In the first analysis of iron deficiency in young women and adolescent girls, a research letter recently published in JAMA reveals that 38.6% of females aged 12 to 20 are iron deficient when “iron deficient” was defined as blood ferritin levels which fell below 25 μg/L.

This underdiagnosed deficit of ferritin, an essential mineral needed to produce red blood cells and a marker for stored iron, may be contributing to fatigue, brain fog, and concentration issues and other problems in nearly 1 in 4 adolescent girls and young women in the United States.  Perhaps more concerning, the authors state that routine screening may have missed 83.6% of these cases of iron deficiency.

With nearly 40% of young American females likely having an iron deficiency, the study shows that those rates spiked further for those who had low-BMI, were low-income, and identified as black and Latina.

Not screening for the extreme

The Centers for Disease Control and Prevention (CDC) currently recommends that non-pregnant female adolescents and women be screened every 5 to 10 years for anemia—not iron deficiency.

Iron is key in producing hemoglobin, an essential protein in red blood cells which carries oxygen to tissues throughout the body.  Insufficient iron means that fewer red blood cells are produced, leading to symptoms such as fatigue, headaches, dizziness, and shortness of breath.  The Centers for Disease Control and Prevention (CDC) recommends that females of reproductive age be tested for anemia every 5 to 10 years—but doctors don’t regularly screen for iron deficiency.  Typically, iron-deficiency must be severe and protracted enough to lead to anemia.

Analysis of over 3400

For the study, researchers from the University of Michigan Medical School, Brigham and Women’s Hospital, St. Michaels Hospital in Toronto, Canada, and Brown University’s Alpert Medical School, analyzed data on girls and women aged 12 to 21 collected over the last 20 years from the long-running National Health and Nutrition Examination Survey (NHANES).  The NHANES database, part of the CDC, is considered to be nationally representative.

The researchers identified 3,490 nonpregnant females in the designated age range who had complete data.  Of the 3,490 in the sample, 6.3% of the females had iron-deficiency anemia when the condition was defined as having a hemoglobin level of below 12 mg/dL.  A much larger percentage (38.6%) of the teens girls and young women studied had iron deficiency when the threshold for iron deficiency was having blood ferritin levels of less than 25 μg/L.  This percentage dropped to 17% when a lower, stricter 15 μg/L ferritin cutoff was used for iron deficiency and rose to 77.5% with a 50 μg/L cutoff.  Among those who had not yet begun to menstruate, 27.1% had iron deficiency when using the 25-μg/L ferritin level threshold.  Thus, for these subjects, any iron deficiency could not be attributed to blood loss from menstruation.

The analysis further found that the likelihood of young women and girls to have iron deficiency or iron-deficiency anemia were significantly linked to race and ethnicity, poverty status, access to sufficient or quality food (food insecurity), and body mass index.  Black and Hispanic girls and women were more likely to have iron level issues compared to white girls and women.  Black girls and women were 4 times more likely to have iron-deficiency anemia, compared to white girls and women.

Iron intake by the numbers

Blood loss through menstruation is a major reason why the National Institutes of Health (NIH) Office of Dietary Supplements recommends that adolescent girls aged 14 to 18 consume a daily intake of iron of at least 15 mg, compared to the agency’s recommended intake for boys of the same age which is 11 mg.  For adult women, aged 19 to 50 years, the recommended daily intake jumps to 18 mg of iron, versus 8 mg for men in the same age range.

The results of the study seemed in keeping with the number of referrals pediatric hematologist-oncologist Angela Weyand, MD, receives from pediatricians and primary care physicians who suspect their patients might have an iron deficiency.  It spurred Weyand’s curiosity.

“I hypothesized that I was just seeing the tip of the iceberg and unfortunately that is true,” stated Weyand, the study’s lead author and an associate professor of pediatrics at the University of Michigan Medical School in Ann Arbor.

Symptoms and solutions

Often girls and young women don’t realize that what they’re feeling is a sign of an iron deficiency because the symptoms can be subtle or may be dismissed as being due to other problems like poor sleep.

Iron deficiency symptoms include fatigue, cold extremities, hair loss, brittle nails, cognitive issues like brain fog, decreased athletic performance, shortness of breath, junk food cravings, headaches, and sleep disorders.  Left untreated, iron-deficiency anemia can make the body more prone to infection and can cause complications in pregnancy.

The researchers hope that their work will lead to more ferritin tests being ordered for teen girls and young women.  Currently, the test is run most consistently on toddlers, pregnant women, or those who have a long list of symptoms associated with anemia.

Asking ‘why’

“Iron deficiency is an under-recognized problem with adverse impacts, but its symptoms and even those of anemia are normalized in young females,” stated Weyand in a press release accompanying publication of the research letter.

“Why are we not screening for a condition that is highly prevalent, easily diagnosed, easily treated and associated with serious symptoms and increased risk of death if not addressed?”

Women and girls lose a lot of iron when they have heavy periods, but even when bleeding is in the normal range, iron stores can be depleted, she continued.  In addition to blood loss from menstruation, many young women may not be getting sufficient iron in their diet, especially vegans and vegetarians.

“Studies have shown that dietary iron intake in the US has dropped over the past decade,” Weyand said.  “Meat, fish and poultry are high in heme iron, which is the most easily absorbed, but non-heme iron can be found in many fruits, vegetables and nuts.”

The study concludes that risk factors for iron deficiency, such as low iron intake and extensive menstrual blood loss, “are not clearly defined,” and that “current screening guidance may miss many individuals with iron deficiency.”

To prevent or treat mineral deficiencies, health experts recommend getting needed nutrients primarily by eating a variety of foods.  For iron, that includes lean meat, seafood and poultry; vegetables such as beans, lentils and spinach; tofu; nuts; raisins; and iron-fortified foods such as cereals and breads.  Iron also is available as a dietary supplement and in some multivitamins.

Click here for a link to access the full research letter, “Prevalence of Iron Deficiency and Iron-Deficiency Anemia in US Females Aged 12-21 Years, 2003-2020.”

The contents of this feature are not provided or reviewed by NPWH.