A 49 year old woman presents with acute kidney injury after an acute illness manifested by myalgia, diarrhoea and vomiting. Her BP is 84/50 mmHg and she has dry mucous membranes. She was taking ibuprofen, paracetamol and domperidone during the illness. Her renal function improves rapidly with intravenous (IV) fluids. Which one of the following findings are likely to be present?