Note: This is the first article in an ongoing series. Make sure to check out the following articles once you’re finished with this one!
What Causes Chronic Fatigue Syndrome? – Part II: The Epstein-Barr Virus & Other Infections
What Causes Chronic Fatigue Syndrome? – Part III: Genetics
What Causes Chronic Fatigue Syndrome? – Part IV: Hormones
What Causes Chronic Fatigue Syndrome? – Part V: A Functional Medicine Approach
Do you have a solid understanding of what chronic fatigue is and the best strategies to fix it?
Chronic fatigue syndrome is an illness that has been notoriously challenging to both name and describe. In fact, there are some reports that date it back hundreds of years! Conservative estimates put one in three doctors visits are due to fatigue. (1, 2) And if you’re reading this, I imagine you are one of the three.
But what exactly is fatigue? Is there an agreed upon medical definition of fatigue?
Defining fatigue
Fatigue, in its most general sense, is the difficulty or inability to initiate activity. The medical community has outlined three different areas where you may experience fatigue. These include:
- A subjective sense of weakness
- A reduced capacity to maintain activity
- Difficulty with concentration, memory, and/or emotional stability.
It is possible to have one of the above or any combination of the above. To further complicate matters, the above fatigue symptoms may occur on their own or combined with any other complaint(s).
Fatigue can also be further classified based on the duration. The three types of fatigue based on duration include:
- Acute fatigue
- Fatigue lasting one month or less.
- Subacute fatigue
- Fatigue lasting between one and six months.
- Chronic fatigue
- Fatigue lasting over six months.
Transient, or acute bouts of fatigue are normal. Fatigue in this sense often can manifest during changes or transitions in life. Think of the last time you were between jobs. Was fatigue more prevalent? For many, that’s the case. And fatigue in this sense is not necessarily pathological. It’s a normal response to a change in your environment. Chronic fatigue, however, is much trickier to name and to treat. Let’s start by uncovering where chronic fatigue syndrome came from.
A brief history of chronic fatigue syndrome
Going back to the year 1750, Sir Richard Manningham described a syndrome called febricula. Sir Manningham described febricula as a combination of fever, the common cold, and an inflammation of the veins (phlebitis). While it may not sound much like chronic fatigue syndrome (as it’s known today) this was the medical communities first foray into understanding it.
Fast forward nearly two hundred years and you’ll find research by Dr. George Millar Beard describing an illness he called neurasthenia (nervous exhaustion). Neurasthenia was thought to consist of fatigue, anxiety, headache, impotence, nerve pain, and depression. (3) Neurasthenia seemed to affect women more often than men. It seemed to occur after an infection. Today, neurasthenia is described as a behavior, not a medical condition. The world health organization (WHO) no longer lists it as an illness.
Chronic fatigue syndrome (as it’s known today) got its start in 1934 at the County General Hospital of Los Angeles, California. Over two hundred members of hospital staff acquired the disorder. At this time, symptoms included muscle pain, memory lapse, difficulty concentrating, sleep disturbance, and inability to walk short distances without suffering fatigue. At the time, doctors thought the disease was related to polio. They coined the term poliomyelitis to describe the condition. Three years later, seventy Swiss soldiers were diagnosed with the same condition.
What was going on?
A decade later, in 1948, another outbreak of poliomyelitis occurred. This time in Iceland. It affected more than 1000 Icelanders. Have you ever heard Chronic Fatigue Syndrome described as Akureyri disease? Akureyri is the Icelandic town where the outbreak occurred. By the end of the outbreak, epidemiologists differentiated the disease from poliomyelitis.
In 1955, the next outbreak hit the United Kingdom. It occurred at the Royal Free Hospital in 1955. At that time 300 staff members of the hospital fell ill with the disease. Examination of the patients revealed that nearly all of them had their central nervous systems affected. In 1959, Dr. Ronald Acheson coined the term myalgic encephalomyelitis (ME). (4)
It wasn’t until 1988 that researchers from the CDC (center for disease control) coined the term chronic fatigue syndrome or, CFS. Up until 2015, the Holmes criteria were the gold standard used to diagnose chronic fatigue syndrome. (5)
In 2015, the Institute of Medicine (IOM) redefined the diagnostic criteria for chronic fatigue syndrome. At the same time, they re-named the disease. Today, chronic fatigue syndrome is known as Systemic exertion intolerance disease (SEID). The name change has not yet caught on. So, you may still know the disease as chronic fatigue syndrome.
The diagnostic criteria were changed to exclude more people from the diagnosis. Unfortunately, doctors were diagnosing many people with chronic fatigue syndrome without performing the necessary tests.
What tests should be ordered for chronic fatigue syndrome?
