Three different definitions of nonanemic iron deficiency (ID), a common disorder causing substantial morbidity in women, were significantly associated with different population prevalence estimates, a data analysis of the cross-sectional Hemochromatosis and Iron Overload Screening Study (HEIRS) study found.
These differences held, regardless of self-reported age, pregnancy, or race and ethnicity, according to HEIRS researchers led by James C. Barton, MD, professor of hematology at the University of Alabama at Birmingham.
“Using higher serum ferritin thresholds to define ID could lead to diagnosis and treatment of more women with ID and greater reduction of related morbidity,” the investigators wrote. The study was published in JAMA Network Open.
The authors noted that ID affects about 2 billion people worldwide, mainly women and children, increasing risks of fatigue, impaired muscular performance, cold intolerance, mucosal and epithelial abnormalities, pica, disturbances of menstruation, and adverse pregnancy outcomes.
Manifestations of ID, including anemia, are less prevalent or less severe in adults with higher serum ferritin (SF), and the three definitions correspond, in sequence, to ID of increasing prevalence and decreasing severity, they explained.
The Study
HEIRS conducted multiethnic, primary care–based screening for iron disorders during 2001-2003 at four field centers in the United States and one in Canada at primary care venues.
In data for the current study analyzed from June to December, 2023, the three ID definitions were: combined transferrin saturation less than 10% and SF less than 15 ng/mL (HEIRS); SF less than 15 ng/mL (World Health Organization [WHO]); and SF less than 25 ng/mL, the threshold for ID-deficient erythropoiesis [IDE).
Among the cohort’s 62,685 women (mean age, 49.58 years, 27,072 White, 17,272 Black), the estimated prevalence of ID emerged as follows across the different definitions:
- 1957 (3.12%) according to HEIRS
- 4659 (7.43%) according to WHO
- 9611 (15.33%) according to IDE
Those figures translated to an increased relative ID prevalence of 2.4-fold (95% CI, 2.3-2.5; P < .001) according to the WHO standard and 4.9-fold (95% CI, 4.7-5.2; P < .001) according IDEs.
In addition, prevalence was higher in younger women, and within each racial and ethnic subgroup of participants aged 25-54 years, prevalence rose significantly from the HEIRS definition to the WHO and IDE definitions.
Notably, ID was significantly higher among Black and Hispanic participants than Asian and White participants.
An accompanying editorial pointed to gender-based health equity issues raised by the HEIRS analysis and argued that a similar passive acceptance of laboratory definitions of a debilitating but correctable condition in White males would be “frankly unimaginable.”
“Iron deficiency is the leading cause of years lived with disability among women of reproductive age,” wrote hematologist Michelle Sholzberg, MDCM, MSc, and Grace H. Tang, MSc, of St. Michael’s Hospital in Toronto, Canada. “It is a factor clearly associated with maternal death and morbidity (including diminished IQ), and it is correctable, and, thus, unnecessary, in high-income, middle-income, and low-income geographic settings.”
The authors listed no specific funding for this analysis of HEIRS data. Dr. Barton reported contracts from the National Institutes of Health, National Human Genome Research Institute, outside of the submitted work. A coauthor reported grants from the National Heart, Lung, and Blood Institute and the National Human Genome Research Institute outside of the submitted work. Dr. Sholzberg reported unrestricted research funding to her institution from Octapharma and Pfizer and speakers’ honoraria from Takeda, Sobi, and Medison outside of the submitted work.