TCM Body Constitutions and Itchy Skin in People on Dialysis: What One Study Found, and What an Ancient Text Once Noted

When chronic kidney disease reaches the point where dialysis becomes part of weekly life, patients often deal with a cluster of frustrating symptoms, and itchy skin is one of the most common. The itch can be persistent, disturb sleep, affect mood, and look very different from one person to the next. Because the symptom has such a real impact on daily comfort, researchers keep looking for ways to predict who is more affected and how the experience might vary.

TCM constitution typing is one way of sorting people into broad categories based on overall characteristics. The three categories used in this study are a balanced constitution, thought of as closer to a neutral baseline; a deficiency constitution, leaning toward insufficiency; and an excess constitution, leaning toward surplus or accumulation. For a general reader, the value of looking at constitution alongside dialysis symptoms is that it gives a structured way to ask a familiar question: if two people have the same kidney condition, why does their day-to-day experience of itching look so different?

So nearly half of the sample sat in the balanced category, and the remaining patients were split between deficiency and excess types.

When the researchers looked at the relationship between constitution and the occurrence of CKD-aP, both deficiency and excess constitutions were statistically significant. In plain language, within this sample, patients with either non-balanced constitution were more likely, in statistical terms, to experience CKD-aP than those with a balanced constitution.

The study also reported something more granular. The two non-balanced constitutions did not just differ in whether itch occurred; they appeared to affect different dimensions of the itch. A deficiency constitution was linked to the duration, severity, disability, and distribution of pruritus, whereas an excess constitution was linked mainly to severity and disability. So the type of constitution a patient falls into may shape not only the chance of itching but also the texture of the itching experience. The authors noted that both deficiency and excess constitutions were correlated with the occurrence of CKD-aP, and that different constitution types affect pruritus differently, which they suggested calls for further precise analysis of the interaction between constitution types and pruritus occurrence.

An odds ratio compares two groups. Here, the balanced constitution is the reference group.

A second layer of interpretation is that the two non-balanced constitutions did not behave identically. Deficiency touched more aspects of the itch experience, including how long it lasted, how bad it was, how much it interfered with daily function, and where on the body it showed up. Excess concentrated on severity and disability. That pattern suggests future work may need to break pruritus into its components rather than treating it as a single yes-or-no outcome.

It also helps to place these numbers inside a wider frame. The Lingshu, an early Chinese medical text, includes the line: "五藏者，固有小大高下堅脆端正偏傾者，六府亦有小大長短厚薄結直緩急，凡此二十五者，各不同。" (Source: 《黃帝內經·靈樞》, seventh juan, dialogue on the morphological differences of the five organs). The passage states that the five organs naturally differ in size, height, solidity or fragility, and whether they sit straight or tilted, and that the six fu-organs similarly vary in size, length, thickness, and so on, totaling twenty-five distinct morphological features. The underlying point is that human beings are not built from the same template, and individual difference is taken as a basic fact. Reading the modern study against that classical line offers a historical echo: a long-standing medical tradition that bodies are diverse, and that constitutional typing is one way of organizing that diversity. It is worth being clear that the Lingshu passage does not prove the modern statistical findings, and the modern findings do not validate the classical anatomy. They sit in conversation, not in a verification relationship.

Because the design was cross-sectional, the study cannot show whether constitution causes pruritus or whether long-standing pruritus and the experience of dialysis simply co-occur with certain constitution classifications in this sample. It also cannot tell us whether a person's constitution changes over time, or whether any such change would track with changes in itching.

The sample came from patients at a single hospital, which limits how far the numbers can travel. We do not know from this study alone whether the same patterns would appear in different cities, healthcare systems, or ethnic groups. For an individual reader, the safest reading is that these are group-level statistics from one Macanese hospital in 2023, not a personal test. Assigning a TCM constitution is a professional assessment, and this study's figures are not a tool for self-categorization or for predicting one's own symptoms.

這篇文章對話了兩個層次的問題：一是2025年發表、樣本來自一所澳門醫院、在2023年進行的橫斷面研究，二是《靈樞》中關於五臟形態本來就各有不同的古典段落。前者以問卷與統計方法，把體質分類與皮膚搔癢的發生連結在一起；後者把個體差異視為人體的基本事實。

田忌信號嘗試做的，是讓這兩種不同時代、不同方法、不同語言的觀察並列在一起。它不聲稱古典支持了現代，也不聲稱現代驗證了古典，只是呈現出在不同的醫學傳統中，人與人之間的差異如何被各自看見、被各自描述。讀者可以把它們看作兩扇望向同一片風景的窗，窗外景觀互有重疊，但框架並不相同。