Understanding Low Red Blood Counts

Quick summary

It wouldn't really be an exaggeration to say that red blood cells are the life force of the body, since they play such an essential role in carrying oxygen from the lungs to the cells. That's why when your parent's red blood count drops, he really feels it -- and shows it. He may be pale, tired, weak, and have trouble catching his breath. Here's what you need to know to understand what's happening and what to do.

Why does cancer cause my parent's red blood cell (RBC) count to drop?

• In most cases, it's not the cancer itself but cancer treatment that leads to a shortage of red blood cells, also called anemia. Chemotherapy often damages the bone marrow that produces red and white blood cells and platelets, a condition called bone marrow suppression, or myelosuppression. As red blood cells die out, which they do naturally every 120 days or so, your parent's body isn't able to replace them and the red blood count drops.

• Radiation therapy can also damage red blood cell production, particularly if the radiation targets areas such as the pelvis, where bones have more marrow and higher blood cell-generation activity.

• Blood loss, either from surgery or from particular cancers, can also cause or exacerbate anemia. Colorectal cancers, for example, often cause blood loss as blood leaks from the intestines. Cancers that affect the blood and bone marrow, particularly lymphoma and leukemia, can also damage the production of red blood cells.

Why is there more than one test for red blood cell counts?

There are several ways that doctors commonly measure red blood counts:

• Red blood cell count . This test counts the number of red blood cells in a single drop (a microliter) of blood. As a general guideline, consider the normal range to be 4.5 to 6.2 million for men; 4.2 to 5.4 million for women.

• Hemoglobin . This test measures the red-pigmented protein that carries oxygen. Normal range for red blood count is 14 to 18 grams per deciliter in men; 12 to 16 grams per deciliter in women. When your parent's hemoglobin drops below 10 grams per deciliter, he's considered anemic.

• Hematocrit . This test measures the percentage of total blood volume made up of red blood cells. Normal range is 40 to 52 percent for men; 35 to 47 percent for women.

A complete red blood count usually includes additional measures of the size, capacity, and number of red blood cells. Your parent's doctor will order a battery of tests to get a complete picture of the health of your parent's red blood cells. For example, a low hematocrit in combination with low hemoglobin may indicate iron deficiency, while a high hematocrit can indicate dehydration.

Can I help prevent my parent's red blood count from dropping?

There are medications called cell growth factors (also called colony stimulating factors) that can be given along with chemo or radiation to prevent red blood counts from dropping. The growth factor that boosts production of red blood cells is epoetin or darbepoetin (brand names Procrit, Epogen, Aranesp). Growth factors can take between two and eight weeks to work, so they're not a solution for dramatic red blood cell loss. There's also a risk of side effects, so your parent's doctor will decide whether to prescribe cell growth factors based on his assessment of your parent's risk of developing a low red blood count.

Get as much information as you can from the doctor about your parent's chemo regimen and the effect you can expect it to have on his red blood count. "Some drugs reduce the red blood cell count by 25 percent immediately; some drugs take a week before the count start to drop. Every drug and regimen is different," says Terry Anders, an oncology nurse at the Zangmeister Cancer Center in Columbus, Ohio. Because side effects include fluid retention and heart palpitations -- both of which can worsen heart conditions -- your parent's doctor will take into account whether your parent has heart problems when deciding whether to prescribe Procrit or other growth factors. Other side effects include diarrhea, vomiting, fever, and upper respiratory infection. In addition, Procrit can cause shortness of breath and edema, so if your parent already has these problems, your doctor may be conservative about prescribing it.

What are the symptoms of low red blood count?

The typical signs of anemia are extreme fatigue and shortness of breath, but a low red blood count can cause a host of different symptoms. Your parent's skin may be pale or clammy, or he may have a rapid heart rate, chest pain, or difficulty staying warm. Because low oxygen in the blood can affect the brain as well, your parent may feel dizzy and light-headed or have difficulty concentrating or remembering things. He may also have headaches.

How low does my parent's red blood count need to go before the doctor recommends treatment?

This is a very individual decision, and the doctor will make it based more on symptoms (such as fatigue or shortness of breath) than on a particular number. It's likely your doctor will take a wait-and-watch attitude for as long as possible before recommending medication or a transfusion, because he's hoping your parent's red blood count will rise on its own. Also, keep in mind that your parent's red blood count won't drop dramatically right after chemo; it usually takes one to two weeks for the blood count to reach what doctors call the nadir, the point at which it drops to its lowest point. Cutoff rates vary according to different labs, but if your parent's hemoglobin drops below eight, most doctors will recommend either growth factors or a transfusion.

How long will it take my parent's red blood count to rise again?

Red blood cells have a long life -- up to 120 days -- so rebuilding your parent's red blood count is going to be a long, slow process. The speed with which your parent's bone marrow makes new red blood cells is also affected by factors such as the type of cancer, type of treatment -- particularly the type and dosage of chemo -- and your parent's general state of health.

One thing to keep in mind is that your parent's red blood count won't drop immediately after chemo but will start dropping after a week or two, and it will then continue to fall for several more weeks. This is because chemo doesn't kill off the red blood cells already in the bloodstream, which are mature and aren't dividing rapidly. It kills off the cells forming in the marrow, and therefore there's a delayed response that corresponds with the rate at which your parent's marrow is creating new cells. The rate of regeneration can be affected by your parent's age and overall health. Also, some types of cancer and some types of treatment (such as radiation and some medications) suppress the production of red blood cells, so the rebuilding process can be much slower.