The other night I was watching a show on the Discovery Channel, "Mystery Diagnosis." The show presents three cases, each taking about fifteen minutes which proceeds like the show's title would suggest. Some background info on the patient is given, the patient then starts having some symptoms, patient bounces around with multiple doctors without resolution, and sometimes more symptoms appear and/or worsen until someone figures out what is going on (a la Mr. Greg House).
One case involved a teenage girl who was involved in a car accident and had slammed her head into the dashboard. She was taken to the ER and was discharged a few hours later. She did not suffer a concussion, and the soreness in her arm and neck disappeared after a few weeks. Several months later, while out with her family her mother notices something strange. After everyone gets their water, she drinks not only hers but everyone else's at the table. Her thirst continues throughout dinner and on the ride home. It's so bad that the family has to stop at every gas station on the way home so she can urinate. This gets worse over the next few days: she now has to get up every hour at night and drink 3-4 glasses of water.
At this point, I'm thinking "huh, she might have an ADH problem and diabetes insipidus. Maybe her pituitary was damaged in the accident, leading to DI and causing her to drink and pass such massive amounts of water. It'd be kind of crazy/sweet if she actually has DI." DI is not the diabetes most are familiar with: diabetes mellitus. DM is the insulin condition in which people's glucose regulation is altered. Specifically, diabetes insipidus is a condition in which a certain chemical (ADH) is malfunctioning at one of two levels. ADH is produced in a certain part of the brain and its role is to induce the kidneys to reabsorb water before it gets passed as urine. Either the brain can not be producing the hormone or the kidneys can just not be responding to the hormone. The end result is the kidney not properly reabsorbing water, leading to water loss which shouldn't be happening. Alcohol affects ADH in an inhibitory fashion, which explains why when drinking you've got to piss like a horse and eventually get dehydrated. If you're drinking beer, it's not just the volume of liquid you're taking in that makes you go wee-wee, its good old ethanol.
The mother, rightly concerned, takes her daughter to the FP. The family has a history of DM, and one of the symptoms of DM is, in fact, frequent urination and increased thirst. The mechanism again involves the kidneys, but is a result of the increased glucose concentrations and the kidneys' inability to handle this. So with aforementioned symptoms and family history, the kid gets tested for DM. The tests are negative and the FP has no explanation for the excessive thirst. With this, she resigns to having to live with constant thirst and urination.
She goes off to college, where this continues. She always brings water with her and continues to drink at night - her total water intake comes to three gallons/day. The nightly routine is so bad that she never gets more than 45 minutes of sleep at a time. She even wakes up one night screaming incessantly. That is, until she's given water. Ironically, she's a premed. With the territory, she learns of a few reasons as to why she might be so thirsty. These reasons scare her into maintaining the notion that her thirst problems are resolved/under control - her family is unaware of how bad things are. Oh yeah, the things she read about were a brain tumor and schizofrenia.
As college wears on, one incident scares her into the reality of her situation. Coming back from a concert, the girl runs out of water. She begins to get dizzy, her heart starts racing, and every muscle starts twitching and aching. She refuses her friends' pleas to be taken to an ER, for fear of a tumor being found. Upon getting home, she immediately drinks a gallon of water and feels better. This incident scares her into finally confiding in her mom and seeking help, as she realizes she can't keep living like this.
She returns home and sees an internal medicine specialist. The IM has several ideas and proceeds to explore them. Through a CT, he rules out a brain tumor. He then has her undergo a 24 hour water deprivation study. She becomes dizzy, feels muscle pains, and continues to urinate every 30-40 minutes even without any water. Four hours into the study, she's critical enough that the IM stops the study: she's severely dehydrated, has lost five pounds in four hours, and her BP is crashing. At this point, I'm thinking "well damn, maybe I was actually right about the DI." The IM comes back on the show and starts talking about the significance of the test and vasopressin. At this point, I think "ooo." Vasopressin is another name for ADH. IM keeps talking, yada yada yada - diabetes insipidus.
!!! Whoa. I didn't just do that. Coolest feeling ever. Well, maybe not ever - but it's up there. At the point the IM mentioned vasopressin I'd stopped laying down in bed and was sitting up. When he said DI, it was over. As the case is wrapping up, the IM gives the girl ADH and all her symptoms immediately stop. Again, pretty sweet feeling.
While I know that I know nothing compared to any med student, much less any MD, it's still pretty cool to actually nail that diagnosis and actually understand what's going on. To go from symptoms to "hey this might be what's happening." To actually knowing how and why things are happening. Knowing why tests are being performed and their significance. To already know what the IM and Discovery Channel narrator are talking about as the case is ending.
As high as this case made me feel, it also made me think. What if I miss something as an MD? Odds are if I were FP, I probably would've done the same thing - expect the most common conditions. There's a phrase tossed around in medicine "if you hear hoof beats, you should look for horses, not zebras." Not a "Mystery Diagnosis." That is, if you see certain symptoms or signs, think of the most common things first, not an obscure condition (not a zebra). Aforementioned Dr. House is all about the zebras. In FP, DM is a common condition, and frequent urination/thirst is a common symptom. While the pathology of DI matches the girl's symptoms, her family history made it much more likely that she had DM. When she tested negative, the FP was at a loss.
This got me thinking again. The girl had never mentioned her car accident to an MD until the IM specifically asked if she'd sustained any head injury (so as to reconcile the diagnosis with the symptoms and tests). She initially responded with no sustained trauma. That is, until her mother later remembered the accident and corrected the IM. Damn, probably should mention car accidents to your doctor. But, I guess it's both on the patient to bring up any medical information and on the doctor to probe for such information.
Overall that fifteen minute segment did a lot. Made me feel pretty damn good and hopefully gave me a preview of stuff I'll be able to do. Got me thinking about possibly missing something or being wrong. I've obviously always been aware that this will happen, but the case gave me a concrete example of this. Also got me thinking about how MDs sometimes don't have all the information they need, and that's kinda freaky. Again, aware of the possibility, but now given a solid example.
Still, awesome feeling. Diabetes insipidus. Although, in watching two hours of the show I didn't do so hot on the other five cases. Got it narrowed down to three possible autoimmune problems, an eye problem (trochlear nerve/superior oblique muscle), and had no idea on the other case. Damn.
