Introduction to Clinical Medicine

Author: China Medical Science Press
Publisher:
Publish Date: 2003-02-01
Features: This book is divided into 12 chapters. Chapter is the foundation of the course content in this textbook, introducing common clinical symptoms, physical examinations, and diagnostic methods, with a focus on laboratory tests for various symptoms. Chapter 2 covers emergency medicine, Chapter 3 introduces infectious diseases (including sexually transmitted diseases), and Chapters 4 to 12 systematically present common clinical diseases in internal medicine, surgery, obstetrics, and pediatrics. Each disease is elaborated on according to etiology, pathology, clinical manifestations, laboratory and ancillary examinations, diagnosis, prevention, and treatment, with particular emphasis on the clinical significance and role of laboratory tests, reflecting the content characteristics of medical laboratory professional textbooks. This book is intended as a specialized textbook for clinical medicine for full-time medical laboratory majors, as well as a teaching material for adult education in medical laboratory (e.g., vocational colleges, evening schools, correspondence courses), or for reference use by other medical personnel. Excerpt: Chapter Common Symptoms When a person is ill, subjective discomfort or abnormal sensations are called symptoms (symptom), such as headache, fatigue, fever, and shortness of breath; while abnormal findings observed through objective examinations are called signs (sign), such as hepatosplenomegaly, heart murmurs, and lung rales. Broadly speaking, symptoms also include signs. Some symptoms are both symptoms and signs, such as fever and shortness of breath. There are many symptoms of diseases, and the main symptoms are important clues for diagnosis. This section only elaborates on some common and relatively important clinical symptoms. I. Fever The normal body temperature of a person is kept relatively constant under the regulation of the hypothalamic body temperature control center. The oral (sublingual) temperature is generally between 36.3 and 37.2°C, the axillary temperature is about 0.2 to 0.4°C lower than the oral temperature, and the rectal temperature is about 0.3 to 0.5°C higher than the oral temperature. When the body temperature regulation function is impaired, leading to a rise in body temperature beyond the normal range, it is called fever (fever). Based on oral temperature, clinically, 37.4 to 38°C is considered low-grade fever, 38.1 to 39°C is moderate fever, 39.1 to 41°C is high fever, and ≥41.1°C is hyperpyrexia. (I) Causes and Mechanisms of Fever There are many causes of fever, in addition to certain physiological reasons (such as mental tension, intense exercise, early ovulation and pregnancy), they can be divided into the following two major categories: 1. Infectious Fever Diseases caused by various pathogens, such as viruses, bacteria, fungi, spirochetes, rickettsiae, mycoplasmas, chlamydiae, and parasites. 2. Non-infectious Fever Mainly include: ① Absorption of sterile necrotic substances, such as after major surgery, internal bleeding, and extensive burns; ② Allergic reactions, such as rheumatic fever and serum sickness; ③ Endocrine and metabolic diseases, such as hyperthyroidism and severe dehydration; ④ Reduced skin heat dissipation, such as generalized dermatitis and heart failure; ⑤ Seizures, epilepsy, etc.; ⑥ Dysfunction of the body temperature regulation center, such as heatstroke, severe sedative poisoning, cerebral hemorrhage, and cerebral concussion; ⑦ Autonomic nervous system dysfunction. Substances that can cause fever in the human body are called pyrogens. Pyrogens are divided into exogenous and endogenous. Biological pathogens, antigen-antibody complexes, inflammatory exudates, and sterile necrotic substances are complex and collectively referred to as exogenous pyrogens, most of which are large-molecule substances and cannot directly act on the body temperature regulation center through the blood-brain barrier. Exogenous pyrogens mainly activate neutrophils and monocytes, causing them to produce endogenous pyrogens, such as interleukin-1, which have a smaller molecular weight and can pass through the blood-brain barrier to act on the body temperature regulation center, increasing heat production and reducing heat dissipation, thereby causing fever. In recent years, new endogenous pyrogens such as interferon and tumor necrosis factor have also been discovered. Fever caused by excessive heat production (such