Friday, February 20, 2009

The White Whale of Endocrinology

Some time last term an endocrinologist was lecturing to us about the autonomic nervous system. He brought up a hypothetical scenario where a patient had overdosed on a sympathetic stimulant, which would cause tachycardia (fast heart rate), bronchodilation, pallor (paleness), diaphoresis (sweating), etc. Turns out this situation rarely occurs from an overdose of drugs because we don't give people many sympathetic stimulants. However, patients can have a pheochromocytoma, a tumour on their adrenal gland, which causes excess adrenaline to be secreted throughout the body. These episodes of excess adrenaline are often on and off, not constant. Adrenaline is a sympathetic hormone which causes the aforementioned symptoms. This illness is VERY rare, yet doctors, especially endocrinologists, cannot stop talking about it. I have heard 6 different doctors tell me about pheochromocytomas, but none, not a SINGLE one, had ever seen one before. They all ended the discussion with some variation of "remember, if you ever see one while you're on the wards, give me a shout if I'm at the hospital".

The pheochromocytoma is the white whale of endocrinology. Endocrinologists keep chasing after this rare disease and, it seems, they will not be fulfilled with their careers until they see it. I'm sure that through the years I will go on to learn about the white whales of other specialties.

Oddly enough, last week, a patient came to talk to my class about his pheochromocytoma. Turns out he had been having regular bouts of panic attacks when he was stressed and went to his family doctor to see what was happening. A cyst was found above one of the patient's kidney in the past, but he had been told that many people have them and that these cysts are entirely normal. The family doctor ran a blood test and measured his blood pressure and saw that everything was normal, so he thought the problem was entirely emotional. Then a few months later, things got worse. The patient would be climbing a set of stairs and have the same "panic attacks". He would also be having these panic attacks more often.

Finally, his doctor sent him to an endocrinologist who began piecing the puzzle together. The patient had panic attacks. Panic attacks are a "fight or flight" response. When you have a panic attack, your heart rate rises, your skin becomes pale, and you are having a sympathetic response. The blood test ordered by the patient's family doctor did not alarm the doctor because the pheochromocytoma had episodic bouts of adrenaline secretion and the patient was not having an episode when his blood was tested. Finally, guess what is sitting right on top of the kidneys, where these "cysts" were...the adrenal glands. Those cysts were actually adrenal medullary tumours.

Surprising how a disease that is mentioned in med school so often (6 times in 5 months!) can go unnoticed because it is so rare in the population. Fortunately, the tumours were removed and the patient has made a full recovery.

Scary that he went undiagnosed for so long because a pheochromocytoma can easily be fatal. Too much adrenaline can cause heart failure. I guess the lesson is that you should always look out for the white whale.

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