The risks of IV iron are both the common, minor reactions and the extremely rare, but potentially fatal, anaphylactic reaction. With increased frequency of use of parenteral iron, the occurrence of this rare, but very real, side effect has been minimized. While it has been dismissed by some, it is so well-recognized by the FDA as a real and important risk such that there is a black box warning.
Accordingly, during an IV iron administration, the patient must be observed (be in line of sight) for signs and symptoms of an anaphylactic type reaction because they will become fatal extremely quickly if not treated absolutely immediately. The black box warning notes that fatal reactions have occurred even following the test dose of iron, despite that the test dose had been tolerated. As a result of the risk of rapid fatality, the black box warning generally mandates that it should only be given to patients 1) who clinical and laboratory investigation have established to be in an iron deficient state; and 2) who are not amenable to oral iron therapy. This risk of anaphylaxis is a side effect of all IV iron preparations.
Indications for IV iron infusions
There are criteria for when IV iron therapy is indicated instead of oral iron replacement. As noted in black box warnings, it is to be given “only in patients in which clinical and laboratory investigation has established an iron deficiency state not amenable to oral iron therapy”
These indications include:
a) Elderly patients who often have poor responses to oral iron often have impaired absorption due to increased antacid use and low gastric acidity limiting iron absorption as well as increased difficulty tolerating oral iron.
b) Inflammatory bowel disease due to association with severe inflammation resulting in impaired bowel movement response to iron, impaired iron absorption, or poor GI tolerance to oral iron preparations. In addition, ongoing low level blood loss may limit the ability of oral iron to maintain adequate systemic iron levels.
c) Gastric bypass surgery due to association with increased multi-nutrient (including iron) absorption deficiencies, due to both GI rapid transit time and impaired absorption secondary to loss of gastric acid post-gastrectomy
d) Other malabsorption syndromes that may impair adequate absorption of oral iron preparations.
e) Ongoing blood loss necessitating frequent and higher dose iron levels to maintain adequate erythropoiesis, such as severe, recurrent menstrual blood loss.
The most common indication to resort to IV iron is in the setting of iron deficiency when oral iron is not tolerated, generally due to adverse GI side effects.
Risks of iv iron infusions medical expert witness specialties include hematology, internal medicine, allergy, and forensic pathology.