Even when serum hemoglobin is normal, insufficient iron stores in the basal ganglia of the brain can impair dopamine synthesis and trigger restless legs syndrome. When the serum ferritin level is below 75 ng/mL, iron supplementation may be considered. It is also common for symptoms to arise from dysfunction of the dopamine circuit itself, without iron deficiency.

Herbal Clinic Perspective

The concept of blood deficiency (血虛) in Korean medicine is broader than a simple hemoglobin value. It encompasses the overall state in which blood fails to adequately supply the lower limbs—pale complexion, numb hands and feet, fatigue, and nighttime aggravation. Nourishing the blood and replenishing yin with Samul-tang family formulas can improve the supply of nourishment to the brain and periphery, contributing to symptom relief.