Kidney Disease Glossary

Medical terminology can be intimidating. This glossary defines over 100 common kidney disease terms in plain language — so you can understand what your doctor is saying, read your lab reports with confidence, and feel less overwhelmed by the vocabulary of kidney care.

If all these terms feel overwhelming — I put together a free guide that explains the most important kidney concepts, lab values, and next steps in plain language.

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A

ACE Inhibitor: A type of blood pressure medication (e.g., lisinopril, enalapril) that also protects the kidneys by reducing pressure inside the glomeruli. Often prescribed for CKD patients, especially those with diabetes or proteinuria.Also: How CKD is managed · CKD and diabetes: kidney-protective medications
Acute Kidney Injury (AKI): A sudden loss of kidney function, usually occurring over hours or days. Unlike CKD, AKI is often reversible with prompt treatment. Causes include severe dehydration, infections, and certain medications.
Albumin: A protein made by the liver that circulates in the blood. When found in urine (albuminuria), it is an early sign of kidney damage. Healthy kidneys do not let albumin pass into urine.Also: Understanding the uACR protein test
Albuminuria: The presence of albumin (protein) in the urine. A key marker for kidney damage and a sign that the kidney's filtering system is leaking. Measured by the uACR test. Learn what albuminuria means for kidney healthAlso: Understanding the uACR test
Albuminuria Categories (A1–A3): A classification system for the severity of albuminuria. A1 (normal, below 30 mg/g) means minimal protein leak. A2 (moderately increased, 30–300 mg/g) signals early kidney damage. A3 (severely increased, above 300 mg/g) indicates significant damage. Used alongside G stages to classify CKD. Read the full CKD staging guide including albuminuria categories
Alport Syndrome: A rare genetic condition that affects the glomerular basement membrane, causing progressive kidney disease, hearing loss, and sometimes eye abnormalities. Caused by mutations in type IV collagen genes. Often diagnosed in childhood or early adulthood.
Anaemia (Anemia): A condition where you do not have enough red blood cells to carry adequate oxygen to your tissues. Common in CKD because the kidneys produce less erythropoietin (EPO), the hormone that stimulates red blood cell production.
Anuria: The near-complete absence of urine output (less than 100 mL per day). A sign of severe kidney failure or complete urinary obstruction. Requires immediate medical attention as waste products accumulate rapidly in the blood.
ARB: Angiotensin II Receptor Blocker — a blood pressure medication (e.g., losartan, valsartan) with kidney-protective effects similar to ACE inhibitors. Used when ACE inhibitors cause side effects like cough.
Arteriovenous Fistula (AV Fistula): A surgically created connection between an artery and a vein, usually in the arm, used for haemodialysis access. Considered the best long-term access option. Needs 2–6 months to mature before use. Learn about dialysis access options
AV Graft: A synthetic tube surgically placed to connect an artery to a vein for haemodialysis access. Used when a patient's veins are not suitable for a fistula. Can be used sooner than a fistula (2–4 weeks) but has a higher risk of clotting and infection. Compare haemodialysis access types

B

Bicarbonate: A substance that helps keep your blood at a healthy pH level (not too acidic). The kidneys normally produce bicarbonate. In advanced CKD, bicarbonate levels drop, leading to metabolic acidosis. Often supplemented with sodium bicarbonate tablets.
BK Virus: A common virus that lies dormant in most people but can reactivate after kidney transplantation due to immunosuppression. BK virus can cause BK nephropathy, damaging the transplanted kidney. Monitored by regular urine and blood tests post-transplant. Read about kidney transplant care and monitoring
BUN (Blood Urea Nitrogen): A blood test that measures the amount of urea nitrogen in your blood. Urea is a waste product from protein metabolism. Elevated BUN can indicate reduced kidney function, but it is also affected by diet and hydration. Understand your kidney blood test results

