Restless leg syndrome (RLS), may be classified into two groups:^[1]

• Primary and secondary:
  • Primary RLS is idiopathic and the cause of that is unknown which is familial in up to two thirds of patients. Primary RLS usually begins before approximately 40 to 45 years of age, and can even occur as early as the first year of life. In primary RLS, the onset is often slow.^[2]
  • Secondary RLS may also be secondary to a number of conditions including:^{[3][4][5][6][7][8]}
    • Iron deficiency
    • Pregnancy
    • End-stage renal failure
    • varicose vein
    • Venous reflux
    • folate deficiency
    • sleep apnea
    • uremia
    • Diabetes
    • Thyroid problems
    • Peripheral neuropathy
    • Parkinson’s disease
    • Certain auto-immune disorders such as:
      • Sjögren’s syndrome,
      • Celiac Disease
      • rheumatoid arthritis
  • Secondary RLS is most common in those presenting for the first time in later life.^[1]