Disorders of the Thyroid Gland

Disorders of the Thyroid Gland

The Thyroid Gland

  • Location: Front view showing surrounding structures including:
    • Jugular vein
    • Thyroid cartilage (Adam's apple)
    • Superior thyroid arteries
    • Carotid artery
    • Thyroid veins
    • Trachea

Feedback System

  • Process:
    • Hypothalamus senses low thyroid hormone levels and secretes Thyrotropin Releasing Hormone (TRH).
    • TRH stimulates the anterior pituitary to release Thyroid Stimulating Hormone (TSH).
    • TSH prompts the thyroid gland to release Thyroid hormones T3 (Triiodothyronine) and T4 (Thyroxine).
    • T3 and T4 hormones circulate in the bloodstream, entering cells and binding to the nucleus, activating genes that control metabolism.

Normal Thyroid Function

  • Primary Functions:
    • Control metabolic rate of all cells.
    • Promote secretion of growth hormone and gonadotropins by the pituitary gland.
    • Regulate metabolism of proteins, carbohydrates, and fats.
    • Stimulate cardiac function (increasing heart rate and blood pressure).
    • Enhance the production of red blood cells.
    • Influence respiratory rate and drive.
    • Promote bone formation while decreasing bone resorption of calcium.
    • Act as insulin antagonists.
    • Aid in fetal development, particularly in neural and skeletal systems.

Causes of Thyroid Disorders

  • Major Causes:
    • Iodine deficiency.
    • Over or underproduction of T3 and T4.
    • Disorders of the pituitary gland.
    • Autoimmune disorders:
    • Grave’s Disease: excess thyroid hormone.
    • Hashimoto’s Thyroiditis: insufficient thyroid hormone.
    • Tumors, such as Toxic multinodular goiter.
    • Excessive thyroid replacement therapy.
    • Infections like Thyroiditis (often viral).

Hyperthyroidism (Thyrotoxicosis)

  • Characteristics:
    • Increased protein synthesis.
    • Weight loss due to rapid protein degradation and fat breakdown.
    • Increased hyperglycemia as a complication.
  • Clinical Manifestations:
    • Diaphoresis (sweating), thinning hair, shortness of breath (SOB).
    • Rapid shallow breathing, palpitations, tachycardia, increased blood pressure.
    • Weight loss, muscle weakness, pruritis, increased tears, eye retraction, exophthalmus (protruding eyes).
    • Heat intolerance, fatigue, decreased attention span, anxiety and manic behavior.
    • Amenorrhea, blurred vision, corneal infections, increased libido, goiter.

Grave’s Disease

  • Also known as toxic diffuse goiter:
    • Autoimmune condition.
    • Gland enlargement resulting in goiter, along with eye problems:
    • Proptosis (bulging eyes)
    • Retracted upper eyelids
    • Visual disturbances.
    • Presence of antibodies against TSH receptors.

Diagnostic/Laboratory Tests for Thyroid Disorders

  • Tests:
    • Thyroid scan, ultrasonography, ECG.
    • Serum tests:
    • TSH levels: normal 2-10 mU/ml; decreased in hyperthyroidism; increased in hypothyroidism.
    • Serum T4: normal range 5-12 mcg/dl; increased in hyperthyroidism; decreased in hypothyroidism.
    • Serum T3: normal range 80-200 ng/dl; similarly, increased in hyperthyroidism; decreased in hypothyroidism.
    • T3 uptake: normal range 25-35%; increased in hyperthyroidism; decreased in hypothyroidism.

Nonsurgical Management for Hyperthyroidism

  • Approaches:
    • Monitoring vital signs
    • Reducing stimulation and room temperature.
    • Eye care provision.
    • Drug therapy:
    • Iodine preparations (e.g., Lugol’s solution, Potassium iodide).
    • Antithyroid drugs (e.g., Propylthiouracil and Methimazole).

Postoperative Care for Thyroid Surgery

  • Postoperative Complications:
    • Hemorrhage, respiratory distress, hypocalcemia, tetany
    • Possible laryngeal nerve damage, thyroid storm or crisis.
    • Monitor for stridor and other vision problems associated with Graves’ disease.

Alert: Thyroid Storm/Crisis

  • Description:
    • A life-threatening medical emergency due to extreme hyperthyroidism.
    • Symptoms include:
    • Hyperthermia (102°F to 106°F)
    • Tachycardia, diarrhea, GI distress, confusion.
    • High mortality if untreated.

Hypothyroidism

  • Literature:
    • Characterized by decreased T3 and T4 levels leading to metabolic slowdown.
  • Types:
    • Primary Hypothyroidism: causes include congenital defects, tissue loss after surgery or radiation, autoimmune disorders (e.g., Hashimoto’s Thyroiditis), and iodine deficiency.
    • Secondary Hypothyroidism: caused by pituitary TSH deficiency or peripheral resistance to thyroid hormones.