C

Calcitriol: The active form of vitamin D (1,25-dihydroxyvitamin D) produced by the kidneys. Essential for calcium absorption and bone health. In CKD, the kidneys lose the ability to convert vitamin D to calcitriol, leading to calcium deficiency, bone weakness, and elevated PTH.
Calcium: A mineral essential for bones, muscles, and nerves. In CKD, calcium levels can become abnormal because the kidneys can no longer activate vitamin D properly. Low calcium can lead to bone weakness and is part of the CKD-MBD picture.
Catheter (Dialysis): A flexible tube inserted into a large vein (usually in the neck or chest) to provide temporary access for haemodialysis. Used when a fistula or graft is not yet ready. Learn about temporary dialysis access
Central Venous Catheter (CVC): A temporary dialysis access device inserted into a large vein in the neck or chest. Used when a fistula or graft is not yet ready. Has higher infection risk than a fistula. Also called a 'tunnelled line' when designed for longer-term use. Learn about dialysis access options
CGA Staging: The complete CKD classification system that combines three factors: Cause of kidney disease (C), GFR category G1–G5 (G), and Albuminuria category A1–A3 (A). This gives your care team a full picture of your kidney health, not just one number. Read the complete CKD staging guide
CKD (Chronic Kidney Disease): A progressive condition in which the kidneys gradually lose their ability to filter waste and excess fluid from the blood. Defined as kidney damage or GFR below 60 for three months or more. Classified in 5 stages based on GFR. Understand what CKD means and what to expectAlso: CKD stages explained (G1–G5) · Early symptoms of kidney disease
CKD-MBD (Mineral and Bone Disorder): A group of problems with calcium, phosphorus, PTH, and vitamin D that develop as kidney function declines. CKD-MBD weakens bones, causes itching, and can damage blood vessels. Managed through diet, phosphate binders, and vitamin D.
CKD Staging (G1–G5): CKD is classified into five stages based on GFR: G1 (≥90, normal GFR with other signs of damage), G2 (60–89, mildly decreased), G3a (45–59, mild-to-moderate), G3b (30–44, moderate-to-severe), G4 (15–29, severely decreased), G5 (<15, kidney failure). Each stage guides treatment decisions. Read the full CKD stages guide
CMV (Cytomegalovirus): A common virus that rarely causes problems in healthy people but can cause serious illness after transplantation when the immune system is suppressed. Prophylactic antiviral medication is routinely given post-transplant. Read about kidney transplant care and complications
Conservative Care: A management approach for advanced CKD (Stage 5) that focuses on quality of life, symptom management, and palliative support, rather than dialysis or transplant. An appropriate option for some elderly or frail patients. Also called 'supportive care' or 'non-dialysis care.' Start with our patient orientation guide
Creatinine: A waste product produced by your muscles that is filtered by the kidneys. Blood creatinine levels are used to estimate GFR. Higher creatinine generally means lower kidney function, though muscle mass and other factors affect the number. Read the full guide to creatinine levels in CKDAlso: How eGFR is calculated from creatinine · Understanding your kidney blood test results
Crossmatch: A pre-transplant test that checks whether a recipient's immune system would immediately attack a donor kidney. A positive crossmatch (meaning antibodies are present against donor tissue) generally means the transplant cannot proceed.Also: The transplant evaluation process explained

D

Diabetic Nephropathy: Kidney damage caused by long-standing diabetes mellitus. High blood sugar gradually damages the glomeruli, leading to proteinuria and declining kidney function. The single most common cause of kidney failure worldwide. Managed with blood sugar control, ACE inhibitors or ARBs, and SGLT2 inhibitors. Read about CKD caused by diabetes
Dialysate: The fluid used in dialysis to draw waste products and excess fluid from the blood. In haemodialysis, blood flows against dialysate across a membrane. In peritoneal dialysis, dialysate is infused into the abdomen. Learn how dialysis works
Dialysis Access: The point on the body where blood is drawn out and returned during haemodialysis. The three main types are AV fistula (preferred), AV graft, and central venous catheter (temporary). Planning access early — ideally 6–12 months before dialysis is needed — leads to better outcomes. Learn how dialysis access is planned and created
Deceased Donor: A person who has died and whose kidneys are donated for transplantation. Deceased donor kidneys last an average of 10–15 years. The waiting list for a deceased donor kidney can be 3–7 years depending on blood type and location. Learn about deceased donor kidney transplantationAlso: The transplant waiting list explained
Diabetes Mellitus: A condition where the body cannot properly regulate blood sugar. Type 1 and Type 2 diabetes are the leading cause of CKD worldwide. High blood sugar damages the tiny blood vessels in the kidneys over time (diabetic nephropathy). Read how diabetes affects the kidneys
Dialysis: A medical treatment that performs the functions of the kidneys when they can no longer work adequately. The two main types are haemodialysis (filtering blood through a machine) and peritoneal dialysis (using the lining of the abdomen). Understand how dialysis works and explore your optionsAlso: Haemodialysis vs peritoneal dialysis — how to choose · Dialysis vs transplant — comparing your options
Diuretic: A medication that helps the kidneys remove extra sodium and water from the body, reducing fluid retention and blood pressure. Common types include furosemide (loop diuretic), hydrochlorothiazide (thiazide), and spironolactone (potassium-sparing). Dosing must be adjusted as kidney function changes.
Dialysis Adequacy: A measure of whether dialysis is removing enough waste from your body. Assessed using Kt/V or URR (urea reduction ratio). Your care team monitors this regularly to ensure your treatments are effective. Read about dialysis adequacy and monitoring
Donor-Specific Antibodies (DSA): Antibodies in the recipient's blood directed against specific proteins (HLA antigens) on the donor kidney. The presence of DSA before or after transplantation increases the risk of rejection. Monitored regularly post-transplant. Read about kidney transplant compatibility testing
Dry Weight: The target body weight for a dialysis patient after a session, when excess fluid has been removed. Maintaining dry weight is important to control blood pressure and prevent fluid overload between sessions. Understand fluid management on dialysis

