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MCD Haematology > Interpreting blood counts > Flashcards

Interpreting blood counts Flashcards

1
Q

why is normal hard to define?

A

dependent on age, gender, ethnicity, physiological status, altitude, alcohol etc

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2
Q

how is a reference range derived?

A

from a carefully defined reference population
collect samples from healthy volunteers with certain characteristics
same instruments and techniques used as that that would be used on patients

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3
Q

how are blood counts analysed statistically ?

A

find Gaussian distribution
use mean
2SD to determine 95% range

Hb shows Gaussian distribution

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4
Q

what are the stipulations of using a reference range?

A

not all results outside reference range are abnormal and not all results within the range are normal

e. g. man with GI bleed with normal Hb count is not normal for the situation
e. g. 95% of people being overweight is not considered normal

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5
Q

what is an ideal test for blood counts in the populations?

A

when there is a clear distinction between sick and well people
you don’t want too much overlap

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6
Q

what are the cell counts and their units?

A

WBC – White blood cell – x109/L.

RBC – Red blood cell – x1012/L.

Hb – Haemoglobin – g/L.

PCV and Hct – Packed cell volume and Haematocrit (ratio).

MCV (fl)
MCH (pg)
MCHC (g/L)
platelets (x109/L).

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7
Q

what is the difference between MCH and MCHC?

A

MCH is the absolute amount of Hb in an individual RBC
MCHC is the concentration of Hb in the RBC

MCH tends to parallel MCV in anaemias

MCHC will change with shrinkage or growth of the cell i.e. takes into account volume and shape of the cell

while MCH will not change, raw Hb

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8
Q

how are WBC, RBC, platelets counted?

A
  • visually on slide
  • machines with electronic impulses generated everything a cell flows between a light source and sensor or electrical beam
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9
Q

how is Hb measured?

A

in spectrometer

convert Hb to stable form and measuring light absorption

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10
Q

what method is used to measure Hct and PCV?

A

centrifugation

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11
Q

how is MCV determined?

A

light scattering
interruption of electrical field
PCV/RBC

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12
Q

MCH

A

Hb/RBC

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13
Q

MCHC

A

Hb/PCV or Hb/Hct

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14
Q

how is MCHC measured?

A

light scattering

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15
Q

what cells show lead to a high MCHC?

A

irregularly contracted cells or spheroidal cells

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16
Q

what is polycythaemia?

A

too many RBCs in circulation

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17
Q

what is increased in polycythaemia?

A

RBCs

Hb, RBC and Hct all increase compare to normal subjects

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18
Q

how would you evaluate someone for polycythaemia?

A

clinical history- splenomegaly , abdominal mass or cyanosis

compare to normal range

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19
Q

what is the relative Hb, RBC and Hct in neonates, children, males and females and adults?

A

neonates have higher
lower in children than adults
lower in women than men

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20
Q

how can polycythaemia also present itself?

A

as pseudopolycythaemia

where there is actually a decrease in plasma volume (increase in concentration)

can be caused by dehydration/poor water intake

e.g. burns draw plasma out to surface

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21
Q

what can cause polycythaemia?

A
  • doping (adding blood to your own)
  • medical negligence (in transfusion)
  • erythropoietin (when its too high, illicit or from ectopic or renal tumour)
  • abnormal function of bone marrow
22
Q

how does abnormal function of the bone marrow cause polycythaemia?

what is this called?

A

there is an inappropriate increase erythropoiesis without erythropoietin

“polycythaemia vera”
classed as myeloproliferative neoplasm, where a mutation has occurred

23
Q

what can polycythaemia vera lead to?

A

this is erythropoietin-ndependent polycythaemia:

- hyper viscous blood leading to vascular obstruction

24
Q

how do you treat polycythaemia?

A

removal of blood (venesection)

drugs- for intrinsic bone disease, reduction of RBC production

25
Q

what does finger clubbing and cyanosis indicate?

A

hypoxia

26
Q

four presentations

A

in young athletes (suspicious)

In breathless, cyanosed patient (hypoxia)

abdominal mass

splenomegaly

27
Q

what is anisocytosis?

A

variable sized cells

28
Q

what is poikilocytosis?

A

variable shaped cells

29
Q

what are spherocytes and name a cause?

A

cells with a loss of membrane with an unequal loss of cytoplasm

hereditary spherocytosis

30
Q

what are irregularly contracted cells and name a cause?

A

reduced central pallor in RBC

oxidant damage

31
Q

what are sickle cells?

A

sickle shaped cells caused by haemoglobin S polymerisation

32
Q

what are target cells and name causes?

A

cells with Hb accumulation in the central area of pallor

LIVER DISEASE, hyposplenism, haemoglobinopathies, obstructive jaundice

33
Q

what is elliptocytosis and name caused?

A

elliptic RBCs

hereditary elliptocytosis, iron deficiency (paler cells compared to hereditary)

34
Q

what are fragments? where are they seen?

A

aka schistocytes

red cell fragmentation like seen in SLE

35
Q

what is rouleaux? cause?

A

stack of red blood cells

changes in plasma protein

36
Q

what are agglutinates? cause?

A

irregular clumps of cells

antibodies on the surfaces causing stickiness

37
Q

what are Howell-Jolly Bodies? cause?

A

nuclear remnants seen in cells

INDICATIVE of hyposplenism

38
Q

what are Heinz Bodies?

A

round inclusions found just outside the cell

damage to Haemoglobin e.g. in G6PD deficiency (causing oxidant formation), alpha thalassemia and chronic liver disease

39
Q

what is polychromasia?

A

blue tinge seen in cell cytoplasm indicative of a young cell i.e. reticulocyte

bone marrow damage

40
Q

what percentage of WBCs are neutrophils?

A

75-80%

41
Q

what are “drumsticks” in neutrophils?

A

Barr body:

female specific elements contains the inactivated X chromosome

42
Q

what percentage of WBCs are lymphocytes?

A

20-25%

43
Q

describe lymphocytes

A

round and regular
large dense nucleus
less cytoplasm
smaller than neutrophils

44
Q

how do monocytes compare to neutrophils in size?

what are some key differences?

A

the same size

but have kidney shaped nucleus, grey-blue cytoplasm with no granules

45
Q

what percentage of WBCs are eosinophils?

A

~1%

46
Q

describe eosinophils

A

bi-lobed nucleus

larger orange-red granules

47
Q

describe basophil granules

A

large purple granules that overlay the nucleus

48
Q

what are the anaemia features of iron-deficiency?

A

key:

  • microcytosis
  • hypochromia
  • anisocytosis
  • poikilocytosis
  • Target cells
  • elongate cells (pencil)
  • normal WBCs and platelets
49
Q

what are the anaemia features of megaloblastic anaemia due to b12 deficiency?

(delayed nucleus maturation)

A

key:

  • hypersegmented neutrophils
  • macrocytosis
  • anisocytosis
  • poikilocytosis
  • normal WBC and platelets
50
Q

what are the anaemia features of sickle cell anaemia?

A

key:

  • moderate neutrophilia
  • polychromasia
  • nucleated RBCs
  • anisocytosis
  • poikilocytosis
  • Target cells
  • sickle cells
  • normal platelets

NB sickle cell anaemia causes reticulocytosis

51
Q

what are the 2 causes of spherocytosis?

A

Hereditary spherocytosis

Autoimmune Haemolytic Anaemia

both involved spleen for removal

52
Q

what does polychromasia indicate about the cells?

A

they are immature

MCD Haematology (11 decks)

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