Nephrology

Nephrology is a field dedicated to understanding, protecting, and treating our body's most vital filters. 

Join us as we delve into the intricate world of these essential organs and the specialists who expertly master them.

Diving deep into the specialty of nephrology

Of all the complex machinery within the human body, none works with the quiet, relentless efficiency of the kidneys. These sophisticated, fist-sized organs are the ultimate purification system, meticulously balancing the body's internal environment—a task so critical that without it, life would cease in a matter of days. They are the unsung heroes of our health, tirelessly filtering waste, managing blood pressure, and even producing essential hormones.

Yet, when this elegant system falters, the consequences are profound. This is the domain of nephrology, a medical specialty that combines the art of managing chronic diseases with the precision of critical care.

The unsung heroes of homeostasis

The kidneys are arguably the hardest-working, yet least-discussed, organs in the human body. These two bean-shaped organs, each about the size of a fist and located below the rib cage, filter an astonishing 200 liters (over 50 gallons) of blood every single day!

The medical specialty dedicated to these microscopic powerhouses is nephrology.

Nephrology definition

The term "nephrology" is derived from the Greek word "nephros," meaning "kidney." A nephrologist is a physician who specializes in diagnosing, treating, and managing diseases and conditions that affect the kidneys, including the profound systemic effects that kidney failure has on the entire body—from blood pressure and bone strength to red blood cell production.

This specialty offers a unique blend of critical care, chronic disease management, and technical intervention. Understanding what a nephrologist is and when to see one is vital, especially since many nephrology diseases, such as chronic kidney disease (CKD), often progress silently until the late stages.

Fun fact: You only need one functioning kidney to lead a healthy life! The remaining kidney often grows larger to handle the extra workload, demonstrating the body's incredible adaptability.

Nephrology definition and scope: More than just urine

The nephrology definition centers on preserving the delicate balance of fluid, minerals, and waste products in the blood. Nephrologists are, fundamentally, kidney disease specialists and masters of internal balance (homeostasis).

The microscopic workhorse: The nephron

Each kidney contains about one million microscopic filtering units called nephrons.

The filtration process

Each nephron consists of a glomerulus (the filter) and a renal tubule. The glomerulus acts like a sieve, filtering large volumes of blood, while the tubule reabsorbs 99% of the water, minerals, and nutrients the body needs, sending only the waste out as urine.

Hormone production

Beyond filtration, kidneys are endocrine organs. They produce:

• Erythropoietin (EPO): A hormone that tells the bone marrow to make red blood cells (explaining why anemia is common in advanced chronic kidney disease)
• Renin: A protein that helps regulate blood pressure (hypertension nephrology)
• Calcitriol (active vitamin D): Essential for maintaining strong bones

Nephrology vs. urology: Distinguishing the specialties

A crucial point of clarification for patients and professionals is the difference between nephrology vs. urology:

• Nephrology focus: The focus is the internal medicine of the kidney—treating the organ's function, managing diseases like CKD and hypertension, and administering dialysis treatment options.
• Urology focus: Urology is the surgical specialty dealing with the anatomy of the urinary tract (kidneys, ureters, bladder, urethra) and the male reproductive system. Urologists work closely with the surgical nurse to treat kidney stones, cancers, and structural blockages.
• Collaboration: Nephrologists and urologists often work together, particularly in cases involving kidney stones or urinary tract obstructions that affect kidney function.

Nephrology diseases list: The silent epidemic

When to see a nephrologist?

The most common reasons to see a nephrologist revolve around the progressive failure of kidney function, often driven by systemic illnesses.

Chronic kidney disease (CKD)

Chronic kidney disease (CKD) is the slow, progressive loss of kidney function over months or years, a process that requires dedicated chronic care management. It is often asymptomatic in the early stages, making early kidney function tests crucial.

• Primary drivers: The two leading causes of CKD are diabetes and hypertension, a comorbidity often managed with the help of a cardiac nurse to control the high blood pressure that damages the kidneys. High blood sugar and high pressure relentlessly damage the glomeruli (the filters).
• Staging: CKD is categorized into five stages based on the glomerular filtration rate (GFR). Stage 5 is end-stage renal disease (ESRD), where replacement therapy is required.

Hypertension nephrology and systemic complications

The connection between hypertension, nephrology, and kidney health is bidirectional: high blood pressure can damage the kidneys, and damaged kidneys can lead to increased blood pressure.

• Electrolyte disorders: Nephrologists are experts in managing dangerous imbalances of sodium, potassium, and calcium that can arise when the kidneys fail.
• Glomerulonephritis: Inflammation of the kidney filters, often caused by autoimmune disorders (such as lupus) or infections. Diagnosing this condition requires specialized nephrology procedures, such as a kidney biopsy.

Acute kidney injury (AKI)

AKI is a sudden, rapid decrease in kidney function, often occurring in critically ill patients due to severe infection, shock, or medication side effects. Nephrologists and intensive care unit (ICU) nurses play a critical role in stabilizing AKI patients and determining if temporary dialysis treatment options are necessary.