E

Edema (Oedema): Swelling caused by excess fluid trapped in your body's tissues. In kidney disease, oedema commonly affects the ankles, feet, legs, hands, and face. It occurs when the kidneys cannot remove enough fluid. Read about symptoms of kidney failure
eGFR (Estimated Glomerular Filtration Rate): A calculated estimate of how well your kidneys filter blood, derived from your blood creatinine level, age, and sex. The most important number for staging CKD. Normal is above 90 mL/min. Understand what your eGFR number meansAlso: eGFR vs creatinine — what is the difference? · CKD stages explained by GFR range
Electrolytes: Minerals in your blood that carry an electric charge, including potassium, sodium, calcium, and phosphorus. The kidneys help maintain electrolyte balance. Imbalances are common in CKD and can be dangerous. Understand your kidney blood test results
EPO (Erythropoietin): A hormone produced by the kidneys that stimulates the bone marrow to produce red blood cells. Declining EPO production in CKD leads to anaemia. Synthetic EPO (epoetin alfa, darbepoetin) can be given as treatment.
ESKD (End-Stage Kidney Disease): The final stage of chronic kidney disease (stage 5, also called ESRD) where kidney function has declined to the point that dialysis or a transplant is needed to sustain life. GFR is typically below 15 mL/min. Read about symptoms of advanced kidney diseaseAlso: Understanding your dialysis options · Kidney transplant overview

F

FSGS (Focal Segmental Glomerulosclerosis): A disease where scar tissue forms on the glomeruli, the tiny filters in the kidneys. 'Focal' means only some glomeruli are affected; 'segmental' means only part of each glomerulus is scarred. A common cause of nephrotic syndrome and can lead to kidney failure. May be treated with immunosuppressive drugs.
Finerenone: A newer medication (non-steroidal mineralocorticoid receptor antagonist) approved for slowing the progression of kidney disease in patients with type 2 diabetes and CKD. Used alongside ACE/ARBs and SGLT2 inhibitors.Also: CKD and diabetes: protecting your kidneys
Fluid Restriction: A limit on how much liquid you drink each day. May be necessary in advanced CKD or on dialysis when the kidneys can no longer remove enough fluid. Your care team sets a daily limit based on urine output, weight gain, and blood pressure.Also: Managing sodium and fluid restriction in CKD

G

G3a and G3b: Sub-stages of CKD stage 3. G3a (GFR 45–59) is mild-to-moderately decreased kidney function. G3b (GFR 30–44) is moderate-to-severely decreased. The split matters because G3b patients have a significantly higher risk of progressing to kidney failure and are typically monitored more closely. Read the complete CKD staging guide
GFR (Glomerular Filtration Rate): The rate at which your kidneys filter blood, measured in milliliters per minute. The gold standard for assessing kidney function. Usually estimated from blood tests (eGFR) rather than measured directly. Learn how GFR measures kidney functionAlso: What eGFR really measures
Glomerulonephritis: Inflammation of the glomeruli, the tiny filters in the kidneys. Can be acute (sudden) or chronic (long-term). Causes include infections, autoimmune diseases (lupus, IgA nephropathy), and other conditions. Symptoms may include blood in the urine, protein in the urine, swelling, and high blood pressure.
Glomerulus: A tiny cluster of blood vessels inside each nephron that acts as the kidney's primary filter. Each kidney contains about 1 million glomeruli. Damage to the glomeruli is a primary mechanism in many forms of kidney disease.
Graft (Dialysis): A synthetic tube connecting an artery to a vein, used as an alternative to a fistula for haemodialysis access. Grafts can be used sooner than fistulas (within 2–4 weeks) but have a higher rate of complications. Compare haemodialysis access types

