What stage 3 CKD actually means
Stage 3 chronic kidney disease is defined by an estimated glomerular filtration rate (eGFR) of 30–59 ml/min/1.73m² that has lasted at least three months. It is divided into:
- STAGE 3a — eGFR 45–59 (mildly to moderately reduced)
- STAGE 3b — eGFR 30–44 (moderately to severely reduced)
Stage 3 is the most common stage of CKD identified in UK primary care. The majority of people in stage 3 are well, do not need dialysis, and never will. The label exists so that GPs and renal teams can monitor kidney function, adjust drug doses safely, control blood pressure and cardiovascular risk, and refer to a nephrologist if the picture changes.
Symptoms and what to watch for
Stage 3 is often silent and discovered on routine bloods. Where symptoms appear they are usually mild and non-specific:
- Tiredness or reduced exercise tolerance
- Mild ankle swelling at the end of the day
- Waking once or twice at night to pass urine
- Itchy skin
- A poorer appetite or a metallic taste
- Breathlessness on stairs
Flag To Your Gp Or Renal Team
- New leg swelling that does not settle overnight
- Visible blood in the urine
- Breathlessness at rest or when lying flat
- Sudden weight loss or persistent vomiting
- Confusion, drowsiness or muscle weakness
These are not typical of stable stage 3 and may indicate an acute kidney injury, fluid overload or a rapidly progressing problem.
Diet in stage 3 CKD — what UK guidance actually says
Aligned with NICE NG203 and the British Dietetic Association Renal Nutrition Group:
PROTEIN
- Aim for around 0.8 g/kg/day of good-quality protein (fish, eggs, poultry, dairy in moderation).
- Do NOT crash-restrict protein — too little worsens muscle loss and recovery.
SALT
- Under 6 g salt per day (about a teaspoon, including hidden salt in bread, sauces and ready meals).
- Reducing salt is the single most effective dietary lever for blood pressure in CKD.
POTASSIUM
- Routine potassium restriction is NOT recommended in stage 3 unless your blood potassium is above the normal range.
- Most people in stage 3 can continue to eat bananas, tomatoes, potatoes and oranges in normal portions.
PHOSPHATE
- Routine phosphate restriction is not needed in stage 3 unless your phosphate or PTH is high.
- The biggest culprits are highly-processed foods, cola-type drinks, and phosphate additives (look for E338, E339, E450 on labels).
FLUIDS
- Drink to thirst. Forced large fluid intakes do not protect the kidneys in stage 3 and can be harmful if you have heart failure or oedema.
ALCOHOL
- Within UK low-risk limits (14 units/week, spread, with alcohol-free days).
Kidney Vitality is a daily multivitamin developed by a UK Consultant Nephrologist using renal nutrition principles. It contains no added potassium, magnesium, phosphorus or iron, and no herbal blends. See the formulation.
Medications that change the trajectory
BLOOD PRESSURE
- Target generally <130/80 in CKD with proteinuria; <140/90 otherwise.
- ACE inhibitors (ramipril, lisinopril) or ARBs (losartan, candesartan) are first-line if there is protein in the urine.
SGLT2 INHIBITORS
- Dapagliflozin and empagliflozin are now NICE-recommended in many adults with CKD, with or without diabetes, and slow progression and reduce cardiovascular events.
DIABETES
- Optimise HbA1c with kidney-safe agents; metformin can usually continue in stage 3 with dose adjustment.
CHOLESTEROL
- A statin (typically atorvastatin 20 mg) is offered for primary prevention in most adults with CKD.
DRUGS TO BE CAREFUL WITH
- Regular NSAIDs (ibuprofen, naproxen, diclofenac) — avoid where possible.
- Some antibiotics, lithium, gadolinium contrast, and unlicensed herbal blends — always check with your GP or pharmacist.
- Over-the-counter potassium-containing salt substitutes are not recommended without advice.
Never stop a prescribed medication on your own — discuss with your GP or renal team.
Lifestyle measures that slow progression
- SMOKING — stopping is one of the most powerful things you can do for both your kidneys and your heart.
- WEIGHT — gradual weight loss if BMI is above 30 reduces proteinuria and improves blood pressure.
- PHYSICAL ACTIVITY — the UK CMO target (150 minutes of moderate activity per week) applies, with simple resistance work twice a week.
- SLEEP — treat snoring or suspected sleep apnoea; both raise blood pressure.
- VACCINES — flu annually, COVID per current UK schedule, pneumococcal once, and hepatitis B if advised by your renal team.
- REVIEW SCHEDULE — at least annual eGFR and urine ACR in stable stage 3a, 6-monthly in stage 3b, more often if anything is changing.
When to ask for a nephrologist referral
Most stage 3 CKD is managed in UK primary care. NICE suggests referral to a nephrologist if any of the following are present:
- eGFR falling rapidly (≥5 ml/min/year, or ≥10 ml/min over 5 years)
- eGFR <30 (i.e. stage 3b moving into stage 4)
- Urine ACR ≥70 mg/mmol on its own, or ≥30 mg/mmol with haematuria
- Uncontrolled blood pressure on four or more agents
- A suspected inherited cause (polycystic kidney disease, Alport syndrome)
- An unexplained drop in eGFR or worrying symptoms
Referral is for advice and shared care — it does NOT mean dialysis is imminent.
