Flashcards in Haematology Deck (215)
Difference between whole blood, blood plasma and serum ?
Whole blood = everything i.e. includes RBCs, WBCs and platelets
Blood plasma = Fluid portion of the blood i.e. excludes RBCs, WBCs and platelets.
Serum = what's left after the clotting factors are removed from blood plasma.
What does serum contain ?
-Electrolytes e.g. sodium, potassium
-Proteins such as immunoglobulins and hormones
Blood cells develop in the bone marrow. Bone marrow is mostly found in the pelvis, vertebrae, ribs and sternum. Pluripotent haematopoietic stem cells are undifferentiated cells that have the potential to transform into a variety of blood cells. They initially become what ?
-Myeloid stem cells (develop in the bone marrow)
-Lymphoid stem cells (develop in the lymphatic tissue)
-Dendritic cells (via various intermediate stages)
How are RBCs formed + what is their lifespan ?
They develop from reticulocytes (immature RBCs) that come from the myeloid stem cells. Their lifespan is approximately 120 days.
How are platelets formed + what is their lifespan
They are made by megakaryocytes that come from myeloid stem cells. Thier lifespan is 10 days.
Myeloid stem cells become myeloblasts that produce ?
-Monocytes then macrophages (in the tissues)
Lymphocytes come from the lymphoid stem cells and become B cells or T cells. Where do B cells mature and what do they differentiate into + where do T cells mature and what do they differentiate into ?
B lymphocytes mature in the bone marrow and differentiate into:
T lymphocytes in the thymus gland and differentiate into:
-CD4 cells (T helper cells)
-CD8 cells (cytotoxic T cells)
-Natural killer cells
What do each of these blood film findings mean and where can they be seen :
-Anisocytosis: Refers to a variation in the size of RBCs. These can be seen in myelodysplasic syndrome as well as some forms of anaemia.
-Target cells: have a central pigmented area, surrounded by a pale area, surrounded by a ring of thicker cytoplasm on the outside. This makes it look like a bull's eye target. These can be seen in iron deficiency anaemia and post-splenectomy.
-Heinz bodies: Are individual blobs seen inside RBCs cause by denatured globin. They can be seen in G6PD and alpha-thalassaemia
-Reticulocytes: Are immature RBCs that are slightly larger than standard erythrocytes and still have RNA material in them. The RNA has a reticular ("mesh like") appearance inside the cell. It is normal for about 1% of RBCs to be reticulocytes. This % goes up where there is rapid turnover of RBCs such as haemolytic anaemia. They demonstrate that the bone marrow is active in replacing lost cells.
-Schistocytes: Are fragments of RBCs. They indicate the RBCs are being physically damaged by trauma and during their journey through the blood vessels. They may indicate networks of clots in small blood vessels caused by HUS, DIC or thrombotic thrombocytopenic purpura. They can also be present in replacement metallic heart valves and haemolytic anemia.
-Sideroblasts: Are immature RBCs that contain blobs of iron. They occur when the bone marrow is unable to incorporate iron into the haemoglobin molecules. They can indicate myelodysplasic sydndrome.
-Smudge cells: Are ruptured WBCs that occur during the process of preparing the blood film due to aged or fragile WBCs. They can indicate chronic lymphocytic leukaemia.
-Spherocytes: Are spherical RBCs without the normal bi-concave disk shape. They can indicate autoimmune haemolytic anaemia or hereditary spherocytosis
What is anaemia ?
A low level of haemoglobin in the blood.
Note: This is the result of an underlying disease and is not a disease itself.
You can diagnose a pt with anaemia when they have a low haemoglobin. When you find an anaemic pt you should also check what ?
Mean cell volume (MCV)
Anaemia is subdivided into three main categories, what are they ?
Microcytic anaemia (low MCV)
Normocytic anaemia (normal MCV)
Macrocytic anaemia (high MCV)
Causes of microcytic anaemia ?
T - Thalassaemia
A - Anaemia of chronic disease
I - Iron defiency anaemia
L - Lead poisoning
S - Sideroblastic anaemia
Causes of normocytic anaemia ?
3 As and 2 Hs
A - Acute blood loss
A - Anaemia of chronic disease
A - Aplastic anaemia
H - Haemolytic anaemia
H - Hypothyroidism
Macrocytic anaemia can but into two different categories, what are they ?
Megaloblastic or normoblastic
What is megaloblastic anaemia the result of ?
Impaired DNA synthesis preventing the cell from dividing normally. Rather than dividing it keeps growing into a large, abnormal cell.
Note: This is caused by a vitamin deficiency.
What is megaloblastic anaemia caused by ?
Normoblastic macrocytic anaemia is caused by ?
-Reticulocytosis (usually from haemolytic anaemia or blood loss)
-Drugs such as azathioprine
Name 6 generic symptoms of anaemia ?
-Worsening of other conditions such as angina, heart failure or peripheral vascular disease
Name 2 symptoms specific to iron deficiency anaemia ?
- Pica - describes dietary cravings for abnormal things such as dirt
- Hair loss
Name 4 generic signs of anaemia ?
-Raised resp rate
Name some signs of specific causes of anaemia ?
-Koilonychia - can indicate iron deficiency
-Angular chelitis - can indicate iron deficiency
-Atrophic glossitis - is a smooth tongue due to atrophy of the papillae and can indicate iron deficiency
-Brittle hair and nails can indicate iron deficiency
-Jaundice occurs in haemolytic anaemia
-Bone deformities occur in thalassaemia
-Oedema, HTN and excoriations on the skin can indciate CKD.
Investigations for anaemia (both initial and further) ?
-Oesophago-gastroduodenoscopy (OGD) and colonoscopy to investigate for a GI cause of unexplained iron deficiency anaemia. This is done on an urgent cancer referral for suspected GI cancer
-Bone marrow biopsy may be required if the cause is unclear.
Scenarios when iron stores can be used up and the pt can become iron deficient ?
-Insufficient dietary iron
-Iron requirements increase e.g. pregnancy
-Iron is being lost e.g. bleeding from a colon cancer
-Inadequate iron absorption
Where is iron mainly absorbed ?
In the duodenum and jejunum.
What does iron require to keep it in a soluble form + what form is this + what is the insoluble form/ when does this occur?
Acid from the stomach.
Fe2+ (ferrous) form.
When the acid level drops it changes to the insoluble Fe3+ (ferric) form.
Which medications can interfere with iron absorption ?
Medications that reduce stomach acid e.g. PPIs as they reduce the amount of stomach acid being produced
What conditions can cause inadequate iron absorption ?
Conditions that result in inflammation of the duodenum or jejunum e.g. coeliac disease or Crohn's disease.
Causes of iron deficiency anaemia?
-Blood loss is the most common cause in adults
-Dietary insufficiency is the most common cause in growing children
-Poor iron absorption
-Increased requirements during pregnancy
The most common cause of iron deficiency anaemia in adults is blood loss. In menstruating women, particularly women with menorrhagia there is a clear source of blood loss. In women that are not menstruating or men the most common source of blood loss is the GI tract. It is important to be suspicious of a GI tract cancer. Oesophagitis and gastritis are the most common causes of GI tract bleeding. IBD should also be considered.