as hyperthyroidism and seizures), reduced heat dissipation (such as generalized dermatitis), and body temperature regulation disorders (such as heatstroke and cerebral hemorrhage) are non-pyrogenic fevers. (II) Clinical Manifestations 1. Fever Process Generally, fever is divided into three stages: (1) Stage of Temperature Rise There is often fatigue, muscle aches, pale skin, chills or shivering. There are two forms of temperature rise: ① Sudden Rise: Body temperature rises sharply and reaches its peak within hours, seen in influenza, malaria, and pneumococcal pneumonia; ② Gradual Rise: Body temperature gradually rises and reaches its peak after several days, seen in tuberculosis and typhoid fever. (2) Stage of High Fever It refers to the period when body temperature rises to its peak and remains at a certain level, lasting for several hours, days, or weeks. It is characterized by flushed and hot skin, accelerated and deepened respiration, and sweating. (3) Stage of Temperature Decline Due to the body's own defense functions and appropriate treatment, body temperature returns to normal, and the decline in body temperature also has two ways: ① Sudden Decline: Body temperature drops to normal within hours, accompanied by profuse sweating, such as in pneumococcal pneumonia and malaria; ② Gradual Decline: Body temperature gradually returns to normal within days, such as in typhoid fever and rheumatic fever. 2. Fever Pattern (1) Continuous Fever Body temperature remains around 39–40°C, with a fluctuation range of no more than 1°C within 24 hours, lasting for several days or weeks, seen in the high fever stage of pneumococcal pneumonia, typhoid fever, and typhus. (2) Remittent Fever Body temperature is above 39°C, but the fluctuation range within 24 hours is more than 2°C, generally still above the normal level even at the lowest temperature, seen in suppurative diseases, sepsis, and severe tuberculosis. (3) Intermittent Fever Alternating periods of high fever and no fever appear. During high fever, body temperature can reach above 39°C, and after several hours, it drops to normal. After an interval period (several hours or days), it suddenly rises again, seen in malaria and acute pyelonephritis. (4) Recurrent Fever Body temperature rises sharply to above 39°C and then suddenly drops to normal after several days. The high fever and no fever periods each last for several days, and this repeats multiple times, seen in recurrent fever and Hodgkin's disease. (5) Wave-like Fever Body temperature gradually rises to above 39°C and then gradually declines to low fever or normal levels after several days, repeating this process multiple times, seen in brucellosis. (6) Irregular Fever Fever has no specific pattern and can be seen in tuberculosis, rheumatic fever, and bronchopneumonia. (III) Laboratory and Ancillary Examinations 1. Blood Routine Most bacterial infections cause leukocytosis and neutrophil elevation; typhoid fever, malaria, and viral infections result in normal or decreased white blood cell counts; leukemia and leukemoid reactions cause extremely increased white blood cells, with primitive cells and immature cells appearing in the periphery; parasitic diseases and allergic diseases cause eosinophilia; prolonged fever caused by infection may lead to anemia. 2. Coagulation Mechanism Severe infections, such as meningococcal and gram-negative bacillary sepsis, can cause thrombocytopenia, with severe cases potentially leading to disseminated intravascular coagulation. 3. Urinalysis Mild proteinuria may occur during fever; significant proteinuria with hematuria or pyuria may be seen in urinary tract inflammation, renal tuberculosis, and renal tumors. 4. Stool Examination Pay attention to appearance, eggs, and bloody or purulent stools. 5. Bacteriological Examination Blood culture, bacterial culture of sputum, urine, and pus should be performed targeting the pathogen. 6. Serological Examination Serological tests have certain value in the diagnosis of fever, such as the Widal test, Weil-Felix reaction, and the streptolysin O test for rheumatic fever. 7. Bone Marrow Examination It has diagnostic value for leukemia, malignant reticulosis, etc. 8. X-ray Examination It has important value in the diagnosis of fever. Pulmonary inflammation and tuberculosis are common causes of fever, so chest X-rays or fluoroscopy should be paid attention to. 9. Ultrasound Examination It is commonly used for the examination of pleural effusion, subphrenic abscess, biliary diseases, and liver abscesses.