What is Normal Level of Hemoglobin

Presentation Notes on Hemoglobin Range Count in Men, Females, during Pregnancy, Functions in Human Body, concentration & Estimation in word/ .ppt/ .pdf Format


Hemoglobin (also spelt, haemoglobin) is present inside the RBCs. It is required for (i) transport of oxygen as well as (ii) transport of carbon dioxide and (ill) it also behaves as a blood buffer.

The iron in the Hb is in ferrous state (Fe++) and even after the combination with oxygen it remains ferrous. The Hb, in health, after catching oxygen, is called oxyHb (HbO2). The combination of oxygen and Hb is loose and reversible so that in the capillaries of the tissues, oxygen can leave the Hb02 and migrate to the tissues (where the O2 tension is low). Reduced hemoglobin can combine with oxygen very speedily and that is why, although the transit time of RBC through a pulmonary capillary may be very short, the uptake of the O2 by Hb is complete. In some diseased states, the iron of Hb is oxidized and converted into ferric (Fe+++) iron. The condition is called methemoglobinemia and oxygen cannot be released easily from such Hb. Normally, the presence of an enzyme, methemoglobin reductase keeps the iron in ferrous state. Hb also normally carries C02' It also acts as a blood buffer.

Normal value for the concentration of Hb is around 15 gm per 100 ml, but the range is somewhat wide; for males it is between 14 to 17 gms/l00 ml and for females between 12 to 16 gms/ 100 ml.

As a bedside method, Hb is commonly estimated by converting it into acid hematin  (Sahli's method) and matching with the standard. In clinical laboratories, cyanmethemoglobin method is very popular; in this method, Hb is converted into cyan­methemoglobin and the color developed is compared against a standard in a suitable colorimeter.

Hemoglobin chemistry and synthesis. A hemoglobin molecule contains two ingredients, viz. haem (also spelt as heme) and globin.The haem is an iron containing compound belonging to the class of compounds called protoporphyrins. Globin belongs to the class of protein called globulins. Hemoglobin thus is a conjugated protein.

The globin molecule contains four polypeptide chains. Two of them have identical amino 'acid number and sequence and are designated as α chains {each containing 141 amino acids} whereas the other two, called ß chains have 146 amino acids each and have identical amino acid sequence. The formula of globin of normal adult hemoglo­bin, that is HbA, is written asα2ß2.            

With each polypeptide chain, one molecule of haem is attached. A  Hb molecule, therefore, has four haem molecules. As the iron of each haem molecule can combine with one molecule (2 atoms) of oxygen, each Hb molecule can, combination with four molecules of oxygen. The molecular weight of Hb is 64500 { = 64.5 KD+}.

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