Kidney disease: understanding the different types

Kidney disease is a common reason for hospitalisation. Dr Riaan Flooks, a nephrologist at Mediclinic Bloemfontein, explains different types of kidney disease, as well as their risk factors and treatment.

Like the heart, liver and lungs, your kidneys are vital for the functioning of your body. They’re situated just behind your abdominal cavity and underneath the ribs, and their primary function is to purify your blood, and produce is a cause for serious concern. Testing for kidney disease in high-risk patients is crucial.

“Renal disease is a worldwide public health problem, something which is on the increase,” says Dr Flooks. “And this applies to both acute and chronic forms of the disease. While the exact causes of this increase are unknown, possible underlying factors include increasing life expectancy, presence of additional diseases like obesity or hypertension, and social deprivation.”

Renal disease can be divided into two categories, acute kidney Injury (AKI) and chronic kidney disease (CKD). And as Dr Flooks explains, it is important to differentiate between the two types.

“AKI is characterised by an abrupt decrease in renal function. While this disease is present in around 2% of hospital inpatients, it’s more common in those who are critically ill. Potential causes of AKI include reduced renal blood supply (prerenal), infections, and compromised immunity (intrinsic), as well as post-renal obstructions like tumours or kidney stones. 

“CKD patients on the other hand, suffer from structural or functional kidney damage for a period of at least three months. This would also be associated with a reduced glomerular filtration rate (GFR) – the function of your kidneys tested by looking at your age, general health status and creatinine levels in your blood (creatinine is a chemical waste molecule generated from muscle metabolism). Diabetes and associated hypertension are the most common potential causes of CKD, as are glomerulonephritis, congenital diseases and HIV/Aids.

In South Africa, HIV-associated renal disease is thought to be the second-most common cause of CKD.

Comprehensive treatment options are available for most types of kidney diseases, and survival rates are good. And while haemodialysis and peritoneal dialysis apply to both forms of kidney disease, a third option is available to those falling into the chronic disease category. “Renal transplantation is the extra dimension reserved for patients diagnosed with CKD,” says Dr Flooks. “But a transplant is only required at the end stage of renal disease, freeing a patient from the constraints of constant dialysis.”