My Medical Philosophy: How TCM Uses the "Excess and Deficiency" Idea to Diagnose Disease

As noted, medicine's core task is to resolve the body's "excess and deficiency." So how do we diagnose whether a patient has an "excess" or a "deficiency" problem?

Ordinary Chinese people know TCM diagnoses disease through "inspection, listening/smelling, inquiry, and palpation" (wang-wen-wen-qie). In ancient times, before modern examinations and lab tests, these were methods of judging a patient's basic condition from external signs and then inferring the cause.

We call this "observing the exterior to know the interior." Its key is "seeing the minute to know the significant": the physician infers obvious, whole-body changes from small, local ones. To be honest, this is demanding work, and the ancients themselves knew its accuracy was limited.

To improve accuracy, traditional TCM requires gathering as complete information as possible for a comprehensive judgment—what TCM calls the "combination of the four examinations." Inspection, listening/smelling, inquiry, and palpation must be organically combined and analyzed to judge the condition comprehensively and accurately, avoiding the limitations of any single method.

Even combining all four, accurate diagnosis remains hard. Pulse findings may contradict inquiry and inspection: the pulse may suggest a "deficiency" pattern, while the patient's complaints and symptoms suggest "excess." At such times conclusions are hard. Some physicians therefore advise sometimes to "abandon the pulse and follow the pattern" and other times to "abandon the pattern and follow the pulse." When to do which depends on each physician's subjective "medical intuition," which is highly subjective and makes the problem extremely complex.

As for pulse diagnosis, Wang Shuhe noted as early as in Mai Jing (The Pulse Classic) that the physician "knows it in the mind but cannot make it clear under the fingers": one thinks one understands pulse theory while studying, but taking a patient's pulse leaves one bewildered, unable to tell which pulse pattern or which disease it represents.

I have a statement that may anger diehard TCM fans and even turn some patients against me: the root cause is that TCM pulse diagnosis is unreliable.

Reading Professor Jiang Chunhua's TCM yu Kexue (TCM and Science), a scholar of great standing, I saw his account of organizing a scientific study of pulse diagnosis commissioned by the Ministry of Health. He brought several famous senior Shanghai TCM physicians together to independently take the pulses of the same patients; the agreement was extremely low. How low? The proportion of concordant pulse findings was around 15%. On this basis he deemed pulse diagnosis too subjective to be worth researching and turned to tongue diagnosis. In fact, tongue diagnosis is, like pulse diagnosis, not very reliable.

After reading his account, I abandoned deep research into pulse diagnosis. I believe spending time and energy on such an unreliable diagnostic technique is a waste; studying it can even confuse oneself. Just consider: each teacher has his own pulse theory with no unified standard. When you study under multiple teachers, what is the result? Only bewilderment.

The day before yesterday, discussing this with someone, a friend asked on the spot: so you don't take patients' pulses when you see them? I answered that I do take pulses, for two reasons.

First, a few typical pulse patterns do have real meaning. For example, the knotted (jie) and regularly-regularly-Intermittent (dai) pulses are hard to misread: the beat pauses regularly, indicating a heart problem. The wiry (xian) pulse also correlates with abnormal blood pressure. Finding such pulses helps judge the condition with reasonable accuracy. There are a few others; I will write about them in detail another time.

Second, taking the pulse gives patients psychological comfort, making them feel the doctor is taking them seriously. Patients are eager for care, and Chinese patients have deep attachment to the TCM "four examinations" method; physicians are walking placebos. Not taking the pulse makes patients uneasy and loses the placebo effect.

Since I abandoned pulse research for the more objective study of clinical symptoms, my effective rate has risen sharply. Why? Because clinical symptoms are not subjective; they are more accurate. The key to prescribing is finding accurate evidence, and objective clinical symptoms are less error-prone.

So although I quote the ancient "combination of four examinations," I do not fully endorse it. I personally prefer not to combine inquiry with pulse taking, because they can contradict each other and cause misdiagnosis. The idea of comprehensive information-gathering is correct—doctors do need integrated information for greater accuracy—but whether that information should include TCM pulse and tongue diagnosis is debatable.

To be honest, most of my own pulse-taking and tongue inspection are just for show, to comfort patients. I value more highly the more objective information from inspection, listening/smelling, and inquiry, combined with the patient's Western-medicine reports, cross-checked—lessening the chance of misdiagnosis.

Many of my articles are uncomfortable reading, and this one probably is too; I know it. Let me apologize and clarify: this is only my personal view. I may be wrong, and I do not insist that anyone agree.

I do not criticize other doctors who diagnose through pulse; perhaps some are genuinely skilled and cure patients that way. I myself have not mastered it to that level, so I will not pretend.

Incidentally, "palpation" in the four examinations is not just pulse-taking; it also includes abdominal examination and touch. Japanese Kampo physicians Inaba Katsu and Waku Tora co-authored Futeki Kiran (A Marvelous Mirror of Abdominal Signs), which details TCM abdominal diagnosis and palpation. It has been translated into Chinese; interested readers may seek it out.

