A previously healthy 4-year-old girl is brought to the pediatric clinic by her parents due to progressive swelling over the past two weeks. They initially noticed puffiness around her eyes in the morning, which later progressed to swelling in her legs and abdomen. They also report that her urine appears frothy, but she has no complaints of pain, burning urination, or hematuria. She has been more fatigued than usual, but there is no fever, rash, joint pain, or recent infections. Her medical history is unremarkable, and she has no known allergies or previous hospitalizations. There is no family history of kidney disease, autoimmune conditions, or systemic illnesses. Physical Examination General: Alert but appears mildly fatigued Vital Signs: Blood Pressure: 98/60 mmHg (normal) Heart Rate: 90 bpm (normal) Respiratory Rate: 20 bpm (normal) Temperature: 98.6°F (37°C) HEENT: Periorbital edema, more pronounced in the morning Cardiovascular: No murmurs, normal heart sounds Respiratory: No crackles, no signs of fluid overload Abdomen: Mild ascites (fluid wave present) Extremities: Pitting edema in both lower limbs Neurologic: Alert and interactive, normal reflexes Diagnostic Workup 1.Urinalysis 3+ proteinuria No hematuria (no RBCs, no casts) No leukocytes or nitrites 2.24-hour Urine Protein >3.5 g/day equivalent, confirming nephrotic-range proteinuria 3.Serum Studies Hypoalbuminemia (1.8 g/dL) Hyperlipidemia (total cholesterol 290 mg/dL) Normal creatinine & BUN Normal complement levels (C3, C4) 4.Renal Ultrasound Normal kidney size and echotexture What is the first-line treatment for this patient?
