Red Blood Cell Conditions

There are a variety of conditions that contribute to abnormal RBC function or counts.

Condition	Physiology	RBC	HGB	HCT	MCV	MCH	MCHC	RDW	Morphology	Followup Tests
Blood loss/hemorrhage		N/↓	N	N	N	N	N	N	Normal
Iron Deficiency Anemia	Insufficient erythropoiesis Inadequate iron intake Chronic blood loss	N/↓	N/↓	↓	↓	↓	↓	↑	Hypo/micro Ovals, pencils Tears, targets (occasional)
Anemia of Chronic Inflammation	Insufficient erythropoiesis								Normal or Hypo/micro
Sideroblastic Anemia	Ineffective erythropoiesis Deficient protoporphyrin synthesis RBCs made but iron doesn't bind to ring	↓	↓	↓	N/↓	N/↓	N/↓	↑	Dual population Normochromic/normocytic Hypo/micro Pappenheimers	Ringed sideroblasts in BM
	Lead poisoning (secondary) Certain drugs and heavy metals	↓	↓	↓	N/↓	N/↓	N/↓	N	Normal OR hypo/micro Stomatocytes Coarse basophilic stippling
Iron Overload	Inherited conditions (hereditary hemochromatosis) Excess iron accumulation from treatment (e.g., blood transfusion)
Thalassemia	Ineffective erythropoiesis	N/↑	N/↓	N/↓	↓↓	↓	N/↓	N	Hypo/micro Targets Tears Increased polychromasia Basophilic stipping NRBCs
Megaloblastic Anemia	Ineffective erythropoiesis Vitamin B12 deficiency Folic acid deficiency Certain cancers or drugs Causes nuclear-cytoplasmic asynchrony	↓	↓	↓	↑↑	↑	N	↑	Macrocytic/normochromic Pancytopenia Oval macrocytes Hypersegmented neutrophils Tears, schistocytes, microspherocytes, targets HJ bodies, basophilic stippling NRBCs	Cell fragmentation/lysis ↑ Serum bilirubin ↑ LDH Vitamin testing Antibody assays
	Pernicious anemia Autoimmune cause (destruction of parietal cells)	↓
Macrocytic non-megaloblastic anemia	Liver disease				↑		N		Macrocytic/normochromic Round macrocytes Targets	Liver panel Bilirubin Coagulation testing
	Chronic alcoholism								Macrocytic Round macrocytes Spur cells Stomatocytes?
	Normal newborn	↑	↑	↑	↑				Macrocytic/normochromic Macrocytes Burrs Fragments Spherocytes Increased poly NRBCs
	Reticulocytosis
	Bone marrow failure
Aplastic Anemia	Insufficient erythropoiesis Hypocellularity due to autoimmune destruction				↑

Insufficient Erythropoiesis

• Iron deficiency anemia
• Erythropoietin deficiency (renal disease)
• Loss of erythroid precursors
  • Aplastic anemia (autoimmune)
  • Infection
  • Destruction/suppression of erythroid precursors (cancers, granulomas, fibrosis)

Anemias

• Ineffective erythropoiesis
  • Defective precursors made that are destroyed or function poorly
• Insufficient erythropoiesis
• Blood loss (acute or chronic)
• Increased RBC destruction (hemolytic anemia)
  • Shortened cell survival
  • Intrinsic RBC defects
  • Extrinsic RBC defects

Hemoglobin & Size

• Normocytic and normochromic
  • Hemoglobinopathies
    • Sickle cell
    • Other abnormal hemoglobins
  • Infections (including malaria and sepsis)
  • Hemolytic anemias
    • HUS, DIC, TTP
  • Membrane disorders (hereditary sph
  • Enzyme disorders (PK and G6PD deficiencies)
  • Poisons, toxins, drugs
  • Aplastic anemia
  • Burns
  • Hemorrhage
• Hypochromic and microcytic
  • IDA
  • Sideroblastic anemia
  • Thalassemia (globin chain deficiency)
  • Anemia of chronic inflammation (severe)
• Macrocytic and normochromic
  • Megaloblastic anemia (B12 or folate deficiency)
  • Liver disease