One of the best ways to differentiate between acute kidney injury (AKI) and chronic kidney disease (CKD) is renal ultrasound - most patients with CKD have bilateral small kidneys. Exceptions to this rule include:

• autosomal dominant polycystic kidney disease
• diabetic nephropathy (early stages)
• amyloidosis
• HIV-associated nephropathy

Other features suggesting CKD rather than AKI

• hypocalcaemia (due to lack of vitamin D)