Pharmacy Pearl 27 June 2001

A 35 y/o female patient comes to your clinic with complaints of throbbing headaches, profuse sweating, constipation, tachycardia, and palpitations. On physical exams her blood pressure is found to be 210/120. Thirty minutes later, her blood pressure is 160/90.

After a quick but thorough physical exam and lab work-up, you make the diagnosis of pheochromocytoma. Your student measure the blood pressure again and her blood pressure is back to 200/115. The student recommends a beta blocker to treat the palpitations and lower her blood pressure.

Do you agree or not? Why or why not?

SELECT here for discussion

NO. Do not order the beta blocker yet. A beta blocker at this time may actually cause her hypertension to become WORSE. The reason is that by blocking only the beta receptors you allow alpha predominance, and a likely worsening of the hypertension. It would be best to give the alpha blocker first. A beta blocker can be added shortly afterwards especially in this patient with tachycardia and palpitations.

The best way I've found to explain this is the "warm water" analogy. With warm water you can make it warmer by either 1) increasing the hot water or 2) decreasing the cold water. If you correlate hot and cold water with alpha and beta receptor stimulation, I think it will make sense. If you lower alpha stimulation by giving an alpha blocker or raise (relatively) beta stimulation you should lower blood pressure. If you lower beta stimulation by giving a beta blocker and raise (relatively) alpha stimulation, you'll likely elevate blood pressure. Make sure the patient doesn't have any other contraindications to medical therapy (ex, reactive airway disease and beta blockers). An option is someone who cannot take alpha and/or beta blockers because of cardiovascular reasons is metyrosine. This drug inhibits the production of endogenous catecholamines by inhibiting tyrosine hydroxylase.

Surgery is the definitive treatment. Before surgery the goal is to control blood pressure, increase intravascular volume, and stop paroxysmal hypertension. Patients should ideally be started on an alpha blocker (usually phenoxybenzamine) 10 days before to allow expansion of contracted intravascular blood volume. A high salt diet may also be recommended.

The incidence of pheochromocytoma is about 2 cases per million in the general population and about 400 cases per million in hypertensive patients. The incidence is slightly greater in females than males. It can occur at any age from infancy to old age. It may be associated with pregnancy. If left untreated, pheochromocytoma can be fatal.

This Pearl is meant for academic and educational purposes only. This Pearl is meant to raise important points regarding the safe and cost-effective pharmacotherapy of patients. It is not meant to be the definitive reference for the treatment or prophylaxis of various diseases. Although every effort is taken to ensure this Pearl is correct and factual, errors may occur. The Pharmacoeconomic Center assumes no liability for incorrect information or harm that may occur from the use of the information included in this Pearl.