A closer look: Acute kidney injury in the hospital

Unlike the slow progression of CKD, acute kidney injury is a sudden, dramatic event, often developing over hours or days. It is a common and serious complication in hospitalized patients, particularly those in the intensive care unit.

The primary goal in managing AKI is to identify and reverse the underlying cause. Causes are often categorized as:

• Pre-renal: Caused by a sudden drop in blood flow to the kidneys. This is common in cases of severe dehydration, blood loss, or shock (like in sepsis).
• Intra-renal (or intrinsic): Caused by direct damage to the kidneys themselves. This can be from severe infections, autoimmune flares (like glomerulonephritis), or exposure to nephrotoxic substances, including certain IV contrast dyes and medications (like some antibiotics or NSAIDs).
• Post-renal: Caused by a blockage after the kidneys, which prevents urine from draining. This can be due to an enlarged prostate, kidney stones, or tumors.

The role of the nephrology team in the hospital is to act as expert detectives, utilizing laboratory tests and imaging to pinpoint the cause of the condition. Management involves a delicate balancing act of fluids, stopping offending medications, and treating the root cause. 

For critically ill patients who are too unstable for traditional hemodialysis, nephrologists often prescribe a gentler, 24/7 form of dialysis at the bedside called continuous renal replacement therapy (CRRT). This continuous process removes waste and fluid much more slowly, preventing the blood pressure drops that intermittent hemodialysis can cause in unstable patients. This requires highly skilled ICU and nephrology nurses to manage the complex circuitry and precise fluid balance.

Diagnostics and nephrology procedures

In this section, we will examine kidney function tests and procedures used for diagnosis and treatment.

Kidney function tests and early detection

• Glomerular filtration rate (GFR): The best measure of kidney function, estimated from a blood test (creatinine level)
• Urinalysis: Examining the urine for the presence of abnormal substances, such as protein (proteinuria or albuminuria)—protein in the urine is often the earliest sign of kidney damage, a key indicator for a nephrologist

Nephrology procedures for diagnosis and treatment

• Renal biopsy: This is the primary nephrology procedure for diagnosing specific causes of kidney disease (like glomerulonephritis). A thin needle is used to take a small sample of kidney tissue for microscopic examination.
• Vascular access creation: Nephrologists play a key role in planning and monitoring the access point (fistula, graft, or catheter) necessary for hemodialysis.

The hemodialysis lifeline: Understanding vascular access

The concept of vascular access is fundamental to hemodialysis and a major focus of the entire nephrology care team. Standard hemodialysis requires circulating a patient's entire blood volume through the dialyzer multiple times in a single session. This demands a blood flow rate of 300-500 mL/minute or more—a rate that a normal, fragile vein simply cannot handle.

To solve this, a specialized, high-flow access point must be surgically created. This is the patient's "lifeline," and its preservation is a top priority for all clinicians. There are three main types:

1. Arteriovenous fistula (AVF): This is the "gold standard" and preferred option. A vascular surgeon directly connects an artery to a vein, usually in the forearm. The high-pressure arterial blood flow causes the vein to thicken, enlarge, and "mature" over several months. Once mature, the fistula is a durable, long-lasting access site with the lowest risk of infection or clotting.
2. Arteriovenous graft (AVG): If a patient's veins are not suitable for a fistula, a surgeon can implant a synthetic tube (graft) under the skin to connect an artery to a vein. A graft can be used much sooner, often within two to three weeks, but it is more prone to clotting and has a higher risk of infection than a fistula.
3. Central venous catheter (CVC): This is a tube placed into a large, central vein (like the internal jugular in the neck). A CVC is the only option for immediate or urgent dialysis. However, it is intended to be a temporary bridge. CVCs carry the highest risk of serious bloodstream infections (CLABSI) and can cause long-term damage and scarring to the central veins.

"Access stewardship" is a critical responsibility. This includes protecting the patient's access arm (no blood pressure cuffs, no IVs, no blood draws) and performing a daily assessment by listening for the "bruit" (a "whooshing" sound) and feeling for the "thrill" (a vibration). Changes in these sounds can be the first sign of a developing clot, and early intervention can save the access.

Nephrology treatments: Extending and replacing life

The goal of nephrology treatments is to slow the progression of chronic kidney disease and, when necessary, replace kidney function through dialysis treatment options or transplantation.

Slowing chronic kidney disease

How to slow down chronic kidney disease?

The four pillars of CKD management

Modern pharmacological treatment focuses on four synergistic drug classes to protect the kidney:

1. RAS inhibitors: ACE inhibitors and ARBs to control blood pressure and reduce proteinuria
2. SGLT2 inhibitors: A newer class of drug originally for diabetes, now proven to protect the kidneys even in non-diabetic chronic kidney disease patients
3. Mineralocorticoid receptor antagonists (MRAs): Agents like Finerenone that block kidney-damaging hormone activity
4. Lifestyle modification: Strict management of blood pressure and blood glucose, along with dietary changes (low sodium, controlled potassium, and protein intake), and counseling on the use of appropriate nonprescription pain relievers

Emerging therapies

Current nephrology research topics focus on new drugs like Baxdrostat, which targets the hormone aldosterone to significantly lower treatment-resistant hypertension and further reduce albuminuria, representing a potential "fifth pillar" of CKD care.

