What Is Nephrology? Research Areas, Funding, and Career Paths

Nephrology is the branch of medicine and biomedical science that studies the kidneys: how they filter blood, regulate fluid, electrolytes and acid-base balance, and influence blood pressure, bone health and red blood cell production, and what happens when they are injured or fail. It is both a clinical specialty, diagnosing and managing kidney disease, dialysis and kidney transplantation, and a research discipline spanning renal physiology, genetics, epidemiology and clinical trials. (The name comes from the Greek nephros, kidney.) This guide explains what nephrology covers and how its subfields divide up, then adds the research-administration layer generic overviews leave out: who funds kidney research, the national data systems and trial networks the field relies on, how kidney outcomes are measured as trial endpoints, and typical training paths. It is educational, not medical advice.

What Is Nephrology?

The kidneys are best known for filtering waste from the blood into urine, but the discipline is organized around several interlocking questions:

• How do the kidneys filter and transport? Each kidney contains functional units called nephrons. The glomerulus filters blood, and the tubules reabsorb or secrete water, sodium, potassium, calcium, phosphate and acid. Renal physiology is the basic-science foundation of the specialty.
• How is kidney function measured? Kidney function is usually summarized as glomerular filtration rate (GFR), most often estimated from serum creatinine (eGFR), together with urine albumin measurement. Estimating equations and their inputs are an active research and policy topic in themselves.
• What injures the kidney? Diabetes, hypertension, glomerular and immune-mediated diseases, genetic conditions such as polycystic kidney disease, obstruction, drugs and toxins, and sudden insults that cause acute kidney injury.
• What replaces lost function? Dialysis (hemodialysis and peritoneal dialysis) and kidney transplantation, plus the supportive care that surrounds both.

How Kidney Disease Is Defined and Classified

Much nephrology research depends on shared definitions. The international guideline organization KDIGO (Kidney Disease: Improving Global Outcomes) defines chronic kidney disease (CKD) as abnormalities of kidney structure or function, present for at least three months, with implications for health. KDIGO classifies CKD by cause, GFR category (G1 through G5, with G3 split into G3a and G3b) and albuminuria category (A1 through A3, based on the urine albumin-to-creatinine ratio). GFR category G5, below 15 mL/min/1.73 m², is labelled kidney failure. Because enrolment criteria, outcomes and risk models in nearly every CKD study are written in these categories, a research administrator reviewing a kidney protocol will see them constantly. Acute kidney injury (AKI), a sudden loss of function, is defined separately and studied as its own subfield.

Major Subfields of Nephrology

• Chronic kidney disease — risk factors, progression, complications such as anemia and mineral-bone disorder, and strategies to slow decline.
• Acute kidney injury and critical care nephrology — detection, causes and outcomes of sudden kidney failure, often in hospitalized patients.
• Glomerular and immune-mediated disease — glomerulonephritis, nephrotic syndrome, lupus nephritis and related conditions, where kidney biopsy and pathology are central.
• Diabetic kidney disease — the kidney complication of diabetes, which overlaps heavily with endocrinology.
• Hypertension and electrolyte disorders — the kidney’s role in blood pressure and in sodium, potassium, calcium and acid-base balance.
• Dialysis and kidney failure care — vascular access, dialysis modality, home therapies and conservative (non-dialytic) kidney care.
• Transplant nephrology — evaluation of donors and recipients, immunosuppression, and long-term graft survival; it draws on immunology.
• Genetic and pediatric nephrology — inherited kidney disorders and congenital anomalies, including the pediatric CKD cohorts described below.
• Kidney stones and interventional work — shared in practice with urology, a neighboring specialty that handles surgical and urinary-tract conditions.

How Nephrology Relates to Neighboring Disciplines

Nephrology is a clinical branch of physiology and medicine; see What Is Biology? and the overview of the branches of science for the wider map. Its closest research neighbors are endocrinology (diabetes and mineral metabolism), pharmacology (drug dosing in reduced kidney function; see What Is Pharmacology?), genomics (inherited kidney disease; see What Is Genomics?), epidemiology and biostatistics for registry and trial work (What Is Epidemiology?, What Is Biostatistics?), and geriatrics, since CKD prevalence rises with age (What Is Geriatrics?). A companion discipline explainer for the nervous system is What Is Neurology?.