H

Haematuria: The presence of blood in the urine. Visible haematuria (you can see it) makes urine look pink, red, or brown. Microscopic haematuria (invisible to the eye) is detected only by lab tests. Can indicate kidney disease, infection, or other urological conditions.
Haemodialysis: A type of dialysis where blood is pumped through an external machine (dialyser) that filters waste and excess fluid. Typically performed 3 times per week at a dialysis centre, each session lasting 3–5 hours. Read the complete guide to haemodialysisAlso: What a week on haemodialysis actually looks like · HD vs PD — comparing dialysis modalities
HLA Matching: Human Leukocyte Antigen matching — the process of comparing donor and recipient tissue proteins to assess compatibility. Better HLA matching generally leads to longer transplant survival, though modern immunosuppression allows transplants with less-than-perfect matches. Read about the kidney transplant processAlso: The transplant evaluation process explained
Home HD (Home Haemodialysis): Haemodialysis performed at the patient's home rather than in a dialysis centre. Allows more frequent or longer sessions, which can improve quality of life and clinical outcomes. Requires training, suitable home setup, and a care partner in some cases. Learn about home haemodialysisAlso: HD vs PD: comparing dialysis options
Hyperkalaemia (Hyperkalemia): Abnormally high potassium levels in the blood (above 5.0 mEq/L). A potentially dangerous condition in kidney disease because high potassium can cause irregular heartbeat or cardiac arrest. See which foods are low in potassiumAlso: CKD diet: foods to avoid
Hypertensive Nephrosclerosis: Kidney damage caused by long-standing high blood pressure. Chronic hypertension hardens and narrows the small blood vessels in the kidneys, reducing blood flow and filtering capacity. The second most common cause of kidney failure after diabetes. Managed primarily through strict blood pressure control.Also: How CKD is managed
Hypertension: High blood pressure — a leading cause and consequence of CKD. The target for most CKD patients is below 130/80 mmHg. Managing blood pressure is one of the most effective ways to slow kidney disease progression. Read how blood pressure affects CKD

I

IgA Nephropathy: The most common form of glomerulonephritis worldwide. Occurs when IgA antibodies (part of the immune system) build up in the glomeruli, causing inflammation and gradual damage. Often presents with blood in the urine after a cold or sore throat. Progresses slowly — about 20–40% of patients develop kidney failure over 20 years.
Immunosuppression: Medications that suppress the immune system to prevent it from attacking a transplanted kidney. Required for life after kidney transplant. Common drugs include tacrolimus, mycophenolate, and prednisolone. Learn about immunosuppression after kidney transplantAlso: The complete kidney transplant guide · Understanding transplant rejection
In-Centre HD (In-Centre Haemodialysis): Haemodialysis performed at a dialysis unit or hospital, typically three times per week. The most common form of dialysis in most countries. Each session lasts around 4 hours. Learn about in-centre haemodialysisAlso: What haemodialysis looks like week to week

K

KDIGO: Kidney Disease: Improving Global Outcomes — an international organisation that develops clinical practice guidelines for kidney disease. KDIGO guidelines are the global standard for CKD classification and treatment.
Kidney Biopsy: A procedure where a small sample of kidney tissue is removed with a needle and examined under a microscope. Used to diagnose the specific cause of kidney disease and guide treatment decisions.
Kidney Failure: When the kidneys can no longer function well enough to sustain health — also called ESKD or stage 5 CKD. GFR is below 15 mL/min. Treatment (dialysis or transplant) is needed. Many people live full lives with kidney failure when properly treated. Read about the signs and symptoms of kidney failureAlso: Your treatment options at kidney failure · Understanding kidney transplant
Kidney Transplant: A surgery in which a healthy kidney from a living or deceased donor is placed into a patient with kidney failure. Offers the best long-term outcomes for most patients and eliminates the need for dialysis. Read the complete guide to kidney transplantationAlso: The kidney transplant evaluation process · Understanding the transplant waiting list
Kt/V: A measure of dialysis adequacy — how much urea has been cleared from the blood during a dialysis session relative to the patient's body water volume. A target Kt/V of at least 1.2 per session (for 3x/week HD) indicates adequate treatment. Understand dialysis adequacy monitoring

