Iron Preparations and Management of Iron Deficiency

Iron Physiology - Rusty Regulation

• Absorption: Duodenum (Fe²⁺ via DMT1); basolateral export via Ferroportin.
• Transport: Transferrin carries Fe³⁺ in blood.
• Storage: Ferritin (main, soluble), Hemosiderin (insoluble, excess).
• Regulation: Hepcidin (liver hormone) is the master regulator.
  • ↑ Hepcidin: Blocks ferroportin → ↓ iron absorption & macrophage release.
  • ↓ Hepcidin: Facilitates iron absorption & release (stimulated by iron deficiency, ↑ erythropoiesis).
• Daily Loss: ~1 mg (GI, skin); menstruation adds. 📌 "Rusty pipes lose a bit daily."

⭐ Hepcidin levels are ↑ in inflammation (e.g., anemia of chronic disease), leading to functional iron deficiency.

Iron Deficiency Anemia - Empty Tanks

• Depleted iron stores → impaired Hb synthesis. Commonest nutritional anemia.
• Causes: Chronic blood loss (GIT/Gynae), ↓intake/absorption, ↑demand (pregnancy, growth).
• Features: Fatigue, pallor, glossitis, koilonychia (spoon nails), pica.
• Labs:
  • CBC: ↓Hb, ↓MCV (<80fL), ↓MCH, ↓MCHC.
  • Iron Profile: ↓Serum Fe, ↓Ferritin (<30ng/mL), ↑TIBC, ↓Transferrin Saturation (<16%).
  • Smear: Microcytic hypochromic RBCs, pencil cells.

⭐ Serum ferritin: best indicator of iron stores; ↓ in IDA before Hb changes.

Oral Iron Therapy - Pill Power Up

• Goal: Correct IDA, replenish iron stores.
• Preparations (Ferrous salts preferred): 📌 "Us" (Ferrous) > "Ic" (Ferric).
  • Ferrous Fumarate (33% elemental Fe), Ferrous Sulfate (most common, 20% elemental Fe), Ferrous Gluconate (12% elemental Fe).
• Dose (Elemental Fe):
  • Therapeutic: 100-200 mg/day (adults); 3-6 mg/kg/day (children).
  • Prophylactic: 60 mg/day.
• Absorption: ↑ Vit C; ↓ food, antacids, phytates, tetracyclines. Best on empty stomach.
• Duration: 3-6 months post-Hb normalization to replenish stores.
• Monitoring & Response:

• ADRs: GI upset (nausea, constipation - common), dark stools (harmless).

⭐ Reticulocyte count is the earliest lab indicator of response to oral iron therapy, peaking in 7-10 days post-initiation.

Parenteral Iron Therapy - IV Iron Impact

• Indications: Oral iron failure/intolerance, severe malabsorption (IBD), CKD on ESAs, significant blood loss, need for rapid Hb ↑.
• Dosing: Total iron deficit calculated (e.g., Ganzoni: $Dose (mg) = BW (kg) \times (Target Hb - Actual Hb) \times 2.4 + Stores (mg)$).
• Common IV Preparations:
  • Iron Sucrose: Safer, multiple doses. Max 200 mg/infusion.
  • Ferric Carboxymaltose (FCM): Higher single doses (up to 1000 mg).
  • Iron Dextran: ⚠️ Higher anaphylaxis risk; test dose.
• Impact: Rapid Hb ↑, improved symptoms, repletion of iron stores.
• Monitoring: Hb, Ferritin (4-8 weeks post-infusion).

⭐ FCM allows for Total Dose Infusion (TDI), replenishing iron stores in a single session for eligible patients.

Treatment & Monitoring - Refilling & Watching

• Oral Iron:
  • Dose: 100-200 mg elemental Fe/day (e.g., ferrous sulfate), preferably on empty stomach.
  • Duration: Normalize Hb, then 3-6 months for stores (Target: Ferritin >50 ng/mL).
  • Monitor: Reticulocytes (peak 7-10d), Hb (↑ 1 g/dL/wk or 2g/dL/3wks).
• Parenteral Iron:
  • Indications: Oral intolerance/failure, malabsorption, severe/ongoing loss, CKD.
  • E.g., Iron sucrose, Ferric Carboxymaltose (FCM). Calculate total dose.
  • ⚠️ Anaphylaxis risk (esp. high MW dextran; less with FCM, iron sucrose).
• Response Monitoring:

⭐ Parenteral iron: Ferric Carboxymaltose (FCM) allows for rapid, high-dose administration (up to 1000 mg Fe per session) via Total Dose Infusion (TDI), ideal for severe cases.

High‑Yield Points - ⚡ Biggest Takeaways

• Oral iron (ferrous salts: sulfate, fumarate) preferred; Vitamin C ↑ absorption, antacids/food ↓.
• Parenteral iron (iron sucrose, FCM) for malabsorption, severe intolerance, or rapid need.
• Iron dextran: highest anaphylaxis risk; test dose mandatory.
• Acute iron toxicity: GI distress, shock; antidote is deferoxamine.
• Chronic iron overload (hemochromatosis): liver/heart damage; manage with phlebotomy or deferasirox.
• Target Hb rise: ~1 g/dL/week with effective therapy.