From the perspective of modern medicine, phlegm-fluid mentioned in Donguibogam can be interpreted not merely as edema, but as a concept encompassing complex problems related to fluid metabolism and electrolyte imbalance, lymphatic circulation disorder, increased microvascular permeability, and broadly, metabolic syndrome. Waking up with a puffy face or experiencing swollen, numb calves often occurs because interstitial fluid leaks excessively from capillaries or because the leaked interstitial fluid is not properly recovered through the lymphatic system. In particular, when the effect of gravity decreases at night, the circulation of lymph slows down, and waste products accumulated during the day are not properly eliminated, which can lead to morning edema. If such edema persists chronically, it can be a warning that problems are developing in the body's major systems beyond simple discomfort. In hormonal imbalance, for example, excessive secretion of hormones such as antidiuretic hormone (ADH) or aldosterone increases the reabsorption of water and sodium in the kidneys, which can induce edema. Furthermore, it can appear as an early symptom of serious underlying disease, such as kidney hypofunction, heart hypofunction (congestive heart failure), or hepatic dysfunction with decreased albumin production. Hypothyroidism is also a common cause of generalized edema, and edema can occur as a side effect of certain medications such as antihypertensives or steroids. Recently, edema often appears as an early sign of metabolic syndrome related to insulin resistance. Repeated blood sugar spikes affect vascular endothelial cell function, leading to increased vascular permeability and promoting internal inflammatory responses that can worsen edema. Modern lifestyle habits such as an unbalanced diet, lack of exercise, and chronic stress are major factors that further worsen these metabolic disorders associated with phlegm-fluid, that is, edema. Because our body is a single organic system, not even a minor signal like edema should be overlooked. Persistent edema is a powerful message that the overall balance of the body is being disrupted, so it requires careful attention and effort to identify and resolve the underlying cause.