L

Lupus Nephritis: Kidney inflammation caused by systemic lupus erythematosus (SLE), an autoimmune disease. The immune system attacks the kidneys, causing proteinuria, haematuria, and declining function. Classified into 6 classes by severity. Treated with immunosuppressive medications. Up to 60% of lupus patients develop some degree of kidney involvement.
Living Donor: A person who donates one of their kidneys while alive, usually to a family member, friend, or through a paired exchange programme. Living donor kidneys last an average of 15–20 years — longer than deceased donor kidneys. Learn about living kidney donationAlso: The living donation process explained
Living Donor Evaluation: The process of assessing whether a potential living kidney donor is medically and psychologically suitable to donate. Includes extensive blood tests, imaging, kidney function assessment, and psychological screening. Read about the living donor evaluation processAlso: Living kidney donation: what to expect
Low Potassium Diet: A dietary approach that limits potassium intake, typically to 2,000–3,000 mg per day. Not all CKD patients need this restriction — it depends on blood potassium levels. Focuses on choosing lower-potassium fruits, vegetables, and proteins. See a guide to low potassium foods for kidney diseaseAlso: Foods to avoid with kidney disease

M

Metabolic Acidosis: A condition where the blood becomes too acidic because the kidneys can no longer remove enough acid or produce enough bicarbonate. Common in CKD stages 4–5. Symptoms include rapid breathing and fatigue. Treated with sodium bicarbonate supplements. See how metabolic acidosis relates to CKD stageAlso: Symptoms of advanced kidney disease
Mycophenolate (MMF): An immunosuppressant medication commonly used after kidney transplantation to prevent rejection. Works by suppressing the proliferation of immune cells. Usually taken with tacrolimus and prednisolone as part of a triple therapy regimen. Read about medications used after kidney transplantAlso: The complete kidney transplant guide

N

Nephron: The basic functional unit of the kidney. Each kidney contains about 1 million nephrons, each consisting of a glomerulus (filter) and a tubule (tube). Nephrons filter blood, reabsorb useful substances, and produce urine.
Nephrotic Syndrome: A group of symptoms caused by severe protein leakage from the kidneys: heavy proteinuria (more than 3.5 g/day), low blood albumin, high cholesterol, and significant oedema (swelling). Caused by conditions like FSGS, membranous nephropathy, and diabetic nephropathy. Treated with immunosuppressants, diuretics, and ACE inhibitors or ARBs.
Nephrologist: A doctor who specialises in kidney disease. Nephrologists manage CKD, perform kidney biopsies, oversee dialysis, and coordinate transplant evaluations. Most CKD patients are referred to a nephrologist by stage 3–4. Learn what a nephrologist does and when to see one
Nephropathy: A general term for kidney disease or damage. Diabetic nephropathy is kidney damage caused by diabetes — the leading cause of kidney failure worldwide. Read about CKD and diabetic kidney disease
Nocturia: The need to wake up during the night to urinate. Common in CKD because damaged kidneys lose the ability to concentrate urine, producing more dilute urine throughout the day and night.Also: Early symptoms of kidney disease

O

Oliguria: Abnormally low urine output, typically defined as less than 400 mL per day in adults. Can indicate acute kidney injury, severe dehydration, or worsening kidney failure. Distinct from anuria (near-zero output). Monitoring urine output is an important clinical marker in hospital settings.

