Family Medicine Board Review · Case-Based · Difficult Level

Iron Deficiency Anemia — Clinical Vignette MCQs

Board-style cases built from the IDA summary — ferritin's acute-phase pitfall, the lab differential vs. thalassemia/ACD, screening/prevention timing, evaluation triggers, and the exact treatment timeline and thresholds. Tap "Reveal Answer" on each, then read the pearl.

15 Questions ●●●● Difficult Single Best Answer
Q1Ferritin — Acute Phase Trap●●●●● Extreme

A 58-year-old man with active pneumonia and microcytic anemia has a ferritin of 110 ng/mL (within the "normal" reference range). A resident concludes iron deficiency is excluded given this ferritin level. Is this reasoning valid?

Reveal Answer

Correct answer: B

Ferritin is the most accurate biomarker correlated with total iron stores, but it is also an acute phase reactant — meaning it rises during infection or inflammation, which can falsely normalize or elevate the value in a patient who is truly iron deficient. In this febrile, infected patient, a "normal" ferritin should not be trusted at face value; additional testing (e.g., transferrin saturation) should be considered.

Why the others are wrong A — this is exactly the false reassurance the acute-phase-reactant property creates; a normal ferritin doesn't reliably exclude IDA during active inflammation/infection. C — ferritin is specifically affected by concurrent inflammatory/infectious illness. D — ferritin remains the single most accurate biomarker for iron stores in the absence of confounding inflammation; it's still highly useful, just not in isolation during active infection. E — this acute-phase behavior isn't age-restricted.
Exam Pearl Ferritin is an acute phase reactant — always factor in concurrent infection/inflammation before trusting a "normal" or elevated ferritin to exclude iron deficiency.
Q2RDW — Best Discriminator●●●●● Extreme

A 30-year-old woman has microcytic anemia. MCV is low in all three leading differential possibilities being considered (IDA, thalassemia trait, anemia of chronic disease). Which single additional lab value would most efficiently help distinguish IDA from the other two?

Reveal Answer

Correct answer: A

RDW (red cell distribution width) is high in IDA but typically normal in both anemia of chronic disease and thalassemia — despite all three sharing a low/normal MCV. This makes RDW an efficient single discriminator to favor IDA over the other two microcytic causes.

Why the others are wrong B — MCV is low/normal across all three conditions in this comparison, making it non-discriminatory by itself. C — hemoglobin level reflects anemia severity broadly but doesn't specifically distinguish the underlying etiology. D/E — neither WBC nor platelet count is part of the specific differential lab pattern distinguishing these three microcytic anemias.
Exam Pearl When MCV alone doesn't discriminate, RDW is your next stop: high = IDA; normal = thalassemia or anemia of chronic disease. This is one of the most efficient single-test board pearls in anemia workup.
Q3TIBC/Transferrin Direction●●●●● Extreme

A 65-year-old woman with rheumatoid arthritis has microcytic anemia. Iron level is low. Which additional finding would favor iron deficiency anemia over anemia of chronic disease as the explanation?

Reveal Answer

Correct answer: B

In IDA, TIBC and transferrin are HIGH — the body upregulates iron transport capacity in response to true iron depletion. In anemia of chronic disease, TIBC/transferrin are low-to-normal, reflecting inflammatory sequestration of iron (iron is present in stores but not released/transported normally) rather than true depletion. A high TIBC/transferrin in this patient would favor true IDA over anemia of chronic disease.

Why the others are wrong A — low/low-normal TIBC is the anemia-of-chronic-disease pattern, not the IDA pattern; this would argue against IDA. C — TIBC is specifically useful and one of the key discriminators in this differential. D — elevated ferritin actually favors anemia of chronic disease (normal/high) over IDA (low); this reverses the correct relationship. E — normal RDW favors anemia of chronic disease or thalassemia, not IDA, which classically shows an elevated RDW.
Exam Pearl TIBC/transferrin move in OPPOSITE directions in IDA (high) vs. anemia of chronic disease (low-normal) — while ferritin also moves oppositely (low in IDA, normal/high in ACD). Learn these as a paired, inverse relationship.
Q4Reticulocyte Count●●●○ Hard

A 26-year-old woman presents with fatigue and pallor. Her physician orders a reticulocyte count to help narrow the differential between iron deficiency anemia and a hemolytic process. What result pattern would be expected for each?

