Chronic kidney disease
Chronic kidney disease, or CKD, means a lasting fall in how well the kidneys work — going on for more than three months — or proven damage to kidney tissue.
On this page
- What lies behind the diagnosis and how kidney function is measured
- Why kidneys give way
- Why nothing bothers you for years
- Who should be checked without waiting for symptoms
- When waiting is not an option
- What genuinely slows the disease down
- Complications treated in their own right
- When the kidneys are no longer enough
- Online consultation
Medicines commonly prescribed for Chronic kidney disease
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: INJECTABLE, 4000 IUActive substance: erythropoietinManufacturer: Roche Registration GmbhPrescription requiredDosage form: INJECTABLE, 40000 IUActive substance: erythropoietinManufacturer: Pfizer Europe Ma EeigPrescription requiredDosage form: INJECTABLE, 66.7 mcg/ml of epoetinActive substance: erythropoietinManufacturer: Ratiopharm GmbhPrescription required
Chronic kidney disease, or CKD, means a lasting fall in how well the kidneys work — going on for more than three months — or proven damage to kidney tissue. The name sounds alarming, but it is not a sentence: only a small minority ever lose kidney function altogether, and the great majority of people with CKD live an ordinary life. The point of the diagnosis is to catch the disease while its course can still be slowed.
What lies behind the diagnosis and how kidney function is measured
The kidneys do more than clear waste products and surplus water. They hold up blood pressure, regulate acidity and salt levels, tell the bone marrow to make red cells, and convert vitamin D into the active form without which calcium is not absorbed. That is why, when they fail, it is not one organ that suffers but the whole body at once.
Two measurements are used, and both are needed. The first is the estimated glomerular filtration rate, worked out from the creatinine in the blood with a correction for age and sex. A healthy value is above 90 mL/min/1.73 m²; as it falls, stages are defined — 60 to 89 is a mild reduction, 45 to 59 and 30 to 44 moderate, 15 to 29 severe, and below 15 the kidneys have lost almost all their function. Creatinine depends on muscle mass, so in a very thin older person the calculation can flatter the picture, and in an athlete it can do the opposite.
The second measurement is albumin in the urine, or more precisely its ratio to urinary creatinine. Protein starts leaking before filtration drops, so it is often the first signal and it is also the strongest predictor of what happens next. Results fall into three bands: normal or slightly raised, moderately raised and heavily raised. The units differ from country to country, so the reference range of your own laboratory is what to go by.
One test is not a diagnosis. The numbers shift with dehydration, fever, hard physical exertion and certain medicines, so an abnormal result is confirmed by repeating it, usually three months later.
Why kidneys give way
CKD is rarely a disease in its own right; it is usually the consequence of another one, and as a rule several causes act together.
- Diabetes. The leading cause worldwide. Years of excess glucose damage the finest filters, and the first sign is albumin in the urine.
- High blood pressure. Second in frequency and a consequence as well: damaged kidneys push the pressure up themselves, closing the circle.
- Glomerulonephritis. Inflammation of the filtering tufts, often autoimmune; kidney involvement in lupus and in vasculitis belongs here too.
- Polycystic kidney disease. An inherited condition in which cysts grow inside the kidneys. If a parent has it, the children are worth testing.
- Obstruction to urine flow. Recurring stones, an enlarged prostate, a narrowed ureter.
- Scars from childhood infections. Urine refluxing up from the bladder, and past episodes of pyelonephritis, leave marks on the kidney that make themselves felt decades later.
- Medicines. Years of anti-inflammatory painkillers, lithium, some treatment regimens — and herbal or "cleansing" supplements of unknown composition, a proportion of which contain aristolochic acid, which destroys the kidneys irreversibly.
- A previous episode of acute kidney injury. Even after an apparently complete recovery the risk of chronic disease stays higher, and such a person is followed up afterwards.
Why nothing bothers you for years
The kidney's reserve is vast: more than half the filtering tissue can be lost without being noticed. That is why the early stages nearly always turn up by chance, in bloods taken before an operation, at a routine check or while investigating something else.
Complaints arrive once function has dropped considerably, and they are non-specific: tiredness that sleep does not touch, swollen ankles and puffy eyelids in the morning, breathlessness, getting up at night to pass water, loss of appetite and of taste, a metallic taste in the mouth, nausea, stubborn itching, cramp in the calves, restless legs, poor sleep, reduced sex drive. Blood in the urine, or urine that froths like beer, is a reason to be seen without delay. None of this makes a diagnosis on its own: every one of these signs occurs in a dozen other conditions, and it is the test that settles the matter.
Who should be checked without waiting for symptoms
The check is cheap and fits into one visit: a blood test for creatinine and a single urine sample for albumin. Repeating it regularly makes sense if even one item on this list applies:
- diabetes of any type;
- persistently high blood pressure;
- heart or vascular disease, a previous heart attack or stroke;
- obesity, gout;
- an autoimmune disease;
- kidney failure or inherited kidney disease in close relatives;
- a previous episode of acute kidney injury;
- a single working kidney;
- long-term use of medicines that affect the kidneys;
- protein or blood once found in the urine and never explained.
How often to repeat it depends on the result and on how high the risk is; with stable numbers once a year is usually enough.
