Syarihan Karim

Senior House Officer, Christchurch Hospital, NZ

 




ABSTRACT

Is a Standard 1g Dose of Intravenous Iron Adequate for Outpatient Treatment?

Karim S1, Butler J1, Barclay M2
Departments of General Medicine1 and Clinical Pharmacology2, Christchurch Hospital

Background: Evidence supports intravenous iron use when oral replacement is insufficient or poorly tolerated.  However, evidence for dosing regimens is limited. This has resulted in variability between guidelines, with some recommending standard 1g doses, and others using variable, calculated doses.

Aim: To assess the response to and appropriateness of a standard 1g dose of intravenous ferrous carboxymaltose.

Methods:  Data for all medical outpatients receiving ferrous carboxymaltose (from August 2013 to June 2015), was obtained from electronic records.  Pre-infusion blood results were compared with planned blood tests taken 5-7 weeks post-infusion (and with any other follow-up tests taken).  Patients without iron deficiency (eg anaemia of chronic disease), with no follow-up tests, and those who had blood transfusion or surgery post iron infusion were excluded.

Results: 194 patients (157 female and 37 male) fulfilled the criteria, with mean age 51 years. Only 50 patients had follow-up tests taken within the 5-7 week period. Mean haemoglobin (Hb) levels were 100.7 g/L pre-infusion, and 125.4 g/L post-infusion (P<0.0001), with a mean Hb increment of 24.7 g/L regardless of the timing of the post-infusion blood test.  For the 50 patients who had follow-up blood tests within 5-7 weeks, the mean Hb increment was 26.7 g/L.  The mean ferritin levels for pre and post-infusion tests were 17.9 mcg/L and 134.2 mcg/L respectively (p<0.0001), with mean ferritin increment 119.5 mcg/L regardless of the timing of the follow-up test.  The mean ferritin increment was 161 mcg/L if the test was taken within 5-7 weeks (n=32).  Five patients remained anaemic (Hb < 100g/L) at 5-7 weeks.

Conclusions: A standard 1g dose of intravenous ferrous carboxymaltose is sufficient for most patients.  For those with higher iron requirements (eg inflammatory bowel disease or significant ongoing blood loss), repeat testing for Hb and ferritin levels 5-7 weeks after infusion can determine the requirement for a second dose. .