P

Palliative Care: Specialist care focused on relieving symptoms and improving quality of life for patients with serious illness. For CKD patients, palliative care can be appropriate at any stage — not only end of life — and can be provided alongside kidney-directed treatment. Find out where to start with CKD
PD Catheter: A soft, flexible tube surgically inserted into the abdomen to allow dialysate to flow in and out during peritoneal dialysis. Usually placed 2–4 weeks before starting PD to allow healing. Learn about peritoneal dialysis accessAlso: How peritoneal dialysis works at home
Peritoneal Dialysis (PD): A type of dialysis performed at home, using the lining of your abdomen (peritoneum) as a natural filter. A special fluid is introduced through a catheter and absorbs waste before being drained. Usually performed daily. Learn how peritoneal dialysis works at homeAlso: A practical guide to peritoneal dialysis at home · HD vs PD — comparing dialysis modalities
Peritonitis: Infection of the peritoneum (the membrane lining the abdomen) — the most serious complication of peritoneal dialysis. Caused by bacteria entering through the PD catheter. Symptoms include abdominal pain, cloudy dialysate, and fever. Requires prompt antibiotic treatment. Read about peritoneal dialysis complications
Polyuria: Producing abnormally large volumes of urine (typically more than 3 litres per day). In early CKD, damaged kidneys lose the ability to concentrate urine, leading to dilute, high-volume output. Also common in uncontrolled diabetes. Despite producing more urine, the kidneys are actually filtering waste less effectively.Also: Early symptoms of kidney disease
Phosphate Binder: A medication taken with meals to prevent your body from absorbing too much phosphorus from food. Necessary when the kidneys can no longer remove enough phosphorus. Common binders include sevelamer and calcium acetate. Read about managing phosphorus in your CKD dietAlso: CKD diet overview
Phosphorus: A mineral found in many foods (dairy, meat, processed foods) that can build up in the blood when kidneys fail. High phosphorus causes itching, weakens bones, and damages blood vessels. Learn how to manage phosphorus in a renal dietAlso: Low phosphorus foods for kidney disease · Foods to avoid with kidney disease
PKD (Polycystic Kidney Disease): An inherited condition where clusters of fluid-filled cysts develop in the kidneys, gradually enlarging them and reducing function. The most common inherited cause of kidney failure.Also: Understanding CKD causes and progression
Potassium: An essential mineral that helps regulate heartbeat, muscle function, and nerve signals. In CKD, the kidneys may not remove enough potassium, leading to dangerous buildup (hyperkalaemia). See which foods are low in potassium for kidney diseaseAlso: Kidney diet essentials — what to eat and avoid · Foods to avoid with kidney disease
PRA / cPRA (Panel Reactive Antibodies): A blood test that measures the percentage of donors a patient is likely to be reactive against. A high cPRA means the patient has many antibodies (often from prior transplants, pregnancies, or blood transfusions) and may be harder to match. Read about transplant compatibility and antibody testingAlso: The transplant evaluation process explained
Pre-emptive Transplant: A kidney transplant performed before dialysis becomes necessary. Associated with better outcomes than transplanting after dialysis has started. Requires early referral and a suitable living donor or timely deceased donor match. Learn about the benefits of pre-emptive transplantationAlso: The transplant evaluation process
Prednisolone: A corticosteroid (steroid) used as part of immunosuppression after kidney transplantation. Also used to treat rejection episodes. Long-term use can cause side effects including weight gain, bone thinning, and elevated blood sugar. Read about immunosuppression after transplant
Proteinuria: The presence of excess protein in the urine. A sign of kidney damage. Protein in the urine (especially albumin) indicates that the kidney's filters are leaking and is a risk factor for faster kidney disease progression. Learn what protein in urine means for kidney healthAlso: Understanding the uACR test
PTH (Parathyroid Hormone): A hormone produced by the parathyroid glands that regulates calcium and phosphorus. In CKD, PTH levels rise because the kidneys cannot maintain normal calcium and phosphorus balance. High PTH weakens bones and is part of CKD-MBD.

R

Renal: Relating to the kidneys. 'Renal function' means kidney function. 'Renal diet' means a diet designed for kidney patients. 'Renal failure' means kidney failure.
Renal Diet: A way of eating designed to reduce the workload on damaged kidneys. Depending on your CKD stage, it may involve managing potassium, phosphorus, sodium, protein, and fluid intake. A renal dietitian creates a personalised plan based on your lab results. Explore the kidney diet guideAlso: Foods to avoid with kidney disease
Renal Dietitian: A registered dietitian who specialises in nutrition for kidney disease patients. They create personalised meal plans that manage potassium, phosphorus, sodium, protein, and fluid based on your CKD stage and lab results. Learn about nutrition support for kidney disease
Renal Osteodystrophy: A bone disease that develops in CKD due to imbalances in calcium, phosphorus, PTH, and vitamin D. Bones become weak, thin, or misshapen. Part of the broader CKD-MBD syndrome. Managed with phosphate binders, vitamin D, and sometimes calcimimetics.

