Mystery Diagnosis: Dizziness

Mystery Diagnosis: What Causes Dizziness?

Rob Lamberts, MD,
June 22, 2010
Episode #052

Since my last mystery diagnosis article (How Do Doctors Solve Medical Mysteries?) was one of my most popular, I thought it would be appropriate to do another mystery diagnosis. 

Mystery Diagnosis: Dizziness

The star of today’s show is Mary, a 30 year-old woman who comes to the office with a complaint of dizziness.

The first step in figuring out the cause of the dizziness is to decide just what Mary means by dizziness.

Different Types of Dizziness

There are several different symptoms that people can refer to as dizziness:

Feeling the room spinning: The sensation of the room spinning is the most common symptom described as dizziness. The medical term for this sensation is vertigo, which also happens to be the name of a great movie starring Jimmy Stewart.

Feeling light-headed: Light-headedness, or the sensation of almost passing out, is also commonly called dizziness. Most people have felt this when they have stood up too quickly. 

Feeling woozy: A woozy or drunk feeling is also referred to as dizziness. Medications, mind-altering substances, and certain medical conditions like diabetes can cause this symptom. 

Feeling excessively tired: Sometimes people who are excessively fatigued also say they are dizzy as well. I think they do this just to make my job harder.

So what symptom is Mary having? She says that she gets light-headed and almost passes out, so I write the chief complaint: light-headedness.

As I explained in the last mystery diagnosis article, the next step is to hear the story of the light-headedness. That is known as the history of present illness, and is perhaps the most important part of the entire visit when it comes to making a quick and accurate diagnosis. 

History of Present Illness

The key to making an accurate diagnosis is for the patient to give good information and for the doctor to listen carefully.

Mary explains that her dizziness has actually gone on for several years, but over the past few months it has gotten more frequent. It used to be mild, but now has even made her pass out twice. At first she had these episodes of dizziness every few months, but now she’s getting them every day, often several times a day. Between the episodes she’s perfectly fine. The episodes aren’t brought on by standing quickly, and they don’t seem to be associated with meals, but they seem worse in the morning. The two times she passed out occured when she got up during the night to use the bathroom.

What Dr. Rob Is Thinking

After hearing Mary’s story, I have a few thoughts. I take note of the fact that this dizziness is a longstanding problem, and that something recently triggered a big jump in frequency and severity.

In order to make a diagnosis, I need to ask more questions, doing a review of systems, which is that litany of questions about any symptom, from head to toe. Here’s what we find out:

  • She is not having headaches, nausea, or vomiting.

  • She is having leg cramps fairly frequently, especially at night

  • She has noticed heart palpitations, or an occasional fluttering feeling in her chest.

  • She has had some leg swelling for which she’s taken diuretic pills prescribed by her Gynecologist.

  • She has recently lost 40 lbs on a diet consisting mainly of high-protein shakes.

I make a mental note that her dizziness got worse around the time she started her diet, but we don’t diagnose yet; I need more information.

An Important Clue: Medical History

Mary is not on any regular medications other than the recent diuretic, or water pills.

[[AdMiddle]Her family history reveals several uncles on her dad’s side with heart problems, one of whom died at a young age. Her mother has diabetes, and her father has a heart arrhythmia.

I focus on her heart exam as my suspicions in this area grow. Her physical examination, however, is basically normal, with no swelling. The exam is normal. Her blood pressure is a little low at 95/60.

Differential Diagnosis

So now is time to make the “differential diagnosis” list of possible causes of her dizzy episodes.

I wonder if her use of diuretics, which make a person urinate extra fluid, has made her dehydrated enough to lower her blood pressure and make her prone to passing out.

The heart palpitations are also significant, because her symptoms are longstanding and don’t necessarily get worse when she stands up. Sometimes a speeding up of the heart makes it beat less efficiently. Also, the use of diuretics can also make the sodium, potassium, and other electrolytes in the blood abnormal, which can make a person more prone to heart arrhythmia.

When considering these two possibilities--that the dizziness is caused by the diuretics or related to heart palpitations--I always focus on the one that poses the most risk, which in her case is the heart problem.

Confirming the Diagnosis

Her EKG confirms my concern, showing an electrical delay in the heart known as long QT syndrome. That is actually a genetic condition that makes the heart prone to a dangerous heart arrhythmia known as torsades de pointes, or "twisting of the points." It’s a genetic problem, which Mary presumably inherited from her father. Unbeknownst to her, she’s had it all of her life.

So why did the condition recently get worse, causing the more frequent dizzy episodes? There are several factors:

Diet: A high-protein liquid diet can increase the risk of this dangerous arrhythmia in a person with prolonged QT,  presumably by messing up a person’s electrolytes.

Medications: Diuretics can lower the potassium and magnesium in the blood, which increase a person’s risk as well.

The low potassium in her blood made her legs cramp. On further questioning, she confessed that she used a friend’s medication for leg cramps on both of the nights that she passed out. This medication, quinine, also makes the bad arrhythmia more likely. It’s off of the market now for that reason.

So what was presumably happening was that her heart was intermittently going into this heart arrhythmia, which would decrease the efficiency of the heart pumping, decrease the blood flow to the head, and make her dizzy. If it went on long enough, she would pass out. She was in a dangerous situation.


So what now? The first thing to do is to have her stop taking the diuretic, start taking potassium and magnesium supplements, and absolutely not take the quinine again. She also needs a treadmill stress test and a heart monitor to look for this dangerous heart rhythm happening without symptoms. This is where I pass the baton to the cardiologist.

The bottom line about making this diagnosis is for the patient to give good information and for the doctor to listen carefully. Jumping to the conclusion that Mary’s dizziness was from vertigo would have delayed her diagnosis and put her at risk. The full history is key here, and a doctor who listens closely and puts together the facts in an organized manner will greatly increase the chances of getting an accurate diagnosis quickly.

That’s it for episode 52. I hope you enjoyed it, and I hope you keep listening, telling friends to listen, and threatening people who don’t listen to it. If you did like it, click here for my previous mystery diagnosis episode.

If you have topics that you want me to cover, send them to housecalldoctor@quickanddirtytips.com, or you can submit them to me on twitter (@housecalldoc) or my Facebook page.

Let me once again remind you that this podcast is for informational purposes only. My goal is to add to your medical knowledge and translate some of the weird medical stuff you hear, so when you do go to your doctor, your visits will be more fruitful. I don’t intend to replace your doctor; he or she is the one you should always consult about your own medical condition.

Catch you next time! Stay Healthy!

Dizzy Woman image courtesy of Shutterstock