Postural orthostatic tachycardia syndrome — structured clinical encounter

A 15-year-old girl is referred to the general paediatrics clinic with four months of daily lightheadedness, palpitations, fatigue and difficulty concentrating that come on within minutes of standing and ease when she lies down. She felt well before this and recalls a viral illness at the onset. She has missed three weeks of school this term. Examination is normal when supine. The registrar runs a 10-minute active stand test: heart rate rises from 76 supine to 124 bpm upright, blood pressure holds at 108/68 mmHg throughout, and her usual symptoms are reproduced. She has no family history of sudden death.