When waiting is not an option
Call an ambulance — in Spain, Italy, Portugal, Poland and Ukraine the number is 112 — if any of the following appear:
- severe and worsening breathlessness, an inability to lie flat, bubbling breathing, pink frothy sputum: this is fluid on the lungs from retained water;
- chest pain, palpitations and a very slow or irregular pulse with marked weakness, which can mean a dangerously high potassium level;
- confusion, fits, or being unable to rouse the person.
Being seen the same day, though without an ambulance, is needed if urine has almost stopped, if swelling has grown sharply over a few days, if relentless vomiting has started, or if fever and loin pain appear.
Separately, it is worth agreeing with your doctor in advance what to do on sick days. Heavy vomiting, diarrhoea or a high fever cost the body water, and some regular medicines are paused temporarily on those days: diuretics, ACE inhibitors and angiotensin receptor blockers, SGLT2 inhibitors and metformin, while anti-inflammatory painkillers are not taken at all. They go back on once the person is drinking and eating normally again. That plan should come from your own doctor beforehand, not be invented in the middle of an illness.
What genuinely slows the disease down
Filtering units that have died cannot be brought back, but the rate at which the rest are lost is very much controllable, and the difference between careful and careless management is measured in decades.
- Blood pressure. The most powerful lever. For most people the mark is around 130/80 mmHg, with the exact target set by the doctor according to age and tolerance. A home monitor with a written record helps.
- Kidney-protecting drugs. When albumin is present in the urine, an ACE inhibitor or an angiotensin receptor blocker is prescribed: they lower the pressure inside the filtering tuft and cut protein loss. Creatinine and potassium are checked after starting.
- SGLT2 inhibitors. A class that has arrived in recent years, slowing the progression of CKD and protecting the heart, including in people without diabetes. It is now one of the mainstays where protein is being lost.
- Blood sugar. In diabetes, good control shows directly on the kidneys.
- Cholesterol. Statins are given not for the kidneys but because someone with CKD is at greater risk from the heart and blood vessels than from reaching dialysis.
- Salt. Around five grams a day — a teaspoon, counting what is already in bread, cheese and processed meat. Salt substitutes are no help here: they contain potassium.
- Smoking, weight, movement. Stopping smoking slows the loss of function; the guide for activity is 150 minutes a week at moderate intensity; losing weight reduces protein in the urine.
- Painkillers. Ibuprofen, diclofenac and naproxen are taken in CKD only on a doctor's instruction and briefly. Paracetamol suits ordinary pain.
- Doses of everything else. Many medicines leave the body through the kidneys and need reducing when filtration is low. Tell any doctor and any pharmacist about your kidney disease, and mention it before any scan with contrast.
Not everybody needs a special diet. In the early stages ordinary healthy eating is enough; restricting protein, potassium or phosphate is something the doctor decides from the results, and it is better done with a dietitian, or it is easy to end up undernourished instead of better.
Complications treated in their own right
As function declines, separate problems appear, each with its own answer. Anaemia develops because a damaged kidney makes too little of the hormone that drives the bone marrow; it is treated with iron and with drugs that stimulate red cell production. Too much phosphate disturbs calcium handling, leaving bones brittle and arteries stiff; cutting phosphate additives in processed food, phosphate binders and active forms of vitamin D all help. High potassium is dangerous to the heart and calls for a review of diet and medication, sometimes with drugs that remove it. Acid build-up in the blood is corrected with bicarbonate, and fluid retention with diuretics and less salt.
Protection against infection deserves its own mention: kidney disease weakens the immune system, so the vaccinations offered to people with long-term conditions under the national schedule apply. Pregnancy with CKD is possible, but it is planned in advance with a kidney specialist: some of the drugs that protect the kidneys are not allowed in pregnancy and have to be swapped before conceiving.
When the kidneys are no longer enough
A small proportion of people reach the point where their own kidneys cannot cope. It usually happens gradually, so there is time to prepare. There are three options, and they are discussed ahead of time rather than in the middle of a crisis.
Dialysis replaces part of the kidneys' work. Haemodialysis cleans the blood through a machine, generally three times a week at a unit or at home; it needs an access created in the arm beforehand, months ahead of starting. Peritoneal dialysis is done at home by the person themselves, using their own peritoneum as the filter; it allows more freedom but demands meticulousness. A kidney transplant usually gives better quality of life and more years, though it means major surgery and lifelong drugs to prevent rejection; the donor may be living or deceased, and the wait can run into years. Conservative care without dialysis is a considered choice for some older people with serious other illnesses, when dialysis would not extend life but would consume what is left of it. It is not a withdrawal of care: symptoms are controlled with medicines and the person is supported to the end.
Online consultation
In an online consultation the doctor will go through your results: what the filtration figure and the urine albumin mean, whether the abnormality is a one-off or a settled one, and which investigations are needed to find the cause. They will advise how often to repeat the checks, help you review your list of medicines against the kidney function you actually have, and talk through what to do on sick days. If the diagnosis is already established, the appointment is the place to look at the blood pressure readings you have recorded at home, discuss food, and work out which changes can wait for the planned review and which mean being seen the same day.
This material is for information only and does not replace medical advice.
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Online doctors for Chronic kidney disease
Discuss your symptoms and possible next steps for Chronic kidney disease with a doctor online.