Reveal Answer

Correct answer: A

The reticulocyte count helps distinguish these processes: it will be LOW in IDA (impaired red cell production due to lack of substrate) and HIGH in hemolytic anemia (compensatory marrow response to increased red cell destruction).

Why the others are wrong B — this reverses the correct relationship. C/E — the two conditions produce opposite reticulocyte responses, not identical patterns. D — reticulocyte count is specifically useful and recommended in this differential.
Exam Pearl Reticulocyte count: low = underproduction (IDA); high = compensatory response to destruction (hemolysis). A simple, high-yield production-vs-destruction framework.
Q5Pregnancy Screening Timing●●●● Very Hard

A 24-year-old woman at 8 weeks' gestation asks about IDA screening during her pregnancy. What is the most appropriate screening schedule?

Reveal Answer

Correct answer: B

IDA screening in pregnancy occurs at two defined points: the first trimester, and again between 24–29 weeks' gestation — capturing both baseline status and the period of peak physiologic demand later in pregnancy.

Why the others are wrong A — a single first-trimester screen misses the later 24–29 week recommended re-screening. C — screening starts in the first trimester, not solely the third. D — routine screening is specifically recommended at defined intervals, not omitted. E — monthly screening throughout pregnancy is more frequent than the recommended two-point schedule.
Exam Pearl Pregnancy IDA screening: first trimester + 24–29 weeks — two specific, defined checkpoints to memorize precisely.
Q6Universal Pregnancy Supplementation●●●● Very Hard

A 29-year-old woman, newly pregnant with a normal hemoglobin and ferritin, asks whether she needs iron supplementation despite having no evidence of anemia. What is the most appropriate recommendation?

Reveal Answer

Correct answer: B

Low-dose (27 mg) iron supplementation is recommended for ALL pregnant women, starting in the first trimester — this is a universal prevention strategy, independent of whether the patient currently has normal labs or established anemia.

Why the others are wrong A — this ignores the universal preventive recommendation; normal current labs don't exempt her from routine supplementation given pregnancy's increased iron demands. C — high-dose iron isn't the described universal preventive dose; 27 mg is specifically the recommended prophylactic dose, and waiting for anemia to develop defeats the preventive purpose. D — iron supplementation is recommended, not contraindicated, in pregnancy. E — supplementation should start in the first trimester, not be delayed to the third.
Exam Pearl 27 mg low-dose iron for ALL pregnant women starting in the first trimester — a universal prevention measure, distinct from higher treatment doses used once IDA is diagnosed.
Q7Pediatric Screening & Supplementation●●●●● Extreme

A mother exclusively breastfeeding her infant asks when routine IDA screening should occur, and whether her baby needs iron supplementation before starting solid foods. What is the most appropriate guidance?

Reveal Answer

Correct answer: B

Routine IDA screening occurs at age 12 months. For exclusively breastfed infants, iron supplementation should begin at age 4 months and continue until iron-fortified foods are started, since breast milk alone becomes insufficient in iron content as the infant grows.

Why the others are wrong A — screening at birth isn't the described timepoint (12 months is), and breastfed infants specifically do need supplementation starting at 4 months. C — 5 years is far later than the recommended 12-month screening point. D — supplementation for exclusively breastfed infants should begin earlier, at 4 months, not wait until 12 months. E — both routine screening (12 months) and targeted supplementation (breastfed infants from 4 months) are specifically recommended.
Exam Pearl Pediatric IDA prevention: screen at 12 months; supplement exclusively breastfed infants starting at 4 months until iron-fortified foods begin. Also remember: delayed cord clamping by 2 minutes reduces IDA risk in infancy at age 6 months.
Q8Delayed Cord Clamping●●●○ Hard

An obstetric team is discussing delivery practices to reduce infant iron deficiency risk. Which specific intervention, and timing, is supported for this purpose?

Reveal Answer

Correct answer: B

Delayed cord clamping by 2 minutes decreases the risk of IDA in infancy specifically at age 6 months, by allowing additional placental blood transfer to the infant at birth.

