red cell disorders (clinical) Flashcards
anemia
- total # of RBCs are reduced –> lower O2 carrying capacity
- measured with Hb, hematocrit, MCV, RBC count etc.
- SYMPTOM of a disease, need to find the underlying cause**
values
- Hb concentration - men (15.8), women (13.8)
- hematocrit % - men (46), women (40)
- MCV (average size of RBC) - men/women (88)
- MCH, MCHC (how much Hb in cell) - men/women (30 MCH), (34 MCHC)
- RDW (variety in size) - men/women (13)
erythropoiesis
- RBC production that takes 3 weeks
- EPO from the kidney –> stimulate bone marrow to produce RBCs
- EPO dependent 1st 2 weeks
- Fe dependent last week
RBC recycling
- degrading RBCs by macrophages in spleen after 120 days
- RBC components like Hb recycled
- Fe transported to liver by transferrin, stored as ferritin (hemosiderin in excess)
- bilirubin further metabolized
Hb molecule
-porphyrin ring, Fe, 2 alpha and beta chains
Fe metabolism
- 10mg absorbed every day by duodenum, 1-2mg are lost due to skin exfoliation
- most Fe in circulation –> bone marrow to make RBCs
- rest of Fe stored in liver as ferritin
- EPO increases Fe absorption
hypovolemia and hypervolemia
- can change the parameters since most are measured on [] (Hb changes with changing volume)
- may look anemic on #s, but may not be and vice versa
mechanisms to compensate for anemia and low O2
- increase CO (can lead to heart failure)
- increase O2 unloading at the tissues
3 ways anemia can develop
- blood loss
- underproduction of RBC
- increased destruction of RBC
blood loss
- not always obvious –> could be slow as in gastric ulcer or prolonged menstrual bleeding
- blood loss = Hb loss = Fe loss –> leads to decreased RBC production when stores depleted
decreased RBC production
- production is lower than loss (bone marrow cannot compensate)
- measure reticulocyte count (>3% with healthy marrow)
- cause: low Fe, B12, marrow disorders or suppression, low levels of EPO or thyroid hormone
ineffective erythropoiesis
- hyperactive marrow but immature production of RBCs
- cause: B12/folate deficiency, myelodysplastic syndromes, thalessemias, sideroblastic anemia
increased RBC destruction
- destruction of RBC earlier than 100 days –> hemolysis
- enlarged liver or spleen
- due to hypersplenism or hemolytic anemia (inherited or acquired)
- high LDH and bilirubin (jaundice), reduced haptoglobin, hemoglobinuria (dark urine due to indirect Hb)
- heme –> biliverdin –> Fe
haptoglobin**
- protein produced by liver –> binds free Hb in circulation
- prevents loss of Fe and toxic effects of Fe
- low in anemia bc it is binding all the free Hb (<25mg/dL)**
what does low Hb/HCT with minimal to no symptoms mean?
anemia is slow and chronic
-want a reticulocyte count
low WBC count
-aplastic anemia or marrow replacement with fibrosis
high WBC count
-infectious process, leukemia
low platelet count
-aplastic anemia, hypersplenism, TMA
high platelet count
-Fe deficiency, inflammation, infection
WBC with B12/folate deficiency
-hypersegmented neutrophils with impaired DNA synthesis
reticulocyte production index (RPI)**
- index adjusts for level of anemia and reticulocyte maturation time**
- cannot judge the function of bone marrow by looking at absolute or % of reticulocyte count
- sever anemia –> reticulocyte count high with marrow trying to compensate**
Fe deficiency anemia
- cause: reduced absorption, blood loss, hemosiderosis (Fe stored elsewhere)
- microcytic anemia, pica/ice craving, restless leg, glossitis
anemia of chronic disease
- infection, inflammation (cytokines), malignancy
- increase production of hepcidin levels from liver –> decrease Fe absorption from GI and release from Macs
- normocytic, hypoproliferative
- shortened survival
- low serum Fe and TIBC, high ferritin, high inflammatory markers (ESR and CRP)
- treat: give EPO after treating Fe deficiency
hereditary spherocytosis
- mutations of genes encoding RBC membrane proteins (ankrin and spectrin) –> damaged cytoskeleton membrane and loss shape
- microcytic, hyperchromic** (no loss of Hb)
- most common RBC membrane disease**
sideroblastic anemia
- ring sideroblasts on Prussian blue stain**
- deficient in porphyrin ring**
- cause: genetics, EtOH, B6 deficient, lead poison, meds
- microcytic, normochromic
- high Fe, ferritin, and RDW; low transferrin
B12 and folate deficiency
- macrocytic (megaloblastic anemia)
- neurologic symptoms with B12 deficiency (not folate)**
- folate deficiency is acute, B12 is chronic**
- give methotrexate without folate –> folate deficient quickly
