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Chapter 32-12: Hyperthyroidism

Andrew Olson

TEXTBOOK PRESENTATION

Classical symptoms include palpitations, heat intolerance, increased sweating, insomnia, tremulousness, diarrhea, and weight loss. Signs of hyperthyroidism include sinus tachycardia, systolic hypertension, frightened stare, an enlarged goiter, a fine resting tremor, and exophthalmos (only if hyperthyroidism is secondary to Graves disease). Other manifestations may include hyperpigmentation, irregular menses, pruritus, and thinning of hair. Complications that occur over time include osteoporosis, tracheal obstruction or dysphagia (from the goiter), tachyarrhythmias (particularly atrial fibrillation), high output heart failure, anemia, and proximal muscle weakness.

DISEASE HIGHLIGHTS

  1. Prevalence, 0.3%.

  2. Hyperthyroidism is actually an endocrine syndrome caused by several distinct pathophysiologic entities (Table 32-2).

Table 32-2.Distinguishing features of several hyperthyroid states.
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Table 32-2. Distinguishing features of several hyperthyroid states.
Disease Pathogenesis/Important features TSH T4, free T4 or T3 Thyroid Scan and Other Tests
Graves disease

Autoimmune production of antibody (TSI) binds and stimulates TSH receptor

Exophthalmos (unilateral or bilateral) a unique finding in Graves

 ↓ ↑

Homogenously increased uptake

Elevated TSI
Toxic multinodular goiter Most common form in elderly ↓ ↑ Patchy increased uptake
Painful subacute thyroiditis Viral or immune inflammatory attack on thyroid resulting in neck pain, tenderness, fever and release of hormone ↓ ↑

Decreased uptake

Elevated ESR
Toxic adenoma Autonomously functioning benign thyroid nodule ↓ ↑ Hot nodule, uptake in rest of gland is suppressed
Iodine or amiodarone Amiodarone1 may cause the release of T4 and T3 ↓ ↑ Usually decreased uptake
TSH-producing pituitary adenoma

Autonomously functioning benign pituitary adenoma

May cause bitemporal hemianopsia

Galactorrhea develops in 33% of women

 ↑ ↑ Diffusely increased uptake
Factitious or iatrogenic Self or provider induced ↓ ↑

Decreased uptake

T4/FTI more elevated than T3

Thyroglobulin concentration low
Weight loss supplements2 Patients may be unaware and not volunteer information ↓ ↑

Decreased uptake

Thyroglobulin concentration low

1Amiodarone causes hypothyroidism in 20% of patients by impairing conversion of T4 to T3.

2Some weight loss supplements have been reported to contain thyroid hormone and result in hyperthyroidism. This is rare, but patients should be asked about specifically about any supplements they are taking.

ESR, erythrocyte sedimentation rate; FTI, free thyroxine index; TSH, thyroid-stimulating hormone; TSI, thyroid-stimulating immunoglobulin.

EVIDENCE-BASED DIAGNOSIS

  1. History and physical exam

    1. Certain findings of hyperthyroidism are quite specific (ie, lid lag and lid retraction) and help rule in the diagnosis (specificity, 99%; LR+, 17−32).

    2. However, clinical findings are not highly sensitive. Therefore, absent clinical findings do not rule out hyperthyroidism.

      1. Goiter is present in 70–93% of cases.

      2. Pulse > 90 bpm is present in 80% of cases.

      3. Lid lag is present in 19% of cases.

      4. Ophthalmopathy is present in 25–50% of patients with Graves disease.

      5. Hyperreflexia is variable depending on the age of the patient.

  2. Elderly patients

    1. Prevalence of hyperthyroidism in the elderly is 2–3%.

    2. Hyperthyroidism often presents atypically in elderly patients. ...

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