Alberto J. Muniagurria 

Fatigue is one of the most frequent symptoms of medical practice. It generally accompanies other symptoms and signs and is part of syndromes or clinical pictures.

It is integrated within medical or psychiatric illnesses. There are authors who think that the terms should be separated to better understand the problem. On the one hand, there is talk of fatigue, lassitude or languor, which tries to define a lack of energy or general decline that alters the state of normality of the individual. On the other hand, it is called weakness, asthenia, or loss of strength (paresis) when it refers to a loss of strength, with decreased muscle capacity, which can be measured.

The fatigue or lassitude is normal appearance when it occurs after a day of work or intense physical effort, even if they correspond to a normal activity.

It can also occur as a response to an unusual activity for the individual, such as sports practice outside of training. It can also appear as a consequence of prolonged emotional tension or serious concern. In the circumstances that have been mentioned the causes of fatigue are obvious and clear to the individual, and therefore he will rarely go to the doctor for help for these reasons. When fatigue or lassitude is no longer an expected response and becomes a chronic situation, and is also no longer related to clear triggers, it may not be a normal state and some underlying pathological reason must be considered.

The cause of fatigue can be a physical illness, although it is more frequently caused by a mental illness. According to some authors, 39% of the cases would have their origin in an organic disease, 41% in a psychiatric picture and in 8% there would be no clear origin. Other authors, perhaps closer to practical reality, speak of 80% of psychic origin and 20% of origin in organic diseases. In the series of a community hospital in the United States there is talk of 75% of anxious neurosis and tension symptoms and 10% of depressive symptoms; the remaining 15% would be physical organic pictures.

Among the psychological causes that most frequently present with fatigue are depression and anxiety. Regarding the fatigue that accompanies the symptoms originated in non-psychic conditions, infectious, metabolic, blood, kidney, liver, lung, cardiovascular, neoplastic and neurovascular diseases, as well as the secondary response to drugs should be mentioned (Table 7 -1).

Physiopathology of fatigue 

Why fatigue or lassitude develops is not fully understood. It also creates difficulty in differentiating normal fatigue from fatigue that responds to an organic physical or psychological cause.

It does not always represent an unpleasant sensation because it can sometimes be pleasant, especially when it is related to the immediate possibility of a good rest.

Attempts have been made to link emotional tension and stress with the generation of fatigue or lassitude. Stress is a type of human response to the environment or interaction between the perception of the environment by the individual and its response mechanisms In special situations this interaction generates stress in humans. In some people, but not so in others.

Studies have been carried out in patients under stress who have had their blood levels of catecholamines and corticosteroids measured, observing a marked variation between the different individuals, which would demonstrate that the environmental situations would be the same and that what would vary would be the response of each individual to that stimulus. In other words, it is concluded: 1) stress causes elevation of catecholamines and corticosteroids in patients; 2) elevation occurs in some, but not others, that is, there is individual variation, and 3) it is the individual's responses that vary and not the environmental stimuli.

If the stimulus or the situation is repeated, the same elevation of corticosteroids does not occur, but the increase in catecholamines does. This may explain the effects of sustained or chronic anxiety.

The increase in catecholamines responds to an acceleration of the heartbeat, with an increase in blood pressure and an acceleration of metabolism, increased neuromuscular activity and increased oxygen consumption. On the other hand, it is known that in the normal individual the greater muscular activity, when there is exercise, determines the glycogen depletion of the muscle with accumulation of lactic acid, which alters its normal functioning. If muscle activity is maintained, muscle fibers become necrotic. This will be more marked if the individual is not trained.

The feeling of tiredness, maintain some authors, would come from the acidosis existing at the level of the muscular fiber. Research has been carried out with beta-blocking drugs that prevent the action of catecholamines at the cellular level, reducing the feeling of fatigue after stress.

Sleep has a restorative effect on fatigue. Sleep deprivation produces a state of autonomic excitement with the appearance of symptoms such as decreased alertness, vigor, progressive confusion and fatigue. In other words, it would be another mechanism that would influence the generation of fatigue. In the depressed or anxious patient, the decrease in their hours of sleep is characteristic.

From the point of view of psychoanalytic theories, the adult individual would be permanently in a fight trying to restrain his primary instincts of desires, sexual impulses, aggressions and appetites. This permanent brake would take place in order to allow it to function within the limits or within the limits imposed by society. The narrower these Emites, the greater efforts will be required to curb the impulses. This work generates conflicts, which are manifested through anguish and its courtship of symptoms. Anguish is expressed as phobias or fears and compulsions. One way to escape from that anguish, from those fears, would be through the feeling of fatigue, since being exhausted does not allow impulses or unacceptable desires to arise.

