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Why Do I Swell Up?: Dehydration, Edema, and the Effects of Purging (Vomiting, Laxatives, and/or Diuretics)

By: Jennifer L. Gaudiani, MD, CEDS

Monday, February 29, 2016

As you all know—and hopefully the rest of the world understands better after National Eating Disorder Awareness Week—eating disorders come in all shapes and sizes. Those who purge—either through vomiting or laxative/diuretic abuse—might meet criteria for anorexia nervosa, bulimia nervosa, or binge eating disorder, depending on a number of factors. What many doctors don’t know is the terrible struggle patients go through to stop purging. And I’m not talking about the emotional and mental struggle, which is hard enough! I’m talking about the medical struggle. Patients who purge chronically may find that when they stop purging…or reduce the frequency/amount of their purging…they immediately start to swell up with fluid. Their fingers become uncomfortably stiff, ankles and feet fill with fluid, body shape and size changes radically, and of course, the scale shows a very different number. This can happen JUST with cessation of purging—not to mention if you go to the emergency department and some well-meaning though woefully uninformed person (while they cheerfully make some comment about your size/weight) hooks you up to an IV and gives you a liter or two of fluids fast. BOOM, weight up, body radically changed.

Needless to say, this phenomenon makes my patients think, “Yep, I knew it. I’m ruined. I can never ever stop purging again.” And back we go to the behavior. I want to tell you why this happens and how to prevent it. I also want you to use this medical knowledge as ammunition against your eating disorder voice (former patients of mine: imagine me “talking” with my right hand near my right ear), because one of the beauties of the internal medicine of eating disorders is we can use the objective evidence of body suffering to combat denial and motivate recovery.

So here we go. When you chronically purge (vomiting, laxative abuse, diuretic abuse, or some combination), you get chronically dehydrated. In internal medicine speak, you’re actually volume depleted, which means that you have low levels of both salt and water in your bloodstream. As a result, your “cave girl brain” (I think of this as the subconscious part of your brain that’s been saving our bodies for years through all sorts of challenges) thinks, "I am dying of dehydration in the desert. If I’m lucky enough to find an oasis where there’s salt and water, I’d better have produced any hormone I can that will prevent me from peeing away these life-saving resources.” And that’s exactly what she does. She tells your adrenal glands (they are little triangular organs that sit on top of your kidneys) to over-produce aldosterone, a hormone that has two key functions in this setting. One, aldosterone truly keeps you from peeing away salt and water. So any salt/fluids you eat or drink when you’re not purging, or any IV fluids you get in the emergency room will stay in your body. That’s actually a good thing at first. You are so dehydrated that your blood and tissues absolutely need the extra salt and water. It’s life-saving. But the body can produce so much extra aldosterone that it overshoots, and before you know it, that salt and water has squeezed out of your bloodstream and is setting in your fingers, ankles, etc. In rare cases, it can be so bad that the extra fluid (called edema) can go into your brain and lungs, which can be life-threatening. Two, aldosterone makes you lose potassium in the urine. Anyone who purges ever been told to increase/increase/increase their potassium supplement until it’s practically burning holes in your stomach? The reason it’s not “sticking” in your system and bringing low potassium levels up is because of aldosterone. Even though your body desperately needs that potassium, you pee it away.

So basically, the act of chronically purging—of giving in to that drive to be totally empty, clean, etc—actually sets you up for rapid and sometimes dangerous body changes due to edema. This process of high production of aldosterone is called Pseudo-Bartter Syndrome. Pseudo-Bartter Syndrome is responsible for that rapid swelling and the inability to get your potassium levels up. And given the underlying emotional drive to live dehydrated/dry/empty, my patients who purge are the least tolerant of the really fast body changes that occur when you stop purging. (This is a not-so-subtle plug, DON’T START purging! It’s no quick fix. It’s a miserable way to live.)

There is hope. On ACUTE we take care of patients of all shapes and sizes who purge, because there’s no one body size that says, “Hey, you’re sick enough for us,” especially when it comes to helping patients detox off purging. My rule of thumb—and I hesitate to even name numbers because I don’t want to invalidate anyone’s personal experience—is that if you’re using more than 10 laxatives a day, you probably need expert medical detox before you enter into residential treatment. (Eyebrows go up, "But I’m using that many and I’m not even close to planning on residential treatment.” Dr. G says you absolutely should be planning it.) The key lab value to give a clue whether you’re at risk for Pseudo-Bartter Syndrome is your bicarbonate (sometimes called the CO2 on your lab sheet). If it’s above 30 for those who vomit/use diuretics, you almost certainly have Pseudo-Bartter syndrome. If it’s above 35, you should be in a hospital ASAP. If you use laxatives, the bicarb is more tricky to interpret. By a nerdy mechanism that I will spare you the details of, diarrheal losses can push your bicarb down, so it’s not as good a marker.

To get rid of Pseudo-Bartter Syndrome, first know that your body is NOT ruined and that you CAN successfully stop purging. Work with your team to do the following, pretty much all on the same week:

  1. You must 100% stop purging. (Ha, you say, like that’s so easy. Where’s your magic wand? But yes, you have to decide…you can’t control your emotions, but you can control how you react to your emotions, and decide to be done purging.)
  2. You must pharmacologically (that means with medicines) block your over-production of aldosterone. The right medicine for this is spironolactone, an old and tested very mild diuretic whose mechanism of action is the direct blockade of aldosterone. 25 mg a day should do, but you may need more if you use laxatives.
  3. You must gently rehydrate yourself. This is not the time to guzzle water. Imagine a bathtub that is on the brink of overflowing. Do you turn the taps full on? No. You might limit yourself to 2-3 liters of fluids a day and eat moderate amounts of sodium in your diet.
  4. Toss the scale. This is good advice anyway with an eating disorder, but the fact is that you are running 5-15 pounds dehydrated all the time if you purge. So even if your body doesn’t overshoot and get edema, you will (appropriately) see changes in your body as it rehydrates. This is appropriate and normal, and you will need lots of support from your mental health professionals.
  5. Stay on spironolactone (note: it causes increases in your blood potassium levels) for 2-4 weeks, depending on what your doctor recommends. After that, you are detoxed from purging and should no longer be at risk from edema.

I send you all wishes for recovery, living life instead of surviving it, and wellness. Dr. G

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