How is the cause of fatigue diagnosed?
The key to finding the cause of fatigue in a patient is the care the health care professional takes in compiling a medical history. It is important to ask questions not only about the loss of energy but also about other potential problems that the patient may be experiencing such as shortness of breath, sleep patterns, hair loss, color of the stools, or any of the myriad of questions that might provide information as to what organ system may be involved.
Usually, a history is taken by the health care professional asking questions about the quality and quantity of fatigue. Examples of some of the questions the health care practitioner may ask include:
- Does the patient feel well in the morning when they wake?
- Does the fatigue progress through the day?
- Does the person nap unexpectedly or take excessive amounts of stimulants
such as caffeine to complete daily activities?
- Does the fatigue come on gradually or abruptly?
- Is it a daily occurrence or intermittent/periodic?
- What makes it better and what makes it worse?
- How has the patient's life changed because of the fatigue?
- Is the fatigue more mental than physical?
Other associated symptoms with fatigue include:
- weight loss,
- chest pain and shortness of breath,
- vomiting and diarrhea,
- fevers and chills,
- muscle weakness or pain, and/or
- anxiety and depression.
It is also appropriate for the health care professional to ask questions about the patient's social situation and to also ask about their psychologic state of mind. Alcohol and drug abuse screening questions should be expected as routine.
Because fatigue is such a non-specific symptom, each answer may direct the health care professional to explore a different potential cause.
A full physical examination is important to look for underlying signs of illness. The general appearance of the patient is important looking for hygiene, vital signs, and evidence of anxiety or agitation. Examination and evaluation of the different systems of the body (heart, lungs, abdomen, neurological system, etc.) and combining any abnormal findings with the clues found in the history taking may help make the diagnosis.
Special attention may be taken to palpate (feel) for an abnormal thyroid gland, swollen lymph nodes, listen for abnormal heart sounds including murmurs and to check for normal muscle tone and reflexes.
Depending on the findings in the history and physical examination, blood tests and other imaging studies may be ordered. Initial screening blood tests may include:
- CBC (complete blood count that includes a red blood cell, white blood cell and platelet count);
- electrolytes (sodium potassium, chloride, carbon dioxide, and sometimes calcium and magnesium);
- glucose (blood sugar);
- BUN/creatinine (to measure kidney function);
- TSH or thyroid stimulating hormone;
- tests for deficiencies in vitamins B12, D, folic acid, and iron;
- CPK (elevated in illnesses that cause muscle inflammation); and/or
- ESR or erythrocyte sedimentation rate (non specific blood marker for inflammation in the body).
CPK and ESR screening tests are rarely done initially. The decision to obtain X-rays, CT scans, electrocardiogram (ECG, EKG) and other imaging or testing will depend upon the individual patient's circumstances and what the health care practitioner suspects may be the underlying cause of the fatigue.