Is sodium feredetate the best preparation for low Hb?
Q: I have read somewhere that sodium feredetate (NaFeEDTA) is now considered to be the safest and most effective iron. My physician prescribed it to my friend whose Hb level is below 9.5 g/dl. He said it should it be taken for four months for effective Hb rise. Kindly advise.
A:Iron is an essential component of several body proteins including haemoglobin (the oxygen-carrying pigment within red blood cells) and myoglobin (the oxygen-storing pigment in muscles). Iron is also a vital component of several enzymes within cells that are required for the uptake of oxygen and the production of energy in the cells. There are several aspects of iron metabolism in the body, which need to be considered as these govern the dose, form and duration of treatment of iron deficiency anaemia, the commonest anaemia in our country.
- The oral dose of elemental iron for the treatment of iron-deficiency anaemia should be 100 to 200 mg/day as only about 10% of iron is absorbed normally but this goes up in iron-deficient individuals.
- Maximum iron absorption is seen when iron tablets are taken 2-3 times a day. Once or twice a day dosing of iron preparations may be effective for preventing iron deficiency or treatment of only mild iron deficiency.
- Different iron preparations differ in their elemental iron content.
- Although iron is best absorbed when taken on an empty stomach, tablets are commonly taken with food to reduce gastro-intestinal side-effects like diarrhoea or constipation, thus limiting iron absorption. The presence of vitamin C enhances iron absorption and taking tablets with fruit juice helps.
- Maximum iron absorption occurs in the first part of the small intestine called the duodenum.
- The gastro-intestinal side effects of different preparations are related to the iron content and there is a lower incidence of side effects with preparations containing less iron. Many doctors use salts other than ferrous sulphate (like ferrous fumarate or gluconate) to decrease the side effects. The reduced side effects of these preparations are not due to the salt used but due to the fact that these formulations contain less iron (thus reducing their therapeutic effectiveness, too).
- Tolerance to iron preparations is improved by starting with a small dose and increasing the dose over a few days.
- Iron is available in two salt forms – ferrous (Fe2+) and ferric (Fe3+). The ferrous salts of iron are water soluble while ferric is not. Also, the cells lining the intestine (duodenal mucosal cells) can absorb the ferrous form and not the ferric form though they have the ability to convert ferric into ferrous form. As the bioavailability of iron to a large extent is a function of its water solubility, ferrous salts are the most effective iron supplements known to-date. If a ferric salt is sufficiently soluble in water, it can be used.
- Modified-release iron capsules carry the iron past the duodenum to parts of the intestine where absorption is poor, thus making such preparations ineffective.
- When given in full therapeutic dose, the rise in haemoglobin is around 1 gm/dl per week after the first week of treatment and haemoglobin value should be normal in about one to one-and-half months.
- Treatment should continue for 3-4 months after haemoglobin has returned to normal so that the bone marrow iron stores are replenished.