Oral Iron Therapy is Not Always Sufficient for the Bariatric Patient Population

Dear Bariatric Times Editor:
I read the November 2011 installment of the column “Nutritional Considerations for the Bariatric Patient,” entitled “Pica: An Ancient Disorder with Modern Casualties,” by Liz Goldenberg, MPH, RD, CDN. I was pleased to see the author present such an excellent overview of the management of iron deficiency in bariatric surgery, which is an issue that goes unrecognized in many practices. However, I disagree with some of the recommendations. In my experience, the degree of gastrointestinal (GI) intolerance is independent of a form of inorganic iron you use: sulfate, gluconate, or fumarate. Rather, the degree of GI intolerance is more dependent on the total dose of elemental iron; the higher the dose of elemental iron, the greater the GI side effects.

Increasing the number of tablets per day in a patient who is not responding to oral iron will not usually improve iron absorption (which has a finite daily maximum regardless of the daily dose since the enzymes/proteins associated with duodenal absorption, duodenal ferric reductase [Dcytb] and divalent metal transporter 1 [DMT 1] can be saturated). An enzyme is saturated when all available active sites on the enzyme or binding sites on the transport protein are occupied by substrate (in this case iron) and a further increase in substrate concentration does not result in an increase in the rate of reaction. Iron must be converted from the ferric to the ferrous state by duodenal ferric reductase (Dcytb) and transported into the duodenal enterocyte by divalent metal transporter 1 (DMT 1) to be absorbed. So, in this case, once this enzyme and this transport protein are saturated, no further increase in the rate of oral iron absorption will occur.

I think all bariatric patients with iron deficiency should be given a trial of oral iron supplementation before switching to parenteral iron, because of the ease and low cost of treatment. However, intravenous iron is a safe and highly effective therapy for patients unresponsive or intolerant to oral iron and its use should not be unduly restricted.

With regards,

Irvin Gross, MD
Medical Director
Eastern Maine Medical Center Patient Blood Management Program

Author Response
Thank you for your comments and your interest in this topic. I always appreciate hearing how other bariatric programs care for their patients. It is the experience of other practitioners that helps us all to advance science and take better care of our patients.

In the short piece on pica, which served to provide an overview of a well-known nutritional complication of bariatric surgery, I was not sharing my experience with regard to iron supplementation so much as referencing a handful of articles from respected sources. However, I am glad that you have given me the opportunity to share my experience.

I think we are in agreement that parenteral iron therapy does play an important role in caring for patients who do not respond to, or are intolerant of, oral iron supplements. I find our hematologists at Cornell immensely helpful. Also, I appreciate your review of iron metabolism. I often find myself in discussions with other experts regarding the need for more evidence-based data on nutrient metabolism specific to the bariatric surgery patient. Often, the best that we can do is to extrapolate information based on “healthy/normal” individuals to our patients who have rearranged GI tracts and tiny stomachs. Lastly, I would like to point you to a more recent issue of Bariatric Times (Vol 7, number 12) on a similar topic, where Jennifer Traub gives us an overview of the three main forms of oral iron available and how the dosing of each is relevant. She also comes to the same conclusion: that oral iron therapy is not always sufficient for our patient population.

With regards,

Liz Goldenberg, MPH, RD, CDN
New York Presbyterian Hospital, Weill Cornell College of Medicine of Cornell University, Department of Surgery, New York, New York.

Category: Letters to the Editor, Past Articles