Chronic kidney disease stage 4 (G4)

Kidney disease is staged on two measurements. The eGFR is calculated from a blood creatinine result and tells you roughly how many millilitres of blood the kidneys clean each minute; healthy kidneys manage more than 90. The ACR is a urine test that detects albumin leaking through damaged filters. The NHS lists stage 4 (G4) as an eGFR of 15 to 29 ml/min, sitting between stage 3b (30 to 44) and stage 5 (below 15).

The stage is a snapshot. A single low reading can reflect dehydration or a recent illness, so the diagnosis rests on results that stay low for at least three months, ideally with a urine test and sometimes a kidney ultrasound. Your team will talk about your result as G4 together with an A category for albuminuria (A1, A2 or A3), and the pair together describes your risk better than the stage alone.

Early kidney disease often causes no symptoms, and stage 4 can still be quiet. When symptoms appear the NHS lists tiredness, swollen ankles, feet or hands, shortness of breath, nausea and blood in the urine. Tiredness at this stage is frequently linked to anaemia, because failing kidneys make less of the hormone that drives red blood cell production. Itch, poor appetite, a metallic taste, cramps and disturbed sleep become more common as function falls further.

• Swelling around the ankles that does not settle overnight.

• Breathlessness lying flat or on mild exertion, which can mean fluid is building up.

• Passing much less urine than usual, or foamy or bloody urine.

• Persistent nausea, vomiting or loss of appetite.

The NHS treatment page describes the usual toolkit. ACE inhibitors, or angiotensin receptor blockers if the cough from an ACE inhibitor is troublesome, lower blood pressure and reduce protein leakage. Statins lower the cardiovascular risk that comes with kidney disease, which is the commonest cause of serious illness at this stage. For people with diabetes, SGLT2 inhibitors such as dapagliflozin can help keep the kidneys working for longer.

Because the kidneys clear potassium less well, blood potassium is checked regularly, and the NHS notes that sodium zirconium cyclosilicate may be used for high potassium at stages 3b to 5. Anaemia is treated with iron where it is deficient and with tablets or injections that help the body make more red blood cells. Medicines that are cleared by the kidneys, and over-the-counter anti-inflammatory painkillers, need review; ask a pharmacist before buying any.

Dietary advice becomes more individual at stage 4 and is best tailored by a renal dietitian. The NHS advises keeping salt below 6 g a day and, where blood phosphate runs high, limiting phosphate-rich foods such as red meat, dairy, eggs and fish. Fluid may be restricted if swelling is a problem. Potassium restriction is not automatic; it depends on your blood results, so avoid cutting out fruit and vegetables on your own initiative.

Stopping smoking, keeping active, keeping blood pressure and glucose within agreed targets, and having vaccinations offered to people with kidney disease all lower the load on both heart and kidneys. Sick-day guidance is worth knowing: during vomiting, diarrhoea or fever, some medicines may need to be paused temporarily, and your kidney team or GP will tell you which.

The NHS describes two kinds of dialysis. Haemodialysis uses a machine to filter the blood, typically three times a week, while peritoneal dialysis is done at home using the lining of the abdomen as a filter. A kidney transplant, from a living or deceased donor, can come before dialysis is needed. The NHS quotes that about 90% of transplants are still working after five years, and notes that anti-rejection medicines are lifelong.

Not everyone chooses dialysis. Conservative kidney management focuses on controlling symptoms, psychological support and advance care planning, and may suit people who are frail or who value time without hospital treatment. Starting these conversations at stage 4, rather than in a crisis, gives time to create dialysis access, assess for a transplant or arrange a pre-emptive plan.

• Ask which route the team expects you may need and roughly when decisions are due.

• Ask about education sessions and meeting other patients.

• Tell the team if a living donor in your family or friendship circle wishes to be assessed.

Call 999 or go to A&E for severe breathlessness, chest pain, collapse, confusion or an irregular, very slow heartbeat. Contact NHS 111 or your kidney team the same day for little or no urine, repeated vomiting that stops you keeping medicines down, a high temperature with a kidney illness, or sudden new swelling. A sudden drop in function on top of chronic disease, called acute kidney injury, is common after infections and dehydration and is reversible more often when caught early.