Hypertension, or high blood pressure, can be classified as primary, in which there is no obvious cause, and secondary, in which a cause can be identified. According to the Lucile Packard Children's Hospital, primary hypertension is the most common cause of hypertension in adolescents and adults, but it is less common in children. The causes of secondary hypertension in children include kidney disease, hormonal problems and obesity.
Kidney Diseases
Kidney disease causes hypertension because the kidneys control the level of sodium and other electrolytes and hormones that can affect fluid retention and blood pressure. For example, children can have renal stenosis, a condition that narrows the artery that supplies the kidneys with blood. The kidney interprets this as a decrease in fluid in the body, so it increases blood pressure to correct what it perceives to be a deficit. According to Children's Healthcare of Atlanta, renal parenchymal disease, in which there is a problem within the kidney tissue, is the most common cause of secondary hypertension in children. Examples of renal parenchymal disease include glomerulonephritis, an inflammation of the glomeruli, the microscopic basic structure of the kidneys.
Hormonal Problems
Various hormones can have an affect on a child's blood pressure measurement. The thyroid hormones control the body's metabolism and in children, contribute to their growth. High levels of thyroid hormone, a condition known as hyperthyroidism, can cause high blood pressure. According to the Children's Hospital Boston, the most common cause of hyperthyroidism in children is Graves' disease, a condition in which the body secretes certain proteins that over stimulate the thyroid gland. Another hormonal cause of hypertension in children is a pheochromocytoma, a tumor of the adrenal gland that secretes excess epinephrine and norepinephrine, hormones that control blood pressure and heart rate.
Obesity
Obesity is a cause of hypertension in children. Obesity can lead to increases in the levels of cholesterol and blood glucose, or sugar, in the body. High levels of cholesterol can cause plaque and narrowing of the blood vessels, leading to increased blood pressure as the heart tries to pump blood through the narrowed vessels. High blood sugar can lead to fluid retention, which also increases blood pressure. Obesity and lack of physical activity weakens the heart, as it has to pump twice as hard to circulate blood in the body, further increasing blood pressure.
