Is it safe for a 27-year-old female patient with a history of Shone's syndrome, who had surgery as a child and has been stable since, with a current ferritin level indicating iron deficiency, to undergo intravenous (IV) iron infusions to boost her iron levels?

IV Iron Infusion Safety in Shone's Syndrome with Low Ferritin

Yes, IV iron infusions are safe and appropriate for this patient with Shone's syndrome and a ferritin of 25 ng/mL, as there are no cardiac-specific contraindications to IV iron therapy, and her ferritin level indicates clear iron deficiency requiring treatment. 1, 2

Understanding the Clinical Context

Shone's Syndrome Considerations

• Shone's syndrome is a rare congenital cardiac malformation involving four obstructive lesions (parachute mitral valve, supravalvular ring, subaortic stenosis, and coarctation of aorta), but it does not create specific contraindications to iron therapy once surgically corrected and stable 3
• The patient's surgical correction in childhood and subsequent stability indicate she has compensated cardiac anatomy without active hemodynamic instability 3
• No guidelines or drug labels identify structural congenital heart disease as a contraindication to IV iron therapy 2

Iron Deficiency Assessment

• A ferritin of 25 ng/mL represents clear absolute iron deficiency, as levels below 30 µg/L are diagnostic of depleted iron stores 4, 5
• At this ferritin level, the patient has insufficient iron stores regardless of her hemoglobin status 1, 4
• Iron deficiency with ferritin <30 ng/mL warrants treatment to prevent progression to iron deficiency anemia and associated symptoms 1, 5

Treatment Algorithm

First-Line Approach: Oral Iron Trial

• Oral iron supplementation should be attempted first unless there are specific contraindications such as malabsorption, intolerance, or urgent need for repletion 1, 6
• Ferrous salts (ferrous sulfate, ferrous fumarate, or ferrous gluconate) at 200 mg elemental iron daily for adults represent reasonable initial therapy 1
• Oral iron should be taken once daily (not multiple times) as hepcidin elevation blocks further absorption for up to 48 hours 1
• Taking iron with 80 mg vitamin C on an empty stomach improves absorption; avoid tea and coffee within one hour of dosing 1

Indications for IV Iron

IV iron is indicated when: 1, 6

• The patient cannot tolerate oral iron due to gastrointestinal side effects (constipation 12%, diarrhea 8%, nausea 11%) 1
• Hemoglobin fails to increase by 1 g/dL within 2 weeks of oral supplementation 1
• Ferritin fails to increase within one month of adherent oral iron therapy 1
• Malabsorption conditions exist (inflammatory bowel disease, post-bariatric surgery) 1
• Rapid iron repletion is needed 1

IV Iron Safety Profile

• Serious hypersensitivity reactions occur in approximately 1:200,000 administrations, with mild reactions in approximately 1:200 cases 1
• Most reactions are complement activation-related pseudo-allergy (not true IgE-mediated allergy), occurring in 4.3% of patients 6, 2
• For mild reactions, stopping and restarting the infusion 15 minutes later at a slower rate typically suffices 1
• Patients should be monitored during and for at least 30 minutes after infusion 2

Specific Recommendations for This Patient

Dosing Strategy

• Ferric carboxymaltose (Injectafer) can be administered as 15 mg/kg up to 750 mg per dose, with a second dose at least 7 days later, for a total cumulative dose of 1,500 mg 2
• Single-dose formulations that replace iron deficits with 1-2 infusions are preferred over multiple smaller doses 1
• At a ferritin of 25 ng/mL, this patient requires approximately 1,000-1,500 mg of total iron to restore normal stores 1, 2

Monitoring Parameters

• Hemoglobin should increase by 1 g/dL within 2 weeks of IV iron administration 1
• Ferritin and transferrin saturation should be rechecked 4-6 weeks after completing IV iron therapy 1
• Reticulocytosis occurs 3-5 days after IV iron administration 1

Cardiac-Specific Precautions

• Blood pressure should be monitored during and after infusion, as transient hypertension with facial flushing can occur 2
• This is particularly relevant given her underlying cardiac anatomy, though not a contraindication 2
• The patient should be observed for signs of fluid overload, though IV iron itself does not cause volume expansion 2

Common Pitfalls to Avoid

Misinterpretation of Ferritin

• Do not withhold iron therapy based solely on "normal" hemoglobin if ferritin is low, as iron deficiency exists before anemia develops 7, 5
• Ferritin can be falsely elevated by inflammation; however, at 25 ng/mL, this represents true iron deficiency regardless of inflammatory status 4, 5

Unnecessary Delays

• Do not delay IV iron if oral iron fails or is not tolerated—prolonged iron deficiency impairs quality of life through fatigue and exercise intolerance 1
• IV iron is substantially more expensive than oral formulations but is cost-effective when oral therapy fails 1

Hypophosphatemia Risk

• IV iron can cause hypophosphatemia, particularly with repeated treatments within 3 months 2
• Check phosphate levels before repeat treatment if needed within 3 months of the last dose 2
• Symptoms include fatigue, muscle weakness, bone/joint pain, and risk of fractures 2

Cardiac Monitoring

• While the patient's stable Shone's syndrome does not contraindicate IV iron, ensure she is not in acute heart failure or volume overloaded before administration 2
• Her surgical correction and long-term stability make acute cardiac complications from IV iron highly unlikely 3