In Traditional Chinese Medicine (TCM) theory, the abundance or decline of the vital essence (Qi and Jing) of the internal organs is clearly reflected through external physical signs. The ancient saying, “Kidney exhaustion shows in long teeth, spleen exhaustion shows in a flat philtrum, lung exhaustion shows in hair loss, liver exhaustion shows in a curled tongue,” is a profound summary of this principle. It does not refer to literal organ “failure” but to the typical external signals when the vital essence of the corresponding organs is severely deficient. Understanding these signals helps us detect bodily imbalances early and conduct targeted regulation.

1. Kidney Exhaustion Shows in Long Teeth: Kidney Essence Deficiency, Teeth Lose Nourishment

• TCM Theory: The Kidneys govern the bones, and the teeth are the surplus of the bones. Kidney Essence (Jing) and Kidney Qi are the fundamental sources of nourishment for bone and tooth growth.

• External Manifestation: When Kidney Essence and Qi are severely insufficient (“Kidney exhaustion”), the gums lose nourishment and atrophy, causing the teeth to appear “longer,” with widened gaps, becoming sparse and loose.

• Accompanying Symptoms: Often accompanied by soreness and weakness of the lower back and knees, clear and copious urine or frequent nocturia, mental and physical fatigue, etc.

• Maintenance Advice: Avoid overexertion, keep warm; eat more black foods like black beans and black sesame; consider using TCM formulas that benefit the Kidneys and strengthen teeth.

2. Spleen Exhaustion Shows in a Flat Philtrum: Spleen Qi Decline, Lips Lose Luster

• TCM Theory: The Spleen opens into the mouth, and its bloom is on the lips. The Spleen governs transformation and transportation, is the source of Qi and Blood production. Ample Qi and Blood are needed to nourish the lips.

• External Manifestation: When Spleen Qi is extremely weak (“Spleen exhaustion”), the production of Qi and Blood is insufficient, causing the lip muscles to lose nourishment, atrophy, become dry, and lack luster. This makes the philtrum groove appear shallow and flat.

• Accompanying Symptoms: Often accompanied by poor appetite, indigestion, loose stools, sallow complexion, anemia, etc.

• Maintenance Advice: Eat regularly, avoid overeating; consume more yellow foods like pumpkin and Chinese yam; consider using TCM formulas that strengthen the Spleen and boost Qi.

3. Lung Exhaustion Shows in Hair Loss: Lung Qi Deficiency, Skin and Hair Lose Their Hold

• TCM Theory: The Lungs govern the skin and body hair, control respiration, and connect with all vessels. Lung Qi disseminates Defensive Qi (Wei Qi) and body fluids to warm, nourish, and secure the skin, hair, and pores.

• External Manifestation: When Lung Qi is severely depleted (“Lung exhaustion”), the skin and hair lose nourishment and secureness, leading to dry skin, dull complexion (e.g., darkening of the face), and abnormal hair loss (including scalp hair, eyebrows, body hair).

• Accompanying Symptoms: Often accompanied by difficulty breathing, weak cough, susceptibility to colds, deformed nails (e.g., clubbing), etc.

• Maintenance Advice: Pay attention to air quality, avoid inhaling harmful substances; eat more white foods like white fungus and lily bulb; consider using TCM formulas that moisten the Lungs and boost Qi.

4. Liver Exhaustion Shows in a Curled Tongue: Liver Blood Depletion, Tongue Tendons Lose Nourishment

• TCM Theory: The Liver governs the tendons, and its bloom is in the nails. The tongue body is composed of numerous tendons and vessels, requiring ample Liver Blood nourishment to be flexible and extended.

• External Manifestation: When Liver Blood and Liver Qi are severely insufficient (“Liver exhaustion”), the tendons and vessels of the tongue body lose nourishment, potentially causing the tongue to curl backward, shorten, and lose agility, possibly affecting speech clarity.

• Accompanying Symptoms: Often accompanied by reddening of the palms (especially the thenar and hypothenar eminences, known as “liver palms”), spider nevi on the skin, abnormal bleeding (e.g., gum bleeding), yellowing of the eyes or skin, etc.

• Maintenance Advice: Maintain emotional ease, avoid depression and anger; eat more green foods like spinach and celery; consider using TCM formulas that nourish Blood and soothe the Liver.

Summary: This TCM adage embodies the diagnostic principle of “what is inside will manifest externally.” It reminds us that subtle bodily changes can be alarms from the internal organs. Paying attention to these signals, combining them with modern medical examinations, and timely intervention through lifestyle adjustments and TCM regulation is crucial wisdom for maintaining health.