Fatigue: A Medical Approach to Discovering the Cause

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One of the more common complaints that I hear from patients is the subjective feeling of being “fatigued” or “tired all the time”, often accompanied by the complaint – “I just don’t have much energy anymore”.  This is always a very difficult complaint to assess because there are so many potential causes and directions that can be taken when hunting for the underlying diagnosis.   It is also a condition that frustrates patients to no end (understandably), making them hunger for a quick solution.  Oftentimes the patient already has visited more than one physician looking for a cause, though often such symptoms are minimalized or never fully addressed.

Getting to the root cause of fatigue is a process, a process that begins by taking a good history and performing a thorough physical exam.  I will ask my patients several probing questions, some of which they may think irrelevant, but need to be answered anyway.  I do this in order to get a handle on what the patient might mean when they use that term, for, the concept and use of the term “fatigue” can be open to interpretation.  It is an inherently vague term, where any two people can define the idea entirely differently.

I always want to know when the fatigue began, was its appearance gradual or sudden, and is it more of a sleepy/tired type feeling or more of a lack of motivation or “want” to get up and do things.  Are there any feelings of depression/sadness or anxiety accompanying the fatigue?  I will also want to know if there is any shortness of breath with exertion, this then potentially making them less active and mimicking true fatigue.  If that be the case, then the core issue really isn’t the fatigue but rather the shortness of breath, which opens up an entirely different diagnostic avenue.  As answers are given I can then direct the questioning into a more specific and appropriate direction from there.

So then, you may be wondering, what ARE the most common causes of fatigue?

By far the most common cause of “fatigue” is going to be OBSTRUCTIVE SLEEP APNEA(OSA). I can say this with confidence because the prevalence of sleep apnea is so high in America (around 20% among men in the US, women a little bit less than that, though the elderly can be up closer to 50%)1, most cases of which are presently remaining undiagnosed and unaddressed.   This is of course directly related to the epidemic of obesity that we have going on in this country.   The main symptoms of OSA are daytime sleepiness, morning headaches, and the sense of never feeling rested/always feeling tired and sleepy.  I will often want a sleep study performed if these symptoms are present.  If OSA is proven by sleep study then a CPAP device (which delivers continuous, positive airway pressure keeping the airway open and oxygenated) MUST be worn at night while sleeping (as the patient tries to lose weight as well), for if the OSA is diagnosed but still not treated it will become the “elephant in the room” and the fatigue will persist no matter what else we try.  It must be treated, or the fatigue may never resolve.

A less common but often underdiagnosed cause of fatigue is NARCOLEPSY WITHOUT CATAPLEXY, which means that such patients can feel on the verge of going to sleep all the time and/or especially when just sitting at a desk without any external stimulation, though are still able to keep themselves awake with effort.  Not every narcoleptic patient will go to sleep without warning (cataplexy) – such examples are only the extreme and more memorable versions of this disorder.  A multiple sleep latency test helps get to the diagnosis, which measures how quickly the brain starts progressing into sleep rhythms in a quiet environment during the day.

Another common cause of fatigue is the one that many patients worry about and that I will certainly always check for in this setting – and that is HYPOTHYROIDISM.  This is also a very common condition that usually results from autoimmune antibodies attacking the thyroid tissue and causing it to produce less thyroid hormone, which can lead to feelings of fatigue, sadness, constipation, hair loss, leg swelling, etc.  Blood work will always be performed when working up fatigue, and this will be one of the conditions I am looking for.

Other causes of fatigue that can be picked up in the bloodwork (and will be part of a panel when searching for causes of fatigue) include ANEMIA (blood/iron loss being the most common cause – either via the GI tract or menstrual-related; also B12 anemias are prevalent), other AUTOIMMUNE DISEASES (like lupus, rheumatoid arthritis, mixed connective tissue disease, gluten allergy/enteropathy, Wegener’s granulomatosis and diseases like it where the anemia and systemic inflammation that they cause can be the primary cause of the fatigue, etc), and VITAMIN DEFICIENIES(including Vitamin D deficiency and B12 deficiency, where Vitamin D deficiency is very common in America and has been associated with chronic fatigue2).

