENING
- Severe hypertension, tachycardia
- Hyperthermia
- Delirium, Coma, Death

Treatment
- ATD (Anti Thyroid Drug)
- Beta-Blockers