Hypertensive nephropathy: how high blood pressure damages the kidneys

The NHS describes chronic kidney disease (CKD) as a long-term condition in which the kidneys do not work as well as they should, usually caused by other conditions that put a strain on them. High blood pressure is one of the causes it lists: over time it puts strain on the small blood vessels in the kidneys and stops them working properly. Hypertensive nephropathy is the name given when CKD is attributed mainly to this mechanism.

High blood pressure and kidney disease reinforce each other. The NHS says that if blood pressure is too high it puts extra strain on blood vessels, heart and organs including the kidneys, and kidney disease is one of the conditions linked to untreated high blood pressure.

There are usually no symptoms of kidney disease in the early stages, because the body is able to cope with a significant reduction in kidney function, according to the NHS. High blood pressure itself does not usually cause symptoms either, although rarely it can cause headaches, blurred vision and chest pain.

At a more advanced stage, symptoms can include weight loss and poor appetite, swollen ankles, feet or hands from water retention, shortness of breath, tiredness, blood in the pee, an increased need to pee particularly at night, difficulty sleeping, itchy skin, muscle cramps, feeling sick, headaches and erectile dysfunction. The NHS says to see a GP if you have persistent or worrying symptoms that you think could be caused by kidney disease.

CKD can be diagnosed using blood and urine tests that look for high levels of certain substances showing the kidneys are not working properly, according to the NHS. If you have a known risk factor such as high blood pressure or diabetes, you may be advised to have regular tests so that CKD is found at an early stage. The results are used to give a stage, with a higher number indicating more serious CKD.

High blood pressure is itself detected by measurement. The NHS says it is usually considered high if the reading is 140/90 mmHg or higher when checked by a healthcare professional, or 135/85 or higher at home, and that the only way to know is to have it checked. Many pharmacies offer checks, and the NHS advises a check if you are 40 or over and have not had one in more than 5 years.

The NHS says there is no cure for CKD, but treatment can relieve symptoms and stop it getting worse. Good control of blood pressure is vital to protect the kidneys: people with kidney disease should usually aim to get blood pressure below 140/90 mmHg, and below 130/80 mmHg if they also have diabetes. Medicines called ACE inhibitors, such as ramipril, enalapril and lisinopril, are often used. If their side effects, such as a persistent dry cough, dizziness, tiredness or headaches, are troublesome, an angiotensin-II receptor blocker can be used instead.

Lifestyle measures it lists include stopping smoking, a healthy balanced diet, restricting salt to less than 6 g a day, regular exercise of at least 150 minutes a week, no more than 14 units of alcohol a week, losing weight if overweight, and avoiding over-the-counter NSAIDs such as ibuprofen unless advised by a medical professional because they can harm the kidneys.

For some people with diabetes and CKD, the NHS says an SGLT2 inhibitor such as dapagliflozin may be used to help keep the kidneys working for longer. In advanced CKD, dialysis or a kidney transplant may be needed.

The NHS says CKD can range from a mild condition with few or no symptoms to a very serious one in which the kidneys stop working, but that most people with CKD can control it with medicine and regular check-ups. It progresses to kidney failure in around 2 in 100 people with the condition. Even mild CKD increases the risk of cardiovascular disease, which is one of the main causes of death in people with kidney disease, although lifestyle changes and medicines can reduce that risk.