Dear Dr. Jeff: I get tired pretty easily, and my coach thinks I may be anemic. Should I come in for blood tests? MW
Dear MW: There are many, many causes of fatigue, only one of which is anemia.
If you're anemic, you have fewer red blood cells in circulation than normal. Red blood cells ("RBCs") are filled with hemoglobin, a substance which binds to oxygen. They're the reason your blood looks red.
They travel through the vast network of arteries and veins in your body, carrying oxygen from your lungs to all of the tissues that require it for "fuel" and function. If you don't have enough red blood cells, your oxygen-carrying capacity is diminished, and you tire ("run out of fuel") more easily.
Red blood cells are made in your bone marrow, but wear out, and have to be replaced, every 120 days or so. Old cells are filtered out of your blood by your spleen, and their chemical building blocks are generally recycled.
Production of new RBCs does require significant amounts of a number of nutrients, including iron, folic acid, and Vitamin B12. Some (like iron) are stored in your body for later use. Others (like B12) need to be taken in practically daily.
There are many causes of anemia. You might not have enough of one of those nutrients, and therefore be unable to keep producing adequate numbers of new red blood cells.
Your bone marrow might not work properly (e.g. if you're missing certain enzymes needed to produce RBCs, or if your marrow function is suppressed by chemotherapy, medication, or infection).
Your blood count could be low because of blood loss?either acute (e.g. from an injury) or chronic (e.g. from very heavy menstrual flow).
Your RBCs might be destroyed prematurely or excessively (e.g. if you have sickle-cell anemia, or if your spleen is acting up, or if you develop some sort of auto-immune disorder.) Very often, these mechanisms act in combination.
Far and away, the most common reasons for anemia in your age group are nutritional and chronic blood loss (or really, a combination of the two). If you're not getting enough iron in your diet, you'll deplete your body's iron stores at some point. Then you won't be able to keep up with your baseline RBC production needs.
If, in addition, you have heavy periods, then your need for replacement RBCs will be even greater still, and you'll more quickly develop an iron deficiency anemia.
Testing for anemia is pretty simple. A blood test is first taken to count the number of RBCs and to measure their size (iron-deficient RBCs are small, for instance, while B12-deficient RBCs are large.)
Other tests can evaluate the state of your body's iron stores and your bone marrow's RBC output levels. If indicated, a thorough history and physical exam may uncover other causes of an anemia, and other laboratory and imaging tests can be ordered.
Treatment for the common anemias is also pretty straightforward. Nutritional counseling is key. Dietary iron is best found in leafy green vegetables, whole grains, many fruits, eggs, and red meat. Vitamin B12 is plentiful in meat, poultry, fish, eggs, dairy products, and whole grains. Folate can be found in wheatgerm, broccoli, green cabbage, and nuts.
If necessary, supplements of iron, B12 and folate can be prescribed. Heavy periods can be tamed with oral contraceptives.
Another, not uncommon cause of anemia is hypothyroidism?a thyroid condition that also causes fatigue.
So, MW, if you're concerned about your energy level, come in to see one of us at the Health Center. We'll see if we can sort things out, and get you back on track!
Jeff Benson, MD
Dudley Coe Health Center