Ferritin and increased vs upper reference interval tibc saturation to identify increased iron stores in African Americans.

Background: Increased serum ferritin (SF) in combination with increased total iron binding capacity saturation (TS) in the upper reference internal was evaluated to identify African Americans with increased iron stores.

Methods: Among 16,856 primary care-based African Americans screened at Howard University Field Center of the Hereditary Hemochromatosis and Iron Overload Screening (HEIRS) Study, 142 with SF >500 microg/l women or >700 microg/l men and increased TS (>45% women or >50% men; main study) and 146 with similar ferritin increases and upper reference interval TS (30-45% women or 35-50% men; ancillary study) were offered clinical evaluation to confirm increased SF and identify the cause.

Results: Repeat SF remained increased in 83% of 92 participants with increased TS initially (main study) vs 58% of 64 with upper reference interval TS initially (ancillary study) (P=0.0002). These persistent SF increases were associated with blood transfusions (treatment for sickle cell disease) in 20% of 76 main study and 11% of 37 ancillary study participants (P=0.4). Ninety percent of participants with persistent non-transfusional increased SF in the main study and 85% in the ancillary study had alanine-aminotransferase, aspartate-aminotransferase, C-reactive protein and/or hemoglobin values outside of the reference interval. Increased iron stores were documented by phlebotomy or liver biopsy in 4 of 7 main study and 2 of 2 ancillary study participants with persistent non-transfusional increase in SF.

Conclusion: Increased iron stores occur in African Americans with increased SF in combination with either increased or upper reference interval TS. Limiting clinical evaluation to only those individuals with both increased SF and increased TS will miss individuals with increased iron stores.