Iron and iron deficiency after bariatric surgery

31 Mar 2021 | Announcements, Bariatric Surgery, Evidence Based Medicine, Gastric Bypass, Sleeve Gastrectomy, Weight Loss

Iron is a mineral used by the body to make the ‘haem’ protein that is part of the haemoglobin molecule in red blood cells that transports oxygen around the body.  Iron is normally absorbed in the upper small intestine, and is better absorbed from meat than non-meat sources.  Iron absorption is reduced when there is increased inflammation in the body (as is common when people carry additional weight around their abdomen).  Iron is also lost from the body with bleeding, such as menstruation or regular bleeding in to the intestine.  Iron deficiency can mean there is not enough iron for the body to make red blood cells, and this is called anaemia.

Before bariatric surgery iron deficiency is common, because of the increased body inflammation reducing absorption, but can be difficult to detect as the blood test used to measure iron stores is also raised by inflammation and therefore can give false normal readings even though iron stores are low.  After bariatric surgery iron deficiency is also common, due to a decreased overall dietary intake, but particularly due to the bypass of the upper small intestine in people who have had a gastric bypass operation.  Iron deficiency is more common in people who do not eat meat, and in menstruating women.  Sometimes iron deficiency that was present before surgery is only detected afterwards as body inflammation levels decrease enough to allow the blood test for iron stores to become accurate.  Approximately half of people who have a gastric bypass will develop iron deficiency within 2 years of surgery, compared with approximately 10% of people who have a sleeve gastrectomy.

We do not recommend routine iron supplementation in addition to a bariatric specific multivitamin, but do measure peoples vitamin levels regularly during follow-up.  For people who develop iron deficiency we recommend the following options:

  •  Ferrograd tablets – available on prescription but can cause constipation, bloating and nausea in some people. Cannot be taken at the same time as food or calcium supplements.
  •  Ferrograd C tablets – these are better tolerated than prescription Ferrograd but not available on prescription. Can be bought from pharmacies for around $15 for 30 tablets. Cannot be taken at the same time as food or calcium supplements.
  •  Maltofer Iron Polymaltose tablets – this is the best tolerated form of oral iron, with the lowest risk of constipation and other side effects. It is not available on prescription but can be bought from pharmacies for around $22 for 30 tablets. It can be taken at the same time as eating.

Because iron is actively absorbed there is some evidence that the incidence of side effects are reduced if it is taken three days a week (i.e. Monday, Wednesday and Friday) instead of daily.

If people are unable to tolerate any form of oral supplementation there is an option to receive iron by a direct intravenous infusion.  The cost of this infusion may be subsidised by the Ministry of Health in certain circumstances, and the infusion can be given either in our rooms or at many GP’s surgeries.  These infusions are usually well tolerated although sometimes may cause mild nausea and decreased energy.  There are small risks of permanent staining of the skin if the iron leaks out of the vein and a very small risk of serious allergic reactions.  For people who rely on intravenous iron supplementation, these infusions are usually required once or twice a year.

In addition, women with heavy menstrual periods should talk to their GP about ways to reduce menstrual blood loss. It is very difficult to maintain iron levels after bariatric surgery with ongoing significant blood loss.