What is the most likely diagnosis and recommended next steps for a 33‑year‑old woman with iron‑deficiency anemia on ferrous sulfate, orthostatic dizziness/vertigo lasting 2‑3 minutes with right‑ward spinning, dull frontal‑to‑nuchal headache, recent viral upper‑respiratory infection, nasal congestion (now yellowish discharge), heavy menstrual bleeding, and a normal neuro exam including a negative Dix‑Hallpike?

Most Likely Diagnosis and Next Steps

The most likely diagnosis is orthostatic hypotension secondary to iron-deficiency anemia, with a concurrent resolving viral upper respiratory tract infection (URTI).

Primary Diagnosis: Orthostatic Hypotension from Anemia

Your patient's presentation—dizziness triggered specifically by standing up, lasting 2–3 minutes with right-ward spinning, and a normal Dix-Hallpike maneuver—does not fit benign paroxysmal positional vertigo (BPPV). 1 BPPV typically produces brief vertigo (seconds to <1 minute) provoked by specific head positions relative to gravity, with a positive Dix-Hallpike test showing characteristic nystagmus. 1

Instead, the orthostatic trigger, moderate duration (2–3 minutes), and recent diagnosis of anemia point to orthostatic hypotension as the primary mechanism. 1 The heavy menstrual bleeding (first 2 days requiring 2–3 pads) is the likely source of ongoing iron loss. 2

Key Distinguishing Features

• Vestibular migraine typically causes attacks lasting hours (not 2–3 minutes), often with photophobia or prior migraine history; your patient lacks these features. 1, 3
• Vestibular neuritis presents with acute, prolonged vertigo (12–36 hours) without hearing loss, not brief episodic spells. 1
• Menière's disease requires fluctuating hearing loss, tinnitus, or aural fullness during attacks lasting 20 minutes to 12 hours; your patient has none of these. 1
• The impacted cerumen and boggy turbinates are incidental findings from the recent URTI, not causes of her vertigo. 1

Immediate Management

1. Optimize Iron Therapy

Start ferrous sulfate 200 mg (65 mg elemental iron) once daily immediately, adding vitamin C 500 mg with each dose to enhance absorption. 2 Once-daily dosing is superior to multiple daily doses because hepcidin remains elevated for ~48 hours after iron intake, blocking further absorption and increasing gastrointestinal side effects. 2

• Expected response: Hemoglobin should rise by approximately 2 g/dL after 3–4 weeks. 2
• Duration: Continue oral iron for 3 months after hemoglobin normalizes to fully replenish iron stores (total treatment ~6–7 months). 2
• Monitoring: Recheck hemoglobin at 4 weeks, then every 3 months during the first year. 2

2. Address Menstrual Blood Loss

Assess menstrual blood loss as the primary underlying cause. 2 Menorrhagia, pregnancy, and breastfeeding account for iron deficiency in 5–10% of menstruating women. 2 Consider:

• Pictorial blood loss assessment chart (80% sensitivity/specificity for menorrhagia). 2
• Gynecology referral if menorrhagia is confirmed, to discuss hormonal contraception, tranexamic acid, or other interventions to reduce menstrual blood loss. 2

3. Rule Out Malabsorption

Screen for celiac disease with tissue transglutaminase IgA antibodies and total IgA. 2 Celiac disease is present in 3–5% of iron-deficiency cases and can cause treatment failure if missed. 2

4. Symptomatic Management

• Orthostatic precautions: Rise slowly from lying/sitting, increase fluid and salt intake, wear compression stockings if tolerated. 1
• Vestibular rehabilitation is not indicated because the Dix-Hallpike is negative and symptoms are orthostatic, not positional. 1

When to Switch to Intravenous Iron

Switch to IV iron if: 2

• Intolerance to at least two different oral iron formulations (ferrous sulfate, fumarate, or gluconate).
• Ferritin fails to improve after 4 weeks of compliant oral therapy.
• Hemoglobin does not rise by ≥1 g/dL after 4 weeks.

Preferred IV formulations: Ferric carboxymaltose (750–1000 mg per 15-minute infusion; two doses ≥7 days apart) or ferric derisomaltose (1000 mg single infusion). 2

Red Flags Requiring Urgent Reassessment

• Persistent vertigo despite iron repletion after 8–10 weeks → Consider MRI brain to exclude posterior circulation stroke, vestibular schwannoma, or demyelinating disease. 1, 4
• New neurologic symptoms (diplopia, dysarthria, dysphagia, limb weakness) → Urgent neurology referral. 1
• Worsening headache with fever, neck stiffness, or altered mental status → Rule out meningitis/encephalitis. 1

Common Pitfalls to Avoid

• Do not prescribe multiple daily doses of oral iron—this increases side effects without improving efficacy. 2
• Do not stop iron therapy when hemoglobin normalizes—continue for 3 months to replenish stores. 2
• Do not overlook vitamin C supplementation when oral iron response is suboptimal. 2
• Do not attribute dizziness to BPPV without a positive Dix-Hallpike—this leads to inappropriate canalith repositioning maneuvers. 1
• Do not delay investigation of menstrual blood loss—failing to address the underlying cause leads to recurrent anemia. 2