Nephrology is the medical specialty focused on the kidneys, their diseases, and the systemic conditions that affect renal function. It spans prevention, diagnosis, and long-term management of chronic kidney disease (CKD), acute kidney injury (AKI), electrolyte and acid–base disorders, and kidney-related hypertension. Nephrologists also oversee dialysis therapies and coordinate care for kidney transplantation alongside transplant teams.
In practice, nephrology intersects with Cardiovascular Risk and Hypertension and Diabetes Care because these conditions are leading contributors to CKD. It also connects to Autoimmune Disease through disorders like lupus nephritis, and to Critical Care Medicine where AKI is common among hospitalized patients. Many nephrology decisions are driven by laboratory trends over time, urine findings, imaging, and sometimes kidney biopsy.
The kidneys filter blood, regulate fluid balance, control electrolytes (such as sodium and potassium), maintain acid–base homeostasis, and produce hormones including erythropoietin and renin. Normal adult kidneys filter roughly 120 mL/min/1.73 m² (a typical “normal” estimated glomerular filtration rate, eGFR), though values vary by age and body size. When function declines, toxins accumulate and fluid, potassium, and acid levels can become dangerous.
Nephrology relies heavily on biomarkers that quantify function and injury. Serum creatinine is used to estimate GFR, while urine albumin-to-creatinine ratio (ACR) detects albuminuria, an early marker of kidney damage. CKD is commonly staged by eGFR and albuminuria categories; persistent abnormalities for at least 3 months support a CKD diagnosis.
CKD is one of the most common long-term conditions worldwide and a central focus of nephrology. The global prevalence of CKD is often estimated around 9–10% of the population, meaning hundreds of millions of people live with some stage of kidney impairment. Diabetes and hypertension are the two most frequent drivers, with contributions from glomerulonephritis, polycystic kidney disease, and medication or toxin exposures.
AKI, a rapid decline in kidney function, occurs frequently in hospitals, especially during sepsis, major surgery, dehydration, and exposure to nephrotoxic drugs. Depending on the patient population and definitions used, AKI is reported in a substantial fraction of inpatients and is particularly common in intensive care settings. Glomerular diseases (such as IgA nephropathy and membranous nephropathy) may present with blood and protein in the urine and can require immunosuppression in collaboration with Immunology and Inflammation.
Kidney-related hypertension is both a cause and consequence of kidney disease. The kidneys regulate blood pressure through sodium handling and hormonal systems; reduced kidney perfusion or scarring can lead to difficult-to-control hypertension. Nephrologists also manage secondary hypertension evaluations, including renovascular disease and endocrine contributors when indicated.
Evaluation typically begins with blood tests (creatinine, electrolytes, bicarbonate), urine testing (dipstick, microscopy, urine ACR), and blood pressure measurement. Renal ultrasound is a first-line imaging tool to assess kidney size, obstruction, and structural abnormalities; small echogenic kidneys may suggest chronic scarring, while hydronephrosis can indicate blockage. Risk stratification in nephrology uses trends rather than single values, because the slope of eGFR decline can predict outcomes.
Kidney biopsy is a cornerstone procedure when the diagnosis is uncertain or when knowing the exact pathology will change therapy. Under ultrasound guidance, a needle sample is obtained and examined by light microscopy, immunofluorescence, and electron microscopy to identify patterns such as immune complex deposition. Biopsy results can guide targeted treatments, prognostication, and decisions about immunosuppressive medications.
Nephrology also includes management of anemia of CKD, bone and mineral disorders, and metabolic acidosis. For example, reduced erythropoietin can lower hemoglobin, while impaired phosphate excretion and altered vitamin D metabolism can weaken bone and raise cardiovascular risk. These complications are monitored with hemoglobin, ferritin/transferrin saturation, calcium, phosphate, parathyroid hormone, and bicarbonate levels.
Core CKD treatment in nephrology includes controlling blood pressure, reducing proteinuria, managing diabetes, and minimizing nephrotoxin exposure. Renin–angiotensin system blockers (ACE inhibitors or ARBs) are commonly used to reduce albuminuria and slow progression in many patients, and newer agents such as SGLT2 inhibitors have shown meaningful kidney-protective effects in diabetic and non-diabetic CKD populations. Dietary strategies often include sodium reduction and individualized protein guidance, with careful monitoring to prevent malnutrition.
When kidneys can no longer maintain homeostasis, renal replacement therapy may be required. Hemodialysis is commonly delivered three times per week in outpatient centers, while peritoneal dialysis offers home-based daily or nightly options for selected patients. Globally, more than 3 million people receive dialysis or live with a functioning kidney transplant, and access varies widely by region and income.
Kidney transplantation generally provides better survival and quality of life than long-term dialysis for many patients with end-stage kidney disease. One-year kidney graft survival in many contemporary programs is commonly above 90% for deceased-donor transplants and higher for living-donor transplants, though outcomes depend on donor factors, recipient health, and immunologic matching. Transplant nephrology includes immunosuppression management, rejection surveillance, infection prevention, and long-term cardiovascular risk reduction, often coordinated with Surgery and Transplantation and Infectious Disease.
Myth: “Kidney disease always causes pain, so you’ll feel it early.” Many kidney disorders are silent until advanced, and early CKD often has no symptoms. This is why screening with creatinine/eGFR and urine ACR is emphasized for high-risk groups such as people with diabetes, hypertension, or a family history of kidney failure.
Myth: “Dialysis cures kidney failure.” Dialysis replaces some kidney functions but does not restore native kidney health in chronic end-stage disease. It can be life-sustaining for years, yet it typically requires ongoing treatments and careful management of fluid, potassium, and phosphorus.
Myth: “Only older adults get serious kidney disease.” CKD risk increases with age, but significant kidney disease can occur in children and young adults through congenital anomalies, inherited disorders, and autoimmune conditions. Pediatric nephrology also addresses growth, developmental impacts, and lifelong risk reduction, linked to Pediatrics.
Myth: “If creatinine is normal, the kidneys must be fine.” Creatinine varies with muscle mass and can appear “normal” even when kidney function is reduced, especially in smaller or older individuals. eGFR calculations and urine albumin testing are essential complements, and persistent albuminuria can indicate kidney damage even with preserved eGFR.
Myth: “Herbal and ‘natural’ supplements are always kidney-safe.” Some supplements contain nephrotoxic compounds, heavy metals, or undeclared drugs and can worsen kidney function or interact with immunosuppressants after transplant. Nephrology clinics routinely review over-the-counter products and encourage patients to discuss supplements before use.
Nephrology continues to evolve with earlier detection strategies, broader use of kidney-protective therapies, and improved outcomes in transplantation and home dialysis. Its impact is amplified by the rising global burden of diabetes and hypertension, making kidney health a central pillar of modern chronic disease care. For related context, see Public Health Screening and Nutrition Science.