Nephraware

A

ACE inhibitors

Medications that relax blood vessels and reduce pressure on the kidneys. Often prescribed to protect kidney function and lower protein in the urine. (Full name: angiotensin-converting enzyme inhibitors.)

Adrenal insufficiency

When the adrenal glands (small glands above the kidneys) don't produce enough hormones, especially cortisol. Seen in conditions like SPLIS.

Albumin

A protein made by the liver that normally stays in the bloodstream. When kidney filters are damaged, albumin leaks into the urine and blood levels drop (hypoalbuminemia). Low blood albumin causes the swelling (edema) seen in nephrotic syndrome. Checked via a blood test.

Albuminuria

The presence of albumin (a specific blood protein) in the urine — a sign that the kidney's filters are leaking. Measurable on a urine dipstick as protein. A hallmark of nephrotic syndrome and a marker doctors track to monitor kidney filter health.

Alpha-galactosidase A

An enzyme the body needs to break down a fatty substance called Gb3. A deficiency of this enzyme causes Fabry Disease.

Anemia

A lower-than-normal number of red blood cells, which can cause fatigue, pale skin, and weakness. Common in chronic kidney disease because the kidneys help produce a hormone (erythropoietin) that tells the body to make red blood cells.

Angiokeratomas

Small, dark red or purple raised spots on the skin caused by widened blood vessels. A hallmark sign of Fabry Disease.

Angiomyolipomas

Noncancerous kidney tumors made up of blood vessels, muscle, and fat. Common in Tuberous Sclerosis Complex.

APOL1

A gene variant more common in people of African descent that increases the risk of certain kidney diseases. The APOLLO research network studies transplant outcomes in people who carry APOL1 risk variants.

APSGN (Acute Post-Streptococcal Glomerulonephritis)

A type of glomerulonephritis that develops after a strep infection, causing the kidney's filters to become inflamed.

ARBs

Medications similar to ACE inhibitors that protect the kidneys by blocking a hormone that tightens blood vessels. (Full name: angiotensin II receptor blockers.)

Autosomal dominant

A pattern of inheritance where only one copy of a changed gene (from one parent) is enough to cause a condition. Medullary Cystic Kidney Disease follows this pattern.

Autosomal recessive

A pattern of inheritance where a child must receive a changed gene from both parents to develop the condition. Nephronophthisis and SPLIS follow this pattern.

B

Basement membrane

A thin layer of tissue that supports and separates cells in organs like the kidneys. In Alport Syndrome, these membranes are abnormally thin or irregular.

Biopsy (kidney biopsy)

A procedure where a tiny sample of kidney tissue is removed with a needle and examined under a microscope to diagnose or monitor a kidney condition.

C

Chemotherapy

Medications used to kill cancer cells or stop them from growing. Used in Wilms Tumor treatment.

Chronic Kidney Disease (CKD)

Long-term, gradual loss of kidney function over months or years. Measured in stages 1–5 based on how well the kidneys filter blood (GFR).

Ciliopathy

A group of genetic disorders caused by problems with tiny hair-like structures (cilia) on cells. Nephronophthisis is a ciliopathy.

Cofactor

A substance the body needs to help an enzyme work properly. In SPLIS research, vitamin B6 is being studied as a cofactor for the SGPL1 enzyme.

Collagen IV

A structural protein found in basement membranes. Mutations affecting collagen IV cause Alport Syndrome.

Complement system

A part of the immune system that helps fight infections. When it becomes overactive, it can damage kidneys, as seen in atypical HUS.

Corticosteroids (steroids)

Medications that reduce inflammation and suppress the immune system. A first-line treatment for Nephrotic Syndrome and Minimal Change Disease. Examples include prednisone and prednisolone.

Creatinine

A waste product from muscle activity that the kidneys filter out. Blood creatinine levels help doctors estimate how well the kidneys are working (see: eGFR).

Cyclosporine

A calcineurin inhibitor used as a steroid-sparing immunosuppressant in nephrotic syndrome when steroids alone aren't enough or cause too many side effects. Requires regular blood level monitoring due to potential kidney toxicity.

D

Dialysis

A treatment that takes over the kidneys' job of filtering waste and excess fluid from the blood when the kidneys can no longer do it well enough. The two main types are hemodialysis (using a machine) and peritoneal dialysis (using the lining of the abdomen).

Diuretics

Medications that help the body get rid of extra salt and water through urine. Used to reduce swelling (edema) in conditions like Nephrotic Syndrome.

E

Eculizumab

A medication that blocks part of the complement system. Used to treat atypical Hemolytic Uremic Syndrome.

Edema

Swelling caused by too much fluid trapped in body tissues. In kidney diseases, it often appears around the eyes, in the legs, or in the abdomen. A key symptom of Nephrotic Syndrome.

eGFR (Estimated Glomerular Filtration Rate)

A calculated number — based on blood creatinine, age, and sex — that estimates how well the kidneys are filtering blood. A normal eGFR is above 90. Doctors use it to stage chronic kidney disease and track kidney health over time. Use the Kidney Bean Visual tool to see your child's eGFR in plain language.

