Secondary Hypertension

What Is It?

In most cases of high blood pressure (hypertension), there is no known cause. About 6 percent of the time, however, hypertension is caused by another condition or disease. When this happens, it is called secondary hypertension.

Most of the conditions that cause secondary hypertension involve the overproduction of one of the body's hormones. Some of the medical problems that can cause secondary hypertension include:

• Kidney disease — Secondary hypertension related to kidney (renal) disease is called renal hypertension. The most common kind of kidney condition that leads to secondary hypertension involves abnormal narrowing of a renal artery, one of the major blood vessels that bring blood to each kidney. When the kidney's blood supply is reduced, the kidney produces high levels of a hormone called renin. High levels of renin trigger the production of other substances in the body that raise blood pressure, particularly a molecule called angiotensin II.
• Adrenal disease — The adrenal glands sit on top of the kidneys, and produce several hormones that can raise blood pressure. Sometimes, tumors develop in the adrenal glands, which leads to overproduction of these hormones. A tumor called pheochromocytoma overproduces the hormones epinephrine (adrenalin) and norepinephrine (noradrenalin). A tumor called an aldosteronoma or Conn's syndrome overproduces the salt-retaining hormone, aldosterone. Tumors in the adrenal glands or elsewhere in the body can overproduce glucocorticoid hormones, which also raise blood pressure.
• Hyperparathyroidism — A hormone called parathormone is made by two tiny glands in the neck, called parathyroid glands. If the glands produce too much hormone, calcium levels in the blood increase, and this can raise blood pressure.
• Other causes — Other causes of secondary hypertension include acromegaly, excess production of growth hormone by a tumor of the pituitary gland; coarctation of the aorta, a malformation of the major blood vessel that carries blood from the heart to the rest of the body; Cushing's syndrome (the body produces too much of a hormone called cortisol) and, rarely, the use of oral contraceptives.

Symptoms

In high blood pressure, the systolic blood pressure (the higher of the two blood-pressure numbers) is 140 millimeters Hg or above, while the diastolic blood pressure (the lower blood-pressure number) is 90 millimeters Hg or above. In secondary hypertension, depending on the cause, there are other symptoms related to the specific medical illness which underlies the hypertension. For example, a tumor of the adrenal gland called a pheochromocytoma can cause sweating, palpitations, severe anxiety and weight loss. In Cushing's syndrome, there may be weight gain, weakness, abnormal growth of body hair and loss of menstrual periods in women, and the appearance of purple "stretch marks" on the abdomen (abdominal striae). Hyperparathyroidism with elevated calcium levels can cause extreme tiredness, mental changes (depression and/or confusion), nausea and vomiting, increased urination and kidney stones.