Dose Titration of Lisinopril in Children Aged 1 to 18 Years With Primary or Secondary Hypertension

Inclusion Criteria: * Parental consent must be granted * Patient age: 1y - 18 y * Documented diagnosis of hypertension as defined in the National Heart, Lung and Blood Institute (NHBLI) 4th report, 2004 * No reversible cause found on diagnostic work-up for hypertension * Children older than 6y: 24h blood pressure monitoring confirms the diagnosis of hypertension Exclusion Criteria: * Pregnancy * Sexually active girls can only be included in the trial if they use an adequate form of birth control; during and until 30 days after ending the trial * Following abnormal laboratory values: Hyperkaliemia (serum potassium \> 5.3mmol/L); Anemia (hemoglobin \< 8g/dL); AST or ALT \> 3 times the upper limit of reference range; Total bilirubin \> 3 times the upper limit of reference range * Abnormalities of the oral cavity that can influence intake of medication * Known sensitivity to ACE-inhibitors * Known lactose intolerance * History of angioedema * Unilateral or bilateral stenosis of the renal artery * Diagnosis of heart failure (NYHA Class II-IV) * History of coarctation of the aorta * Current treatment with: other drugs influencing the renin-angiotensin-aldosterone system; lithium; potassium sparing diuretics; non-steroidal anti-inflammatory drugs; aspirin; oral antidiabetic medication