What Is a Nephrologist?

A nephrologist is a medical physician who specializes in the diagnosis, treatment and care for diseases and disorders of the kidneys. They may also be referred to as a kidney doctor, just as a cardiologist is referred to as a heart doctor. Most nephrologists specialize in internal medicine and then focus on the sub-specialty field of nephrology. Examples of diseases treated by a nephrologist include chronic kidney disease (CKD), polycystic kidney disease (PKD), acute renal failure, kidney stones and high blood pressure.

Nephrology is the science or study of the medical diagnosis and treatment of kidney diseases including electrolyte disturbances and hypertension, and the care of those requiring renal replacement therapy, including dialysis and renal transplant patients (KCC, 2017). This includes conditions like systemic vasculitides and autoimmune diseases (such as lupus) as well as congenital and genetic conditions of the kidneys. Only nephrologists can extend a patient’s life after the failure of an organ.

A kidney doctor will see patients with acute renal failure, stage 4 or 5 chronic kidney disease, decline in kidney function, chronic or repeat urinary tract infections, high blood pressure that is resistant to medication, a low glomerular filtration rate (GFR), repeat kidney stones, blood in the urine and protein loss in the urine. Based on the patient’s condition, the nephrologist will begin the process of evaluation, treatment and diagnosis.


What Does a Nephrologist Do?

Most patients seen by a nephrologist are referred by their primary care physician due to kidney-related issues, including high blood pressure in some cases. Nephrologists will then review the patient’s medical history and perform blood testing and urinalysis to determine how well the patient’s kidneys are functioning.  In some cases, a kidney ultrasound or a biopsy will be completed in order to further analyze the structure and function of the kidneys.

Based on the results of the tests and procedures, the nephrologist will provide a diagnosis and a treatment plan. They will coordinate with dieticians, social workers and other specialists and nurses to execute the treatment plan established. Kidney doctors interact and coordinate with cardiologists, endocrinologists and pharmacists to provide comprehensive medical care to their patients.

Nephrologists typically see their patients several times a month or once every few months, depending on the severity of their disease or disorder. Dialysis patients typically require several visits per month. Depending on their specific employer, a nephrologist may also have a management role in the function of the medical center.

Tests done by a nephrologist may include renal biopsies to obtain a tissue sample of the kidney, ultrasound scanning of the urinary tract and/or renal blood vessels, CT scans to identify mass lesions, nuclear medicine for measurement of renal function, angiography or magnetic resonance imaging angiography for blood vessel analysis.

Therapies prescribed by nephrologists include medication such as steroids, anti-rheumatic drugs or anti-hypertensives.  Many times, erythropoietin and vitamin D are used to replace hormones in order to stagnate chronic kidney disease. If the chronic disease reaches stage 5, kidney dialysis or transplant is required to prevent the death of the patient.


Kidney Function

The American Journal of Kidney Disease indicates the prevalence of chronic kidney disease will rise 27% from the current rate by the year 2030. The kidneys’ main function is to filter the blood flowing throughout the body, up to 150 quarts of blood per day. They are also responsible for stabilizing electrodes, making hormones which build red blood cells, strengthen bones and regulate blood pressure (Doctorly, 2017).

The two kidneys in normal adult weigh approximately 300 g; that is, about .5% of total body weight.  Yet, kidneys receive about 25% of the total cardiac output of blood flow and consume 20 –25% of the oxygen used by the body at rest.  The kidneys have key roles in the maintenance of plasma composition (excretion of waste proteins), maintenance of water balance (conservation of water, particularly under stress), maintenance of pH in extracellular fluid, and endocrine function (regulates water pressure, erythropoietic factor – release of red cells from marrow stimulated by erythropoietin).  Due to these roles and functions, the kidney uses a disproportionate amount of energy, filtration functions, enzyme dependence, and employment of active transport when compared to the rest of the mammalian body. 

Any drug or chemical in the systemic circulation will be delivered to this organ in relatively high amounts.  The processes involved in forming concentrated urine also serve to concentrate potential toxicants in the tubular fluid.  A non-toxic concentration of a chemical in the plasma may reach toxic concentrations in the kidney.

