Lab 3 Full Blood Count & Reticulocytes Flashcards
What are reticulocytes?
Juvenile red cells which contain remnants of ribosomal RNA.
How is stages of maturation of reticulocytes identified?
Identified depending on the amount of stained precipitate present.
Adult reticulocyte count is __%
0.5-2.5%
At birth or in cord blood reticulocyte count is ___%
2-5%
How is reticulocyte maturation assessed more accurately?
Quantitative flow cytometry.
What is erythocytosis?
increase in RCC.
- commonly seen in dehydration, smoking, polycythemia
What is leucocytosis?
Increase in WCC
Seen in inflammation, infection, leukaemias.
What is leucopenia?
Decrease in WCC.
Seen in liver + spleen disorders, severe infection, marrow failure.
What is thrombocytosis?
Increase in platelet count.
Seen in infection, bleeding, iron deficiency or due to essential thrombocythaemia.
What is Thrombocytopenia?
Decrease in platelet count
Seen in marrow failure, immune thrombocytopenic purpura.
What to include in table when examining a blood film (4)
- Staining quality
- Red cell and platelet comment
- White cell differential count
- can do absolute differential count (anaemic patients)
- Comment and possible diagnosis.
What does a low Hb and low Platelet count indicate?
First check the sample is not clotted which can give false low results.
Possible diagnosis if not clotted:
1. Anaemia
2. Increased destruction of RBCs/platelets = DIC (widespread clotting activation), autoimmune (SLE), Hypersplenism (spleen overactive destroys RBCs + platelets).
3. Blood loss
Further investigations to perform if Hb is low and platelet count is low in patient
- Reticulocyte count
- Check peripheral blood smear
- Coagulation tests (PT, aPTT, Fibronogen)
- Bone marrow biopsy ( if marrow failure suspected).
- Liver function tests.
What would blast cells in peripheral blood smear indicate?
Leukaemia
What does reticulocyte count tell us?
If retic count is high = haemolysis or blood loss occurring.
Low = bone marrow problem.
What would schistocytes in peripheral blood smear indicate?
Haemolytic anaemia
Disseminated intravascular coagulation.
What are schistocytes?
Fragmented RBCs
WHat are fragmented RBCs called?
Schistocytes
What are macrocytes and when are they seen?
Big RBCs
Seen in liver disease, alcoholism, megaloblastic anaemia.
When are target cells seen?
IDA, liver disease, haemoglobinopathies, post-splenectomy.
What are and when are stomatocytes seen ?
RBC with pale slit in centre.
Seen in liver disease, alcoholism.
When are pencil cells (elliptocytes) seen?
IDA
When are tear drop RBCs seen?
Extramedullary haematopoiesis.
When are sickle cells seen?
Sickle cell anaemia.
When are acanthocytes seen?
Unevenly spiked cell membrane.
Liver disease, renal failure
When are echinocyte seen?
Evenly thorned cell membrane
Seen in liver disease, post-splenectomy, storage artefact.
What may cause high retic count which isnt anaemia?
- bone marrow disorder.
- Pregnancy
- Certain medications.
- Recent blood loss - triggers compensatory increase in RBC production.
What does low RBC, low Hb, and high retic count, and polychromasia indicate?
Haemolytic anaemia
Erythropoiesis increased => more immature RBCs + retics explain polychromasia.
= Autoimmune haemolytic anaemia.
Can be identified using direct antibody test (DAT) aka coombes test.
How is a haemolytic anaemia confirmed?
Perform a Coombes test (direct antibody test) which checks blood for antibodies that targets host RBCs.
used to screen blood before transfusion and for conditions like autoimmune haemolytic anaemia.
What to do if platelet count is very low?
Check feathered edge for platelet clumping.
If it is clumped then the platelet count is inaccurate and test has to be redone.
Fresh sample is required and should be collected in a ThromboEaxct tube instead of EDTA.
What are nucleated RBCs ? (normoblasts)
Very immature form of RBCs seen when there is a severe demand for RBCs to be released by bone marrow.
Seen in acute blood loss, severe anaemia, thalassaemia.
NRBCs contain a large nucleus.
What are howell-joly bodies?
Small round remnants of nuclear DNA inside cell - seen in sickle cell anaemia, haemolytic anaemia, megaloblastic anaemia, following splenectomy.
What is basophillic stipling?
Dark blue dots inside RBC
Due to precipitation of nuclear material - seen in VitB12/folate defiencies, myelofibrosis.
What are heinz bodies?
Large inclusion bodies (granules) in RBCs when stained with crystal violet.
Due to enzyme (G6PD) defiency, unstable Hb variant, thalassaemia, autoimmune haemolytic anaemia.
% reticulocyte count in anaemia patients
Misleading because it can be falsely elevated due to patients RBCs being depleted.
%retic is #retic as percentage of # RBCs.
Why is retic count HIGH in thalassaemia?
*In thalassaemia, there is genetic defect in globin chain synthesis leading to ineffective erythropoiesis
*However bone marrow is hyperactive and tries to compensate for defective RBCs by producing more reticulocytes
WHy is retic count LOW in IDA?
- in IDA there is not enough iron available for Hb synthesis so RBC production is limited.
*Cannot increase retic production due to lack of iron.
Why is retic count LOW in ACD?
- In ACD, inflammatory cytokines (IL-6) increase hepcidin which traps iron in macrophages + enterocytes, blocking its release leading to reduced RBC production.
- Inflammation also suppresses erythropoitin (EPO) reducing BM activity.
Absolute reticulocyte count formula
%reticulocyte/100 x RBCs = ___ x10^9/L.
