ABSTRACT
At times the cause of renal failure is almost self-evident. A patient with normal renal function in the preoperative period, who sustains unexpected rapid blood loss with hypotension at the time of operation, and develops postoperative uraemia, will almost certainly have acute renal tubular necrosis (see Chapter 5). An individual with a strong family history of polycystic kidney disease, which is inherited in a dominant mode (and thus with an even chance of having the disorder), who presents with renal impairment and enlargement of both kidneys on clinical examination, will be very likely to have the condition. In many cases, however, the cause of renal impairment is unclear. A substantial number of patients present as a result of a routine biochemical screen. The first essential action is to define whether a correctable problem exists. Pre-renal uraemia due to blood volume depletion and impaired cardiac performance have been dealt with in the previous chapter. Here, we shall focus upon poor blood flow to the kidneys owing to disease of the main renal vessels, diseases of the kidney substance, and obstruction to the flow of urine at any point between the pelvi-calyceal system (see Figure 1, p 2) and the exterior.
