The eight principles (category of syndromes) differentiation is the foundation of basic diagnostic methods, including Yin, Yang, exterior, interior, cold, heat, deficiency, and excess. Using these differential diagnostic tools, one may determine the pathogenic factors (heat or cold), the location (interior or exterior), the situation between lack of anti-pathogenic Qi (deficiency) and of pathogenic factors (excess), and the overall category of diseases (Yin or Yang), based on a comprehensive analysis of all the information obtained by means of Four-Pillars diagnosis. According to the eight principles, the correct diagnosis is the foundation for all the other methods.
The eight principles are the most basic method for differentiating syndromes. They can define the fundamental features of any disease, elucidate contradictory symptoms or signs, and simplify the treatment principle. The essential principles for differentiating syndromes for the procedure of diagnosis are not simply isolated into eight categories, but interrelated.
Pathological changes occur at one time, but different syndromes occur simultaneously. Thus, it is necessary to know not only the characteristics of each syndrome, but also their simultaneous occurrence, transformation, interrelatedness, and true or false conditions to make a correct diagnosis.
Syndrome Differentiation on Yin and Yang
Yin and Yang are the principles for categorizing diseases and are the leading ones in the differentiation of syndromes. The Basic Questions (Great Treatise on the Correspondences and Manifestations of Yin and Yang) states, “Yin and Yang are the law of heaven and earth, the outline of everything, the parents of all changes, the origin of birth and destruction, and the source of all configurative forces with mysteries. A good treatment for a disease is to seek its nature or root cause.”
The book titled Complete Works of Jingyue states, “Although there are many theories of medicine, the one term that sums up all the theories is Yin–Yang.” Clinically, syndromes are always of two patterns — Yin or Yang — but syndromes vary and are changeable. For diagnosis, Yin and Yang must be differentiated first. Exterior syndromes of heat and excess conditions are classified as Yang syndromes, while interior syndromes of cold and deficiency conditions are classified as Yin syndromes. The eight principles are arranged into two outlines and six essentials, as follows:
Yin syndrome and Yang syndrome
Yin syndrome manifests as a weakening of Yang and leads to cold syndrome. It also belongs to deficiency and interior syndromes. There are linked deteriorative symptoms, such as a weak pulse, a pale tongue with white fur, lassitude, paleness, a dull complexion, dispiritedness, fatigue, slow movements, cold limbs, chills, or a bland taste without thirst.
The manifestations of Yang syndrome are external and heat. It often pertains to a flushed complexion; a dark-red tongue with a crimson, thorny coating; a rolling, rapid or slippery, forceful pulse; feverishness with a preference for cold; restlessness; agitation; harsh breathing and a loud voice; forceful movements; a dry mouth with thirst and a preference for cold drinks; scanty, deep, yellow urine; or foul stools.
Syndrome of Yin deficiency or Yang deficiency
According to Chinese philosophy and TCM, Yin and Yang are closely related, combined, and opposite of each other, but “Yang is dominant and Yin is submissive” . This requires, as emphasized by Zhang Zhongjing about 2000 years ago, that all doctors should pay more attention to the condition of Yang-Qi. The treatment should be based on supporting the Yang-Qi to survive the Yin essence.
Yang deficiency syndrome appears from cold of insufficient Yang-Qi to control Yin. The manifestations are most Yin syndromes, such as a slippery tongue coating, deep slow weak pulse, a pale complexion, dispiritedness, cold limbs, chills, listlessness, spontaneous perspiration, dizziness, weak legs, impotence, premature emissions, a diminished sense of taste, poor appetite, a moist mouth without thirst, or thirst with a preference for hot drinks, clear polyuria, loose stools, and thin pale lips.
Yin deficiency syndrome appears from heat symptoms of insufficient Yin to control Yang, hence resulting in shortage of Yin fluid. The manifestations are insufficient vital essence, such as a deep-red tongue with a scanty coating and a thin rapid pulse, emaciation, dry mouth and throat, a tidal fever in the afternoon, or even a burning sensation on the palms, soles and chest, dizziness, night sweats, nocturnal emissions, flushed cheeks, lumbar weakness, palpitations, insomnia, blurred vision, and ringing in the ears.
Depletion of Yin and Yang
Collapse of vital essence (Yin) is called “depletion of Yin,” whereas collapse of Yang-Qi is referred to as “depletion of Yang.”
Kidney essence and Yang-Qi are also known as “primary Yin” and “primary Yang,” thus, depletion of Yin and depletion of Yang are closely related to impairment and collapse of the vital essence and Yang-Qi of the kidney, resulting from chronic or acute diseases. For example, a lasting high fever, profuse sweating, severe vomiting, or massive blood loss may all lead to the depletion of Yin and depletion of Yang with the following symptoms:
Depletion of Yin refers to the critical condition of severe exhaustion of Yin fluid. The manifestations are a dry reddish tongue, a fine rapid forceless pulse, salty and sticky sweat, fever, hot dry skin and lips, warm hands and feet with aversion to heat, a flushed complexion, thirst with a preference for cold drinks, irritability, even coma and harsh breathing in severe cases, and so on.