Why the others are wrong A — immediate clamping is the opposite of the protective practice. C — the specific interval described is 2 minutes, not 30 minutes. D — cord clamping timing does have a described effect on infant iron status. E — the benefit described is specifically for the infant's iron status.
Exam Pearl Delayed cord clamping by 2 minutes → lower infant IDA risk at 6 months. A simple, low-cost, evidence-based delivery practice worth remembering as an isolated fact.
Q9Sign Recognition●●●○ Hard

A 34-year-old woman reports craving and chewing on ice cubes daily for the past several months. On exam, her nails show a concave, spoon-like shape. What are these findings most classically associated with?

Reveal Answer

Correct answer: B

Pica (craving/chewing non-food substances like ice — "pagophagia" specifically for ice) and koilonychia (spoon-shaped nails) are both classic, highly specific signs of iron deficiency anemia.

Why the others are wrong A — B12 deficiency has its own distinct findings (glossitis, neurologic symptoms) but isn't specifically associated with pica or koilonychia in this framework. C — hyperthyroidism has its own characteristic signs unrelated to these findings. D — these are specific, clinically significant findings, not incidental normal variants. E — CKD isn't the classic association for this specific symptom-sign pairing.
Exam Pearl Pica + koilonychia = iron deficiency anemia until proven otherwise — two of the most specific, pattern-recognition-friendly findings in all of hematology.
Q10Targeted Ferritin — RLS●●●●● Extreme

A 52-year-old woman with iron-deficiency-associated restless leg syndrome is being treated with oral iron. Her ferritin has risen to 55 ng/mL, and her physician considers this adequate given it's within the general "normal" range. Is this treatment target appropriate?

Reveal Answer

Correct answer: B

Restless leg syndrome has a specific, higher target ferritin of >75 — distinct from and higher than what might be considered adequate for general anemia resolution. Her ferritin of 55 remains below this condition-specific goal, and continued iron therapy toward that target is appropriate.

Why the others are wrong A/C — RLS has a specifically elevated target (>75) distinct from a generic "normal range" ferritin; treating to a lower general threshold under-treats the RLS-specific goal. D — the specific target is >75, not >200. E — treatment target should be guided by the condition-specific ferritin goal, not simply stopped once hemoglobin/anemia has resolved, particularly when RLS symptoms are the treatment driver.
Exam Pearl Condition-specific ferritin targets exceed generic reference ranges: RLS >75; IDA-related alopecia >70. Don't stop iron therapy at a "normal" ferritin if the specific indication calls for a higher target.
Q11Evaluation — Endoscopy Trigger●●●●● Extreme

Two patients are diagnosed with IDA: a 62-year-old asymptomatic man, and a 24-year-old woman with well-documented heavy menstrual bleeding. How should their initial evaluation differ?

Reveal Answer

Correct answer: B

The AGA recommends bidirectional endoscopy (EGD + colonoscopy) specifically for asymptomatic men and postmenopausal women with IDA, given the higher relative concern for an occult GI source (including malignancy) without an obvious alternative explanation. In a younger patient with a plausible cause (heavy menstrual bleeding), it is reasonable to treat the bleeding, provide iron supplementation, and follow up to document clinical response — without immediately pursuing endoscopy.

Why the others are wrong A — the young woman with a plausible explanation doesn't require immediate endoscopy per this approach. C — the man specifically requires endoscopic evaluation given the AGA recommendation for his demographic; treatment alone isn't sufficient. D — this reverses the correct approach; the man (not the young woman) is the one specifically flagged for endoscopy. E — echocardiography isn't part of the described IDA evaluation pathway.
Exam Pearl Bidirectional endoscopy is specifically triggered in asymptomatic men and postmenopausal women with IDA — populations lacking an obvious physiologic explanation for iron loss. A young woman with a clear, plausible bleeding source can be treated and monitored first.
Q12Oral Iron Administration●●●● Very Hard

A 40-year-old woman newly started on oral ferrous sulfate for IDA asks for advice on how to take it most effectively and what to avoid. What is the most appropriate counseling?

Reveal Answer

Correct answer: B

Every-other-day dosing of oral iron can be more effective than daily dosing, and patients should avoid tea, coffee, and calcium-containing foods for 1 hour around taking iron, since these inhibit absorption.

