Definition
A.If the thyroid-stimulating hormone (TSH) level is too low, the thyroid is producing too much hormone, specifically T3 and possibly T4. This is called hyperthyroidism.
B.Set of disorders that involve excess synthesis and secretion of thyroid hormones by the thyroid gland, which leads to the hypermetabolic state of thyrotoxicosis.
C.The main autoimmune cause of hyperthyroidism is Graves’ disease.
D.Three main causes.
1.Diffuse toxic goiter (Graves’ disease).
2.Toxic multinodular goiter.
3.Toxic adenoma.
Incidence
A.Hyperthyroidism affects approximately 3 million people.
B.Graves’ disease.
1.This is the most common form of hyperthyroidism in the United States, causing approximately 60% to 80% of cases of thyrotoxicosis.
2.Its peak occurrence is at age 20 to 40 years.
C.Toxic multinodular goiter causes approximately 15% to 20% of thyrotoxicosis, occurring more frequently in regions of iodine deficiency. Toxic adenoma is the cause of approximately 3% to 5% of cases {9}.
Pathogenesis
A.Hyperthyroidism results from excess production of thyroid hormone from the thyroid gland.
B.Untreated toxicosis can increase the incidence of cardiovascular and pulmonary complications, skin and bone conditions, and eye disease.
Predisposing Factors
A.Genetic factors: Graves’ disease often occurs in multiple members of a family.
B.Autoimmune thyroid disorders.
C.Hashimoto’s disease.
Subjective Data
A.Common complaints/symptoms.
1.Palpitations, sweating, extreme fatigue, may have presence of goiter, and weight loss.
B.Common/typical scenario.
1.Patient presents with extreme fatigue or anxiety and/or significant weight loss over a short period of time and often complains of palpitations.
C.Family and social history.
1.May have a genetic or familial history.
D.Review of systems.
1.Cardiovascular: Ask about palpitations or recent increases in blood pressure medications.
2.Head, eyes, ears, nose, and throat (HEENT: Hair loss.
3.Psych: Insomnia, anxiety, irritability, nervousness, increased perspiration.
4.Endocrine: Menstrual irregularities, weight loss, heat intolerance, thinning skin.
5.Musculoskeletal—muscle weakness, myalgias, arthralgias.
Physical Examination
A.Constitutional—appears toxic.
B.Cardiovascular—systolic hypertension with a wide pulse pressure, tachycardia, atrial fibrillation.
C.HEENT: Palpable diffuse goiter, thyroid bruit, exophthalmos, periorbital edema, proptosis, lid lag.
D.Neurological/musculoskeletal—tremors, hyperreflexia.
E.Dermatological—warm moist skin, pretibial myxedema.
F.Psychological—anorexia, difficulty focusing.
Diagnostic Tests
A.TSH level: Most reliable screening measure. It is usually suppressed to an immeasurable level (<0.05 mIU/L) in thyrotoxicosis.
B.Free T4—may or may not be elevated.
C.Free T3—will be elevated.
D.Thyroid-stimulating immunoglobulin (TSI) or thyrotropin receptor antibodies (G1) to establish Graves’ disease. Thyroid peroxidase (TPO) level or antimicrosomal antibodies are usually elevated with Graves’ disease but are usually low or absent in toxic multinodular goiter and toxic adenoma.
E.Thyroid uptake scan to determine the pattern of uptake, which varies with the underlying disorder. Normal radioactive iodine uptake after 6 hours is 2% to 16%; after 24 hours, it is about 8% to 25%. In hyperthyroidism there will be markedly increased uptake.
Differential Diagnosis
A.Euthyroid sick syndrome.
B.Thyroiditis.
C.Goiter.
D.Struma ovarii.
E.Graves’ disease.
Evaluation and Management Plan
A.General plan.
1.Symptom management—help the patient to establish symptom control with medications.
2.Further laboratory studies.
a.Repeat TSH every 6 weeks or as needed until symptoms controlled.
b.Check TSI and TPO to rule out Graves’ disease or Hashimoto’s thyroiditis, respectively.
3.Nuclear thyroid scanning to differentiate hyperthyroidism from thyroiditis.
B.Patient and family teaching.
1.Definitive treatment plan must be established and coordinated with endocrinology.
2.Reinforce need to see endocrinology on a regular basis.
3.If you develop flu-like symptoms while on antithyroid medications, call your provider immediately and stop your medications completely.
C.Pharmacotherapy.
1.Treatment consists of symptom relief with the following drugs.
a.Beta-blockers—titrate to heart rate less than 90 beats per minute and to reduce the sympathetic response associated with peripheral conversion of T4 to T3. Effects of beta-blockers are dramatic and rapid (within 10 minutes).
i.Propranolol best studied in this class of medications.
ii.Other beta-blockers have similar effects and can be used.
b.Antithyroid medications—prevents thyroid hormone synthesis.
i.Methimazole (Tapazole) is considered the first-line drug therapy.
ii.Propylthiouracil (PTU) is preferred in thyroid storm and first trimester of pregnancy.
c.Corticosteroids.
i.Dexamethasone contributes to blocking T4 to T3 conversion, which will control symptoms. Useful in emergencies, but has long-term complications to consider.
2.Radioactive iodine-131 therapy ablates thyroid tissue.
a.Thyroid cancer.
b.Hyperthyroidism not controlled with medical therapy.
3.Thyroidectomy: May be preferable to radioactive iodine-131 therapy.
a.May be required for large goiters causing airway constriction and severe dysphagia.
b.Thyroid cancers not responsive to radioactive iodine 131 therapy.
D.Imaging studies: Ultrasound, CT scan, and chest x-ray are routine. Fine needle aspiration for biopsy, vocal cord evaluation, or esophageal evaluation may be needed depending on the patient’s presentation.
1.Monitor for thyroid storm, particularly in the first 18 hours postsurgery.
a.Treat with antithyroid medications until euthyroid.
b.Beta-blockers: Atenolol should be taken 1 hour before surgery to maintain blockade.
E.Discharge instructions.
1.Before discharge, refer the patient to outpatient endocrinology and to ophthalmology, if needed, for eye disease.
Follow-Up
A.Continue to monitor symptoms and thyroid levels.
B.Check TSH 6 weeks after discharge.
Consultation/Referral
A.Refer to endocrinology to manage symptoms and disease progression.
Special/Geriatric Considerations
A.In the acute care setting, the focus should be on the adverse effects of antithyroid medications.
1.Rash.
2.Urticaria.
3.Arthralgia.
B.Monitoring of results of lab studies is also important.
1.Complete blood count (CBC) for agranulocytosis if patient develops a fever or sore throat. Routine monitoring not recommended.
2.Hepatic profile for hepatitis.
C.In addition, monitor the development of fever (>100.5°F) or a sore throat; the medication will need to be stopped.
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