Depletion of Yang is a critical condition resulting from the declination of Yang-Qi. The manifestations are a pale moist tongue and a fading fine pulse, profuse cold perspiration, cold limbs and skin, a pale complexion, chills, dispiritedness, or even unconsciousness, coma, feeble breathing, a bland taste in the mouth without thirst or if thirsty with a preference for hot drinks, and so on.
Depletion of Yang or Yin is the omen of a critical condition and is a life-threatening situation. Since the body’s Yin and Yang are mutually supporting each other, depletion of Yin will result in dispersion of Yang and vice versa. When depletion of Yin is present, Yang-Qi will ultimately fail; when depletion of Yang occurs, vital essence will be damaged. It is impossible to isolate one condition from the other. Clinically, the first consideration is to support the Yang-Qi to survive the Yin .
Differentiation of Exterior and Interior Syndromes
“Exterior” and “interior” are two related concepts describing the depth and tendency of a disease. The superficial parts of the human body are external, such as skin, hair, muscle, interstitial spaces, and shallow meridians and collaterals, which are easily invaded by pathogenic factors; while the “interior” indicates disorders in the viscera, Qi, blood, vessels, bone, and marrow; The Fu-organs are the exterior, while the Zang-organs are the interior.
The differentiation of exterior and interior syndromes is significant for exogenous pathogenic diseases. The exterior disease may be superficial and mild, whereas the interior disease may be deep and severe. However, in some cases, an interior syndrome may also result from the transmission of exogenous pathogenic factors to the interior, or may involve both the interior and the exterior. This differentiation can be used to analyze the situation of pathologic factors and development.
Exterior syndromes
These may refer to the symptoms at the primary stage of the superficial invasions of the six exogenous factors via the skin, mouth, and nose. They are usually seen at the early stage of illness, due to exogenous pathogenic factors appearing suddenly and in a short duration.
Interior syndromes
These refer to the syndromes of disorders stemming from internal areas, such as the Zang–Fu organs, Qi, blood systems, bone, and marrow. All syndromes of Zang–Fu are interior syndromes.
There are various interior syndromes due to the transmission of exogenous factors to the interior. The basic manifestation is dysfunction of the viscera. Deficiency of Yang rises to a feeling of cold. Irritability and mental confusion are caused by disturbance of excess heat.
Syndrome identification
To correctly distinguish an exterior syndrome from an interior syndrome, it is essential to observe all manifestations of cold and heat, changes of the tongue with its fur and the pulse condition, while combining all data to make a correct diagnosis. In general, an existing disease of short duration with little change of the tongue coating, a combined fever with chills and a floating pulse, usually belongs to an exterior syndrome. Compared to a chronic illness, visible changes of the tongue fur, a fever without chills or vice versa, and a deep pulse seem to belong to an interior syndrome.
Differentiation of Cold and Heat Syndromes
Since cold and heat reflect the waxing and waning of Yin and Yang, it is necessary to differentiate syndromes of cold and heat for a better understanding of the condition of Yin and Yang. Usually, Yin predomination, Yang asthenia, or exposure to pathogenic cold factors leads to cold syndromes. Heat syndromes result from the hyperfunctioning and abundance of Yang or exposure to pathogenic heat factors.
Cold syndromes
These refer to cold factors such as taking in cold foods, or asthenia Yang-Qi or Yin predomination, depleted Yang-Qi, or invasion of cold pathogenic factors.
There are various clinical manifestations but the usual symptoms are aversion to cold and a preference for warmth, a whitish moist tongue with slippery fur, a slow or tense pulse, headache or body pain, pallor and lying curled up, cold limbs, tastelessness without thirst, a pale or light-colored complexion, clear sputum, saliva and snivel, clear profuse urine, loose stools, and so on. If attacked by pathogenic cold and stagnation of Yang-Qi, the body cannot keep warm.
Heat syndromes
The heat syndromes are due to attack by the exogenous fire, internal heat transformed from pathogenic cold, seven emotional upsets, irregular diet accumulation or Yin asthenia, and hyperfunctioning of Yang heat. They can include heat in a deficiency or an excess condition.
The clinical manifestations vary according to different types of heat syndrome. The usual manifestations are fever, aversion to heat and a preference for cold, a reddish tongue with dry yellow fur and a fast pulse, flushed face or cheeks, irritability, insomnia, thick yellowish sticky sputum and nasal discharge, hematemesis, vomiting blood or epistaxis, deep-yellow scanty urine, constipation or dry stools, and so on.
