Pre-testing diet (Dex) - wtf?!

Well, here I am, being harassed by bureaucracy again.

1. I finally found a spare moment to schedule my hospital appointment (specifically for a dexamethasone suppression test and an OGTT)—and get this—my endocrinologist said absolutely nothing, nor did my primary care doctor. When I first called the clinic to book, there was no mention of prep work; then today, when I called to confirm I’d be coming in tomorrow, the receptionist just goes: ''Are you on the required diet?'' Me? I'm like: ''What diet? No one mentioned anything about a diet...'' And she responds: ''Well, you aren't allowed to eat fresh fruit, coffee, cocoa, tea, or pastries for a week—which means no vanilla in any baked goods either.'' Now, sensing the sheer irritation in her tone, I didn't want to push for a full explanation, but I did ask about sugar and refined carbohydrates in general (I was genuinely confused because she didn't say "no sweets," she specifically singled out fruit and pastries because they contain vanilla), and she just went: ''Sugar is fine, just no pastries... blah blah blah... vanilla.'' Honestly... I don't find it particularly difficult to give up pastries and coffee since I don't really consume them anyway (though I did shed a tear over the thought of losing fruit!), but the logic escapes me...

...Why specifically fruit and vanilla? I mean, what on earth? It makes zero sense to me, so if anyone could explain why vanilla plays such a role or which specific components in fruit are problematic, I would be eternally grateful. I had absolutely no idea there was a mandatory seven-day dietary restriction prior to the dexamethasone test—I thought the only thing to watch out for was medications, diuretics, and things of that nature. I mean... vanilla?😂 I even called a friend who's in her sixth year of medical school, and even she was completely stumped. Did they perhaps make a mistake? Or are they just pulling my leg? Should I call them back? (Classes are starting soon and I really needed to get these tests out of the way, but now I have to wait another entire week.)

2. Also: I don't actually consume much glucose myself (aside from what's in the fresh fruit I'm now forbidden from eating)—is it a bad idea if my glucose intake is low right before the OGTT? (I think I heard somewhere that avoiding glucose entirely for several days leading up to the actual test isn't recommended?)

3. And... I assume menstrual blood in the urine interferes with cortisol testing??

Thanks in advance!😍

Unfortunately, I’ve had my own run-ins with endocrinology labs, so allow me to share what I know:
There are essentially two possibilities here: either the nurse simply misunderstood you, or they intend to run a 24-hour urinary vanillylmandelic acid test. This particular test is used to assess adrenal gland function; to put it in layman's terms, if I recall correctly, it measures how much of this specific acid your adrenal glands are secreting. An excess can indicate an underlying medical condition—though I can't recall the exact diagnosis, apologies. The catch is that many foods naturally contain these acids, particularly those your sister mentioned, which means you have to strip them from your diet for a period to ensure the results aren't skewed. I remember being on such a restrictive diet while staying at the hospital, and they suggested that sticking to "white foods" was the safest bet—which, along with that business about cookies, meant things like potatoes and plain pasta. It was quite unpalatable, but one does what one must.
The dexamethasone suppression test is a different matter entirely and requires no dietary preparation. In healthy individuals, dexamethasone can trigger insomnia or mood swings, so perhaps bring a book or some headphones in case sleep eludes you.

As for the OGTT, there shouldn't be any issues; they will administer glucose and monitor your insulin response. If your pancreas is functioning normally, it should respond appropriately. If you exhibit an excessive insulin spike, you might already be carrying a bit of extra weight 🙂, whereas a diminished response would suggest diabetes. Usually, cutting back on sweets leads to a slight normalization of pancreatic function, so everything should be fine.

Regarding menstrual blood and cortisol, I haven't the slightest clue, though I imagine it shouldn't interfere. I only know that blood can complicate a standard urinalysis, where they look for red blood cells as an indicator of potential issues within the urinary tract.

Anyway, best of luck, and please do let us know how it goes! Are you heading over to the Mayo Clinic or somewhere similar?

Amy Hill92 said:Dexedrine can be quite the little troublemaker when it comes to sleep—and let’s not even get started on the mood swings! It really can throw your whole equilibrium off balance, can't it? So, if you find yourself staring at the ceiling in the middle of the night, I’d highly recommend packing a good book and perhaps an old-school Walkman just to keep your mind occupied. A little distraction goes a long way, don't you think?

Insomnia and these constant mood swings—well, they’ve been playing havoc with my constitution lately, to be honest—so, I suppose I am bringing my laptop along.😂 I mean—seriously. Is there any other way to put it? Truly.

Oh, thank you ever so much for this—honestly, I was just starting to think that nobody would bother to get back to me! I think I’ll give them a call first thing tomorrow morning; there is really no sense in sitting around waiting if they happened to make a mistake on their end, is there? By the way—and please forgive my lack of expertise here—I don't believe I have ever even heard of vanillamandelic acid before... I suppose I am not quite the scholar I'd like to be! 😵 😁 ).

Is there anything quite as overwhelming—and frankly, as massive—as navigating the sprawling corridors of a major metropolitan hospital system? I was recently thinking about the sheer scale of an institution like Mayo Clinic, and it got me wondering... does anyone else feel that specific sense of vertigo when walking through those endless, sterile hallways? It’s a bit much, isn't it? One moment you're looking for a simple outpatient clinic, and the next, you've somehow wandered halfway into a different zip code!

Thanks again—really, truly! 😘

You are quite welcome. It seems there is an unwritten protocol at places like Mayo Clinic where they follow specific diagnostic sequences. Essentially, if a physician suspects one particular condition, they initiate a certain battery of tests, whereas a different suspicion triggers an entirely different set of screenings. In the specific diagnostic track involving the OGTT and dexamethasone, a VMA test is typically included as a standard requirement. It is entirely possible that your nurse was simply following that established clinical pathway, which might be why she caught you off guard.
Anyway, hang in there and best of luck!