Why the others are wrong A — coffee inhibits iron absorption and should be avoided around dosing, not paired with it. C — milk is calcium-containing and would inhibit absorption, not enhance it. D — every-other-day dosing can actually be more effective than daily dosing, contrary to this statement. E — timing relative to these specific inhibitors (tea, coffee, calcium) meaningfully affects absorption.
Exam Pearl Oral iron counseling: every-other-day dosing may outperform daily dosing; avoid tea/coffee/calcium-containing foods for 1 hour around dosing due to absorption inhibition.
Q13Treatment Response Timeline●●●●● Extreme

A 45-year-old woman starts oral iron for IDA with a baseline hemoglobin of 9.2 g/dL. She returns for follow-up labs 3 weeks later, reporting good adherence. Her hemoglobin is now 10.8 g/dL. Is this an adequate response, and what would be the next step?

Reveal Answer

Correct answer: B

Hemoglobin should be checked 2–4 weeks after starting oral iron (3 weeks fits this window), and a rise of 1–2 g/dL (10–20 g/L) is considered an adequate response. Her rise from 9.2 to 10.8 (a 1.6 g/dL increase) falls within this expected range, supporting continuation of oral therapy.

Why the others are wrong A — this response is adequate, not inadequate; switching to IV iron is reserved for a response <1 g/dL despite adherence. C — 3 weeks falls squarely within the recommended 2–4 week recheck window. D — the adequate response threshold is 1–2 g/dL, not 5 g/dL; this overstates the expected rise. E — reticulocytosis begins much earlier (3–4 days after starting iron), so by 3 weeks it would already be well underway/reflected in the improving hemoglobin.
Exam Pearl Memorize the full sequence: reticulocytosis at 3–4 days → Hgb recheck at 2–4 weeks → adequate response = +1–2 g/dL (10–20 g/L). Practice recognizing both adequate and inadequate response scenarios with real numbers.
Q14IV Iron Switch Criteria●●●●● Extreme

A 50-year-old man with confirmed excellent adherence to oral iron therapy for IDA has a hemoglobin of 9.5 g/dL at baseline and 9.9 g/dL after 4 weeks of treatment — a rise of only 0.4 g/dL. He currently has no active infection. What is the most appropriate next step?

Reveal Answer

Correct answer: B

Patients adherent to oral therapy with a hemoglobin response <1 g/dL after 2–4 weeks should be transitioned to IV iron. His rise of only 0.4 g/dL despite confirmed adherence meets this criterion, and he has no active infection (which would otherwise argue against IV iron use).

Why the others are wrong A — continuing the same inadequate oral regimen without escalation ignores the specific criterion for switching to IV therapy. C — his iron deficiency remains untreated; discontinuing all therapy leaves the underlying problem unaddressed. D — simply doubling the oral dose isn't the described next step for documented inadequate response with confirmed adherence; IV transition is. E — further delay without changing management wastes time in a patient who has already demonstrated an inadequate response with confirmed adherence.
Exam Pearl IV iron transition criterion: adherent patient + Hgb rise <1 g/dL after 2–4 weeks of oral therapy. Also remember IV iron should be avoided during active infection, and can cause hypophosphatemia (screen if fatigue/bone pain/muscle weakness develops after infusion).
Q15IV Iron Complication●●●●● Extreme

A 38-year-old woman received IV iron for refractory IDA two weeks ago. She now reports new fatigue, diffuse bone pain, and muscular weakness. What laboratory test should specifically be checked given this presentation?

Reveal Answer

Correct answer: B

New fatigue, bone pain, or muscular weakness following IV iron administration should prompt checking a phosphorus level, as IV iron can cause hypophosphatemia — a specifically recognized complication with this symptom triad.

Why the others are wrong A — calcium isn't the specifically implicated electrolyte in this IV iron complication; phosphorus is. C — potassium isn't the specifically flagged abnormality here. D — uric acid isn't relevant to this IV iron-associated complication. E — this symptom triad after IV iron specifically warrants phosphorus testing, not dismissal.
Exam Pearl IV iron → hypophosphatemia — check phosphorus in any patient developing fatigue, bone pain, or muscular weakness after IV iron administration. This is a distinct, specifically testable adverse effect.
Iron Deficiency Anemia Board Review · Case-Based MCQ Set · 15/15 Questions