Unconjugated Hyperbilirubinemia

00:01 But let’s focus for now on unconjugated hyperbili.

00:05 Basically, there are – We start with hemolysis.

00:08 These red blood cells are breaking down.

00:11 And this can be from ABO incompatibility between the mother and the child.

00:17 It could be from Rh incompatibility between the mother and the child or it could be from some other alloimmunization.

00:26 Those are usually a bit more mild.

00:28 Let’s start with Rh incompatibility.

00:32 Here we have a couple that have decided to have a child.

00:35 The mother is Rh negative.

00:38 She does not express this protein on her red blood cells.

00:41 The father is Rh positive.

00:44 He does.

00:45 They decided to have their first baby.

00:47 Now this baby seems to have accidentally, just by luck, just got dad’s proteins.

00:54 So the baby has Rh positive red blood cells.

00:58 But remember the baby is inside the mother who does not.

01:02 During the course of our first pregnancy, a little bit of that baby’s blood, just a tiny amount gets out into the mother.

01:11 She, her immune system, sees these Rh positive red blood cells and says, “This isn’t me" and she manufactures antibodies that will now be sticking to these Rh positive red blood cells.

01:23 Fine.

01:25 Now, the second baby comes along.

01:27 She’s had her first baby, everything went great.

01:30 Now, they’re having their second baby and amazingly enough, just by freak of chance alone, this child also inherited dad’s Rh protein.

01:42 Now, the baby is expressing Rh positive red blood cells.

01:47 Mom has antibodies formed against Rh positive red blood cells already from the last pregnancy.

01:54 These antibodies are floating around in small number.

01:57 But remember, antibodies can be transplacental.

02:01 When the baby is born, these immunoglobulins cross over into the baby and now, the baby has a problem with mom’s antibodies attacking the baby’s blood.

02:14 This results in a hemolysis and it can be quite severe.

02:20 Basically, we can prevent this from happening because we can easily test mom’s blood.

02:25 And one of the standard tests we do in moms is understanding whether they’re Rh positive or Rh negative.

02:31 If they’re Rh negative, there’s not really anything we have to be doing here except we have to treat to prevent this child from getting in trouble.

02:38 But if they’re Rh positive, there’s really nothing we have to do.

02:42 This mom’s not going to mount antibodies against here own Rh.

02:45 Okay.

02:46 So let’s look at the Rh negative mother.

02:50 We’re going to prevent newborn hemolysis by giving here anti-Rh antibodies.

02:55 What’s going to happen is these are going to bind to any Rh positive cells from the baby that actually sneak into her circulation and will prevent her from making her own Rh positive antibodies.

03:08 These sites will all be taken up by the RhoGAM or Rh-positive gammaglobulin that we’ve given this patient, the mother, already.

03:17 We give this typically at 28 weeks gestation.

03:20 And again, three days after delivery to block any another that came across during the delivery for the next child.

03:30 Additionally, patients may have red blood cell membrane defects.

03:35 Hereditary spherocytosis, hereditary elliptocytosis.

03:39 These cells are more fragile and can break down and cause unconjugated hyperbilirubinemia.

03:46 Or patients may have glucose-6-phosphate dehydrogenase deficiency or G6PD Those infants may have oxidative stress, resulting in unconjugated hyperbilirubinemia.

04:00 Patients may have pyruvate kinase deficiency, which can cause red blood cell breakdown or a hemoglobinopathy such as thallasemia or sickle cell, which may cause increased red blood cell breakdown.

04:12 Really anything that causes the cells to break down can cause unconjugated hyperbili.

04:18 Additionally, patients may not have an increased fragility or autoimmune attack on their red blood cells, but they may just be sick.

04:27 Patients with sepsis have red cell breakdown.

04:30 Patients in DIC may have breakdown.

04:33 Also, there can be blood collections outside the blood vessel that then break down.

04:39 For example, a very bad cephalohematoma.

04:43 There can be a lot of blood in there and as that breaks down, it’s resorbed into the body as bilirubin.

04:50 Infants of diabetic mothers may have polycythemia and those infants are at greater risk for unconjugated hyperbilirubinemia.

04:59 Also, metabOlic problems are associated with this such as hyperthyroidism.

05:05 Crigler-Najjar is an inability to clear the unconjugated hyperbili through the liver, so is Gilbert syndrome.

05:14 So both of those patients, although it’s a liver disease, which we usually think of as causing conjugated hyperbili, those two in particular can be an unconjugated hyperbili.

05:24 Galactosemia is classic for this, also don’t forget about the cataracts, but that can cause a conjugated hyperbilirubinemia also because of the liver damage.

05:35 So it can actually cause both.

05:37 Also, hereditary tyrosinemia can cause an unconjugated hyperbili.