There is a significant increase in the number of patients with pruritus due to cooler, windy and dry weather, and itching is usually caused by skin disorders, mostly in autumn, when the climate is dry and pruritus is likely to occur if one does not drink enough water, eats less vegetables and fruits, bathes too often, likes to use alkaline soap and when the elderly have insufficient qi and blood and the blood cannot nourish the skin. Itchy skin is generally considered to be caused by skin disorders, but some itching, especially obvious, persistent or recurrent itching without any aura or itching accompanied by a rash, is often a sign of other diseases. 1. Thyroid disease is seen not only in patients with hyperthyroidism, but also in patients with hypothyroidism. Pruritus in hyperthyroidism appears earlier and is predominantly associated with moist skin and aggravation in summer. Pruritus due to hypothyroidism tends to develop slowly, and the skin tends to be dry and lose its luster, worsening in winter. When the thyroid disease is cured the itching can be relieved by itself. 2, hepatobiliary diseases Itching due to hepatobiliary system diseases are mostly found in cirrhosis, cholelithiasis, bile duct tumor diseases. The itching of hepatobiliary system diseases appears earlier, may appear before jaundice, lasts longer, and is more stubborn, and is often aggravated in winter. Due to bile stagnation, the concentration of bile acid salts in the blood rises and histamine is retained and thus deposited on the skin, causing itching. Pregnant women with liver disease and patients with liver disease who take oral contraceptives have a higher incidence of itching. 3, chronic renal insufficiency Patients with chronic insufficiency, especially in the later stages (uremic phase), are unable to excrete metabolites such as urotoxins and urea in the blood, but are retained in large quantities in the body and excreted with sweat, thus causing generalized intractable itching, which is unbearable. In addition, itching is also related to disorders of calcium and phosphorus metabolism, hyperparathyroidism and increased urea content in the epidermis. 4, diabetes About 10% of early diabetic patients will have generalized or localized itchy skin, and more persistent, with the most severe symptoms in the vulva or anus. The itchy skin of diabetes is not proportional to the disease, and some patients with hidden diabetes are often found to have diabetes only when they have a physical examination because of itching. The reason for itchy skin is the increase of sugar content in the skin, the increase of lactic acid in the skin, the loss of water in the skin becomes dry, the body’s defense ability decreases, the fungal infection takes advantage of the opportunity, the peripheral nerves of the skin are stimulated and itchy occurs. 5, blood system diseases some blood system disorders can also cause skin itching, such as true erythrocytosis patients can be manifested as generalized or limited skin itching, often aggravated in the summer, warm baths can intensify itching, and may be related to the release of a large number of histamine granulocyte renewal. According to foreign reports, pruritus occurs in about 13% of men and 7% of women with iron deficiency anemia, and itching is relieved by iron supplementation and anemia correction. The cause is due to nutritional disorders of skin tissue, reduced epithelial cell function, dryness, wrinkling and atrophy of the skin. 6, central nervous system diseases Patients with neurasthenia and cerebral arteriosclerosis can often occur paroxysmal itching, while patients with brain tumors can often cause intense and persistent itching, and this itching is confined to the nostril area. 7, malignant tumors Malignant tumor-induced itching is mainly seen in certain lymphatic system tumors, such as meat-like granuloma, Hodgkin’s disease, or patients with myeloproliferative disorders, often accompanied by generalized itching. Cancers of internal organs, such as stomach, intestinal, ovarian and prostate cancers, can cause intractable pruritus. When the cancer is removed, the pruritus disappears; when the tumor recurs before the pruritus reappears. Therefore, it can be said that the appearance of pruritus is also one of the signals of tumor recurrence.