There is no specific blood test used to diagnose chronic fatigue syndrome. This makes proper diagnosis very tricky. With that said, there are a number of blood tests that should be performed to rule out other illnesses that can cause similar symptoms. These blood tests include:
- Complete blood count (CBC)
- Creatine kinase (to exclude muscle diseases)
- Blood glucose
- Iron & ferritin
- Complete thyroid panel (TSH, free T3, free T4, reverse T3, reverse T4, thyroid antibodies)
- Erythrocyte sedimentation rate (ESR)
- Alkaline phosphatase
- Hepatitis B & C
- Lyme disease
- Celiac screen
- Autoimmune and rheumatology screens
- Pituitary and adrenal function
Please, note that the above tests are ones recommended to be performed by your primary care physician or family doctor. This is the most basic blood panel to be run. It rules out the severe infections. It is by no means a comprehensive panel from a functional perspective.
After ruling out the above markers, I recommend working with a knowledgeable functional medicine practitioner who can order blood and serum markers that are specific to chronic fatigue syndrome.
How is chronic fatigue syndrome diagnosed?
Prior to 2015, chronic fatigue syndrome was a disease of exclusion. That means it was diagnosed if all your other lab markers for other disease/illness come back in normal ranges. Assuming your above lab results fall within normal ranges, an individual was said to have chronic fatigue syndrome (prior to 2015 criteria) if she presents with three main symptoms: (5)
- Severe, persistent fatigue
- This must be present for six or more successive months.
- The fatigue must be present 50% of the time or more.
- The fatigue must notably affect the patient’s daily physical and work routine.
- The patient must have at least 4 concurrent symptoms from the below list:
- Neurocognitive issues
- Memory loss
- Clumsiness
- Difficulty concentrating or thinking
- Non-refreshing sleep or sleep issues
- Muscle or joint pains without swelling or inflammation
- Headaches
- Painful or tender lymph nodes
- Frequent sore throat
- Mental fogginess
- Low blood pressure
- Aggravated allergy symptoms
- seasonal, food, or, environmental
- Irritable bowel syndrome
- Night sweats
- Chronic or long-lasting cough
- Palpitations or escalated heart rate
- Recurring flu-like illness
- Undetermined reasons for weight change
- Neurocognitive issues
Unfortunately, doctors weren’t performing robust diagnostic tests to rule out other illnesses. Instead, chronic fatigue was a diagnosis given out of convenience for the physician. Fortunately, in 2015, the diagnostic criteria were revamped. Chronic fatigue syndrome (CFS) or systemic exertion intolerance syndrome (SEID) as it is now referred to, is diagnosed through the following rubric: (6)
You must have the following three symptoms:
- A substantial reduction or impairment in the ability to engage in pre-illness levels of occupational, educational, social, or personal activities that persists for more than six months and is accompanied by fatigue, which is often profound, is of new or definite onset (not lifelong), is not the result of ongoing excessive exertion, and is not substantially alleviated by rest;
- Post-exertional malaise
- Unrefreshing sleep
You also must have one of the following two symptoms:
- Cognitive impairment
- Orthostatic intolerance
As with previous definitions, your symptoms should be present for at least six months and have moderate, substantial, or severe intensity at least one-half of the time. Other criteria include post-exertional malaise, sleep problems, cognitive impairment, and orthostatic-related symptoms.
The new diagnostic criteria are intentionally restrictive. The thought is that the restrictive nature of the diagnostic criteria will maximize the chance physicians correctly identify other illness(es) that are causing fatigue before diagnosing CFS or SEID. (7)
Who is affected by chronic fatigue syndrome?
Chronic fatigue can affect men, women, and children. Though it affects women nearly 2x as frequently as men. This is thought to be due to the fact that women are much more likely to report the above symptoms to their doctor. Due to cultural stereotypes, it is thought that men are hesitant to report fatigue, headaches, and/or joint pain to their physician.
Chronic fatigue syndrome is quite rare in children. It is most prevalent between the ages of 40-50. CFS is more likely to occur in children if one of their parents also suffers from CFS. The diagnostic criteria for children are different than it is in adults. For example, in children, fatigue only needs to be prevalent for three months (6 months in adults). Should you suspect your child is suffering from chronic fatigue syndrome, a pediatrician knowledgeable in both functional medicine and chronic fatigue syndrome should be consulted!
What causes chronic fatigue syndrome?
Is chronic fatigue syndrome a psychiatric disorder? Or, an infection? Maybe it’s genetic?
At the time of this writing, there is no known cause of chronic fatigue. There are many theories that offer partial glimpses into what may be causing chronic fatigue syndrome. The following series of posts will address the most popular suspects. Click the below link for a deep dive into each of the potential causes of chronic fatigue syndrome:
What Causes Chronic Fatigue Syndrome? – Part II: The Epstein-Barr Virus & Other Infections
What Causes Chronic Fatigue Syndrome? – Part III: Genetics
What Causes Chronic Fatigue Syndrome? – Part IV: Hormones
What Causes Chronic Fatigue Syndrome? – Part V: A Functional Medicine Approach
