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Old 07-03-2014
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Default why in sideroblastic anemia TIBC is decreased ?

why in sideroblastic anemia TIBC is some times decreased ? while Iron is increased because as my understandings when iron increase in blood transferrin should bind and contain the elevated iron in blood
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TIBC usually correlates inversely with Serum ferritin levels, so in most anemia a where the serum ferritin levels are high, TIBC is low.
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TIBC usually correlates inversely with Serum ferritin levels, so in most anemias, where the serum ferritin levels are high, TIBC is low. TIBC correlates directly with transferrin saturation.

Now in the early stages, not enough iron becomes trapped by mitochondria or picked up by bone macrophages, so the TIBC levels are normal (as the iron spilling out in the serum is binding to transferrin) and the ferritin levels are slowly increasing. But in later stages, the ferritin levels increase significantly (due to increased uptake by macrophages), thus resulting in decreased TIBC levels.

This is how I understood it. I would also go through Pathoma for this topic as it's well explained.
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Quote:
Originally Posted by abdallah48 View Post
why in sideroblastic anemia TIBC is some times decreased ? while Iron is increased because as my understandings when iron increase in blood transferrin should bind and contain the elevated iron in blood
You are getting the idea mixed, so here is the thing.

-FerritIN is the INtracellular Iron binder
It is ELEVATED in states of iron overload, like hemochromatosis, anemia of chronic disease, sideroblastic anemia etc why? well because there is A LOT of iron available to bind. It is DECREASED in states of iron deficiency like ferropenic anemia.

-Transferrin in the other hand is a plasma protein, that transports iron in the plasma, and you measure it indirectly with TIBC (say the name out loud "Total Iron Binding Capacity") so why is it DECREASED in sideroblastic anemia? well, because in this anemia, as well as in hemochromatosis and anemia of chronic disease, you have A LOT of iron, which means transferrin is BINDING A LOT of iron so it's packed, which means that its "capacity of binding" is low hence LOW TIBC. Look at it as if you were eating...when you have a lot of food and you eat, your capacity of eating more is DECREASED because you are full.

TIBC is ELEVATED in states of LOW IRON, like ferropenic anemia. Here you don't have iron around to bind, which means that the "CAPACITY to bind is high" you are empty there is no "food".

That's the easiest way I could explain, I hope that helps
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Quote:
Originally Posted by coliris View Post
You are getting the idea mixed, so here is the thing.

-FerritIN is the INtracellular Iron binder
It is ELEVATED in states of iron overload, like hemochromatosis, anemia of chronic disease, sideroblastic anemia etc why? well because there is A LOT of iron available to bind. It is DECREASED in states of iron deficiency like ferropenic anemia.

-Transferrin in the other hand is a plasma protein, that transports iron in the plasma, and you measure it indirectly with TIBC (say the name out loud "Total Iron Binding Capacity") so why is it DECREASED in sideroblastic anemia? well, because in this anemia, as well as in hemochromatosis and anemia of chronic disease, you have A LOT of iron, which means transferrin is BINDING A LOT of iron so it's packed, which means that its "capacity of binding" is low hence LOW TIBC. Look at it as if you were eating...when you have a lot of food and you eat, your capacity of eating more is DECREASED because you are full.

TIBC is ELEVATED in states of LOW IRON, like ferropenic anemia. Here you don't have iron around to bind, which means that the "CAPACITY to bind is high" you are empty there is no "food".

That's the easiest way I could explain, I hope that helps
so you wanted to say that when iron in blood increases so the transferrin will be less depending on the fact that iron is binding to it (but these is the concept of saturation) not the number of protiens secreted from liver "transfferin"
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Quote:
Originally Posted by abdallah48 View Post
so you wanted to say that when iron in blood increases so the transferrin will be less depending on the fact that iron is binding to it (but these is the concept of saturation) not the number of protiens secreted from liver "transfferin"
I wanted to say what I already said.
You don't really measure the transferrin molecules directly, you measure its ability to BIND iron, to saturate; that's what really matters and you measure that indirectly with TIBC.

Lets make it simpler:
-Iron levels low = transferrin saturation is low --> TIBC is high
-Iron overload = transferrin saturation increases --> TIBC is low

Oh, and the saturation measures the PERCENTAGE (%) of transferrin molecules bound by iron and they usually correlate inversely (I say usually because in anemia of chronic diseases although TIBC is low, % of sat is also low due to iron being saved inside the cell).
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Originally Posted by coliris View Post
I wanted to say what I already said.
You don't really measure the transferrin molecules directly, you measure its ability to BIND iron, to saturate; that's what really matters and you measure that indirectly with TIBC.

Lets make it simpler:
-Iron levels low = transferrin saturation is low --> TIBC is high
-Iron overload = transferrin saturation increases --> TIBC is low

Oh, and the saturation measures the PERCENTAGE (%) of transferrin molecules bound by iron and they usually correlate inversely (I say usually because in anemia of chronic diseases although TIBC is low, % of sat is also low due to iron being saved inside the cell).
Thank you very much I got the idea I just had some confusion
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Originally Posted by abdallah48 View Post
Thank you very much I got the idea I just had some confusion
You are welcome. Many of us have been there
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