Electrolytes

Minerals in the blood (like sodium, potassium, magnesium, and calcium) that carry electrical charges and help muscles, nerves, and organs work properly. Many kidney conditions disrupt electrolyte balance.

Electron microscopy

A powerful type of microscope used to examine kidney tissue at extremely high magnification. Used to diagnose Minimal Change Disease, where damage is too subtle for a regular microscope.

End-stage renal disease (ESRD)

The final stage of chronic kidney disease (stage 5), when the kidneys no longer function well enough to sustain life. Treatment requires dialysis or a transplant.

Enzyme replacement therapy (ERT)

A treatment that provides the body with the enzyme it can't make on its own. Used in Fabry Disease (examples: Fabrazyme, Elfabrio).

Erythropoietin

A hormone made by the kidneys that signals the bone marrow to produce red blood cells. Kidney disease can reduce erythropoietin production, leading to anemia.

F

Fibrosis

The formation of scar tissue. In kidneys, interstitial fibrosis means scarring between the kidney's filtering structures, which reduces function over time.

Foamy urine

Persistent bubbling or foam in the toilet after urinating, caused by protein spilling into the urine (proteinuria). One of the earliest visible signs that kidney filters may be damaged — and a common reason parents first bring their child to the doctor. What foamy urine means and when to investigate →

Frequent relapser

A child with nephrotic syndrome who has two or more relapses within six months of initial response, or four or more relapses in any 12-month period. Frequent relapsers are often considered for steroid-sparing medications to reduce long-term steroid exposure. See also: recognizing a relapse.

FSGS (Focal Segmental Glomerulosclerosis)

A condition where parts of some glomeruli become scarred. Can cause Nephrotic Syndrome and may progress to kidney failure.

G

Gb3 (Globotriaosylceramide)

A fatty substance that builds up in cells when alpha-galactosidase A is deficient, causing the organ damage seen in Fabry Disease.

GFR (Glomerular Filtration Rate)

A number that estimates how well the kidneys are filtering blood. A normal GFR is above 90. Doctors track GFR to stage chronic kidney disease and adjust treatment. In practice, doctors measure eGFR — the estimated GFR calculated from a blood creatinine test.

Genetic counseling

A process where a trained specialist helps families understand inherited conditions, discusses testing options, and explains what results may mean for siblings or future children.

Glomeruli (singular: glomerulus)

Tiny clusters of blood vessels inside the kidneys that act as filters, removing waste and extra fluid from the blood while keeping proteins and blood cells in. Damage to glomeruli is central to many pediatric kidney diseases, including Glomerulonephritis and IgA Nephropathy.

Glomerulonephritis

Inflammation of the glomeruli, which can be caused by infections, immune reactions, or genetic factors. Leads to blood and protein leaking into the urine. Read the full guide →

H

Hematuria

Blood in the urine. It can be visible (gross hematuria, turning urine pink, red, or brown) or only detectable under a microscope (microscopic hematuria).

Hemolytic anemia

A condition where red blood cells are destroyed faster than the body can replace them. One of the three hallmarks of Hemolytic Uremic Syndrome.

Hypokalemia

Abnormally low potassium levels in the blood. A key feature of Gitelman Syndrome.

Hypomagnesemia

Abnormally low magnesium levels in the blood. Another hallmark of Gitelman Syndrome.

Hypoalbuminemia

Abnormally low levels of albumin in the blood. In nephrotic syndrome, albumin leaks through damaged kidney filters into the urine, causing blood albumin to drop. Low albumin causes fluid to shift into tissues, producing the swelling (edema) characteristic of the condition.

I

IgA (Immunoglobulin A)

An antibody the body uses to fight infections. In IgA Nephropathy and HSPN, IgA deposits build up in the glomeruli and cause inflammation.

Immunosuppressants

Medications that calm down the immune system to prevent it from attacking the body's own tissues. Used when steroids alone aren't enough. Examples include cyclosporine, tacrolimus, mycophenolate, and rituximab.

Interstitial

Refers to the tissue between the kidney's filtering structures (tubules and glomeruli). Interstitial fibrosis means scarring in these in-between areas, as seen in Nephronophthisis.

K

Kidney transplant

Surgery to place a healthy kidney from a donor into a person whose kidneys have failed. The new kidney takes over the work of filtering blood.

L

Lysosomal storage disorder

A group of genetic conditions where the body can't break down certain substances, causing them to accumulate and damage organs. Fabry Disease is one example.

M

Microangiopathy

Damage to small blood vessels. In Hemolytic Uremic Syndrome, microangiopathy causes red blood cells to break apart and platelets to clump, leading to anemia and kidney injury.

Minimal Change Disease (MCD)

The most common cause of nephrotic syndrome in children. Under a regular microscope, kidney tissue looks nearly normal — damage is only visible under a powerful electron microscope (as loss of "foot processes" on filter cells). Most children respond well to corticosteroids. Read the full guide →

Mycophenolate (MMF)

A steroid-sparing immunosuppressant used in nephrotic syndrome when steroids alone aren't enough or cause too many side effects. Full name: mycophenolate mofetil.