Toxic agents that disrupt key kidney functions can be life threatening.  The kidney is a highly metabolic organ sensitive to deprivation of oxygen, and any agent that significantly impedes blood flow will cause two adverse effects leading to renal failure.  First, less blood plasma will reach the kidney, resulting in a decrease in removal of blood wastes with a resulting increase of wastes in the blood (i.e. uremia).  This can cause death by poisoning from the body’s own waste products. Second, if blood flow is compromised long enough, tissue ischemia will result in irreversible organ damage.


The Kidneys and Toxic Injury

The proximal tubule is the most common site of toxicant induced injury in the kidneys.  It is formed by cuboidal epithelial cells, actively reabsorbs substances from the filtrate and plays a role in secreting substances into it.  It also has large mitochondria and surfaces that have dense microvilli, which increases surface area and its capacity for reabsorbing water and solutes from the filtrate.  The proximal tubule is sometimes referred to as the workhorse of the nephron, as it reabsorbs 60-80% of the solute and water that is filtered in the glomerulus.  Toxicant induced injury to the proximal tubule affects the solute water balance.  Glucose, phosphate, uric acid, sodium, amino acids, potassium, sulfate and all actively reabsorbed in the proximal tubule, and it also reabsorbs virtually all of the filtered low molecular weight proteins.  

The proximal tubule also contains numerous transport systems that drive concentrative transport of many metabolic substrates (amino acids, glucose).  Interruptions in the energy production or the function of critical enzymes or transporters for any of the transport mechanisms or can affect proximal tubule and/or whole kidney function. 

Xenobiotics can accumulate in the proximal tubule, it has a leaky epithelium which can increase the amount of xenobiotic that reaches this region, and it is the site of tubular transport of organic anions and cations, low molecular weight proteins and peptides, GSH conjugates, and heavy metals.  Cytochrome P-450 and cysteine conjugate B-lyase enzymes are localized almost exclusively in the proximal tubule with negligible activity in the glomerulus.  Therefore, nephrotoxicity requiring P-450 and B-lyase mediated bioactivation will be localized in proximal tubules (chloroform, haloalkane biotransformation – lesions). These factors make the proximial tubule the most susceptible and frequent kidney site of xenobiotic injury. 


How to Become a Nephrologist

Nephrology is a specialty of internal medicine, and extensive education and training is required in order to become a licensed nephrologist. An undergraduate degree, medical school and a residency must all be completed before attempting the American Board of Internal Medicine (ABIM) certification exam. Only after that does a future nephrologist focus on their specialty through a fellowship program.

Information that a nephrologist learns in training are fluid and acid base and electrolyte physiology, medical management of acute and chronic renal failure, glomerular and vascular disorders, tubular/interstitial disorders, mineral metabolism, clinical pharmacology, hypertension, epidemiology, and nutrition (GKK, 2017).

Subspecialties within nephrology include interventional nephrology, dialytician, and transplant nephrology.


Undergraduate Education

An aspiring nephrologist must first complete an undergraduate degree, although a specific major is not required.  Many students choose to major in science (biology, chemistry, physics) or a social major such as psychology. Medical school is highly competitive, so a high GPA is beneficial in being accepted, in addition to volunteering and extra-curricular activities.

Prior to completing the undergraduate degree, you will need to take and pass the Medical College Admissions Test (MCAT) exam to be accepted into an accredited medical school. 


Medical School

Medical school programs are typically 4-5 years in duration, depending on the degree you decide to pursue. A Doctor of Medicine (M.D.) or a Doctor of Osteopathic Medicine (D.O.) degree is offered, and the D.O degree usually requires an additional year of training.

Medical School typically requires a 4-year commitment. The first two years are spent in the classroom with coursework in anatomy, biochemistry, medical law and ethics, microbiology, pathology, pharmacology, physiology and psychology. The last two years consists of clinical experience under the supervision of a licensed physician. Rotations in a hospital setting allow students to receive training in a variety of areas including internal medicine, family practice, obstetrics and gynecology, pediatrics, psychiatry and surgery.



After completing medical school, a nephrologist will then complete an internal medicine residency which lasts approximately 3 years. A residency allows physicians to receive hands-on clinical experience in the evaluation, diagnosis and treatment of patients with kidney diseases and disorders.

During the residency, the resident receives further specialized training in the field of nephrology. When the residency has been completed, the nephrologist will take the American Board of Internal Medicine (ABIM) to become officially licensed in the nephrology field, although additional state licensing may be required.


