Haemosiderosis- The Iron Deposit Disorder

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IRON OVERLOAD DISEASES

Iron is an essential mineral to the body. But the capacity of body to metabolize iron is limited so, in high doses it may turn toxic and adversely affect the body.

Iron overload diseases such as Thalassemia,

hemochromatosis are usually genetic and are extremely common

in many part of the world. In places, such as South East Asia it

constitutes a major public health problem. In Australia the gene

for hemochromatosis is carried by about 1% of the population.

Iron accumulate in the patients and precipitates in various

parts of the body in the form of  the iron oxyhydroxide encapsulated

by the protein ferritin.

Iron is stored in the tissues in 2 forms which are Ferritin and

Haemosiderin.

The excessive storage of both of these, leads to haemosiderosis. Accordingly the effects of

haemosiderin excess are as under.

i. Localised haemosiderosis :

This develops whenever there is haemorrhage into tissues

with lysis of red cells, haemoglobin is liberated which is taken up

by macrophages where it is degraded and stored as

hemosiderrin.

For example

Black eye

Brown indurations lung

ii. Generalised haemosiderosis

Systemic overload with iron may result in generalized

haemosiderosis.

Generalised or systemic overload of iron may occur due to

following causes.

a. Increased erythropoietic activity

b. Excessive intestinal absorption

c. Excessive intake of dietary iron

Parenchymal deposits:

Liver, Pancreas, Kidney, Heart, Skin

RE cell deposits:

Liver, Spleen, Bone marrow

Transmission electron – micrograph of iron particles

encapsulated in the spherical protein shell of ferritin. Each

particle is about 7nm across. The iron oxide particles appear

because they are electron dense.

An R2 image of an iron loaded human liver, superimposed

on a T2 weighted cross sectional image of the patient: The bright

region indicates areas of higher concentration. The darker areas

correspond to regions of lower iron concentration.

The blood test such as serum ferritin and transferritin

saturation are used for assessing the degree of iron overload in

these patients, these test can be confounded by factors such as

the presence of infection and inflammation. In order to make a

definitive measurement of the degree of iron overload, the widely

accepted method is chemical analysis of iron from liver Needle

Biopsy specimen.

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