Transcription
Pyruvate kinase deficiency is a cause of extravascular hemolysis due to an enzymatic deficiency. It's way less common than glucose six phosphate dehydrogenase deficiency. Pyruvate kinase is an enzyme in glycolysis, as you know. A deficiency of this enzyme will lead to deficiency of ATP that the red blood cell get and the kid will get jaundice due to hemolysis. We have elaborated on pyruvate kinase on the previous video.
This video, just know that when there is no pyruvate kinase, there is no ATP, so the red blood cell is set. Also, when this pathway is blocked, 13 bisphosphoglycerate will be converted into 23 bisphosphoglycerate. 23 bisphosphoglycerate will increase and it will shift the oxygen dissociation curve to the right. Pyruvate kinase deficiency is autosomal recessive. Now listen, this is not science, but many of the diseases that are autosomal recessive are due to enzyme deficiency.
So please keep this in mind. It might help you memorize many diseases. When it's autosomal recessive, usually it's an enzyme deficiency. Okay. Pyruvate kinase deficiency occurs in newborn.
It's an intracorposcular or intrinsic defect. Yes, because the problem is in the red blood cell. It's lacking pyruvate kinase. Will lead to extravascular hemolysis, which means in the spleen. When there is no pyruvate kinase, there is no ATP.
Of course, you know that. Red blood cell is set and dehydrated, and it will form something called BR cells or echinocytes. These are red blood cells with some tiny projections but this is different from acanthocyte. Acanthocyte also has some spurs but acanthocytes, the spurs are larger and less numerous. Echinocytes, the spurs are multiple and small.
Second, increase to three bisphosphoglycerate will cause the oxygen dissociation curve to shift to the right, which means hemoglobin is releasing oxygen to the tissue. This will mitigate the symptom of anemia. Why? Anemia is no red blood cells, so there is no oxygen. Okay.
But this will shift the oxygen dissociation curve to the right, which means red blood cells are releasing oxygen to the tissue. So the deoxygenation is less severe, Thanks to two three bisphosphoglycerate. I hope this is clear. So on one hand, you have an enzyme deficiency causing red blood cell to lose energy, which is bad. But on the other hand, you have two three bisphosphoglycerate, which shifts the curve to the right.
Hemoglobin releases oxygen to the tissue. We are slightly happier. Okay. So this mitigates the symptoms of anemia. Extravascular hemolysis, as you know, we have discussed this like a gazillion times before.
Problem here is abnormal red blood cell due to an enzyme defect. Clinical signs and symptoms are the same anemia plus jaundice maybe some splenomegaly here. It's a newborn with neonatal jaundice Diagnosis is made clinically. You have a yellow baby plus some investigation CBC again hemoglobin low hematocrit low because this is anemia Reticulocyte count will be increased because this is hemolysis when there are tick count increase MCV will be normal or high due to reticulocytes, which are bigger than the red blood cells. Okay, LDH will be high, unconjugated bilirubin high, haptoglobin low.
Pyruvate kinase enzyme level will clench the diagnosis. Blood film or peripheral smear may show ber cells, which are echinocytes not acanthocytes Diagnosis is likely to occur during pregnancy. Why? Because in pregnancy there is something called dilutional anemia. When you have anemia already in pregnancy and you have another cause of anemia, which is pyruvate kinase deficiency, it's more likely to be diagnosed at that time.
Treatment, again, there is nothing new here. Iron and folate due to rapid cell turnover. If it's severe, we do red blood cell transfusion and if we are giving a lot of blood, we should do iron chelation to prevent secondary hemochromatosis. Splenectomy can help because it's an extravascular hemolysis. When we remove a spleen of a kid, we vaccinate, okay, such as strep pneumo, haemophilus influenza, neisseria, meningitidis, and we give antibiotics which is penicillin v until the kid reaches five years of age.
Definitive treatment is bone marrow transplant. That's it. Now you know everything you need to know about pyruvate kinase deficiency.