What is the recommended dose of ferrous fumarate (Iron Supplement) for a 95-year-old patient with Chronic Kidney Disease (CKD) and anemia (Hemoglobin level of 91 g/L)?

Ferrous Fumarate Dosing for 95-Year-Old with CKD and Anemia

For a 95-year-old patient with CKD and hemoglobin of 91 g/L (9.1 g/dL), prescribe ferrous fumarate 200 mg of elemental iron per day, divided into 1-2 doses, which translates to approximately 200 mg (one 325 mg tablet) of ferrous fumarate once daily, or 100 mg (one-half tablet) twice daily. 1

Rationale for Dosing

• Standard adult dosing for oral iron in CKD patients is 200 mg of elemental iron per day in 2-3 divided doses 2, 1
• Ferrous fumarate contains 108 mg of elemental iron per 325 mg tablet 2, making it the most iron-rich oral preparation available
• To achieve 200 mg elemental iron daily, this patient would need approximately two 325 mg tablets of ferrous fumarate per day (providing 216 mg elemental iron) 2

Special Considerations for Advanced Age

• In elderly patients (95 years old), starting with lower doses is prudent to assess tolerability, particularly given the high risk of gastrointestinal side effects 3
• Consider starting with 100 mg elemental iron once daily (approximately one-half to one 325 mg ferrous fumarate tablet) for symptom-free patients, which can be increased to 200 mg daily if tolerated 3
• If side effects occur, alternate-day dosing (100-200 mg every other day) may improve tolerance while maintaining efficacy 3

Administration Guidelines

• Take oral iron without food or other medications for optimal absorption 2, 1
• Avoid taking iron within 2 hours of meals or 1 hour after, as food reduces absorption by up to 50% 2
• Do not co-administer with phosphate binders, especially aluminum-based binders, as they significantly reduce iron absorption 2, 1

Monitoring and Response Assessment

• Check hemoglobin, ferritin, and transferrin saturation (TSAT) at baseline before initiating therapy 2, 1
• Monitor iron parameters every 3 months during oral iron therapy 2
• Oral iron is appropriate if TSAT ≤30% and ferritin ≤500 ng/mL 2
• Continue therapy until target hemoglobin is reached and iron stores are replenished 1

When to Consider Intravenous Iron Instead

• If oral iron fails after 1-3 months trial, consider switching to IV iron 2
• Severe anemia or symptomatic patients may benefit from IV iron for more rapid hemoglobin improvement 3
• Dialysis-dependent CKD patients respond better to IV iron than oral iron 4, 5
• Functional iron deficiency (TSAT ≤20% with ferritin >100 ng/mL) typically requires IV iron rather than oral 4

Important Caveats

• Oral iron is less effective in CKD compared to the general population due to elevated hepcidin levels that impair intestinal iron absorption 5
• Gastrointestinal side effects are common (nausea, constipation, abdominal discomfort) and may limit adherence, particularly in elderly patients 1, 3
• At 95 years old, quality of life considerations are paramount—if oral iron causes significant GI distress, the risks may outweigh benefits, and IV iron should be considered 2
• This hemoglobin level (91 g/L) is below the anemia threshold for adults (120 g/L for females, 130 g/L for males), warranting treatment 2