Ferritin

Only if you're deficient. TRT raises hematocrit via erythropoietin, not iron — extra iron without deficiency just adds oxidative stress. Donating blood for high HCT actually helps men with iron overload too.

Ferritin is the protein that stores iron inside your cells, and the blood test is the best single gauge of your total body iron reserves. A low ferritin means your iron stores are running down, while a high ferritin usually means they're full or overloaded. Because it reflects stores rather than a moment-to-moment level, it's more stable and informative than a single serum iron reading.

A common adult male reference range is roughly 30–400 ng/mL, with many clinicians considering something like 80–150 ng/mL optimal. Values below about 30 point toward iron deficiency, while persistently high values can signal iron overload or inflammation. Interpret it alongside the rest of the iron panel rather than on its own.

Ferritin is an acute-phase reactant, meaning inflammation, infection, fatty liver, or heavy alcohol use can raise it independently of your actual iron stores. So a high ferritin doesn't always mean too much iron — it can reflect an inflammatory state. This is why clinicians read ferritin together with transferrin saturation: a genuinely overloaded man usually has both a high ferritin and a high TSAT, whereas inflammation tends to raise ferritin while TSAT stays normal or low.

Iron stores deplete before the blood count suffers, so ferritin can fall well before hemoglobin drops — this is early or latent iron deficiency, before it becomes frank anemia. It's especially common in men on TRT who do frequent therapeutic phlebotomy or blood donation to manage a high hematocrit: each draw removes iron, steadily draining ferritin even while hemoglobin still looks fine. Catching a falling ferritin early lets you and your physician adjust before you feel run-down.