Diagnostic Approach to Restless Legs Syndrome

Understanding the Core Diagnostic Criteria

The International Restless Legs Syndrome Study Group establishes five essential criteria that ALL must be met for RLS diagnosis, including symptoms beginning or worsening during periods of rest or inactivity such as both lying down OR sitting, and symptoms during rest or inactivity only occurring or being worse in the evening or night than during the day 1, 2
The American Academy of Sleep Medicine notes that symptoms must worsen in the evening/night and during both sitting AND lying down, and the absence of symptoms when lying down at night violates essential diagnostic criterion #4 1, 2

Venous insufficiency worsens with prolonged sitting but improves when lying down with legs elevated at night, and the American Geriatrics Society notes that venous varicosities are specifically listed as RLS mimics that meet criteria 1-4 but are NOT RLS 4, 3, 5
Morbid obesity creates mechanical stress on joints and soft tissues that worsens with sitting but resolves when lying down, and this is explicitly listed as an RLS mimic that must be excluded 1, 2

The American Academy of Sleep Medicine recommends asking specific differentiating questions, including "Do you have an urge to move your legs, or is it just discomfort/pain?" and "When you lie down at night to sleep, do the symptoms return or worsen?" 1, 4
The American Geriatrics Society suggests performing a focused vascular and musculoskeletal exam, including checking for pitting edema and assessing for venous varicosities and skin changes of chronic venous insufficiency 4, 3, 5

If true RLS is suspected after excluding mimics, check morning fasting serum ferritin and transferrin saturation, as ferritin <50 ng/mL suggests iron deficiency contributing to RLS 4, 5, 6

For venous stasis/edema, optimize heart failure management, use compression stockings during daytime, and elevate legs when sitting, as recommended by the American Geriatrics Society 4
If true RLS is confirmed, check iron studies and supplement if ferritin ≤75 ng/mL, and use first-line treatment such as gabapentin, gabapentin enacarbil, or pregabalin, as recommended by the American Academy of Sleep Medicine 8