When a patient's hemoglobin (Hb) and hematocrit (Hct) are not out of range, it is sometimes difficult for them to convince a gatekeeper that they need additional tests to rule out an iron problem.
Because too much iron can act as a pro-oxidant, I do not have patients take iron for more than seven days if they do not feel a big difference. Usually, a subtle change is noticed on the third day. By the fourth and fifth days, the change becomes noticeable. When a patient with normal Hb and Hct informs their gatekeeper how much better they feel after a few days of iron, additional tests for iron are almost always approved. When that happens, I tell the patient that even though one week of iron has made them feel better, it is not nearly enough to alter tests that measure iron reserves.
|TABLE 1: LAB TESTS FOR IRON EVALUATION|
|Hemoglobin||Often within normal ranges until anemia develops.|
|Hematocrit||Dehydration and high altitude can cause false normal by raising test scores.|
|Serumiron||Used alone, it isn’t an accurate marker because of diurnal variations.|
|Serum ferritin||The most accurate single test for low iron. Injury, infection and immune problems that promote inflammation can cause a false normal by elevating ferritin. Alcohol can also increase.|
|TIBC||Total Iron Binding Capacity; the amount of iron that can be bound to serum protein. Positive when high. Oral contraceptives may elevate and cause a false positive.|
|Transferrin||Concentration is proportional to the amount of iron bound to serum protein; therefore it is another way of expressing TIBC and is high when iron is low.|
|% transferrin saturation||Serum iron divided by TIBC x 100 = percent of transferrin saturation. Like hemoglobin, this test may not be low until iron deficiency is significant.|
|Note: Specific numbers were not included because normal ranges vary between labs.|
Once you start looking for iron problems, you will discover three categories of patients who, with questioning, have diagnosed deficiencies they have not acted on:
- Patients with low hemoglobin and/or hematocrit on a recent CBC.
- Patients who were told that they have anemia, but never acted on it.
- Patients who tried iron and quit because of constipation, nausea or GI upset.
|TABLE 2: RECOMMENDED DIETARY
ALLOWANCES FOR IRON BY AGE
|Age Range||Mg / Day|
|7-12 months||11 mg|
|1-3 years||7 mg|
|4-8 years||10 mg|
|9-13 years||8 mg|
|14-18 years||11 mg (men);
15 mg (women)
|19-50 years||8 mg (men),
18 mg (women)
|51+ years||8 mg|
|Lactation (under age
19 / over age 19)
|10 mg / 9 mg|
There are many types of iron supplements available over the counter. The amount of elemental (actual) iron in them varies; so does the labeling. Some products list both total and elemental amounts. Others, such as most bis-glycinate (aka, glycinate) will only list elemental levels. For example, a 300 mg iron pill from ferrous gluconate provides a true iron dose of 36 mg. See Table 3.
The dosing guidelines for iron also vary. Treatment for a deficiency can range from 30 to over 150 mg a day of elemental iron. In general, I begin with 50-120 mg a day in divided doses, taken away from food. Iron, unlike most minerals, is absorbed best on an empty stomach. I do not recommend more than 60 mg at one time. I will start with one dose in the morning and one before bed. If taking iron away from food causes nausea or an upset stomach, I have the patient take it with food.
|TABLE 3: COMMON IRON SUPPLEMENTS|
|Type||% Elemental Iron|
|Ferric ammonium citrate||16.5%|
For those patients who have had or do have side effects, such as constipation or stomach problems (even when taking with food), I recommend iron glycinate, technically known as bis-glycinate. This form normally comes in elemental doses in the 28-30 mg range. It causes dramatically fewer side effects than other forms.
Iron is tricky enough that this could easily be a 6-8 part series. If you have any questions, feel free to contact me.
- Killip S, Bennett JM, Chambers MD. Iron deficiency anemia. Am Fam Phys, 2007;75(5):671-8.
- Center for Disease Control and Prevention. Recommendations to prevent and control iron deficiency in the United States. MMWR, 1998;47(No. RR-3).
- Centers for Disease Control and Prevention. Iron deficiency - United States, 1999-2000. MMWR, 2002;51:897-9.
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