How, then, does TCM judge whether a patient is "excess" or "deficiency" through the four examinations? This brings us to another diagnostic principle: "using the normal to measure the abnormal." The normal is the healthy, balanced state (the "pingren" or balanced person); the abnormal is the state of illness.

"Using the normal to measure the abnormal" simply means taking the healthy person's (or the patient's own baseline) state as reference and judging whether the patient's present state is "excess" or "deficiency." Weaker or more subdued than normal is "deficiency"; stronger or more hyperactive than normal is "excess."

Pulse diagnosis is TCM's most distinctive diagnostic tool; I personally largely exclude it from my own method, which is just my leaning. Readers who wish to learn TCM pulse diagnosis can study chapter 19, "Yuzhen Zhenzang Lun," of Huangdi Neijing to learn what an "excess pulse" and a "deficiency pulse" are.

There are also Wang Shuhe's Mai Jing and Li Shizhen's Binhai Maixue, which discuss these at length. Since I do not trust pulse diagnosis's accuracy, although I studied them in my youth, I will not explain them carelessly here.

Inspection, listening/smelling, and inquiry easily reveal abnormalities. But in modern times this is not always so: many patients are found on Western-medicine workups to have major diseases like cancer yet show no clinical symptoms, because they are still early or mid-stage.

How do we prescribe in such cases? We must refer to the "overt symptoms" and "covert symptoms" idea I discussed in the chapter "Symptoms Are the Common Language Between Medical Traditions."

Nor should we be dazzled by Western theory: Western treatment of symptoms is not necessarily more effective than TCM. TCM classifies and treats symptoms by pattern, which is far better than Western medicine. Studying Western medicine, I found it too mechanical in this respect, so for concrete symptoms I often prefer Chinese herbs.

For example, constipation is common. TCM divides it into at least three major categories: "excess-evil constipation," "vital-qi-deficiency constipation," and "deficiency-excess mixed constipation." Their clinical presentations differ subtly, each with different accompanying symptoms and different prescribing principles.

Western medicine is not so refined; seeing constipation it just gives laxatives (lactulose, glycerin suppositories, etc.), which sometimes works, sometimes does not, and sometimes backfires.

For excess-evil constipation, TCM uses the various Chengqi (Qi-Coordinating) Decoctions (Da Chengqi Tang, Xiao Chengqi Tang, Tiaowei Chengqi Tang, Taoren Chengqi Tang, Da Chaihu Tang). For deficiency-type constipation, it uses tonifying formulas (Buyang Huanwu Tang, Renshen Yangrong Tang). For mixed deficiency-excess, it uses formulas combining pathogen-removal with vital-qi support (Zengye Chengqi Tang, Xinjia Huanglong Tang). Pattern-based treatment markedly raises the effective rate.

Finer still, excess-evil constipation splits into subtypes, each requiring the most suitable Chengqi Decoction—making treatment even more precise.

For example, excess-evil constipation due to blood stasis may show markedly tortuous sublingual veins, purpura on the skin, and agitated behavior; such patients need Taoren Chengqi Tang, which both activates blood and resolves stasis and purges, sometimes combined with Xia Yu Xue Tang.

When a physician's study of symptoms reaches this level, clinical results exceed the ordinary. Because this approaches a one-to-one correspondence between formula or herb and concrete symptom. Prescribing this way is the ideal evidence-based model—and the precision-medicine model everyone hopes for; there is no reason the effective rate should not be high.

TCM today has accumulated a vast database of formulas and herb indications. I often leaf through the ten-volume Zhonghua Bencao (Chinese Materia Medica) compiled under the State Administration of TCM and the eight-volume Zhongyi Fangji Dacidian (Dictionary of TCM Formulas) from People's Medical Publishing House, building my knowledge. I take notes, organize the herbs and formulas relevant to my research direction, read them over and over, use them often, and gradually build my own effective regimens.

I also read large numbers of real TCM case records to see how other doctors choose formulas and herbs, cross-checking against my own knowledge. When I encounter an unfamiliar herb or formula in a case record, I repeatedly look it up in Zhonghua Bencao and the Dictionary, deepening my knowledge and memory.

I cannot claim this is the best way to learn TCM, but it fits my own thinking best and is therefore the best way for me. I value rigor, objectivity, and evidence, and dislike composing unverified new formulas by subjective reasoning and so-called philosophical thinking.

Because formulas composed on yin-yang and five-phase generative/overcoming theories are usually inferential, while medicine is practical and empirical. Inferential formulas are not without effect—sometimes they work, even well—but they often turn the patient into a guinea pig for a new formula, with lower efficacy and safety. That is unsafe for both patient and doctor.

Because this is the general-theory part, this section only covers basic principles; detailed discussion of each symptom and diagnostic method will appear in the specific-treatment sections, organized by concrete symptom and disease.

Note: From this article onward, the original "My Medical Thoughts" has been renamed "My Medical Philosophy."