The hypertensive child

A boy aged 11 years presented to a rural emergency department with two days of intermittent headaches, abdominal pain, non-bilious vomiting and diarrhoea. He was previously well and had no family history of hypertension. Examination revealed a heart rate of 58 beats per minute, a respiratory rate of 20 breaths per minute, temperature 36.8 degreesC, dry mucus membranes and significantly elevated blood pressure of 160/90 mmHg (>95th centile for age, sex and height). The rest of the physical examination was unremarkable. Full blood examination, liver function tests, urea, electrolytes, creatinine and urinalysis were unremarkable apart from mild haemoconcentration. Electrocardiography showed sinus bradycardia with no left ventricular hypertrophy. Urine culture, stool culture and viral polymerase chain reaction were negative. He was admitted for rehydration and investigation of hypertension.