Ferritin

Women: 15 to 150 ug/L · Men: 30 to 400 ug/L

Ranges differ by sex and rise with age, particularly in women after the menopause; laboratories vary widely in the lower limit they print (from 12 to 30); use the range your lab printed.

Ferritin is the protein in which the body stores iron, and the small amount circulating in the blood reflects the size of those stores. It is the single most useful blood test for low iron. It is also an acute phase protein, which means it rises with inflammation whether or not iron stores are full.

Doctors request it when the haemoglobin is low or the red cells are small, in tiredness, in restless legs, in heavy periods, in pregnancy, and when checking that iron replacement is working. It is also used when iron overload is suspected, and it rises in many inflammatory and liver conditions.

• Inflammation or infection from any cause, including a recent cold
• Liver disease, including fatty liver and alcohol
• A high body weight and diabetes
• Iron overload, including inherited haemochromatosis and repeated blood transfusions
• Some cancers and blood conditions
• Iron tablets or infusions, particularly soon after an infusion
• Older age

• Low iron stores, from blood loss (including heavy periods), pregnancy, poor absorption or a diet low in iron
• Regular blood donation
• An underactive thyroid, slightly
• Vitamin C shortage, rarely

• Any recent infection or inflammation raises it and can hide low iron stores; the test is often repeated once well
• It rises steadily with age and after the menopause in the general population
• Heavy drinking in the days before the test raises it
• A value in the low part of the range is common in women who have periods and in regular blood donors

No fasting needed. Best taken when free of infection, and read together with a full blood count and, where the picture is unclear, a CRP.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.