May 1, 2006  
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Understanding and Applying Differential Diagnosis (Zhen Duan): The Heart of TCM Clinical Methodology.

By David Frierman, LAc

Although traditional Chinese medicine practitioners are expected to follow a standard clinical methodology, it is not detailed in college textbooks. Hao Wan-Shan and Dr. Lin Zhi-Xiu summarized this in a recent article:

In modern clinical practice, it is a normal practice for physicians to gather the clinical symptoms and signs via the four diagnostic methods and analyze the pathogenesis of the diseases, then establish the name of the disease and differentiate the pattern.

After this process, a treatment principle is put forward in accordance with the pattern differentiation, a formula selected in accordance with the treatment principle, and appropriate herbs prescribed to achieve the requirements of the formula. This process is the standard methodology employed in clinical diagnosis and treatment.1

Figure 1 presents TCM clinical methodology as a flowchart, with differential diagnosis (zhen duan) in the middle or "heart." One may also view zhen duan as the bridge between intake and treatment.

All of the elements of this clinical methodology are presented in American TCM colleges, but it is unusual for them to provide a systematic, detailed presentation of the entire methodology as a separate course. Consequently, few of us graduate with a comprehensive understanding of routine clinical procedure and its specifics.

TCM Clinical Methodology - Copyright – Stock Photo / Register Mark

This is especially true with regard to zhen duan. Zhen duan consists of two levels of differentiation: a disease differentiation (bian bing) and a syndrome differentiation (bian zheng). We rarely appreciate the importance of the bian bing, the distinction between it and bian zheng, and the importance and appropriate use of each bian zheng. We may skip the bian bing or try to use it as the complete differentiation, and/or try to use incomplete bian zheng. On the other hand, we may use syndrome differentiation according to the viscera and bowels (zang fu bian zheng) to the exclusion of all of the other bian zheng, since this is overly emphasized in school.

I believe a review of the importance and application of each of the elements of zhen duan will help us learn how to use them more proficiently. We must understand how to differentiate diseases and syndromes in the most accurate and complete manner to provide the most effective treatment for our clients.

Distinctions Between Bian Bing (Disease Differentiation) and Bian Zheng (Syndrome Differentiation)

Bing ("disease" or "illness") in Chinese medicine refers to the pathological condition of an individual or part of an individual with a characteristic train of signs and symptoms. Bian bing means the identification or differentiation of a disease: a diagnosis. In current TCM clinical methodology, the bian zheng is most often used to differentiate the syndromes of a disease. In other words, the bian zheng describes how a disease manifests in a particular individual at a particular time. The bian zheng may also be used to differentiate the patient's constitution.

Importance of the Bian Bing

The bian bing is important for many reasons:

  1. As a historical fact. Although it is anathema to practitioners of styles of Chinese medicine that use syndrome differentiation, most Chinese medical practitioners in all ages have treated diseases, not syndromes.
  2. To understand and research important Chinese medical literature. The Nei Jing, Shang Han Lun, Jin Kui Yao Lue, and many other works often refer to diseases.
  3. To research contemporary treatment. Current books on Chinese medical treatment describe diseases. The common syndrome differentiations associated with these diseases are listed under these rubrics.
  4. To understand the "direction" of development of an illness. Bensky has likened the bian bing to a "movie" of an illness, as opposed to the bian zheng, which is more like a "snap shot."
  5. To help determine precise bian zheng. For example, if one first differentiates an upper respiratory infection as tai yang disease, wind warmth, spring warmth, autumn dryness, etc., one may research the particular bian zheng correlated with each of those diseases through long clinical practice, as well as through established treatment strategies and formulas.
  6. To determine the proper medicinals and formulas. Let's take the disease evil differentiation of wind as an example. Wind is associated with eczema, the common cold, and Bell's palsy, but the medicinals used for wind in each disease vary. Again, both plum-pit qi and painful periods may be the result of binding depression of liver qi, but the representative formulas differ.

Chinese and Western Diseases

In the modern TCM clinic, Western disease designations are often used for the bian bing. Even in books from China that focus on treating diseases, the chapter designations are often Western diseases. In some of these books, references are made to similar Chinese diseases. While a Western disease diagnosis is sufficient in many clinical situations, it is usually helpful, and sometimes indispensable, to understand the Chinese concept of the disease. Research into historical theories and accounts of the disease necessitates a grasp of the Chinese medical impression. This research, in turn, leads to more accurate bian zheng.

Applying the Bian Bing

The bian bing should be applied to all diseases. For those clients without an immediately discernable disease, or those who want a constitutional, preventative or "wellness" treatment, one may proceed directly to the bian zheng. (Constitutional and preventative treatment remains an extremely important aspect of Chinese medicine, for "the superior doctor treats disease before it manifests.")

The Importance of the Bian Zheng

While I have called zhen duan the "heart of TCM clinical methodology," many have called bian zheng the "essence" of Chinese medicine. Its importance is reflected in the overriding principle of TCM - bian zheng lun zhi, i.e., determining treatment by differentiation of syndromes. This means that if we are to properly use TCM, we must direct treatment at those syndromes diseases manifest, not the diseases themselves.

