Vitamin B12 Metabolism

00:00 B12 meat products.

00:04 You pick up R-factor.

00:06 Next, you’re done in your acid in your stomach.

00:09 You need that acid to properly convert your pepsinogen into pepsin.

00:12 We talked about that.

00:13 While you’re there, in your stomach from your parietal cell, you pick up intrinsic factor.

00:18 This intrinsic factor then binds to B12, along with this you also have R-factor.

00:22 All of this we just did.

00:22 You get into duodenum.

00:26 From the pancreas, you get your enzyme.

00:28 This enzyme from the pancreas removes the R-factor only.

00:32 So now, what are you left with? Intrinsic factor, B12.

00:37 This complex will then move to where? Terminal ileum for reabsorption.

00:43 B12, intrinsic factor.

00:46 IF is intrinsic factor.

00:48 Goes to terminal ileum and here comes transcobalamin type II.

00:52 I would know that.

00:54 I would know transcobalamin.

00:54 What’s another name for B12? Cobalamin.

00:58 Know that as well.

00:59 Make sure you know all the different names of your B vitamins.

01:00 That’s important, very.

01:04 For example, if you say B1, you’re going to think about thiamine.

01:08 B3, niacin, right? So on and so forth.

01:12 If you’re thinking B6, pyridoxine.

01:13 B12, cobalamin.

01:17 Be careful.

01:17 So you wonder transcobalamin II, it delivers the B12 from the terminal ileum to the liver.

01:24 So can you have a patient that has -- Know this.

01:29 can you have a patient that has transcobalamin II deficiency? Yeah.

01:33 Results in B12 deficient.

01:35 Okay now, we’re not quite done yet because you might have heard of Schilling test.

01:41 And it’s not that you’re actually going to perform it.

01:42 It’s out of date and clinical practice, you don’t want to unnecessarily expose your patient to radioactivity.

01:51 Is that clear? So I’m not going to walk you through the procedure for Schilling, any of that.

01:55 But there is one huge physiologic concept that you need to take out of Schilling and then utilize that with your treatment.

02:04 You’ll see what I’m referring to.

02:06 Before we move on though, let me ask you a question.

02:07 When you find a substance in your urine and you've eaten it, meaning that you ate it first -- Make sure we’re clear.

02:16 You’ve eaten something first and it ends up in your urine, tell me what happened to that substance first.

02:23 You reabsorbed that substance first from the intestine, then you got it into the blood and then you went to the kidney and you filtered it.

02:32 That’s the only way.

02:32 The kidney doesn’t filter the intestine, right? So meaning to say that if you find something in your urine, it had to have been reabsorbed first.

02:43 Is that clear? If it’s not reabsorbed, where does it end up? What did you do this morning maybe? You passed stool? Yeah, it will end up in your feces.

02:53 Is that clear? Why is that important? Because -- Let me ask you a simple question.

02:56 If your patient has megaloblastic anemia and starts showing signs of neurologic deficit and now at this point, there is absolutely no B12 in the urine.

03:08 You give intrinsic factor and you find B12 in the urine, what’s your diagnosis? Pernicious anemia.

03:16 So what we’ll do, ladies and gentlemen, we’ll go from head to toe.

03:21 Is it a vegan? Or is it an elderly with malnutrition? Is it a patient with pernicious anemia? Is it a patient with pancreatitis? Is it a patient with bacterial overgrowth? Anytime you then find cobalamin in your urine with giving that companion, whether it be R-factor, intrinsic factor or whatever enzymes, then you know that that is your diagnosis.

03:43 So you will see what I’m referring to but I’m just setting things up here for you.