My doctor orders a complete blood count several times each year. Do I need to get this test so frequently?
A complete blood count (CBC) is an excellent screening test. It helps the doctor diagnose illnesses, monitor disease activity, and look out for medication side effects. How frequently a physician orders a CBC has a lot to do with your health history, your concurrent illnesses, the types of medications you are taking, and your present complaints.
The following examples describe how the CBC can be employed.
Case 1
A female patient with RA reports that lately she has been feeling weak, short of breath, and easily fatigued. This patient has a history of emphysema. A physical examination appears unchanged from her previous exam two months ago. A stool sample, however, is noted to contain traces of blood. It is not clear whether the fatigue and shortness of breath are related to the underlying RA, the emphysema, or some other medical problem. A CBC is ordered, and a low red blood cell count is noted; a diagnosis of anemia is made.
Later, the patient undergoes an endoscopy test that reveals the presence of gastric ulcers. The increased dose of ibuprofen taken by the patient is believed to be to blame for these ulcers. The patient's ulcers are treated, and her arthritis medication regimen is changed to avoid this complication. The patient receives a transfusion of two units of blood, and her symptoms of fatigue and shortness of breath improve dramatically.
Case 2
A patient limps into an emergency room at a local hospital. He complains of pain, swelling, and redness of his right knee for the past week. The pain appears to be getting worse, even though the patient has taken aspirin and used ice packs. The physician examines the knee, but is unsure if this is the first presentation of RA, a traumatic injury, or an infection. The doctor orders x-rays and a CBC, among other tests. The x-ray does not show any signs of fractures or dislocations. By contrast, the CBC demonstrates a markedly elevated white blood cell count, which suggests that the knee swelling is a result of an infection. The doctor uses a needle and syringe to aspirate a sample of the knee fluid. Under a microscope, the doctor can see many bacteria. A diagnosis of a knee joint infection is made—a condition called septic arthritis. After taking a course of antibiotics, the patient recovers fully.
Case 3
A 47-year-old woman complains of swelling and pain of her hands and wrists. She states that she has recently gone back to work as a secretary and is doing a lot of typing. She thinks that her pain could be from the typing. She has a history of RA, but states that this disease has only bothered her knees in the past. When the doctor examines the patient, he notes swelling of the wrists and knuckles of both of her hands. When the doctor takes a more detailed history, the patient states that she had noticed the swelling and mild stiffness before she returned to typing, and that both are worse when she gets up in the morning to go to work. The pain and stiffness seem to decrease by midmorning, especially if she takes aspirin or ibuprofen. She also mentions that she has experienced increasing fatigue: Working every day is a struggle, and she seems to tire more quickly than before.
The doctor orders a CBC, among other tests. The CBC indicates that the patient's white blood cell count is normal, but demonstrates a moderate decrease in the red blood cell count. This result suggests to the doctor that the patient does not have an acute infection, but rather has a moderate amount of anemia that is associated with active RA. The doctor diagnoses a worsening (flare) of the patient's RA. He institutes a more aggressive regimen of arthritis medication and prescribes iron supplements to help with her anemia. When he reassesses the patient after three months of treatment, both her joint pain and her fatigue have improved.
As you can tell from these examples, the CBC is useful in many clinical situations. It is a standard test that can help your doctor to both diagnose and monitor your disease.