There are numerous possible causes of fatigue among persons with HIV infection. Often, a person with fatigue has several problems that can interact to cause this symptom. Fatigue can be caused by inappropriate attention to basic human requirements such as rest, diet, and exercise. Anxiety and depression are also associated with fatigue. Fatigue can be caused by alcohol consumption, smoking, and recreational drug use. Fatigue can be a symptom of one of several opportunistic infections associated with HIV and may be the first sign of infection. Abnormalities of the endocrine system, a common occurrence in people with HIV, may also cause fatigue. Finally, fatigue can be caused by anemia, a very common disorder associated with HIV.
Let's look at each of these possible causes in more detail:
Rest, diet, and exercise
Many people, whether they are HIV-infected or not, fail to get an adequate amount of rest and/or exercise and do not eat properly. Getting adequate amounts of sleep and exercise, and eating well-balanced meals, is often difficult. There are always bills to pay, important projects to finish, and friends and family to see. In fact, many people with HIV push themselves to work too hard, despite – or even because of – feelings of exhaustion. In turn, working (or playing) too hard is often accompanied by poor nutrition and insufficient rest and exercise. In addition, sleep disturbances may be associated with anxiety and depression, the use of diuretics, caffeine, alcohol, nicotine, antihistamines, decongestants, marijuana, cocaine and methamphetamines (e.g., crystal meth), or lack of exercise. Drinking too much alcohol and the use of drugs like cocaine and methamphetamines are often associated with poor diet, which can lead to anemia, liver disease, weight loss, and fatigue.
Psychological causes
Anxiety and depression are often associated with fatigue and are also common among people with HIV. In addition to being associated with fatigue, anxiety and depression are also linked with insomnia, loss of appetite, and difficulty with concentration. Virtually every HIV-infected person goes through periods of feeling upset, worried, anxious, or depressed. Psychological causes of fatigue in HIV-infected individuals are treatable but are often overlooked.
Alcohol, tobacco, and recreational drugs
No one knows for sure if drinking alcohol, smoking cigarettes, or doing recreational drugs speeds up HIV disease progression. However, the use of these substances is often associated with fatigue in people with HIV. While these substances may not necessarily directly cause fatigue in all people, substance abuse is often a sign – or cause – of anxiety, depression, sleep disorders, and poor diet, all of which can cause fatigue. What's more, alcohol and certain drugs may magnify the side effects of anti-HIV/AIDS treatments that are known to cause fatigue.
Fatigue can be the first sign of an opportunistic infection. Close attention should be given to other symptoms – such as cough, fever, and headaches – which may also point to the presence of an opportunistic infection. Anemia (low red blood cells), which is discussed in much greater detail in the next section, is quite common in people with opportunistic infections and is a frequent cause of fatigue.
Endocrine abnormalities: adrenal insufficiency and hypogonadism
The adrenal glands, located on top of the kidneys, are responsible for producing many essential hormones that regulate how the body functions. Adrenal insufficiency – or inadequate production of adrenal hormones – can be caused by contain anti-HIV/AIDS drugs, HIV infection itself, or by opportunistic infections such as CMV and TB that can directly infect and damage the adrenal glands. Adrenal insufficiency can result in fatigue, chronic weight loss, decreased blood pressure, dizziness, and, ultimately, death.
Hypogonadism – decreased testosterone production – is a common problem of HIV-infected men. Like many hormones, testosterone, which is primarily produced in the testes, helps regulate men's moods, sexual function, nutrient metabolism, and energy levels. Approximately 45% of all people with AIDS suffer from low levels of testosterone, as do 25% of all asymptomatic HIV-infected individuals. There are several causes of low testosterone production, including testicular dysfunction (damaged testicles, possibly due to an opportunistic infection), drug side effects (especially megestrol acetate, ketoconazole, and ganciclovir), and elevations in the adrenal hormone cortisol (which is produced in abundance during chronic infections as a normal body defense against physical stress).
Anemia
Red blood cells are made in the bone marrow and carry oxygen from the lungs to the rest of the body using an iron-containing protein called hemoglobin. Red blood cell production requires a natural hormone called erythropoietin, which is produced in the kidneys and stimulates the bone marrow to produce an adequate number of red blood cells. Normal red blood cell production is also dependent on many other factors, including adequate sources of iron, vitamin B-12, folic acid, and trace minerals.
The number of red blood cells can be counted directly or can be estimated by the hematocrit or the hemoglobin. The hematocrit (HCT) is the volume percentage of red blood cells in whole blood. Normal HCT values vary, but generally range from 40% - 52% in men and 35% - 46% in women. Hemoglobin concentration (Hb) is reported as grams of hemoglobin per deciliter of blood (g/dL). Since red blood cells are approximately 33% hemoglobin, the hemoglobin result normally is about one third of the HCT. Normal hemoglobin (Hb) values are 14 - 18 g/dl for men and 12 - 16 g/dl for women.
Certain diseases and medications can cause the number and percentage of red blood cells to fall below normal levels. When a person becomes anemic, the body tries to compensate in a number of ways. The heart rate increases in an attempt to get more blood, and more oxygen, to the tissues, putting an increased burden on the heart muscle. The respiratory rate also increases. Certain capillary beds (tiny blood vessels in the tissues) open up wider in an attempt to provide more oxygen to vital tissues, while other capillary beds constrict (get smaller) in an attempt to preserve oxygen. This redistribution of blood leads to the common paleness and cold sensation of people with anemia, but provides more oxygen to critical organs such as the heart, brain, and muscles. Increased activity, however, produces and even greater need for oxygen in these tissues, resulting in a sensation of fatigue, weakness, palpitations, shortness of breath, and other symptoms.
Anemia, or an abnormally low number of red blood cells, is one of the most common causes of fatigue in people with HIV. As many as 70% - 80% of HIV infected patients develop anemia at some time during the course of infection. Moreover, a recent report has concluded that anemia, should it not resolve, is associated with shorter survival of HIV-infected patients.
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