Why is a patient with a history of low ferritin levels, taking Adderall (amphetamine and dextroamphetamine), and experiencing heavy menstrual bleeding, scheduled for an ablation procedure, feeling her heartbeat, particularly at night, despite having normal blood pressure readings and staying hydrated?

Why Is This Patient Experiencing Palpitations?

This patient is experiencing palpitations primarily due to severe iron deficiency (ferritin 5 μg/L) causing increased cardiac output demands, compounded by Adderall's sympathomimetic effects on an already stressed cardiovascular system. 1, 2, 3

Primary Mechanism: Severe Iron Deficiency

Iron deficiency forces the heart to work harder to deliver adequate oxygen to tissues, creating a hyperdynamic circulatory state that patients perceive as pounding heartbeats. 3, 4

• With ferritin of 5 μg/L (far below the <15 μg/L threshold for absolute iron deficiency), this patient has virtually no iron stores, requiring increased cardiac output to compensate for reduced oxygen-carrying capacity 1, 3
• Even without anemia, iron deficiency causes fatigue, exercise intolerance, and cardiovascular symptoms including palpitations 3, 5
• The heart must increase stroke volume and heart rate to maintain tissue oxygen delivery when hemoglobin's oxygen-carrying capacity is compromised 4
• This hyperdynamic state is particularly noticeable at rest and when lying down, when patients become more aware of their heartbeat 3

Compounding Factor: Adderall's Cardiovascular Effects

Amphetamine-dextroamphetamine (Adderall) causes sympathomimetic stimulation that increases heart rate, blood pressure, and cardiac contractility—effects that become more pronounced in iron-deficient patients with already elevated cardiac demands. 2, 6

• Adderall stimulates norepinephrine release affecting both α- and β-adrenergic receptors, causing increased heart rate, stroke volume, and enhanced cardiac contractility 2, 6
• The FDA label explicitly warns that "stimulant medications cause a modest increase in average blood pressure (about 2 to 4 mmHg) and average heart rate (about 3 to 6 bpm), and individuals may have larger increases" 2
• Clinical signs of Adderall effects include tachycardia, hyperactivity, and increased awareness of cardiac activity 6
• In an iron-deficient patient whose heart is already working harder, Adderall's sympathomimetic effects amplify the sensation of pounding heartbeats 2, 3

Why Blood Pressure Readings Are Low-Normal

The blood pressure readings of 103/55 and 96/53 mmHg reflect the vasodilatory compensation that occurs in chronic iron deficiency, despite increased cardiac output. 3, 4

• Iron deficiency causes peripheral vasodilation to facilitate oxygen delivery to tissues, which can lower systemic vascular resistance and blood pressure 4
• The pulse in the 70s is actually relatively elevated for a resting state, particularly when lying down—normal resting heart rate should be 60-70 bpm 2
• These findings represent a hyperdynamic circulation: increased cardiac output with decreased peripheral resistance 3, 4
• Adderall's α-adrenergic effects (vasoconstriction) may be partially offset by the vasodilatory state of iron deficiency 2, 6

Clinical Significance and Urgency

This patient requires immediate iron supplementation and consideration of Adderall discontinuation or dose reduction until iron stores are repleted. 1, 3

• Ferritin of 5 μg/L represents severe absolute iron deficiency requiring urgent treatment—this is not a borderline case 1, 3
• The scheduled ablation for heavy menstrual bleeding addresses the source of iron loss but does not resolve the current deficiency 3
• Oral iron supplementation has failed due to side effects, making intravenous iron the appropriate next step 3, 5
• Continuing Adderall while severely iron deficient places unnecessary stress on the cardiovascular system 2, 3

Recommended Immediate Actions

Initiate intravenous iron therapy immediately and reassess Adderall necessity once iron stores begin to normalize. 3, 5

• Administer IV iron (ferric carboxymaltose or ferric derisomaltose) as oral iron has failed due to intolerance 3, 5
• Target ferritin >100 μg/L to restore iron stores and resolve cardiovascular symptoms 1, 3
• Consider temporarily discontinuing or reducing Adderall dose until ferritin reaches at least 30-50 μg/L 2, 3
• Recheck ferritin and transferrin saturation 4-6 weeks after IV iron administration 3
• Proceed with planned ablation to prevent recurrent iron deficiency from ongoing menstrual blood loss 3

Critical Pitfalls to Avoid

• Do not dismiss palpitations as purely anxiety-related or Adderall side effects without addressing the severe iron deficiency 3, 4
• Do not continue oral iron supplementation when the patient reports intolerance—IV iron is indicated 3, 5
• Do not wait until after the ablation to treat iron deficiency—the patient is symptomatic now and requires immediate intervention 3
• Do not assume normal blood pressure excludes cardiovascular stress—the hyperdynamic state of iron deficiency can present with low-normal pressures 3, 4
• Do not overlook that Adderall's cardiovascular effects are amplified in iron-deficient states 2, 3, 6