Differential diagnosis of autoimmune and nonautoimmune hyperthyroidism

Table 6.7-2. Differential diagnosis of autoimmune and nonautoimmune hyperthyroidism
Criteria	Graves disease	Nonautoimmune hyperthyroidism (toxic MNG, solitary autonomously functioning nodule)
History	Recurrent hyperthyroidism; family history of autoimmune thyroid disease or other autoimmune diseases	Previous nontoxic MNG
Signs and symptoms of thyrotoxicosis	No differential features
Goitera	Features of vascular goiterb	MNG or solitary nodule
Ocular signs and symptoms	Features of orbitopathy (immunologic inflammation), overt orbitopathy in 20%-30% of patients, severe form of progressive ophthalmopathy with infiltrates and edema in 2%-3% of patients	Ocular signs and symptoms of sympathetic hyperactivity (lid lag and stare) do not preclude the diagnosis
Pretibial myxedema	1%-3% of patients	None
Laboratory thyroid function tests	↓ TSH and ↑ FT4 (less commonly ↑ FT3), no differential features
TRAb	95% of patients	Absent
↑ Anti-TPOc	70% of patients	15% of patients (elderly)
Thyroid Doppler ultrasonography	Diffuse vascularity of thyroid parenchymab	Nodules
Thyroid radionuclide scintigraphy	High uptake and homogeneous concentration of tracer	Autonomously functioning (hot) nodules and nonfunctioning (cold) areas
a Lack of goiter is not a differential feature. b Nodules may be present in one-fourth of patients. c Usually not indicated as not helpful in clarifying etiology (may also be present in healthy individuals and patients with nonautoimmune thyroid diseases).
↑, increased level; ↓, decreased level; anti-TPO, anti-thyroperoxidase; FT3, free triiodothyronine; FT4, free thyroxine; MNG, multinodular goiter; TRAb, thyroid-stimulating hormone receptor antibodies; TSH, thyroid-stimulating hormone.