This is a complaint I hear again and again.
The causes of fatigue takes several pages in medical textbooks, involving pretty much every organ system, metabolic and pathological possibility. As I instruct my medical students and residents, a complaint of fatigue can be one of the most challenging to diagnose and to treat.
Anemia and low thyroid are well-known causes of fatigue to every third-year medical student. Although these conditions must be ruled out, they seldom explain the problem so simply. It’s a good start but in most cases doesn’t get us to first base, much less home plate.
Without trying to be comprehensive and in no particular order, I’m going to run through some of the more probable causes of fatigue.
Leading causes of chronic fatigue in a primary care practice are depression, poor sleep and medication side effects. Patients who sleep poorly because of sleep apnea, insomnia or pain issues are naturally going to be fatigued during the day.
Those whose “get up and go has got up and went,” as my mother used to put it, may have a mental health issue rather than a physical one. Depression is highly prevalent and often presents with the lack of motivation, energy and disturbed sleep that characterize fatigue.
Paradoxically, many folks with fatigue experience it because of lack of exercise. While they may feel “too tired” to exercise, motion is lotion, and preventing de-conditioning and improving circulation and attitude through exercise is often a helpful first step.
Chronic pain often leads to fatigue as day-to-day activities are exhausting, and sleep is disturbed. Organ system failure or malfunction such as heart, lungs, liver, kidneys and endocrine organs like pancreas, adrenal, ovarian, testes and pituitary may be a part of the picture. Examples are poorly controlled chronic lung disease, heart failure or diabetes.
Of course, nutrition plays a part in fatigue. Deficiencies of B vitamins, iron and other essential micronutrients as well as macronutrients, a balance of healthful proteins, carbohydrates and fats is essential to overall energy and good functioning. Subclinical malnutrition can be a subtle cause of fatigue. Fast-food fatigue comes to mind.
Malignancies should be considered especially if fatigue is accompanied by weight loss, night sweats, fevers. These symptoms also can show up in chronic infections like tuberculosis, certain connective tissue disease but also lymphomas, leukemias and solid organ tumors.
The new kid on the fatigue block is COVID. Initial presentation of this viral infection can be characterized not only by fever, cough, muscle aches, gastrointestinal problems and/or headaches but also extreme fatigue. The long-haul or post-COVID syndrome very often includes fatigue as part of a picture.
My advice is to be patient with yourself and your health care team as we try to figure out the cause of your fatigue. Some conditions, like fibromyalgia and chronic fatigue syndrome, remain elusive as to cause and treatment.
Next week, we’ll delve into a variety of treatments for your chronic fatigue and offer some helpful tips to help you function at your best.
Dr. Victor S. Sierpina is the WD and Laura Nell Nicholson Family Professor of Integrative Medicine and Professor of Family Medicine at UTMB.