Figure (1): Hb molecule (after birth)
Determination of hemoglobin concentration
Introduction
Hemoglobin (Hb) is the protein molecule in red blood cells that carries oxygen
from the lungs to the body's tissues and returns carbon dioxide from the tissues
back to the lungs (iron-containing oxygen-transport metalloprotein in the red
blood cells)
- Hb consists of four protein molecules (globulin chains) that are connected
together (α and β or γ).
Each globulin chain contains an important central
structure called the heme molecule
Embedded within the heme molecule is iron that
is vital in transporting oxygen and carbon dioxide
in our blood and maintains RBCs’ shape
- The main 2 types:
- Hemoglobin F (α2γ2) in the fetus
- Hemoglobin A (α2β2) after birth
- Low hemoglobin level is referred to as anemia or low red blood count.
. Reasons of low Hb level other than low RBC count could be:
- (iron, vitamin B12, folate) deficiency
- Abnormal hemoglobin structure (sickle cell anemia or thalassemia)
- Higher hemoglobin level can be seen in people who
- living at high altitudes
- smoke.
Dehydration produces a falsely high hemoglobin measurement which
disappears when proper fluid balance is restored.
Measuring Hb concentration by Sahli’s method (acid hematin)
Sahli apparatus and main kit
- Two lateral standard tubes
- One central bi-graduated tube (g/dl and %)
- Sahli pipette (20 µg)
- HCL (0.1 N HCL)
Principle
Hb + 0.1N HCL ------------ Acid hematin (Brown)
Globulin
The resulting brown color is matching with the standard class color.
Procedure
1- Add the 0.1N HCL into the bi-graduated tube up to (10%)
2- Disinfect your finger by ethanol 70%
3- Puncture your finger pad by a blood lancet
4. The blood collected into the Sahli pipette until reach 20 µl
(Note that you should collect the blood quickly to prevent clotting, and
without leaving air bubbles inside the pipette)
(Note: If it is difficult to collect blood by finger puncture, you can collect it into
anti-coagulant containing tube)
5- Add the blood into the acid and mix them well by a glass stirrerLet it stand
for 10 minutes
6- Add few distilled water drops (drop by drop) to the mixture with mixing using
stirrer glass. Repeat the addition of the distilled water several times until the
mixture matches the color of the lateral standard tubes
7- When you have the same matched color, read where the mixture has been
reached on (g/dl) scale, this is the estimated Hb concentration.
Normal values: - Male: 13.5- 17.5 g/dl
- Female: 12- 15.5 g/dl