1. A 65-year-old man with a history of hypertension, diabetes mellitus,

and chronic kidney disease (CKD) stage 3 presents to the

emergency department with dyspnea, orthopnea, and bilateral

crackles on chest auscultation. His blood pressure is 180/100

mmHg, pulse is 110 beats/min, respiratory rate is 28 breaths/min,

and oxygen saturation is 90% on room air. His serum creatinine is

2.5 mg/dL and blood urea nitrogen (BUN) is 50 mg/dL. What is the

most likely diagnosis for this patient?

 - A) Acute kidney injury (AKI) due to volume overload

 - B) AKI due to contrast-induced nephropathy

 - C) AKI due to acute tubular necrosis

 - D) CKD exacerbation due to heart failure*

 - Rationale: The patient has signs and symptoms of heart failure,

which is a common cause of CKD exacerbation. Heart failure can

lead to reduced renal perfusion, increased venous pressure, and

activation of neurohormonal pathways that worsen renal function.

Volume overload, contrast-induced nephropathy, and acute tubular

necrosis are possible causes of AKI, but they do not explain the