Several years ago, a 55-year-old English professor was referred to me for a suspected overactive thyroid. She had a two-year history of episodes of lightheadedness, nervousness, headache, sweating, and palpitations—thought to be panic attacks. Tranquilizers were of no help, and the attacks (which often occurred before lectures) never lasted long enough for her to be examined while having one. She had also been taking medication for high blood pressure for five years.

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By the time I saw her, thyroid tests had been done and were normal. But she had an elevated blood pressure of 160/100. Her description of her so-called panic attacks reminded me of what I’d often observed in asthma sufferers after an injection of epinephrine (Adrenaline and generic), a now-antiquated treatment for acute asthmatic wheezing.

The reminiscence paid off. A blood sample showed a level of metanephrine (an epinephrine derivative) five times the upper normal limit. An MRI disclosed the source of the metanephrine: a tumor of her left adrenal gland. This pheochromocytoma (or pheo) was removed and found to be benign. That normalized her blood pressure and eliminated her panic attacks.

A Rare Cause of Hypertension

The vast majority of people with high blood pressure have primary or essential hypertension—implying that the cause is unknown. Five to 10 percent may have secondary hypertension, where elevated blood pressure is due to a definable cause. (Pheos are a very rare cause.)

Unlike primary hypertension, secondary hypertension may actually be curable rather than simply controlled. The larger consideration is whether it is fruitful to subject millions of people to the expensive and possibly harmful tests to find the tiny number whose disease is potentially curable. From a cost-effectiveness standpoint, the answer is no, especially if the blood pressure is controlled by medication. Sometimes, however, clues can alert a doctor or patient to be more selective in their choice of suspects.

A Few More Possible Causes

One of the most common causes of secondary hypertension in older adults is renal artery stenosis (narrowing of one of the two arteries feeding each kidney). Proper diagnosis and artery stenting can cure this, provided the process has not gone on too long. Keen judgement is required to make that decision.

Another cause is primary hyperaldosteronism (the inappropriate secretion of the adrenal hormone aldosterone). The sole culprit was originally thought to be an adrenal tumor, removal of which cured the low potassium and high blood pressure it caused. But it has been found that sometimes both adrenal glands are at fault, making medical treatment with the diuretics spironolactone or triamterene preferable to surgery.

Cushing’s disease and syndrome result in hypertension, type 2 diabetes, brittle bones, and easy bruisability due to the excessive secretion of the steroid hormone cortisol. This is usually cured by eliminating the source of the excess cortisol. However, because the symptoms are so common, this eventually fatal disorder often eludes diagnosis for years.

Obstructive sleep apnea, by dint of its sympathetic nervous-system stimulation and episodic lack of oxygen during sleep, is considered by many to be a cause of secondary hypertension. Treatment of apnea can improve blood pressure.

Raising the Red Flag

Such secondary, and possibly curable, causes of high blood pressure need not be sought if your blood pressure is being well controlled. Consider talking to your doctor if you have hypertension and:

  • You are younger than 35 years of age.
  • Your blood pressure is not controlled (over 130/80) despite the use of up to three medications in appropriate doses.
  • Your serum potassium is low or you require prescription potassium.
  • You have a sudden deterioration of kidney function and visual changes.
  • You experience sweating, headaches, palpitations, shaking, and anxiety.
  • You have type 2 diabetes, osteoporosis, easy bruisability, and abdominal obesity.
  • You have sleep apnea.

As for our English professor, she is now well into her 70s and continues to have normal blood pressure, and delivers lectures with no qualms beforehand.

Editor's Note: This article also appeared in the February 2018 issue of Consumer Reports on Health.