Causes

The more common causes of a drop in kidney function are:

1. Chronic high blood pressure – the pressure damages the small vessels within the kidney
2. Diabetes – The high sugars damage the small blood vessels within the kidney
3. Medications – overuse of things like anti-inflammatory drugs can damage the kidneys
4. Kidney autoimmune conditions (glomerulonephritis) – directly damage the kidney
5. Polycystic kidney disease

This list only touches the surface.

Very rarely, when there is severe narrowing in the kidney arteries, one of three things can occur

1. Patients develop high blood pressure over time, challenging to treat with standard medicine. Blood pressure elevates due to this narrowing, tricking the kidney into thinking the blood pressure is low. The kidney then releases hormones to raise blood pressure, as the narrowing results in false information about blood pressure.
2. Patients can suddenly develop severe fluid in the lungs (flash acute pulmonary oedema) or heart failure. Once again, this is related to fluid and salt retention signalled by the kidneys
3. The patient’s kidney function can slowly decline as parts of the kidney die off from not enough blood

Diagnosis

It is tough to diagnose kidney dysfunction from a lack of blood to the kidney, as opposed to one of the many other conditions. This diagnostic pathway is usually undertaken by a nephrologist (kidney physician). They will check blood and urine and order ultrasounds of CT scan to evaluate the potential culprits for kidney failure.

Renal arteries are best investigated using an arterial Doppler ultrasound or sometimes a CT scan with contrast (although contrast can further damage kidneys, this is to be used cautiously when the kidney filtration rate is low!).