As an oncology/hematology provider, I don’t treat iron deficiency as a supplement problem — I treat it as a clinical warning sign. In adults, iron deficiency is blood loss until proven otherwise. This is the framework I use: • confirm it’s real by trending labs over time • assess ferritin (iron storage) and iron saturation (usable iron) • check for hidden gastrointestinal bleeding • evaluate gynecologic causes — chronic iron deficiency is never “normal” • don’t forget urine testing for occult bl