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Lab D > LAB 5 Examination of RBCs > Flashcards

LAB 5 Examination of RBCs Flashcards

1
Q

How can you measure haemoglobin concentration in the blood?

A

Spectrophotometry - Darbkin´s methode
Reagent: K3Fe(SCN)6
Orange end product
(sum of Hgb molecules from the RBCs haemolysed by the reagent)

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2
Q

Normal Hb concentration in blood

A

18-20 mmol/l

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3
Q

Does the Hb concentration increase during intravascular haemolysis?

A

NO!

Hb binds to a carrier protein (haptoglobin) after haemolysis, it is not free in the plasma.

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4
Q

Oxygen dissociation curve:
Right shift?
(revision from physiology)

A

Right shift –> reduced affinity to oxygen due to:

  • Increased temperature (hyperthermia)
  • Increased 2-3 DPG level in RBCs
  • Increased pCO2 level in the blood (resp. acidosis)
  • Decreased pH
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5
Q

Oxygen dissociation curve:
Left shift?
(revision from physiology)

A

Left shift –> increased affinity to oxygen due to:

  • Decreased temperature (hypothermia)
  • Decreased 2-3 DPG in RBCs
  • Decreased pCO2 level in the blood (resp. alkalosis)
  • Increased pH
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6
Q

Oxygen saturation (SAT %)

A

% of oxygenated Hb molecules compared to the whole amount of Hb in one unit blood.

Arterial blood: 95-99%
Venous 80-90%

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7
Q

What is methaemoglobin?

A

Hb molecules containing oxidised iron (Fe3+) instead of Fe2+.
Unable to carry oxygen.
Always a constant small amount of methaemoglobin in the blood.
Blood colour: dark brown, chocolate brown
Methaemoglobinaemia.

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8
Q

Causes of increased Hb concentration

A
  • Dehydration

- Absolute polycytaemia

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9
Q

Causes of decreased Hb concentration

A
  • Hyperhydration

- Absolute oligocytaemia = anaemia

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10
Q

Red blood cell count method?

A
  • Burker-chamber method

- Haemocytometer

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11
Q

Normal RBC count

A

4.5-8 x 10^12/l

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12
Q

Parameters frequently used for RBC examination

A
  • Hematocrit (Ht) or PCV (packed cell volume)
  • RBC count
  • Hb concentration
  • MCH (average Hb content of RBCs)
  • MCV (average size of RBCs)
  • MCHC (average conc. of Hb in RBCs)
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13
Q

Terminology:

Increased and decreased MCH

A 
Increased = hyperchromasia
Decreased = hypochromasia
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14
Q

Terminology:

Increased and decreased MCV

A 
Increased = macrocytic RBCs
Decreased = microcytic RBCs
Normal = normocytic RBCs
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15
Q

Normal MCH value

A

12-30 pg

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16
Q

Normal MCV value

A

60-70 fl

17
Q

Causes of microcytosis

A
  • Chronic blood loss (hyperosmosis)
  • Iron, copper, vitamin B6 deficiency
  • Portosystemic shunt
18
Q

Causes of macrocytosis

A

Mostly degenerative anaemias

  • Polycytaemia absoluta vera (erythroleukemia)
  • Vitamin B12 deficiency
  • Erythroleukemias
19
Q

Terminology:

Increased an decreased MCHC

A 
Increased = hyperchromic
Decreased = hypochromic
Normal = normochromic
20
Q

Normal MCHC value

A

30-35%

Lab D (4 decks)

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