Hypothyroidism and Lid Lag: Mechanism and Clinical Significance

Lid lag (von Graefe's sign) is the delayed descent of the upper eyelid on downward gaze. In hypothyroidism, it results from sympathetic overactivity (unopposed α-adrenergic tone on Müller's muscle) due to reduced thyroid hormone modulation of adrenergic receptors.

Pathophysiology

• Thyroid hormone normally downregulates β-adrenergic receptors and modulates sympathetic sensitivity.
• In hypothyroidism, upregulation of α-receptors causes Müller's muscle (sympathetically innervated) to remain contracted.
• On downgaze, the levator relaxes, but Müller's muscle retracts slowly → lid lags behind globe.

Clinical Context

• Seen in both hypo- and hyperthyroidism (different mechanisms).
• In hypothyroidism: often with periorbital edema, thinning eyebrows, cold intolerance.
• Not specific; also seen in midbrain lesions, cerebellar disease.

Evaluate with TSH, free T4. Treat underlying thyroid disorder; lid lag resolves with euthyroidism.