Several physiologic systems are located within multiple body regions and are assessed continuously during the exam. Diseases of these systems most commonly present with nonspecific constitutional symptoms and recognition depends on integrating all exam findings. This concept is captured by the saying “he who knows syphilis knows medicine.”
Constitutional symptoms are those that relate to the body or a person as a whole. They are combined with physical exam and laboratory findings to make 1–3 general physiologic hypotheses. For example, a middle-aged patient presenting with anorexia, weight loss, and night sweats suggests neoplasm, chronic infectious or inflammatory disease, or possibly Addison disease.
Fatigue results from serious organic disease, mood disorders, or deconditioning. Patients describe decreased energy and endurance during usual activities. Clinical fatigue incorporates three components, present to variable degrees in individual patients: inability to initiate activity (perception of generalized weakness in the absence of objective findings); reduced capacity to maintain activity (easy fatigability); and difficulty with concentration, memory, and emotional stability (mental fatigue). It is important to distinguish fatigue from shortness of breath, muscle weakness, and sleepiness. Fatigue can complicate any chronic disease, e.g., anemia, hypothyroidism, hyperthyroidism, and autoimmune or neurologic disorders. DDX: History should determine the severity and temporal pattern of fatigue as follows: Onset—abrupt or gradual and relationship to an event or illness. Course—stable, improving or worsening, duration and daily pattern, factors that alleviate or exacerbate symptoms, and impact on daily life. Symptoms suggesting underlying occult medical illness should be explored in a detailed review of systems, including presence of weight loss or night sweats. The history should include screening questions for psychiatric disorders (particularly depression, anxiety disorders, somatoform disorders, and substance abuse). When a complete history, physical examination, and screening laboratory evaluation do not find a specific explanation, consider deconditioning, depression, sleep disorders, and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).
CLINICAL OCCURRENCE: These are examples only and not meant to be all-encompassing. Congenital: Muscular dystrophies, mitochondrial myopathy; Endocrine: Hypothyroidism, hyperthyroidism, Addison disease, hypopituitarism, hypoparathyroidism, hypogonadism; Degenerative/Idiopathic: ME/CFS, inclusion body myositis, amyotrophic lateral sclerosis, multiple sclerosis, dementia; Infectious: Tuberculosis, infectious mononucleosis, hepatitis, following other viral illnesses, hookworm infestation, HIV infection; Inflammatory/Immune: Systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), polymyositis, dermatomyositis, vasculitis, myasthenia gravis; Metabolic/Toxic: Hypokalemia, hypocalcemia, hypomagnesemia, hyponatremia, anemia, uremia, hypoglycemia, congestive heart failure, drugs (e.g., β-blockers, sedatives, opioids, anticholinergics), alcohol; Neoplastic: Acute and chronic leukemia, myelodysplastic syndromes, myeloproliferative syndromes, solid tumors, lymphomas; Psychosocial: Disordered sleep, depression, deconditioning, overwork and overtraining, insomnia, chronic anxiety; Vascular: Claudication, strokes.
Appetite is controlled by the hypothalamus under the influence of multiple hormones, metabolites, neural afferents (especially vagal visceral afferents), and cortical inputs reflecting emotional and cognitive state. Disturbances in any of these systems change appetite.