How Kidney Research Is Funded

In the US, the lead federal funder of kidney research is the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of NIH. Within NIDDK, kidney, urologic and hematologic research is administered through the Division of Kidney, Urologic, and Hematologic Diseases. NIDDK also funds the shared infrastructure the field depends on, including:

• The Chronic Renal Insufficiency Cohort (CRIC) Study, established by NIDDK in the early 2000s as one of the largest and longest-running studies of CKD epidemiology in the United States, examining risk factors for CKD progression and cardiovascular disease.
• The Chronic Kidney Disease in Children (CKiD) consortium, which follows children with CKD over time.
• The Kidney Precision Medicine Project (KPMP), which pairs kidney biopsies from people with AKI or CKD with deep molecular profiling and clinical follow-up to define disease subtypes.
• The United States Renal Data System (USRDS), a national data system on CKD and end-stage kidney disease supported by NIDDK.
• The NIDDK Central Repository, which archives data and biospecimens from NIDDK-funded studies for secondary use; sharing is governed by NIH data-sharing policy (see the NIH Data Management and Sharing Plan guide).

Funding mechanisms vary: investigator-initiated awards, and cooperative agreements such as the U01 that consortia often use, where NIH staff take a substantive role. Early-career investigators commonly enter through mentored awards such as the K99/R00, and competitiveness varies by institute and year (see NIH paylines for FY2026). Disease-focused charities and professional societies also fund fellowships and pilot grants. One notable public-private model is KidneyX, a partnership between the US Department of Health and Human Services and the American Society of Nephrology that runs prize competitions to spur innovation in kidney care. Funding opportunities and priorities change, so always confirm current details with the funder.

Clinical Trials, Networks and Endpoints

Kidney disease progresses slowly, so trials that wait for hard outcomes such as kidney failure can be long and large. That has made endpoint selection one of the central methodological questions in the field. Typical kidney trial outcomes include:

• Kidney failure (starting dialysis or receiving a transplant) and death, which are clinically unambiguous but occur late.
• A sustained decline in eGFR, used as a time-to-event outcome. In the CKD trial literature this is commonly expressed as a sustained percentage decline from baseline, sometimes combined with kidney failure and death.
• Albuminuria change, a laboratory marker used in earlier-stage disease and as a secondary measure.
• Composite endpoints that combine several of these, often with cardiovascular death added because people with CKD are at high cardiovascular risk (see the dictionary entry on composite endpoints).

A March 2018 scientific workshop sponsored by the National Kidney Foundation in collaboration with the US Food and Drug Administration and the European Medicines Agency examined whether changes in albuminuria and GFR can serve as surrogate endpoints in early-stage CKD. Its supporting analyses included a meta-analysis of 47 randomized trials covering 60,620 participants and 12 interventions. The workshop report noted that the FDA and EMA were already willing to consider a 30% to 40% GFR decline as a surrogate for kidney failure under appropriate conditions, though such endpoints may not be practical in early-stage disease; it concluded that both early change in albuminuria and GFR slope fulfill surrogacy criteria under certain conditions, with stronger support for GFR, and that each should be used only in the settings where it performs well. Surrogate endpoints also interact with regulatory pathways such as accelerated approval and the FDA Biomarker Qualification Program; the CKD Epidemiology Collaboration clinical-trials consortium (CKD-EPI CT) is one group that pools trial data for this kind of analysis.

Recent trials show endpoint choices at work. The CREDENCE trial of canagliflozin was halted early on efficacy grounds (results were published in 2019), DAPA-CKD (dapagliflozin) was stopped early in 2020, and EMPA-KIDNEY (empagliflozin) was also stopped early because of positive results; its primary outcome was a composite of kidney disease progression or cardiovascular death, reduced by 28% over about two years among 6,609 participants. CREDENCE enrolled people with type 2 diabetes and diabetic kidney disease, while EMPA-KIDNEY broadened the population studied. For design background see non-inferiority vs. superiority trial design. Because many of these trials run for years and enroll participants with advanced disease, administrators should expect careful data and safety monitoring plans and long follow-up budgets.

