Inborn Errors: Screening and Management (Nursing)

00:01 How do we figure out if we're dealing with an inborn error? Now, a lot of inborn errors, especially the more common ones are routinely included in newborn screening.

00:12 Galactosemia is one that we can detect with newborn screening.

00:17 PKU can be detected.

00:20 Additionally, we have Mucopolysaccharidosis Type 1, and Maple Syrup Urine Disease.

00:27 Those can all be detected with newborn screening.

00:31 Now, if this isn't something that is going to be on a newborn screen, because as we said, there are many, many, many different types of inborn errors of metabolism.

00:41 How do we know we need to test for this? Well, we want to get history from the patient and see if their symptoms line up with us being a little bit worried that they might have an inborn error.

00:53 So if your patient is positive for lethargy, if they have recurrent hypoglycemia that is not explained by any kind of diabetes or other endocrine issue, if they have recurrent vomiting that we just can't explain.

01:10 If they're experiencing diarrhea, or episodic abdominal pain, and you've gone through all of the workup for a GI issue, and everything looks fine, but they're still having these symptoms, we might worry about an inborn error of metabolism.

01:25 Additionally, if you have infants that are having trouble feeding, maybe they are not coordinated enough to latch onto a bottle or the breast, if they're having poor growth or their hypotonic, or looking a little bit floppy.

01:41 If patients are particularly photophobic, they can't handle bright lights but we haven't found anything wrong with their eyes.

01:50 If they experience a lot of muscle cramping, or particularly if they have symptoms after ingesting a particular food, like a protein containing food or a carbohydrate.

02:02 If patients have these types of symptoms, then we may want to test them for an inborn error of metabolism.

02:09 Some other screening that we can do our initial laboratory testing, and there are several categories of lab tests that can give us clues that we might be dealing with an inborn error.

02:21 We can get a CVC and blood counts.

02:24 We can get a CK, that's going to measure our muscle activity.

02:29 Additionally, chemistries can help.

02:31 We're going to be checking those blood glucoses, making sure that the electrolytes are normal, and kidney function with the BUN and creatinine.

02:40 Often inborn errors of metabolism will cause our patients to be acidotic.

02:45 So we can get a blood gas and a lactate to see if our patients are having acidemia or acid in their blood.

02:54 We can do specific lab testing that really will give us an indication that we're dealing with an inborn error.

03:00 So we can send uric acid. We can send plasma amino acids, pyruvate, and an acetyl carnitine profile.

03:09 Additionally, the liver is very important in metabolism.

03:13 So we can check our liver labs, our ammonia levels AST, ALT, bilirubin, and prothrombin.

03:22 Those are all liver laboratory levels.

03:24 We can also check the LDH.

03:28 We can also send urine tests off so we can send a routine urinalysis.

03:33 But We can also check for urine myoglobin.

03:35 So if this inborn error is causing us to break down muscle, then that's going to show up as myoglobin in our urine.

03:43 We can look for reducing substances in organic acids that are going to give us clues that we might have an inborn error of metabolism.

03:51 And then additionally, there is molecular genetic testing that can get a little bit more granular when we're trying to figure out which inborn error we might be dealing with.

04:02 So the cost of genetic testing has really dropped dramatically with the development of this next generation sequencing.

04:09 And this can include whole-exome sequencing.

04:12 It's a little bit more available to the public than it used to be.

04:17 So when we do our next generation sequencing, we can send either the whole-exome sequencing or if we think that there's a particular inborn error that we're more likely to have, we can ascend off a particular pieces of that sequencing.

04:33 And we do need some further refinement for clinical diagnostic use, but it can give us some useful information as we're working through this problem.

04:44 So the management of these disorders is going to depend on which inborn error is diagnosed.

04:49 And all of the focus is then going to be on supporting that patient's metabolism.

04:55 So, let's work through the clinical judgment model to think about inborn errors of metabolism.

05:03 So the first step that we're going to do is try to recognize the clues that our patient is giving us.

05:10 And in inborn errors of metabolism, we might see a patient come in that is hypotonic.

05:18 So maybe their muscles are weak. The patient looks floppy.

05:21 They have been losing their developmental milestones.

05:24 They might have a big liver, signs and symptoms of shock.

05:27 And we really can't explain this by another condition or any kind of infection.

05:32 If it's unexplained, then we're going to suspect an inborn error of metabolism.

05:38 So when we're analyzing these cues, and we recognize that the cues that we saw in the patient really aren't attributed to infection, then we can send off laboratory tests to see if what we're dealing with is an inborn error.

05:53 So that'll really help us analyze those cues.

05:57 And then, once we figure out we do have an inborn error of metabolism, again, the management is really going to depend on which one you find.

06:05 And all of that focus is going to be on supporting that patient's metabolism and trying to keep them as healthy as possible.

06:14 So when you're thinking about the clinical judgment model, you want to go through all of these steps.

06:20 And we've highlighted a few of them to help you think through it.