Ferritin is the storage form of iron—or, more specifically, it is a protein that itself stores iron. More often I tend to see it low than high for a variety of common reasons–a situation that often leads to hair loss, among other things.
But ferritin can also be abnormally high. The reasons for this have to do with 1) what it is (stored iron), and 2) where it is stored (in the liver cells and in the reticuloendothelial cells of the immune system), as you will see.
Causes of High Ferritin
Because ferritin is stored primarily in the liver, when the liver cells are injured, they release ferritin into the bloodstream. For that reason, the top differential I always consider as a cause is fatty liver. If I see high ferritin consistently, and there is reason to suspect it (particularly obesity or insulin resistance, possibly elevated liver enzymes), I’ll generally run a liver ultrasound to rule this in or out (though the liver has to be >10% fatty for it to show up on an ultrasound). Other forms of liver disease can elevate ferritin also, including hepatitis.
(Along those lines—ferritin is often elevated with Type 2 Diabetes and insulin resistance, because these often also involve fatty liver as part of the symptom picture.)
The number two cause on my differential is elevated iron generally—so I’ll check iron and IBC (iron binding capacity). If iron is high and IBC is low, the next rule-out is hereditary or secondary hemochromatosis.
Ferritin is also an ‘acute phase reactant’; this means that it increases when the body is inflamed. Again, this is because it is stored in the immune cells; these damaged cells will release ferritin into the bloodstream also. Therefore, any condition that can cause inflammation can trigger raised ferritin.
Hyperthyroidism also increases serum ferritin levels; the reasons for this aren’t clear, but since thyroid is responsible for metabolism, this article postulates that it may be due to inefficient metabolism.
If your ferritin is high, first line relevant tests to determine the cause include metabolic syndrome markers such as glucose, lipids, and HbA1c; iron and IBC; and a thyroid panel. It would also include a workup to determine possible sources of inflammation; tests for this would depend on the symptom picture.