Bian Zheng Used in Traditional Chinese Medicine

TCM often uses the nine bian zheng presented in the following chart:

Nine Bian Zheng Used in TCM2-3
Bian Zheng Principal Use4
1. syndrome differentiation according to the eight principles
(ba gang bian zheng)
all diseases
2. syndrome differentiation according to cause (bing yin bian zheng)
3. syndrome differentiation according to disease evils
(bing xie bian zheng)
external contraction
(wai gan)
4. syndrome differentiation according to the six channels
(liu jing bian zheng)
cold damage5
(shang han)
5. syndrome differentiation according to the defense, qi, construction,
blood (wei qi ying xue bian zheng)
6. syndrome differentiation according to the triple burner
(san jiao bian zheng)
warm disease6
(wen bing)
7. syndrome differentiation according to the channels and collaterals
(jing luo bian zheng)
internal damage
miscellaneous disease
(nei shang za bing)
8. syndrome differentiation according to the qi, blood and body fluids7
(qi xue jinye bian zheng)
9. syndrome differentiation according to the viscera and bowels8
(zang fu bian zheng)

Preliminary and Complete Bian Zheng

Of the nine bian zheng presented above, numbers 1, 2, 3, 7, and 8 are considered "preliminary" or incomplete syndrome differentiations. Only numbers 4, 5 (in combination with 6), or 9 can provide complete or conclusive syndrome differentiation.

The Bian Zheng Verifies the Bing Ji (Disease Mechanism)

Dr. Long has written:

Pathology is a bridge ... between ... theories and clinical practice. Pathology ... is also called bing ji, mechanism of ... diseases. It studies the occurrence, development and prognosis of diseases. Bing ji is [the] center ... of bian zheng lun zhi [determining treatment by differentiation of syndromes]. In [other] word[s], the ultimate purpose of bian zheng is to verify bing ji.9

For the bian zheng to be complete, it must verify all three elements of the diseases mechanism. These are presented in the following chart.

Elements of the Bing Ji
1. Disease cause (bing yin) External evils such as wind, cold, etc.; internal affects such as sorrow, fear, etc.; and neutral causes such as trauma, congenital factors, taxation fatigue, etc.
2. Disease location (bing wei) Exterior or interior; specific channels and collaterals; individual organs; particular aspects such as the blood aspect or qi aspect; etc.
3. Disease nature (bing xing) Yin, yang, cold, hot, replete, vacuous, fixed, moving, etc.

Each Bian Zheng Is Important to the Verification of the Bing Ji

Specific bian zheng verify specific elements of the bing ji. None are completely comprehensive. Since TCM requires a great deal of specificity in treatment, we should verify each element of the disease mechanism as completely as possible. Since each bian zheng has its role in verifying the disease mechanism, we should learn to apply them all. A summation of the strengths and shortcomings of each bian zheng is presented in the following chart.

Specific Bian Zheng Verification of Bing Ji
Bian Zheng
1. Eight principles nature and location too general
2. Disease cause
not enough information for treatment
3. Disease evils cause and nature
4. Six stages structural location
(implies progression
and cause)
inadequate for miscellaneous diseases, warm diseases
5. Defense, qi,
functional location
(implies nature, cause and progression)
inadequate for miscellaneous diseases, cold damage
6. Triple burner structural location
(implies nature, cause and progression)
7. Channels and
structural location does not indicate organ involvement, nature, cause
8. Qi, blood and
body fluids
structural location does not indicate organs or channels, cause
9. Viscera and
structural location,
nature (implies cause)
does not indicate channels; inadequate for external contraction

Applying the Bian Zheng

How can we learn to apply all of the bian zheng and when to use particular bian zheng for particular bian bing? I propose the following procedure.

Step 1: Use (1) syndrome differentiation according to the Eight Principles (ba gang) and (2) syndrome differentiation according to cause (bing yin) to differentiate all diseases. Using these two bian zheng, we should be able to determine if the disease is external contraction febrile disease (wai gan re bing), internal damage/miscellaneous damage (nei shang zi bing), or "other diseases" (bu wai nei bing).10 These other diseases that defy categorization as either external contraction febrile disease or internal damage constitute a kind of tertium quid, and include certain types of bi syndrome, lin syndrome, and various painful diseases from traumatic injury.

Categories of Diseases
Disease Category
Definition Characterized By:
External contraction febrile disease
(wai gan re bing)
"Any disease caused by influences originating outside the body, characterized by heat effusion and a usually rapid stage-by-stage progression."11 "Struggle" between right qi (zheng qi) and evil(s) (xie)
Internal damage/ Miscellaneous disease
(nei shang za bing)
"Various diseases due to internal damage, i.e., to causes other than externally contracted heat (febrile) diseases."12 "Imbalance" of yin and yang
Other diseases
(bu nei wai bing)
Types of diseases difficult to categorize in disease category 1 or 2. Mixture of struggle and imbalance

For External Contraction Febrile Disease

Step 2: If the disease is external contraction febrile disease, use (1) syndrome differentiation according to the Eight Principles to determine whether it is hot or cold, then use (3) syndrome differentiation according to disease evils (bing xie) to determine the external evil(s) present.

