What to expect from a blood test for restless legs syndrome

The clinician may request a blood count and tests of iron stores, kidney function, thyroid function, or vitamin levels. Low iron stores can be relevant even when the blood count does not show anaemia. Results are interpreted alongside the urge to move, unpleasant sensations, timing at rest, sleep disruption, medicines, and family history. Blood tests support the assessment but do not by themselves prove restless legs syndrome.

Tell the clinician about heavy menstrual bleeding, pregnancy, kidney problems, dietary restrictions, and medicines such as antihistamines or medicines for nausea. Do not start iron supplements before discussing the plan, because the clinician may want an accurate baseline and a safe explanation for low iron. Ask whether fasting is required for the selected tests.

Seek urgent care for a suddenly swollen, hot, or painful leg, chest pain, breathlessness, fainting, or new weakness. These features are not typical explanations for night-time restlessness and need prompt assessment rather than waiting for a routine blood result.

Ask which iron measures are being checked, whether a low result needs treatment or further investigation, and when symptoms should be reviewed. Ask whether any current medicine could worsen the restlessness or alter sleep.