Syndrome identification
Differentiating syndromes of cold and heat cannot be based on one clinical manifestation. All the clinical characteristics should be collected and analyzed carefully. The most important considerations are aversion to cold or heat, thirst or absence of thirst, a pale or flushed complexion, cold or warm limbs, details of defecation and urination, and the real condition of the tongue and pulse.
Zhang Jingyue advised on how to distinguish the false cold or heat syndrome from the truth: “Give a little cold water to the patient, who may refuse in the case of the false heat; if this patient drinks the cold water, vomiting might follow right after. In this case the patient should be treated with warm herbs. However, a patient of pseudo-cold would take the cold water and feel comfortable. In this case the patient should be treated with cold herbs.” This is a valuable and helpful distinguishing method. The pulse and tongue conditions are the key factors in diagnosis. It is crucial to be able to tell the false manifestations from the true ones. False manifestations are usually found in the limbs, skin and complexion.
Syndrome Differentiation of Asthenia and Sthenia
Basic Questions of the Inner Conon of the Yellow Emperor states, “The predominant evil is sthenia and the loss of essential Qi is asthenia”; “Hyperactivity of pathogenic factors causes sthenia, and the consumption of essential Qi produces asthenia.” Asthenia shows that body resistance or healthy Qi is lowered and its function is weak, as well as Yin, Yang, Qi, blood, and body fluid; asthenia indicates the hyperactivity of pathogenic factors. The key point of syndrome differentiation of asthenia and sthenia is to know the relative strength of healthy anti-pathogenic Qi.
Asthenia syndromes
The formation of asthenia is mostly due to congenital deficiency or acquiring derangement. There are descriptions of four kinds of asthenia: fine pulse, cold skin, shortness of breath, and diarrhea. Clinically, many conditions are attributed solely to a deficiency of Qi, blood, Yin, or Yang. The endogenous diseases are mainly asthenia syndromes. Most of the exogenous diseases belong to sthenia syndromes. However, for an endogenous disease, the visceral dysfunction could lead to Qi stagnation, blood stasis, fluid or dampness retention, food retention and parasitoids, all of which are symptoms of sthenia syndromes.
Defensive Qi is dependent upon Yang-Qi, Yin fluid, essence, blood and body fluid, all of which are related to the viscera. Asthenia syndromes mainly result from asthenia or deficiency of Qi. The various clinical manifestations exhibited are fatigue, pallor or a sallow complexion, shortness of breath, lassitude, listlessness and no desire to speak, palpitations and insomnia, chills and cold limbs with a preference for warmth, a feverish sensation in the palms, soles and heart region, spontaneous sweats or night sweats, dry stools and incontinence urine, dry mouth and throat, thirst with a desire to drink, a pale tongue with a thin coating or no coating, a fine weak pulse, and so on.
Congenital weakness and lack of proper care after birth are the causes of asthenia syndromes, such as irregular diet, extreme emotional stimuli or stress which injures viscera, Qi, and blood. Asthenia of Yang-Qi is the most common and basic pattern of dysfunction syndromes. The treatment is always to support the Yang.
Sthenia syndromes
These syndromes are described for exogenous pathogenic factors attacking the body or pathological factors accumulating inside the body. The dysfunction of the viscera leads to retention of phlegm, fluid, dampness, and blood stasis in the body or metabolic system. In general, the body’s resistance remains strong enough to combat them, although sthenia syndromes are characterized by hyperactivity of pathogenic factors.
The clinical manifestations vary with different sthenia syndromes. The common symptoms of sthenia syndromes are fever, distension and pain in the abdomen (aggravated by pressure), a sensation of fullness in the chest, irritability, even coma, delirium, harsh breathing, profuse phlegm and saliva, constipation or dysentery, inhibited urination or dripping urine, a tough rigid tongue with sticky fur, a forceful pulse, and so on.
Syndrome identification
Usually, the situations of asthenia and sthenia syndromes are complicated, such as a sthenia syndrome complicated by an asthenia one or vice versa, coexistence of the asthenia and sthenia syndromes, mutual transformation, and syndromes of true or false asthenia and sthenia change. Some clinical analyses are required. Under the Yin and Yang are the exterior and interior, the asthenia and sthenia, the cold and heat. All diseases are included in the six various conditions, which together constitute the eight principle syndromes. These syndromes are inseparable from and interrelated with one another, and are used in diagnosis and treatment. For example, the disease of a patient can be identified as either an exterior or an interior syndrome, or a half-exterior or a half-interior syndrome. There are complicated syndromes, but the eight principles of all the various diagnostic methods in TCM provide an important basis for diagnosis and treatment. Syndrome differentiation should be made clearly so as to make a correct diagnosis.