Fever of 38°C persisting for a full day and night without subsiding

38 degrees refers to 38°C. Fever reduction means antipyresis. A persistent fever of 38°C lasting for 24 hours may be caused by conditions such as upper respiratory tract infection, rheumatoid arthritis, hyperthyroidism, pulmonary tuberculosis, or systemic lupus erythematosus. Patients should go to the hospital for examination, identify the underlying cause, and receive treatment under a doctor's guidance. Specific analyses are as follows:

1. Upper Respiratory Tract Infection

Viral or bacterial metabolic products or toxins can damage white blood cells, causing them to release endogenous pyrogenic substances that cross the blood-brain barrier and affect the body's temperature regulation center, resulting in a fever reaching 38°C. Under medical guidance, patients may take medications such as amoxicillin-clavulanate potassium tablets or levofloxacin lactate dispersible tablets.

2. Rheumatoid Arthritis

This is an autoimmune disorder in which the immune system attacks the body's own joint tissues, causing inflammatory reactions in the joints and possibly leading to fever. Patients may follow medical advice to take anti-rheumatic drugs such as tofacitinib citrate tablets or methotrexate tablets to help control disease progression.

3. Hyperthyroidism

This condition is usually caused by excessive secretion of thyroid hormones and may lead to symptoms such as excitability, irritability, tachycardia, fatigue, heat intolerance, excessive sweating, and weight loss. Under a doctor’s guidance, medications such as propranolol hydrochloride tablets or methimazole tablets may be used for treatment.

4. Pulmonary Tuberculosis

This may result from Mycobacterium tuberculosis infection, potentially causing fever along with symptoms like fatigue and night sweats. Treatment should follow medical advice using medications such as isoniazid tablets and rifampicin tablets.

5. Systemic Lupus Erythematosus

In patients with systemic lupus erythematosus, immune system dysfunction leads to the production of pyrogenic factors that affect the thermoregulatory center, causing fever up to 38°C. Under medical supervision, patients may take medications such as prednisone acetate tablets or hydroxychloroquine sulfate tablets.

In summary, after experiencing any of the above conditions, patients should promptly visit a hospital for evaluation. Once the cause is identified, targeted treatment should be administered under a doctor's guidance to prevent worsening of the condition.