Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss (Part 8)

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Abnormalities of the Glycolytic Pathway (Fig. 101-1) Since red cells, in the course of their differentiation, have sacrificed not only their nucleus and their ribosomes but also their mitochondria, they rely exclusively on the anaerobic portion of the glycolytic pathway for producing energy in the form of ATP. Most of the ATP is required by the red cell for cation transport against a concentration gradient across the membrane. If this fails, due to a defect of any of the enzymes of the glycolytic pathway, the result will be hemolytic disease. Pyruvate Kinase Deficiency Abnormalities of the glycolytic pathway are all inherited...

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Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss (Part 8) Abnormalities of the Glycolytic Pathway (Fig. 101-1) Since red cells, in the course of their differentiation, have sacrificed not only their nucleus and their ribosomes but also their mitochondria, they rely exclusively on the anaerobic portion of the glycolytic pathway for producing energy in the form of ATP. Most of the ATP is required by the red cell for cation transport against a concentration gradient across the membrane. If this fails, due to a defect of any of the enzymes of the glycolytic pathway, the result will be hemolytic disease. Pyruvate Kinase Deficiency Abnormalities of the glycolytic pathway are all inherited and all rare (Table 101-4). Among them, deficiency of pyruvate kinase (PK) is the least rare, with an estimated prevalence of 1:10,000. The clinical picture is that of an HA that often
presents in the newborn with neonatal jaundice; the jaundice persists and is usually associated with a very high reticulocytosis. The anemia is of variable severity; sometimes it is so severe as to require regular blood transfusions; sometimes it is mild, bordering on a nearly compensated hemolytic disorder. As a result, the diagnosis may be delayed, and in some cases it is made in young adults—for instance, in a woman during her first pregnancy, when the anemia may get worse. In part the delay in diagnosis is due to the fact that the anemia is remarkably well- tolerated because the metabolic block at the last step in glycolysis causes an increase in bisphosphoglycerate (or DPG), a major effector of the hemoglobin- oxygen dissociation curve. Thus, the oxygen delivery to the tissues is increased. Table 101-4 Red Cell Enzyme Abnormalities Causing Hemolysis Enzyme Chro Pre Cli Commen (Acronym) mosomal valence of nical ts Location Enzyme Manifest Deficiency ations (Rank) Extra- Red Cell Gly Hexokina 10q22 Ver Other
colytic se (HK) y rare isoenzymes pathway known. Glucose 19q31 Rar N 6-phosphate .1 e (4) M, CNS isomerase (G6PI) Phosphof 12q13 Ver My ructokinase y rare opathy (PFK) Aldolase 16q22 Ver -24 y rare Triose 12p13 Ver CN phosphate y rare S isomerase (TPI) (severe), NM Glycerald 12p13 Ver My
ehyde 3- .31–p13.1 y rare opathy phosphate dehydrogenase (GAPD) Diphosph 7q31- Ver Erythrocy oglycerate q34 y rare tosis rather than mutase (DPGM) hemolysis. Phosphog Xq13 Ver CN May lycerate kinase y rare S, NM benefit from (PGK) splenectomy. Pyruvate 1q21 Rar May kinase (PK) e (2) benefit from splenectomy. Red Glucose Xq28 Co Ve In almost ox 6-phosphate mmon (1) ry rarely all cases only dehydrogenase granulocy AHA from (G6PD) tes exogenous
trigger. Glutathio 20q11 Ver CN ne synthase .2 y rare S γ- 6p12 Ver CN Glutamylcystein y rare S e synthase Cytochro 22q13 Rar CN Methemo me b5 reductase .31–qter e S globinemia rather than hemolysis. Nu Adenylate 9q34. Ver CN cleotide kinase (AK) 1 y rare S metabolis m Pyrimidin 3q11– Rar May e 5'-nucleotidase q12 e (3) benefit from
(P5N) splenectomy. Note: CNS, central nervous system; AHA, acquired hemolytic anemia.