Diffuse Toxic Goiter Clinical Presentation

Symptoms of the hyperthyroidism, the goiter itself, and of comorbid conditions are present. The symptoms may be present for weeks, months, or even years before diagnosis.

The hyperthyroid symptoms may be multisystemic or predominate in a single organ system and mask the correct diagnosis in this manner. Many symptoms are adrenergic in origin and may be misdiagnosed as an anxiety disorder.

Elderly patients may have no adrenergic symptoms and present as weight loss (malignancy), atrial fibrillation (cardiac), or apathy (depression), and this presentation is referred to as apathetic thyrotoxicosis.

The presenting symptoms may be modified by preexisting medical or psychiatric disorders, which may be modified or worsened. Symptoms are described below.

• Hypermetabolism with heat generation and protein catabolism - Weight loss with good appetite, heat intolerance, sweating, muscle weakness (proximal more than distal), osteoporosis
• Adrenergic - Palpitations, tremor, emotional lability, insomnia, restlessness, hyperdefecation
• Other - Gynecomastia, lighter menses, insomnia, decreased concentration, fatigue, shortness of breath on exertion, and decreased exercise tolerance
• Goiter - May be mildly tender, may have difficulty swallowing if large
• Associated oculopathy (clinically present in about 25% of cases) - Tearing, pain, puffiness, grittiness, double vision, prominent appearance, rarely visual loss

General physical examination findings may include restless appearance, evidence of weight loss, pruritus, palmar erythema, and onycholysis of the finger nails.

• Hypermetabolism with protein catabolism - Warm hands, often with heat radiation, velvety skin, proximal muscle weakness in the arms and legs compared with distal muscle strength
• Hyperadrenergic - Bounding and fast pulse, wide pulse pressure with higher systolic and lower diastolic blood pressure, active precordium and abdominal aorta to palpation; lid retraction (upper eyelid more than halfway from pupil to top of iris) and lid lag or globe lag, tremor of fingers, brisk reflexes
• Organ decompensation - Atrial fibrillation, congestive heart failure, jaundice
• Oculopathy - Periorbital puffiness, chemosis, conjunctival redness, proptosis (sclera visible below iris), double vision with eye movements, loss of color vision (rare), or papilledema (rare)
• Thyroid gland - Mildly enlarged (but may be normal in size, many times normal in size, or difficult to palpate); smooth, rubbery firm in texture; nontender or mildly tender; systolic bruit on auscultation
• Miscellaneous - Pretibial myxedema (uncommon), rare may be finger clubbing, diffuse lymphadenopathy, and splenomegaly

Diffuse toxic goiter and its hyperthyroidism are caused by TSH-receptor stimulating antibodies. Although the exact cause is not understood, it has been suggested that there is a genetic lack of suppressor T cells that results in the unregulated production of the antibody, resulting in the autoimmune disease. The antibody may pass the placenta and result in fetal and neonatal hyperthyroidism.

As with most such disorders, usually a combination of genetic and environmental factors is present. The familial association indicates a strong genetic factor. Predisposing factors include genetic susceptibility (including HLA factors); female gender; mental stress; viral infection; surgery; postpartum state; iodine administration; drugs such as lithium and iodine-containing agents, such as amiodarone, interferons and interleukins, and antiretroviral agents.

Associated ophthalmopathy is not well understood, but it is a related but separate autoimmune disorder directed toward the extraocular muscles. It may run a course similar to or different from the hyperthyroidism. Smoking is an environmental aggravating factor. The presence and degree of clinical ophthalmopathy does correlate with the degree of elevation of the anti-TSH receptor antibodies.

Dermopathy (pretibial myxedema) may be brought on or aggravated by local trauma.