Fellowship Program

The fellowship program is optional for nephrologists. It lasts approximately 2 to 3 years, and it must be accredited by the Accreditation Council for Graduate Medical Examination (ACGME). A fellowship allows a nephrologist to focus more on their area of specialized medicine and improve their expertise. During the fellowship program, the following is covered (Davita, 2017):

Glomerular/vascular disorders — Glomerular/vascular disorders are disorders of the glomeruli or clusters of blood vessels in the kidneys. Nephrologists learn treatment methods to help slow the progression of these disorders to preserve kidney function for as long as possible.

Tubular/interstitial disorders — Tubular/interstitial disorders affect the tubules of the kidneys and the surrounding tissues. The tubules collect the filtered fluid from the kidneys that ultimately becomes urine. Nephrologists learn the symptoms and treatments of these disorders.

Hypertension — Hypertension is another word for high blood pressure, and it is the second leading cause of end stage renal disease (ESRD) in the U.S. When kidneys excrete too much of a substance called renin, it may cause an increase in blood pressure. Nephrologists learn about medicines that can lower blood pressure, as well as other methods for lowering blood pressure such as diet and exercise.

Dialysis — Dialysis is the process of cleaning the blood when the kidneys no longer function. Nephrologists learn about hemodialysis and peritoneal dialysis so they can match their patients with the dialysis treatment that works best for their specific needs.

Kidney transplantation —  A kidney transplant takes place when someone receives a kidney from someone else to replace their own damaged kidneys. Nephrologists learn about all aspects of kidney transplantation so they can help their patients understand and prepare for this procedure.

Mineral metabolism — Mineral metabolism disorders occur when there are abnormal amounts of minerals in the blood. Nephrologists learn how to correct or manage mineral metabolism disorders to ensure their patients get the minerals they need for proper body function.

Management of acute kidney failure — Acute kidney failure occurs when the kidneys suddenly stop working. In some cases, the kidneys can recover from this failure, although not always. Kidney doctors learn to treatment options to reversible disorders that cause acute kidney failure, such as kidney stones, infections or significant blood loss.

Management of chronic kidney disease — Chronic kidney disease (CKD) occurs when the kidneys slowly stop working over a period of time. There are five stages to CKD, with the last stage being end stage renal disease (ESRD). Kidney doctors learn about the five stages of chronic kidney disease and how to manage them so they can slow the progression of the disease and provide their patients with the best possible quality of life.

Nutrition — Nutrition plays a big part in slowing the progression of kidney disease and overcoming kidney failure. Nephrologists use their nutritional knowledge to provide the proper recommendations to their patients.

Interpretation of x-rays, sonograms and other tests — Some kidney diseases are discovered through x-rays, sonograms and other tests. Nephrologists learn how to evaluate and interpret the test results to make an accurate diagnosis.

The fellowship program provides the physician the opportunity to practice diagnosing, treating and managing diseases of the kidneys. Surgical procedures such as vascular access and catheter placement are also involved, in addition to a strong focus on kidney dialysis treatments and biopsies. Once the fellowship has been completed, the future neurologist can take the ABIM nephrology exam. Additional courses and examinations are required to become a nephrologist.


History of Nephrology

The Early Days – Richard Bright

Richard Bright was born in London, England in 1789. He graduated from the University of Edinburgh in 1813 and then went on to work in various hospitals in London before setting at Guy’s Hospital as a physician assistant and eventually becoming a physician himself in 1824. Nearly 20 years later he retired from the hospital and opened his own private practice.

One of Bright’s talents was keeping meticulous records of his clinical observations and comparing them to post-mortem examinations (autopsies).  Disease of the kidneys as an independent medical condition was first recognized by Richard Bright, in his 1827 book titled “Reports of Medical Conditions.”

This book detailed the features and consequences of kidney disease, and any kidney disease from that point on was known as “Bright’s disease.” Richard Bright’s research and evaluation of kidney disease led to the very common practice of testing urine for protein as a way to analyze kidney function. Richard Bright is known to this day as the pioneer of nephrology.

In the 1870’s additional medical advances in nephrology emerged with a description of acute nephritis and familial kidney disease by William Howship Dickinson, and the discovery of the link between kidney disease and high blood pressure by Frederick Akbar Mahomed. Mahomed was also employed at Guy’s Hospital in London, and he was inspired by Richard Bright’s work.

