Fatigue (Weak and Very Tired)

What is fatigue?

Fatigue is a general tiredness or an overwhelming lack of energy. It may be associated with an increasing need for rest, an inability to regain energy with rest, difficulty concentrating, or a disinterest in activities or events. Compared with symptoms such as nausea or pain, fatigue can be very difficult to identify and discuss. Sensations such as weakness, dizziness, difficulty thinking, and tiredness may be part of the feeling. People sometimes think they are just being lazy or depressed. They may tell themselves, “I can snap out of this if I really try.” Sudden changes in feelings of fatigue may mean there is a serious problem. Slower more gradual development of fatigue may lead to a decreased ability to perform everyday activities. There are no medical tests to measure fatigue, however, fatigue can be treated in many circumstances. If you are experiencing fatigue, report this feeling to your oncology nurse or physician.

“Tumor markers” is a general term used to describe a blood test that helps monitor how well your body is responding to a given cancer treatment. There are a variety of tumor markers that can vary depending on the type and kind of disease. Not all cancers have available tumor markers. Typically, tumor markers are monitored every one to three months. The frequency of monitoring is highly variable and is determined by your doctor. Tumor marker results are sent to an outside lab and generally take 48 – 72 hours to obtain results. In some special cases, tumor markers are so highly specific that they need to be sent to very advanced labs such as the Mayo Clinic. These results can sometimes take up to 10 – 14 days.

Managing Causes of Fatigue

The reasons that patients experience fatigue are many and complex. In fact, fatigue often results from more than one cause and may require the use of many strategies for effective treatment. All of the factors listed below can contribute to fatigue by decreasing the body’s ability to produce energy or by consuming the limited energy produced.

Anemia:

Anemia is an inadequate supply of red blood cells, resulting in a decrease in the oxygen-carrying capacity of the blood. A common reason that cancer patients experience anemia is as a side effect of chemotherapy. Anemia is important because it may cause unwanted symptoms, such as fatigue, tiredness, or shortness of breath, and may exacerbate or cause other medical problems like a heart condition. Fortunately, the administration of the blood growth factor — erythropoietin — can increase the production of red blood cells and can help you feel less fatigued. In some instances, a blood transfusion may be necessary.

Infection

When you have an infection, the body utilizes any extra energy to fight the infection, which can contribute to fatigue. Report a temperature of 101F or greater immediately.

Cancer Medications or Other Medications:

Many drugs, including those used for the treatment of nausea (anti-emetics), pain (analgesics), anxiety (anti-depressants), and other conditions, can cause fatigue as a side effect.

Decreased Appetite and Lack of Nutrition:

Cancer or cancer treatments may also cause you to lose your appetite, or feel full early. Decreased intake of calories and vitamins reduces the body’s ability to produce energy and may cause anemia. Please refer to the section on nutrition.

Imbalance Between Rest and Activity:

Long periods of rest may contribute to fatigue and modest amounts of activity and movement can improve fatigue. Here are some tips for managing your balance between rest and activity:

Listen to your body, rest when you feel tired.
If possible, take a 15 – 30 minute walk every day.
Try to take short naps, no more than one hour during the day.
Sleep at least eight hours every night.