My name is John Olynyk,
I'm professor of gastroenterology at
the University of Western Australia and the Department of Gastroenterology
at Fremantle Hospital.
Today I'm going to discuss issues relating to
hereditary hemochromatosis, and what we have learned from population studies.
First, I would like to review normal iron homeostasis.
The amount of iron in the body is tightly regulated.
The average individual has about four grams of iron in their body,
of which 2,400 milligrams is in a utilization pool divided between the muscle,
bone marrow and circulating erythrocytes
(which comprise the greatest pool of use in the body),
and 1,600 milligrams in storage,
of which the liver contains the greatest storage deposits,
followed by the reticuloendothelial macrophages.
I'd like to contrast this with the amount of iron absorbed each day,
which is only 1 to 2 mg on average
and is balanced by losses.
Thus we can see that iron is highly conserved within the body, and tightly regulated.
Having an understanding about what comprises normal body iron stores
I'd now like to move on to discuss the definition of hemochromatosis,
which can be taken as any disorder that is characterized
by tissue injury due to iron overload in many organs.
How do we diagnose iron overload?
Iron overload can be suspected on the basis of
clinical assessment, based on history and examination findings.
Iron overload can also be suspected on the basis of
abnormal serum iron studies, with elevation of the transferrin saturation or ferritin.
Iron overload can be determined by measurement of the hepatic iron concentration (HIC),
and this can be achieved either biochemically (by measuring
iron content in liver tissue following liver biopsy)
or non-invasively (using a range of technologies of
which magnetic resonance imaging - MRI - is the most practical).
Finally, iron overload can be suspected on the basis of quantitative phlebotomy,
where serial phlebotomy has been undertaken, iron stores
have been reduced, and the amount of iron removed
from the body can be calculated retrospectively.