Common Research Methods and Tools

• Kidney function and injury biomarkers — serum creatinine and cystatin C for eGFR, urine albumin-to-creatinine ratio, and emerging injury markers.
• Kidney biopsy and pathology — light microscopy, immunofluorescence and electron microscopy remain the diagnostic standard for many glomerular diseases, and are now combined with single-cell and spatial molecular methods as in KPMP.
• Registries and administrative data — USRDS-style national datasets for population-level questions on dialysis and transplantation.
• Prospective cohorts — CRIC and CKiD-style studies with repeated measurement and biobanking.
• Genetics and genomics — sequencing for monogenic kidney disease and genome-wide association studies for common CKD.
• Animal and cell models — mouse models, kidney organoids and tissue-chip systems, conducted under the same oversight as other vertebrate research (see the animal research ethics guide).
• Randomized and pragmatic trials — including trials embedded in care-delivery networks.

A Brief History

Modern nephrology grew from advances in treating kidney failure. The Dutch physician Willem Kolff built the first practical artificial kidney during the Second World War, and in 1954 the first successful kidney transplant, between identical twins, was performed in Boston. In the United States, federal legislation in the early 1970s extended Medicare coverage to most people with end-stage kidney disease, a policy decision that shaped the dialysis industry and the data systems that now support research. More recently, the field’s attention has moved toward earlier detection, standardized classification and drugs that slow progression.

Career and Training Pathways

The clinical path runs through medical school, an internal medicine (or pediatrics, for pediatric nephrology) residency, and a nephrology fellowship. In the US, the American Board of Internal Medicine requires a period of ACGME-accredited fellowship training (confirm the current length with ABIM), prior internal medicine certification, an unrestricted license and a passing score on the Nephrology Certification Examination; many fellows add research years. The American Society of Nephrology (ASN) administers an in-training examination, usually taken in the second year of fellowship.

The research path runs through graduate study in physiology, cell and molecular biology, genetics or epidemiology, typically a PhD followed by postdoctoral training. Many investigators are physician-scientists who combine a fellowship with research training, often supported by the mentored K awards noted above.

Societies and Journals

Major professional bodies include the American Society of Nephrology (ASN), the International Society of Nephrology (ISN), the National Kidney Foundation (NKF), the European Renal Association (ERA) and KDIGO, which issues the guidelines cited above. Leading journals include the Journal of the American Society of Nephrology (JASN), the Clinical Journal of the American Society of Nephrology (CJASN), Kidney International and the American Journal of Kidney Diseases (AJKD).

Frequently Asked Questions

What is nephrology in simple terms?

Nephrology is the study of the kidneys and their diseases. It covers how healthy kidneys work, why they fail, and how conditions such as chronic kidney disease, acute kidney injury and kidney failure are diagnosed, studied and managed, including dialysis and transplantation.

What is the difference between nephrology and urology?

Nephrologists mainly manage medical kidney disease, such as CKD, glomerular disease, electrolyte problems and dialysis. Urologists are surgeons who treat the urinary tract and related organs, including stones, obstruction and tumors. The two overlap on conditions such as kidney stones.

What do nephrologists study or treat?

They study and treat chronic and acute kidney disease, glomerular disorders, blood pressure and electrolyte disturbances linked to the kidney, kidney failure requiring dialysis, and care before and after kidney transplantation.

Who funds kidney research?

In the US the lead federal funder is NIH’s NIDDK, which also supports shared resources such as CRIC, CKiD, KPMP and USRDS. Charities and public-private programs such as KidneyX add to this.

How long does it take to become a nephrologist?

In the US, after medical school and an internal medicine residency, ABIM requires completion of an accredited nephrology fellowship (confirm the current length with ABIM). Extra research years are common for academic careers.

Why are surrogate endpoints important in kidney trials?

Because kidney disease progresses slowly, waiting for kidney failure makes trials long. Validated surrogate endpoints, such as a sustained eGFR decline, can shorten them, but their acceptability depends on the population and intervention studied.

Related Guides

This guide is part of a series on scientific disciplines from a research-administration perspective. See the overview of the branches of science, the What Is Endocrinology? and What Is Neurology? companion guides, and What Is Immunology?.