Iron deficiency sometimes goes unseen
Because iron deficiency and anemia are relatively common, routine blood tests are used for diagnosis. However, recent research indicates that at least a third of those with very low iron reserves are likely to be missed by the typical sequence of blood tests and therefore go undiagnosed for some time.
University of Hawaii graduate student Brian Hill reported these findings in April at the Annual College of Tropical Agriculture and Human Resources Student Research Symposium. He analyzed blood data related to iron status from the National Health and Nutrition Examination Survey. Using blood values from greater than 13,000 people collected between 1976 and 1994, Hill extracted the data for people with iron deficiency based on clinically low levels of a blood component called serum ferritin. Among these men and women who were clearly iron deficient, Hill found that about 35 percent of them would have been missed using the most common clinical blood tests for iron status.
Question: How is iron deficiency and anemia usually determined?
Answer: The most common blood tests for these conditions are hemoglobin and hematocrit.
Typically, if a person's blood values for these tests fall within the normal range for individuals thought to be healthy, iron status is considered to be normal.
Hill's analysis indicates that iron-related health problems of many people might go undiagnosed when more sensitive indicators of iron status are not measured. Adding serum ferritin to the testing procedure almost doubled the number of people diagnosed as iron deficient.
Q: What level of serum ferritin is considered to be ideal?
A: The optimal level for serum ferritin is unknown. The clinical cutoff to indicate an iron deficiency is usually 11 to 15 micrograms per liter (mcg/L). However, physicians specializing in the treatment of restless legs syndrome consider serum ferritin below 50 mcg/L to be too low. In addition, British dermatology researchers treating people for certain types of hair thinning and hair loss consider ferritin below 70 to be an indicator for needed iron therapy.
Q: What does a high ferritin level indicate?
A: High ferritin can indicate that there is a fair amount of iron stored in the body. It also can mean that a person is in an inflammatory state such as rheumatoid arthritis or psoriasis. Recent research indicates that obese individuals are often in an inflammatory state and can have high ferritin levels even when iron deficient. Therefore additional blood tests are needed for those with inflammatory conditions. Extremely high ferritin levels can indicate iron overload disease.
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S. are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa. Dr. Dobbs also works with University Health Services.