Another important factor in chronic fatigue is of course – OVERSEDATION from POLYPHARMACY(too many medications).  This is a very common cause of fatigue, particularly when patients are having to take pain medication (like opiates and/or muscle relaxers) and/or sleeping medication (like benzodiazepines or other sedative/hypnotics like Ambien).  Of course, if more than one of these medications are taken together this can really increase the likelihood of fatigue (and other consequences, including death!).  Because of this I am always trying to encourage patients to back off the dose/quantity of any opiate or sedative/hypnotic medication that they may be taking (the ultimate goal being to discontinue them altogether).  Overuse of alcohol would fit into this category as well, another sedative agent.

A potential cause of fatigue that patients often worry about (because they may have heard about it from a friend or read about it on the internet) but that is very rare and unlikely to be the case – is LYME DISEASE (a tick-born spirochete infectious disease).  I bring it up here only to discourage patients from worrying about this one, namely because of its rarity.  Other general symptoms can be associated with the fatigue (including headaches, arthritis, muscle pain and rashes) and when a patient has more than one of these occurring in tandem they can often jump to the conclusion that they have Lyme Disease.  The work-up for it can be misleading because the antibodies (when checked) can return positive but yet still represent a false positive (there is a high false positive rate using Lyme antibodies), further confusing the picture.  There must be a very specific history with a very specific rash to diagnose Lyme Disease accurately, and without everything in place it is folly to pursue this diagnosis too aggressively.  The rarity of this disease (especially in Texas) makes it an avenue to go down only in the most specific of circumstances.

Certainly, other INFECTIOUS DISEASEScan be considered, although a good/thorough history and exam taken from and performed on the patient will help determine whether this path of diagnosis needs to be pursued and, if so, in which direction.   This would apply to work-ups for potential MALIGNANCY (CANCER)as well, which certainly can cause fatigue.  There will be signs in the bloodwork (including anemia) that might indicate the need to go down this path as well.

So, in the end, in order to do a really good job of getting to the root cause of fatigue (where of course correcting that root cause is the only way to resolve the fatigue), the physician must spend enough time with the patient to take a thorough history and perform a complete exam, so that any testing he does can be focused in on what matters.  The problem is that many primary care doctors live in a rushed, fast-paced world, where taking the time that is really needed to get to the bottom of any problem in an efficient and cost-effective process is virtually impossible.  As such, often a shotgun approach is taken where several things are checked for at once but without any individualized reasoning or intentionality; and/or the patient’s fatigue is marginalized and the physician thinks to himself “I’ll deal with that next time because this time I need to focus on the more important issues at hand”.

Fortunately, the concierge setting in which I operate allows for ample time to take a thorough history and formulate a plan that takes into account everything going on with that specific patient so that an individualized diagnostic approach can be taken.  This helps arrive at the diagnosis in a more effective and efficient manner, so that a solution can be rendered more quickly (where many times the solution takes some time to be implemented and render full effect, meaning that getting the problem diagnosed quickly is paramount).  Also, in the end, less money is spent on diagnostics when a very specific and intentional course of action is taken that is fully based upon an accurate and thorough medical history and exam, tailored to a specific patient’s very specific problem(s).

As such, if you are ever facing a symptom or symptoms that leave you perplexed and/or that no one has yet to be able to ascertain the cause of, I would encourage you to give me a call (972-993-5003).  I can devote as much time as is needed to assess your symptoms, take a thorough history, perform a comprehensive exam, and formulate an intentional diagnostic and eventual therapeutic plan.   When it comes to a complaint of “fatigue” such an approach MUST be taken for, because so many things can cause it (both benign and easy to fix as well as insidious and ultimately deadly), the symptom must be taken seriously and dealt with immediately, in a very thorough and well-thought-out manner.




  1. https://www.ncbi.nlm.nih.gov/pubmed/27568340
  2. https://bmjopen.bmj.com/content/7/11/e015296