Step 3: If the diseases is cold with a prominent cold evil, use (4) syndrome differentiation according to the Six Channels (liu jing) to determine what stage is affected, then the specific syndrome within the stage. If the disease is hot with a prominent heat evil, use (5) syndrome differentiation according to the defense qi, construction, blood (wei qi ying xue, a.k. si feng) and (6) syndrome differentiation according to the Triple Burner (san jiao) to determine which level and/or burner is affected, then the specific syndrome in the level or burner.

For Internal Damage

Step 2: If the disease is internal damage, then use (3) syndrome differentiation according to disease evils to determine if there are internal evil(s) present.

Step 3: Use (8) syndrome differentiation according to the qi, blood and body fluids (qi xue jin ye) as a preliminary differentiation.

Step 4: Use (9) syndrome differentiation according to the viscera and bowels (zang fu) to make a complete differentiation (that is, assign the evils and vacuity and repletion of qi, blood and body fluids to particular organs).

For Other Diseases

Step 2: If the disease is in the "other diseases" category (i.e., it is not exactly an external contraction febrile disease or internal damage miscellaneous disease), use (3) syndrome differentiation according to disease evils to determine the evil(s) present.

Step 3: Use (7) syndrome differentiation according to the channels and collaterals (jing luo) to determine which channels are affected.

Step 4: Use (8) syndrome differentiation according to the qi, blood and body fluids to determine which humors are affected.

Step 5: Use (9) syndrome differentiation according to the viscera and bowels to make a complete and final differentiation.

Final Considerations

After determining the various syndromes, we should try to discover the root and analyze the constitution. (Many practitioners use the Five Phase-Element syndrome differentiation [wu xing bian zheng] to analyze the constitution.) We should then decide which syndromes we will focus on, and determine if these are "branch" or "root." The complete procedure is summarized below.

Bian Zheng - Copyright – Stock Photo / Register Mark

Concluding Remarks

The procedure described in this article is useful as a learning exercise, but far too rigid in practice. We must use the bian zheng with great flexibility and adaptability. For example, syndrome differentiation according to the Five Phase-Elements is mentioned prominently in the classics, where it not only explains constitutional types, but also progression of disease in the zang fu. Syndrome differentiation according to the Six Channels has been used for 2,000 years to differentiate internal damage as well as external contraction. Although syndrome differentiation according to the viscera and bowels does not indicate progression, stage or level, it may still be used for external contraction if proficiency is lacking in cold damage or warm disease theory. Syndrome differentiation according to confirming prescription achieves solid results if used with discretion. We may also read ancient case histories that use "preliminary" differentiations as a basis for treatment with outstanding results, and study with excellent practitioners who have idiosyncratic approaches. Therefore, this exercise should be viewed only as a step in the development of a more flexible and personal procedure.


  1. Hao WS, Lin ZX. Discussion of the methodologies employed in the Shanghan Lun for pattern differentiation and formula making. The Journal of Chinese Medicine June 2003;72:20. North American edition, Eastland Press, Vista, CA.
  2. This chart is an expanded version of one in Steven Clavey's Fluid Physiology and Pathology in Traditional Chinese Medicine. New York: Churchill Livingstone, 1995, p. xxvi.
  3. While TCM uses the Five Phase-Elements (wu xing) correspondences for part of its theory or physiology, it is often critical of using differentiation according to Five Phase-Elements (wu xing bian zheng) to differentiate diseases. TCM prefers to use differentiation of syndromes according to viscera and bowels (zang fu bian zheng). However, the Five Phase-Elements are often used to differentiate the constitution. Syndrome differentiation according to herbal prescription and application according to Western theory are beyond the scope of this article.
  4. Several of these bian zheng have important uses besides those mentioned here. See "Concluding Remarks" at the end of this article.
  5. For a discussion of cold damage, see Shang Han Lun, On Cold Damage, Translation and Commentaries by Craig Mitchell, Feng Ye and Nigel Wiseman, published by Paradigm Publications.
  6. For a discussion of warm disease, see Warm Diseases, A Clinical Guide by Guohui Liu, published by Eastland Press.
  7. For a discussion of body fluids, see Fluid Physiology and Pathology in Traditional Chinese Medicine by Steven Clavey, published by Churchill Livingstone.
  8. For a discussion of zang fu, see The Five Organ Networks of Chinese Medicine by Heiner Fruehauf, published by the Institute for Traditional Medicine.
  9. Long R. "Chinese pathology." Class notes from his course at National College of Naturopathic Medicine.
  10. Bu nei wai bing: literally, "not internal-external disease."
  11. Wiseman N, Feng Y. A Practical Dictionary of Chinese Medicine. Brookline, MA: Paradigm, 1998, p. 186.
  12. Ibid, p. 313.

Editor's note: If you would like to comment on this article, please contact Acupuncture Today by fax (714-899-4273) or e-mail ( ). You also are encouraged to discuss the article on Acupuncture Today's online discussion forum at


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