Hypertension and hypokalemia in a 15-year-old boy: question

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A 13-year-old boy was admitted to our hospital with recurrent headaches that had been localized to the occipital region for the past year. His medical history was unremarkable, with no known history of kidney disease. The family history was also unremarkable, and consanguinity was not present between his parents. His weight and height were within normal ranges; casual blood pressure was measured as 150/100 mmHg. The systemic examination revealed no abnormal results. Ambulatory blood pressure monitoring (ABPM) obtained mean 24-h, daytime, and nighttime systolic and diastolic blood pressures of 140/99, 148/106, and 135/95 mmHg, respectively; the daytime and nighttime systolic and diastolic blood pressure load were 100%, and abnormal dipping (8%) was present. The laboratory findings were: hemoglobin, 14.8 g/dl; white blood cells, 8,400/mm; platelets, 479,000 /mm; blood urea, 17 mg/dl; creatinine, 0.5 mg/dl; Na, 137 mEq/l; Cl, 105 mEq/l; K, 3.8 mEq/l; uric acid, 3.3 mg/dl; Ca, 9.5 mg/dl; P, 4 mg/dl; total protein, 7.9 g/dl; albumin, 4.9 g/dl; pH, 7.45; pCO2, 40 mmHg; HCO3, 27.4 mEq/l; base excess, 3.2; plasma renin activity, 146 pg/ml (normal range: 3–16 pg/ml); aldosterone concentration, 62.7 ng/dl (normal range: 0.29– 16.1). The urinalysis and lipid profile were normal. Echocardiography showed concentric left ventricular hypertrophy and a left ventricular mass index (LVMI) of 51.7 g/m (upper limit of normal: 38 g/m). The results of the ophthalmologic examination, abdominal ultrasound, renal arterial Doppler ultrasound, Tc-99 m dimercaptosuccinic acid scintigraphy, and renal arterial magnetic resonance angiography were all normal, as were plasma adrenocorticotropic hormone and cortisol levels and 24-h urinary metanephrin and vanillylmandelic acid levels. Treatment with enalapril (10 mg/day) and amlodipine (10 mg/day) was initiated for severe hypertension. Three months later, the ABPM was completely normal, and after 12 months, the LVMI had decreased to 43.7 g/m. The patients voiced no complaints in the 18 months thereafter; periodic ABPMs were performed during the follow-up, and minor drug adjustments were made accordingly. Approximately 2.5 years after the first diagnosis, the patient came to our outpatient department for a routine control. He had no complaints, was on triple antihypertensive therapy (enalapril, amlodipine, and propranolol), and the ABPM was The answer to this question can be found at http://dx.doi.org/10.1007/ s00467-010-1440-2.