Have a patient with unexplained fatigue? Check a serum ferritin level!
Remember, ferritin is the major iron storage protein of the body, therefore it is an indirect way to measure how much iron the body has.
The normal ferritin level in adults is between 20-250 ng/ml. This range is very wide and patients can become symptomatic at the lower range even with normal blood counts.
I have seen countless patients who have normal hemoglobin and hematocrit levels with ferritin levels of 5 ng/ml! Their predominant symptom? Fatigue! Many of these patients become exhausted just walking up stairs.
If you have a patient complaining of fatigue and their lab work is otherwise normal, check a ferritin level. Sometimes, this will be very low.
I have found that supplementing with 65mg elemental iron daily for 4-6 weeks and rechecking the levels will provide significant relief in their symptoms. Sometimes you need to dose this twice a day depending on the symptoms and levels.
As always, use your clinical judgement!