Ruby was a 5-year-old girl with good past health. She had insect bites on her feet 2 weeks ago, and her feet became swollen. Her family doctor treated her with oral antihistamines and antibiotics. Her symptoms improved, but 2 days ago, she started vomiting repeatedly, up to 10–20 times per day. On admission, her body weight was 20 kg, and her height was 110 cm. Her blood pressure was 120/80 mmHg, and her pulse rate was 100 bpm. Her initial blood test showed a normal cell count. However, her serum urea was 24 mmol/L (RI: 1.6–6.4 mmol/L), serum creatinine 184 umol/L (RI: 28–52 umol/L), sodium 130 mmol/L (RI:136–145 mmol/L), potassium 4.2 mmol/L (RI: 3.5–5 mmol/L), venous pH 7.3, bicarbonate 19 mmol/L (RI: 22–25 mmol/L) and serum albumin 29 g/L (RI: 38–54 g/L). What is your approach to evaluating and managing Ruby, a child presenting with acute kidney injury?