Iron deficiency anemia can manifest as: 1. Gradual pallor of the skin and mucous membranes, especially noticeable on the lips, oral mucosa, and nail beds. Older children may experience dizziness, darkening before the eyes, and tinnitus. Additionally, anemia can lead to extramedullary hematopoiesis, and enlargement of the liver, spleen, and lymph nodes can occur. The younger the age and the longer the duration of the disease, the more severe the anemia and the more prominent the enlargement of the liver and spleen. 2. In terms of gastrointestinal tract: reduced appetite, pica, vomiting, diarrhea, and stomatitis may occur. 3. Nervous system manifestations include: restlessness or lethargy, lack of concentration, reduced memory, and intelligence often lower than peers of the same age. 4. Cardiovascular system: an increased heart rate may be observed, and in severe cases, cardiac enlargement and even heart failure can occur. 5. Immune system: Iron deficiency can affect hematopoietic function, often leading to reduced cell-mediated immune function and combined infections.