What are the symptoms of hemorrhagic fever with renal syndrome?

The symptoms of hemorrhagic fever with renal syndrome (HFRS) progress through the following stages: 1. **Febrile phase**: Patients commonly develop high fever, with body temperature reaching 39–40°C. This phase is often accompanied by the "three pains"—headache, lumbar pain, and orbital pain—as well as the "three reds"—facial flushing, neck redness, and upper chest redness. Other symptoms may include nausea, vomiting, abdominal pain, diarrhea, and generalized joint pain. Petechiae (small hemorrhagic spots) may also appear on the face, neck, chest, and other areas. 2. **Hypotensive shock phase**: As the disease progresses, body temperature may decline, but blood pressure drops significantly, potentially leading to shock. Poor tissue perfusion may trigger severe complications such as disseminated intravascular coagulation (DIC) and renal failure. 3. **Oliguric phase**: During this phase, kidney function is significantly impaired, resulting in marked reduction in urine output. Symptoms may include electrolyte disturbances and metabolic acidosis. In severe cases, uremia may develop. 4. **Diuretic phase**: This phase follows the oliguric phase and is characterized by a marked increase in urine output, which may lead to decreased blood volume. Close monitoring is required to prevent complications such as shock and hypokalemia. 5. **Convalescent phase**: With appropriate treatment, symptoms gradually subside, urine output returns to normal, and kidney function slowly recovers. However, the entire illness may last several months before full recovery is achieved. It is recommended that patients seek timely medical attention and receive professional treatment.