Frederick Akbar Mahomed

In detailed clinical studies, he separated chronic nephritis with secondary hypertension from what we now term essential hypertension, and he also described the constitutional basis and natural history of essential hypertension and pointed out that this disease could terminate with nephrosclerosis and renal failure (O’Rourke, 1992). His clinical studies were done without the benefit of a sphygmomanometer (instrument that measures blood pressure) but with the aid of a quantitative sphygmogram that he had initially developed while a medical student (O’Rourke, 1992). Mahomed described unique features of pressure pulse in patients with high blood pressure and the hardening of the arteries that comes with aging.

Twentieth Century and Beyond

The 20th century continued to see advances in the identification and treatment of kidney diseases. In the early 1900’s, Homer Smith further explained the physiology and function of the kidneys, which led to significant developments for kidney disease therapies and treatments. The first successful use of hemodialysis was in 1945, by Dr. Willem Kolff, with the first successful kidney transplant to follow in 1954.

The first transplant was performed on identical twins by Dr. Joseph E. Murray in Boston, MA. The procedure lasted over 5 hours long. The receiver of the kidney was dying of chronic nephritis, and after the transplant he lived for eight more years. Dr. Murray and his team continued to research kidney disease and immunology, and they performed the first kidney transplant on non-related patients shortly after. By 1965, the success rate of kidney transplant from non-related donors was approximately 65%.

Kidney disease has continued to be researched and new and improved medical technology continues to emerge to allow for significant improvements in the evaluation, diagnosis and treatment of kidney diseases and disorders. Today, clinical nephrology continues to advance with many forms of renal replacement therapy (both acute and chronic) including hemodialysis, peritoneal dialysis, hemofiltration and hemodiafiltration, the use of erythropoietin for anemia in chronic kidney disease, treatment of renal osteodystrophy, ongoing improvements in immunosuppression for transplantation, and specific treatments for many nephropathies.


Job Prospects

A nephrologist may work in a hospital, clinic or private practice, or possibly in a specialized kidney dialysis center. The only surgery they typically perform are biopsies and catheter replacements, although some specialize in kidney transplant procedures. Kidney doctors typically form long-term relationships with their patients.

The majority of nephrologists work in a private practice, but that is far from the only area where a nephrologist can practice; doctors of nephrology can work in academic settings, healthcare organizations, hospitals, office-based group practices, solo practices, outpatient clinics and more (Doctorly, 2017). A nephrologist can be hired as a direct employee, as an independent contractor or be an owner or partner in a private practice.

Work hours for nephrologists are often long and irregular due to emergencies, on-call and overtime situations. Many kidney doctors work more than 60 hours a week, with some working up to 80 or more hours weekly. The extra hours may not be accounted for financially if the doctor works on salary and not an hourly income. This is important for any aspiring nephrologist to consider.

Currently, the field of nephrology does not offer many job openings for newly licensed nephrologists. Based on the expected rate of increase in kidney disease, it would seem likely that there will be an increased demand and opportunities for practicing nephrologists. The field of nephrology is expected to see significant job growth in the near future – up to 14% growth in the next decade.

The salary of a kidney doctor varies depending on their employer and their specialty or sub-specialty. Typically, nephrologists within a sub-specialty field (for example, pediatric nephrology) make a higher salary than those who are not. The state and location may also affect the salary rates, in addition being employed in an urban versus a rural community. The median annual income for a nephrologist working in the United States is $212,000.

Nephrology is an extremely demanding and challenging profession that often comes with long hours and irregular work schedules. Although they make a fairly high salary, they are also required to complete extensive education and training in order to become licensed as a nephrologist. Current job prospects are slim; however, they are expected to see growth in the future, in alignment with the increased prevalence of kidney diseases and disorders.





KCC – Kidney Care Center of Georgia. What is Nephrology? 2017. Retrieved September 23, 2017 from: http://www.kidneycarega.com/what-is-nephrology


Doctorly. How to Become a Nephrologist. 2017. Retrieved September 23, 2017 from: http://doctorly.org/how-to-become-a-nephrologist/


Davita Kidney Care. What is a Nephrologist? 2017. Retrieved September 23, 2017 from: https://www.davita.com/kidney-disease/overview/treatment-overview/what-is-a-nephrologist?/e/6884


Klaassen, Curtis D.  Casarett and Doull’s Toxicology: The Basic Science of Poisons, 8 ed., 2013. 

O'Rourke MF. Frederick Akbar Mahomed. Journal of Hypertension. 1992 Feb;19(2):212-7.

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