Hemolytic anemias Intrinsic defects

Hemolytic anemia is a condition characterized by an increased rate of destruction of red blood cells (RBCs) that exceeds the marrow's ability to produce new cells, resulting in a shortened lifespan for the RBCs.
This leads to a reduced capacity to carry oxygen, resulting in increased production of erythropoietin as the body attempts to compensate for the anemia.
The bone marrow is capable of increasing production of RBCs up to 6 to 8 times the normal rate before anemia becomes clinically evident.
If bone marrow compensation fails, hemolysis leads to an increased loss of RBCs, manifesting as anemia.

Intravascular Hemolysis: Occurs predominantly due to fragmentation of RBCs within blood vessels.
Extravascular Hemolysis: Involves macrophage-mediated phagocytosis of senescent or damaged RBCs, primarily in the spleen and liver, either normally or in an accelerated manner.

Bilirubin:
- In cases of fragmentation or macrophage-mediated hemolysis, there will be elevated bilirubin levels leading to icterus (jaundice) in plasma/serum.
- Bilirubin assays show increased indirect (unconjugated) bilirubin.
Plasma and Urine Hemoglobin and Urine Hemosiderin:
- Visual examination may indicate RBC fragmentation;
- Possibility of hemoglobinemia (elevated free HGB).
CBC Report and Peripheral Blood Findings:
- Indicative of decreased RBC, HGB, and HCT levels.
- Spherocytes indicate macrophage-mediated hemolysis.
- Presence of schistocytes or RBC fragments indicates intravascular hemolysis.

Approximately 87% of the time, a low haptoglobin level indicates the presence of hemolytic disease.
Haptoglobin levels may show false-positive or false-negative results.
Decreased levels of haptoglobin occur in fragmentation hemolysis, while mild decreases may be evident in macrophage-mediated hemolysis due to increased cell fragility.

Spherocytes, elliptocytes (ovalocytes), acanthocytes, burr cells, schistocytes, and erythrophagocytosis.
Each morphology corresponds to specific hemolytic disorders, including:
- Hereditary Spherocytosis
- Hereditary Elliptocytosis
- Conditions like Pyruvate Kinase Deficiency and Microangiopathic Hemolytic Anemia

Caused by mutations in membrane proteins leading to defective membrane structure.
RBCs exhibit abnormal permeability to cations (Na/K), resulting in water loss and increased cellular viscosity leading to spherocyte formation.
Hallmarks of HS are increased MCHC, reticulocytosis, and the presence of spherocytes in the peripheral blood smear (PBS).

Utilizes fresh heparinized blood in gradually hypotonic saline solutions to measure hemolysis via spectrophotometry.
Spherocytes demonstrate increased osmotic fragility and lyse in higher concentrations of NaCl than normal RBCs.
The test curve correlates to the severity of the membrane defect, with left shifts indicating increased fragility and right shifts indicating decreased fragility.

Mild Cases: Usually do not require treatment.
Moderate to Severe Cases: May require splenectomy which significantly reduces hemolysis and lessens bilirubin levels, although spherocytes may still be present post-surgery.

Caused by mutations leading to cell membrane instability; characterized by elliptocytes in PBS.
Diagnostic criteria include a family history of hemolytic anemia and elevated reticulocyte counts.

Caused by a defect in cation permeability causing increased intercellular cation concentration leading to water influx and increased cell volume without surface area increase.
Laboratory findings may include decreased intercellular potassium and increased sodium concentration, along with increased osmotic fragility.

An autosomal recessive disorder leading to ATP depletion, inducing chronic hemolysis with symptoms of anemia and jaundice.
Laboratory findings include normocytic, normochromic anemia with reticulocytosis, and abnormal RBC morphology.

Most common enzyme deficiency leading to free radical buildup and oxidative stress, resulting in hemolysis.
Key laboratory findings during hemolytic episodes include elevated indirect bilirubin, reticulocytosis, and Heinz body formation in RBCs.

Qualitative and Quantitative Approaches for diagnosing G6PD deficiency:
- Quantitative tests measure NADPH formation as an indicator of G6PD activity.
- Qualitative tests utilize fluorescent spot testing to determine G6PD functionality.

Important for maintaining RBC integrity and energy supply, diverts glucose metabolism through several pathways:
- Hexose Monophosphate Pathway: Detoxifies hydrogen peroxide and maintains membrane integrity.
- Methemoglobin Reductase Pathway: Reduces methemoglobin to maintain oxygen transport capacity.
- Rapoport-Luebering Pathway: Produces 2,3-DPG, crucial for regulating hemoglobin's oxygen affinity.