S

SGLT2 Inhibitor: A class of medications (e.g., dapagliflozin, empagliflozin) originally developed for diabetes that have shown remarkable kidney-protective effects. They slow CKD progression by 30–40% and are now recommended for most CKD patients. Read about CKD treatment and SGLT2 inhibitors
Shared Decision-Making: A collaborative approach to treatment planning where the patient and care team discuss options, weigh the patient's values and preferences, and make decisions together. Especially important for major choices like dialysis modality or transplant listing. Start here — a guide for newly diagnosed CKD patientsAlso: Dialysis vs transplant: weighing your options
Sodium: A mineral found in salt and many processed foods. In CKD, excess sodium causes fluid retention, raises blood pressure, and makes the kidneys work harder. Most CKD patients are advised to limit sodium to under 2,000 mg per day. Learn about sodium restriction in CKDAlso: Sodium and fluid restriction in CKD explained · Foods to avoid with kidney disease

T

Tacrolimus: The most commonly used immunosuppressant after kidney transplantation. Prevents rejection by inhibiting T-cell activation. Requires careful blood level monitoring as too little increases rejection risk and too much causes toxicity (kidney damage, tremor, infection risk). Read about immunosuppressant medications after transplantAlso: The complete kidney transplant guide
Transplant Rejection: The immune system's attack on a transplanted kidney, recognising it as foreign. Acute rejection can often be reversed with treatment. Chronic rejection causes gradual loss of transplant function over time and cannot be fully reversed. Learn how rejection is prevented and treated after transplantAlso: The complete kidney transplant guide · Living kidney donation — what donors need to know

U

uACR (Urine Albumin-to-Creatinine Ratio): A urine test that measures the ratio of albumin (protein) to creatinine. Used to detect early kidney damage. A result above 30 mg/g is considered abnormal. One of the most important screening tests for diabetic kidney disease. Learn how to read your uACR test resultAlso: Kidney disease blood tests explained · Early signs of kidney disease
Ultrafiltration: The removal of excess fluid from the blood during haemodialysis. Controlled precisely to bring the patient to their dry weight. Too-rapid ultrafiltration can cause cramping, low blood pressure, and longer-term cardiovascular harm. Understand fluid removal during dialysis
Ultrasound (Renal): A painless imaging test that uses sound waves to create pictures of your kidneys. Shows kidney size, shape, and structure. Used to check for cysts, stones, blockages, or other abnormalities. Often one of the first tests in a kidney disease workup.
Urea: A waste product created when the body breaks down protein. Healthy kidneys filter urea from the blood into urine. When kidney function declines, urea builds up — measured by the BUN (blood urea nitrogen) test. Learn about kidney blood test markers
Uraemia (Uremia): The buildup of waste products (urea and other toxins) in the blood when the kidneys can no longer filter them adequately. Symptoms include fatigue, nausea, mental fogginess, and itching. Treatment is dialysis or transplant. Read about symptoms of advanced kidney diseaseAlso: Understanding your dialysis options

V

Vitamin D (Active): The kidneys convert inactive vitamin D into its active form (calcitriol or 1,25-dihydroxyvitamin D), which is essential for absorbing calcium from food and maintaining bone health. As kidney function declines, active vitamin D production drops, leading to calcium deficiency, bone weakness, and rising PTH levels. Often supplemented in CKD stages 3–5.
Vascular Access: The site on your body where blood is removed and returned during haemodialysis. The three types are fistula, graft, and catheter. A well-functioning access is essential for effective dialysis. Learn about dialysis vascular access options

W

Waiting List: The national registry of patients approved for a deceased donor kidney transplant. Time on the list depends on blood type, antibodies, location, and other medical factors. Average wait is 3–7 years. You can be listed while still on dialysis or even before starting. Understand the kidney transplant waiting listAlso: The transplant waiting list explained · Living donation as an alternative

Educational information only. This glossary provides simplified definitions for general understanding. Discuss your results and treatment with your clinician. Read our editorial policy.