The causes of kidney disease

Dr Derek Miller, a physician and kidney specialist at Mediclinic Constantiaberg, explains what various causes of kidney disease.

Diabetes

The most common cause of kidney failure is diabetes, which accounts for about half of all patients with kidney problems in South Africa. If you’ve been diagnosed with diabetes mellitus it means your body fails to process glucose (sugar) correctly. Insulin is needed to regulate the sugar levels in your blood, preventing them going too high after a meal and too low between meals.

If you have type 1 diabetes, then you have a progressive autoimmune disease where your body does not produce enough insulin. If you have type 2, mostly caused by an unhealthy lifestyle, your body doesn’t use the insulin effectively. When diabetes is poorly controlled, too much glucose can build up in your blood and damage the tiny filters in the kidneys. In turn this affects your body’s ability to filter out waste products and fluid.

“The kidneys don’t really cause problems until they get to the end of the line,” says Dr Miller. “You’ll feel bad from other complications related to the diabetes. When you get to stage five kidney disease, you’ll notice you don’t get rid of fluid properly, so you start swelling up.” But there is hope, he adds: “If the diabetes is better treated, you’re less likely to progress to stage five kidney disease and need dialysis.”

Hypertension

Hypertension (high blood pressure), is the second biggest cause of kidney disease and worldwide it causes one in four cases of kidney failure. “In South Africa we have a high number of people with high blood pressure. If this is not managed properly, they can progress into kidney failure as well,” says Dr Miller.

He warns that it’s particularly important for black Africans with hypertension to manage the condition, as they’re vulnerable to a particularly severe form of hypertension that is genetic and probably related to salt sensitivity. “If you’re sensitive to salt and you eat a lot of salt, your blood pressure goes up. If you’re not sensitive to salt you can eat a lot of salt and it won’t affect you,” he explains.

Genetic conditions

Other causes of chronic kidney disease may be genetic conditions such as polycystic kidney disease, where both kidneys are larger than normal due to the gradual growth of masses of cysts on these organs. “With polycystic kidneys, patients bleed, having ruptured the cysts. They then get pain and inflammation from the rupture. Normally the cysts don’t cause problems until patients reach the age of 20-25,” explains Dr Miller.

Inflammation

There is also the glomerulonephritis group of kidney diseases, caused by inflammation of the tiny filters in your kidneys. The inflammation may be acute (a sudden attack) or chronic, coming on more gradually. Secondary glomerulonephritis occurs if another disease, such as lupus or diabetes, is the cause.

“Systemic lupus is where the body attacks the kidneys as if it were foreign tissue,” says Dr Miller. “Many of those patients need a lot of immuno-suppressive therapy to suppress the inflammation and to prevent it from permanently damaging their kidneys and their bodies.”

Dr Miller also warns that everyone should exercise caution with the regular use of certain medicines such as non-steroidal anti-inflammatory drugs, including aspirin and ibuprofen.

Are there ways to avoid kidney damage?

“There’s not a lot you can do,” says Dr Miller. “If you’re worried about kidney damage, the most important things are to eat a healthy, balanced diet, to control your weight, to do a moderate amount of exercise and to avoid salt. You should also avoid excessive use of drugs that may affect the kidneys, especially when you’re exercising.”