Medications Causing Hypothyroidism

  • Common Drugs:
    • Amiodarone, anabolic steroids, lithium, phenytoin, propranolol, antithyroid drugs.

Key Features of Hypothyroidism

  • Symptoms:
    • Cool, pale skin, thick brittle nails.
    • Dry coarse hair and decreased hair growth, dyspnea, dysrhythmias, fatigue.
    • Low metabolic rate, muscle aches, cognitive slowing, lethargy.
    • Paresthesia of extremities, decreased tendon reflexes, depression, weight gain,
    • Changes in menstrual cycles: amenorrhea in women and impotence in men.
    • Goiter, facial puffiness, anemia, easy bruising, iron/folate, and vitamin B12 deficiencies.

Nursing Care for Hypothyroidism

  • Care Strategies:
    • Monitor vital signs, particularly for cardiac complications.
    • Daily weights, provide warm environments, and a low-calorie diet.
    • Ensure adequate fluid intake and avoidance of sedatives.
    • Administer stool softeners, as constipation is common.

Drug Therapy for Hypothyroidism

  • Goals:
    • Replace thyroid hormones.
    • Medications include:
    • Levothyroxine sodium (T4): Synthroid, Levoxyl.
    • Liothyronine sodium (T3): Cytomel.
    • Liotrix (T3-T4): Euthyroid, Thyrolar.
    • Myxedema coma is a medical emergency requiring IV thyroid hormones.

Nursing Management for Hypothyroidism

  • Considerations:
    • Imbalanced nutrition: more than body requirements.
    • Activity intolerance due to insufficient oxygen.
    • Constipation resulting from reduced peristalsis.
    • Skin integrity issues due to edema.
    • Impaired comfort due to cold intolerance and risks for social interaction challenges.

Disorders of the Parathyroid Gland

Calcium Regulation by Parathyroid and Thyroid

  • Mechanism:
    • Low Blood Calcium:
    • Parathyroid glands sense low levels and secrete PTH (Parathyroid hormone).
    • PTH increases blood calcium levels by promoting bone resorption and kidney reabsorption of calcium.
    • High Blood Calcium:
    • Thyroid gland senses high levels and secretes calcitonin, which decreases blood calcium by increasing bone formation.

Hyperparathyroidism

  • Characteristics:
    • Increased parathyroid hormone (PTH) leads to hypercalcemia and hypophosphatemia.
  • Causes:
    • Primary: tumors or hyperplasia of parathyroid glands.
    • Secondary: result of malabsorption syndromes or chronic renal failure.
  • Assessment Findings:
    • Symptoms include bone pain, kidney stones, anorexia, nausea, and muscle weakness.

Diagnostic Tests for Hyperparathyroidism

  • Key Indicators:
    • Elevated serum calcium level (over 10.5 mg/dl, normal range is 8.5-10.5 mg/dl).
    • Decreased serum phosphorus levels.
    • X-rays may show bone demineralization.

Interventions for Hyperparathyroidism

  • Management:
    • Administer IV normal saline and diuretics, monitor vital signs, and observe input/output for fluid overload and electrolyte imbalance.
    • Dietary adjustments to provide low calcium and high phosphorus intake.
    • Encourage fluid intake, especially acid-ash juices.
    • Medications include bisphosphonates (Pamidronate, Alendronate) and calcitonin to inhibit bone resorption.

Hyperparathyroidism: Surgical Management

  • Procedure:
    • Parathyroidectomy to remove hyperactive glands.
  • Postoperative Care:
    • Monitor for respiratory distress, potential for hypocalcemic crisis, and recurrent laryngeal nerve damage.

Hypoparathyroidism

  • Description:
    • Decreased function of the parathyroid gland leading to hypocalcemia.
    • Causes include hereditary factors, accidental damage during surgery, or hypomagnesemia.
  • Symptoms and Assessment:
    • Symptoms include muscle cramps, spasms, seizures, personality changes, and dry scaly skin.

Diagnostic Tests for Hypoparathyroidism

  • Blood Tests:
    • Decreased serum calcium levels (<8.5 mg/dl) and increased serum phosphorus levels.
    • X-rays could show increased bone density.

Interventions for Hypoparathyroidism

  • Acute Management:
    • Administer Calcium gluconate via slow IV for acute hypocalcemia.
    • Medications include oral calcium supplements and Vitamin D for absorption.
    • Initiate safety precautions including seizure precautions and monitoring for Chovstek’s and Trousseau’s signs.

Nutritional and Lifestyle Adjustments

  • Teaching Points:
    • High calcium and low phosphorus diet.
    • Importance of compliance with medication and follow-up appointments.