Dialysis treatment options

When chronic kidney disease progresses to ESRD, the nephrologist manages renal replacement therapy.

• Hemodialysis (HD): Blood is filtered by a machine outside the body, typically three times a week in a nephrology clinic.
• Peritoneal dialysis (PD): A fluid is introduced into the patient's abdominal cavity through a catheter, using the peritoneal lining as a natural filter. PD can often be done at home, offering more flexibility.
• Kidney transplant: This is the best long-term option for ESRD, involving surgery and immediate post-operative monitoring by a PACU nurse.

A day in the life: The hemodialysis treatment process

For the millions of patients with ESRD, the hemodialysis clinic becomes a central part of their lives. The treatment itself is a highly technical, multi-step process managed by skilled nurses and technicians.

1. Pre-treatment assessment

The process begins the moment the patient walks in. They are weighed, and this "pre-treatment weight" is compared to their "dry weight" (their ideal weight without excess fluid). The difference is the amount of fluid that needs to be removed during the treatment. 

The patient then washes their access arm, and a nurse or technician takes their vital signs and performs a physical assessment, including checking the vascular access.

2. Cannulation and connection

The dialysis nurse or technician performs aseptic cannulation, placing two large-gauge needles into the mature fistula or graft. 

1. One needle, the "arterial" line, will pull blood from the patient to the dialysis machine. 
2. The second, the "venous" line, will return the clean blood to the patient. 

These lines are securely taped and connected to the dialysis machine.

3. The filtration process (dialysis)

The dialysis machine (the "artificial kidney") is a marvel of engineering. 

The patient's blood flows on one side of a special filter, called a dialyzer, which contains thousands of hollow, semipermeable fibers. On the other side of these fibers, a carefully prepared sterile fluid called "dialysate" flows in the opposite direction. This creates a concentration gradient:

• Diffusion: Waste products, such as urea, potassium, and phosphorus, are present in high concentrations in the blood and low concentrations in the dialysate. As a result, they are pulled out of the blood and into the dialysate, which is then discarded.
• Ultrafiltration: The machine creates pressure to "squeeze" the excess fluid (water) from the blood across the membrane. This is how the fluid gained between treatments is removed.

4. Monitoring

This is not a "set it and forget it" procedure. For the next three to four hours, the patient is monitored constantly. The machine checks blood pressure every 15 to 30 minutes. 

The single most common complication is hypotension (a sudden drop in blood pressure) as fluid is removed. Nurses are experts at managing this, often administering a bolus of normal saline to raise blood pressure or adjusting the ultrafiltration rate.

5. Disconnection

Once the treatment is complete, the machine returns all the blood from the lines back to the patient. The needles are removed, and the technician or nurse applies firm, precise pressure to the needle sites until the bleeding stops. 

A post-treatment weight and final vital signs are taken, and the patient is cleared to go home.

The nephrology care team: A multidisciplinary hub

The complexity and chronic nature of kidney disease require a highly coordinated team operating within a network of a nephrology clinic (often dialysis centers).

The nephrologist (MD/DO)

The nephrologist has a specific role and path to practice:

• Role: They are the ultimate kidney disease specialists. They manage patient charts, interpret kidney function tests, adjust dialysis treatment options, perform nephrology procedures (biopsies), and oversee the transition to transplant. They are often involved in research and training through nephrology fellowship programs.
• Path to practice: Becoming a nephrologist involves four years of medical school, three years of internal medicine residency, and two years of dedicated nephrology fellowship programs. The average nephrology salary reflects the extensive and specialized training required for this field.

The nephrology nurse (RN/LPN)

The nephrology nurse has a specific role and practice:

• Role: In dialysis settings, they are highly skilled in operating dialysis machines, accessing fistulas and grafts, administering medications (such as heparin and antibiotics), monitoring fluid balance, and, most importantly, providing patient education on diet and self-management.
• Advanced practice: Nephrology NPs and PAs manage patients with stable chronic kidney disease, order follow-up kidney function tests, and work to control hypertension in collaboration with the physician.

The dialysis technician

The dialysis technician, often working alongside a CNA, performs essential, hands-on tasks under the supervision of the registered nurse. This includes preparing and maintaining dialysis equipment, cannulating access sites (fistulas/grafts) to start and stop treatment, and monitoring the patient's physiological response (blood pressure, machine settings) during the four-hour procedure.

The multidisciplinary support team

The support team might involve:

• Renal dietitian: Essential for patient education, helping adjust diet to limit potassium, phosphorus, and sodium to manage chronic kidney disease
• Social worker: Provides critical emotional and financial support, often in collaboration with a case management nurse, to help patients navigate the complexities of their care

Nephrology research topics and the future

The field of nephrology is characterized by long-term relationships, high technical skill, and exciting research. The focus of nephrology research is currently expanding from dialysis optimization to regenerative medicine and the development of implantable artificial kidneys.

The need for compassionate kidney disease specialists and support staff continues to grow, offering reliable salaries in nephrology and profound professional fulfillment.

Want to learn more? 

Explore the related field of urology.