Screening for Iron Deficiency May Prevent Progression

VANCOUVER, British Columbia — Screening for iron deficiency in patients with risk factors may be a prudent way to prevent progression to other conditions, according to a presentation at the Family Medicine Forum 2024.

Discussing iron deficiency and anemia, Anmol Lamba, MD, the co-director of the family practice residency’s enhanced skills program at The University of British Columbia in Vancouver, British Columbia, Canada, explained that by screening certain patients for iron deficiency, even in the absence of anemia, clinicians have an opportunity to treat the condition.

“Can you show me the paper that states there was a mortality benefit [from identifying iron deficiency and treating it], which is the main thing [one] cares about?” he asked rhetorically. “That study doesn’t exist, but I feel like there are other studies which I can bring together to say that I would like to treat this patient, so they don’t go on to develop a microcytic anemia that might cause problems.”

Nonanemic Iron Deficiency

Nonanemic iron deficiency (NAID) is relatively common, noted Lamba, citing an Ontario retrospective study of 784,132 nonpregnant women of reproductive age. The study reviewed data from outpatient laboratories on complete blood counts (CBC), with or without ferritin or iron indices.

About 13% of screened patients had iron-deficiency anemia, whereas 38.3% had NAID, said Lamba, adding that most patients in the study were screened for iron deficiency despite the absence of Canadian recommendations to perform such screening.

The investigators also found that more than 55.6% of patients with iron-deficiency anemia had normal mean corpuscular volumes, meaning that most did not have microcytosis.

“What most of the literature seems to suggest is that when you follow people (often persons of reproductive age who menstruate) temporally, iron deficiency comes first, iron-deficiency anemia comes second, and microcytosis comes third,” he said.

NAID is increasingly being recognized, he noted. “NAID is known to cause symptoms and has some associations in the research with hospitalizations. Additionally, there are concerns about progression to a severe microcytic anemia,” as well as adverse impacts on quality-of-life.

Some studies show the benefits of identifying and treating iron deficiency early in specific populations, he said, citing a recent systematic review of patients with heart failure and iron deficiency. The review described NAID as a strategic target that must be addressed to improve clinical outcomes such as reduced functional capacity, recurrent hospitalizations, and cardiovascular death.

Treatment for NAID involves oral or parenteral iron intake; intravenously delivered iron is a choice if orally administered iron is not tolerated or cannot be absorbed, said Lamba.

Patients can experience gastrointestinal adverse events such as epigastric distress, abdominal cramps, nausea, vomiting, and constipation with the intake of high doses of iron, which is something family physicians should keep in mind, he advised. These events are rare, however.

Much of the published literature on the topic consists of observational studies. Lamba cautioned that correlation is not causation. “Does iron deficiency alone cause bad outcomes or is someone with iron deficiency at risk of various other comorbidities and risk factors that cause bad outcomes?” he wondered.

Adult Guidelines Lacking

The Canadian Task Force for Preventive Care does not issue screening guidelines for iron deficiency or anemia, and the United States Preventive Services Task Force has also found insufficient evidence to recommend screening in specific populations, such as pregnant patients.

In Canada, the Canadian Pediatric Society (CPS) sets iron requirements for children. The CPS states that healthy term infants with no risk factors who are exclusively breastfed for 6 months are unlikely to have iron deficiency. The CPS calls for ordering a CBC and assessing serum ferritin when screening high-risk children, including those with low socioeconomic status or those with suboptimal intake of iron-rich foods. 

The CPS practice recommendation allows family physicians to exercise their clinical judgment in managing children who may be iron deficient, Lamba said, adding that clinicians’ decision to screen is largely driven by risk factors.

“Perhaps there is a kid who is a picky eater and has come to my practice,” he said. “I might consider that a risk factor. Recognizing the risk factor, I might feel like I have enough agency from the CPS to order a CBC and a [serum] ferritin at a minimum.”

Lamba reported no relevant financial relationships.