There are other theories to explain these phenomena, one of which suggests that through fatigue the individual can evade the responsibility or the demands that society imposes on him; that is, it would be like an abnormal learning mechanism that teaches which is the most logical method to respond to demands, or to attract attention, or gain affection and understanding. It would be a reflection similar to that described by Pavlov. Other authors link organic psychic fatigue with genetic predisposing factors or experiences of childhood life.

Fatigue of organic or physical origin would be explained, in infectious processes, by the hypermetabolic state that exists in these patients. There is an increase in the consumption of oxygen by the tissues, which is added to the lack of appetite, which does not help to replace the existing metabolic losses. Endocrine alterations would generate hypermetabolism symptoms with increased energy consumption, loss of electrolytes, exaggerated protein catabolism and difficulty in using various nutrients.

On the other hand, the depression picture that precedes in several months the presentation of pancreatic cancer is classic. Cancer can cause a decrease in the nutrition of the patient by neoplastic invasion of the gastrointestinal tract or loss by fistulas or drains. The paraneoplastic processes would act by the action of hormones through 'mechanisms similar to those previously explained. Anorexia and loss of smell and taste in these patients are also involved, which decreases their appetite. There is evidence that there is an increased basal metabolism and energy consumption in malignancies.

Kidney diseases cause retention of toxic substances, which reduces the appetite for food. Cardiopulmonary diseases, in turn, provide insufficient oxygen supply to the tissues. Drugs work by producing toxic effects at the cellular level.

General weakness or asthenia. It is demonstrated by a clear decrease in normal forces linked, in general, to disorders of the nervous and muscular system. In hysterical patients, a superposition of generalized and localized loss of forces can be seen, which requires recognition in order to differentiate it from that produced by organic symptoms.

The blamed clinical processes of fatigue and lassitude, if intensified, can lead to objective motility losses that will be discussed in the corresponding chapter.

Questioning of the symptom

Much can be learned by obtaining a medical history of a patient who presents with lassitude, fatigue or languor as a reason for consultation. The patient will report that he is "tired", "exhausted", that he is "done", "ironed", "exhausted", "crushed", "busted" or "screwed".

Because, as has been described, the psychic origins of this symptom are the most frequent, it is necessary to internalize his affective and emotional life. You should also ask about the associated symptoms and signs, such as insomnia, anorexia, weight loss, other diseases, personal history, etc.

The anxious and depressed patient generally get up as tired in the morning as they go to bed at night. Actually, sometimes they get better with the day. There are trigger situations that can increase the feeling of tiredness, such as facing phobia-generating situations.

The depressive generally complains that, despite fatigue, he does not sleep the necessary hours, he wakes up early and stays in bed for a long time without being able to fall asleep again. You feel weak to face new situations and even your usual tasks.

You may have thoughts of suicide, sexual impotence, a deep sadness. Sometimes the picture is linked to the loss of a close family member or friend, problems in business or work, or critical ages such as adolescence, menopause, or old age. There may be loss of interest in your surroundings. You may cry frequently.

Something bad happens in your mind and body and it is the responsibility of the doctor who interviews you to know how to differentiate it, and this is what the patient suggests. Questions should be asked about the onset and evolution, the factors that improve and aggravate it, whether there is a history of something similar in your life or a family history of the same condition. In turn, it should be found out if the situation alters the normal functioning of the patient's life.

It is just as important to spend time with this type of individual to obtain complete information from them as to gain their trust and open them up to questioning. The doctor-patient relationship must be very close in order to obtain data on the type of person being interviewed. The family should also be questioned to assess their behavior towards them, which can provide unsuspected clues to the medical history.

The feeling of fatigue of organic psychic origin or organic depressive is not accompanied by special physical signs. The patient looks sad, lazy, with the expressionless, tearful gaze. He speaks in a low, monotonous, monotonous voice, which bores the interlocutor. The facies is of sadness, of an individual locked in his thoughts. Thorough clinical and neurological examination is required.

Each of the symptoms and signs that usually accompany fatigue should be explored on questioning and on physical examination, which guides one of the diagnoses in Table 7-1.

Study methodology

Assessing a fatigued patient requires careful follow-up of the medical history and physical examination. Once this is completed, the laboratory evaluation, radiology and special techniques that lead to the diagnosis can be carried out.

In general terms, it can be said that it is appropriate to request a complete blood count, erythrocyte sedimentation, uremia, glycemia, and a glucose tolerance curve, analysis of urine, transaminases, alkaline phosphatase, proteinogram by electrophoresis, calcernía, fosfatemia, sodium, potassium, chlorine and magnesium, dosage thyroxine, triiodothyronine, thyrotropic and cortisol. In turn, chest x-rays and profile, electrocardiogram, blood and urine cultures must be obtained, as well as specific analyzes for infectious diseases. Consultation with the psychiatrist should then be made.