Migalastat

An oral medication for certain Fabry Disease mutations that helps the body's own enzyme fold correctly so it can function.

N

Nephrologist (pediatric nephrologist)

A doctor who specializes in kidney diseases. A pediatric nephrologist focuses on children.

Nephron

The basic filtering unit of the kidney. Each kidney has about one million nephrons, each containing a glomerulus and a tubule.

Nephrotic syndrome

A kidney condition where damaged glomeruli (filters) leak large amounts of protein into the urine, causing low albumin, fluid buildup (edema), and high cholesterol. The most common cause in children is Minimal Change Disease. Relapses — when protein returns — are common. Read the full guide →

Nephrotoxic

Harmful to the kidneys. Some medications are nephrotoxic, meaning they can cause or worsen kidney injury if not monitored carefully.

Neuropathic pain

Pain caused by nerve damage. In Fabry Disease, this often appears as burning or tingling in the hands and feet.

P

Paresthesias

Abnormal sensations like tingling, prickling, or numbness. Can occur in Gitelman Syndrome due to low electrolyte levels.

Periorbital edema (puffy eyes)

Swelling around the eyes caused by fluid accumulation. Often the first visible sign of nephrotic syndrome in children — parents frequently notice morning puffiness that improves through the day. Commonly mistaken for allergies or a reaction to insect bites.

Phosphate binders

Medications that prevent the body from absorbing too much phosphorus from food. Used in CKD when the kidneys can no longer remove enough phosphorus.

Prednisone / Prednisolone

The most commonly prescribed corticosteroids (steroids) in pediatric kidney disease. Prednisone is converted to prednisolone by the liver; prednisolone is the active form often preferred for children. Both are first-line treatments for nephrotic syndrome. Side effects with long-term use can include weight gain, mood changes, increased infection risk, and effects on bone density.

Proteinuria

Excess protein in the urine. Healthy kidneys keep protein in the blood, so finding protein in the urine is a sign the kidney's filters are damaged. Foamy urine can be a visible clue. A defining feature of Nephrotic Syndrome. Learn what proteinuria means and when to investigate →

R

Relapse

The return of symptoms after a period of improvement (remission). Common in Nephrotic Syndrome, where protein may start leaking into the urine again. Families learn to monitor at home with urine dipstick strips. Learn the early warning signs →

Remission

A period when symptoms improve or disappear. In Nephrotic Syndrome, remission means urine protein levels return to normal (trace or nil on dipstick) — the goal of treatment. Understanding remission and relapse →

Rituximab

An immunosuppressant medication that targets specific immune cells (B cells). Used in some cases of Nephrotic Syndrome and HSPN when other treatments haven't worked.

S

SGLT2 inhibitors

A class of medications originally developed for diabetes that are now also used to protect kidney function by reducing how hard the kidneys have to work. Used in Alport Syndrome.

SGPL1

The gene that provides instructions for making sphingosine phosphate lyase, an enzyme involved in breaking down certain fats. Mutations in SGPL1 cause SPLIS.

Steroid-sparing

Medications used to reduce or eliminate the need for long-term steroids, which carry significant side effects when used continuously. Common steroid-sparing agents in nephrotic syndrome include cyclosporine, tacrolimus, mycophenolate, and rituximab.

Steroid-dependent

When a child achieves remission on steroids but relapses every time the dose is reduced or stopped. Different from steroid-resistant (where steroids don't work at all). Steroid-dependent nephrotic syndrome often leads to consideration of steroid-sparing medications to reduce long-term steroid exposure.

Steroid-resistant

When a condition does not respond to corticosteroid treatment. Steroid-resistant nephrotic syndrome often requires alternative immunosuppressants or genetic testing.

T

Thrombocytopenia

An abnormally low number of platelets (cells that help blood clot). One of the three hallmarks of Hemolytic Uremic Syndrome.

Tacrolimus

A calcineurin inhibitor used as a steroid-sparing immunosuppressant in nephrotic syndrome. Works similarly to cyclosporine and also requires regular blood level monitoring.

Tubules

Small tubes in the kidney that reabsorb useful substances (like water, salt, and sugar) and send waste to become urine. Damage to tubules is called tubulointerstitial disease.

Tubulointerstitial

Relating to both the kidney tubules and the tissue between them. Tubulointerstitial diseases (like Nephronophthisis and Medullary Cystic Kidney Disease) cause scarring in these areas.

U

Urine dipstick

A quick test using a paper strip dipped in urine to check for protein, blood, and other substances. Families of children with Nephrotic Syndrome often use dipsticks at home to catch relapses early. How to use a dipstick at home →

UPC ratio (Urine Protein:Creatinine ratio)

A urine test that measures how much protein is leaking relative to creatinine — more precise than a dipstick. Used to quantify proteinuria and track how a child is responding to treatment. A UPC ratio above 2 mg/mg indicates nephrotic-range protein loss.

V

Vasculitis

Inflammation of blood vessels. IgA vasculitis (formerly called Henoch-Schönlein Purpura) causes inflammation in small vessels, which can affect the skin, joints, gut, and kidneys. Read about HSPN →