Nephrology is the branch of internal medicine that focuses on how the kidneys work, what happens when they are damaged, and how kidney diseases are diagnosed and treated. Healthy kidneys quietly filter blood, remove waste and excess fluid, balance minerals, and help control blood pressure, so problems in this system can affect the entire body. This Health Guide is designed for patients and curious readers who want clear, reliable information about kidney health and nephrology care.
What Do the Kidneys Do?
The basic role of the kidneys
The kidneys are two bean-shaped organs located deep in the back, just below the rib cage, one on each side of the spine. They continuously filter the blood, removing waste products and extra water to produce urine. At the same time, they keep the right balance of salts and minerals such as sodium, potassium, calcium, and phosphate, which are essential for nerves, muscles, and bones.
How kidneys support overall health
Beyond filtration, the kidneys play several critical roles in keeping the body stable:
- Helping regulate blood pressure through hormones that control blood vessel tone and salt–water balance.
- Supporting red blood cell production by releasing a hormone (erythropoietin) that signals the bone marrow to make more red blood cells.
- Maintaining acid–base balance so the blood does not become too acidic or too alkaline.
- Influencing bone health by activating vitamin D and managing calcium and phosphate levels.
When the kidneys are working properly, these processes are automatic and silent; when they are not, a person may feel tired, swollen, short of breath, or may have no symptoms until damage is advanced.
What Is Nephrology?
Definition of nephrology
Nephrology is the medical specialty dedicated to the kidneys, their functions, and their diseases. A doctor who specializes in this area is called a nephrologist. Nephrologists are first trained as internal medicine physicians and then complete additional years of training focused specifically on kidney disorders, complex blood pressure problems, and fluid and electrolyte imbalances.
What a nephrologist does
A nephrologist evaluates patients with suspected or known kidney problems, interprets kidney-related tests, and designs individualized treatment plans. In daily practice, this usually involves:
- Assessing symptoms such as swelling in the legs or around the eyes, changes in urination, or difficult-to-control blood pressure.
- Ordering and interpreting blood and urine tests to estimate kidney function and detect damage.
- Managing chronic conditions that affect the kidneys, such as diabetes and high blood pressure.
- Deciding when to start dialysis and which dialysis method is most suitable.
- Coordinating care before and after a kidney transplant, often in collaboration with transplant surgeons and other specialists.
Because kidney disease is often linked with heart disease, diabetes, and other systemic illnesses, nephrologists frequently work as part of a multidisciplinary team.
Common Kidney Conditions Seen in Nephrology
Chronic kidney disease (CKD)
Chronic kidney disease means that the kidneys are damaged and cannot filter blood as well as they should for at least three months or longer. CKD usually develops slowly and may have few symptoms at first, which is why regular blood and urine tests are important for people at higher risk. Over time, CKD can progress through stages, from mild loss of kidney function to kidney failure (end-stage kidney disease), where dialysis or a transplant is needed to sustain life.
Acute kidney injury (AKI)
Acute kidney injury is a sudden decline in kidney function that can occur over hours or days, often during a serious illness, infection, dehydration, or after certain medications or contrast dyes. People with AKI may produce less urine, retain fluid, and have rapidly changing blood test results. Prompt treatment of the underlying cause and careful support of blood pressure, fluids, and medications can allow the kidneys to recover fully in many cases.
Other frequent kidney-related problems
Nephrologists also manage a wide range of other kidney conditions, including:
- Glomerulonephritis – inflammation of the microscopic filters in the kidneys (glomeruli), which can lead to blood and protein in the urine.
- Diabetic kidney disease – damage caused by long-term high blood sugar levels in people with diabetes.
- Hypertensive kidney disease – injury caused by long-standing high blood pressure.
- Polycystic kidney disease – a genetic condition in which fluid-filled cysts gradually replace normal kidney tissue.
- Kidney involvement in autoimmune diseases – such as lupus nephritis or vasculitis.
Many of these conditions are chronic and require years of follow‑up, lifestyle adjustments, and medication management.
Symptoms and Early Warning Signs
Why kidney disease can be “silent”
In many people, early kidney damage does not cause noticeable symptoms. The kidneys have a large reserve capacity, which means a person may feel well even when kidney function is significantly reduced. This is why doctors often call chronic kidney disease a “silent” condition in its early stages.
Symptoms that may suggest kidney problems
As kidney function worsens, a range of symptoms may develop. Common signs and complaints include:
- Swelling in the ankles, feet, hands, or around the eyes (fluid retention).
- Changes in urination: foamy urine, blood in the urine, getting up at night to urinate, or noticeably less urine.
- Fatigue, weakness, or difficulty concentrating due to anemia or toxin buildup.
- Loss of appetite, nausea, vomiting, or an unpleasant metallic taste in the mouth.
- Itching, muscle cramps, or restless legs.
- Shortness of breath or chest discomfort from fluid around the lungs or heart.
- High blood pressure that is hard to control, even with several medications.
These symptoms are not specific to kidney disease and can be caused by other conditions, but they are important signals to see a doctor for evaluation.
Who Is at Risk for Kidney Disease?
Major risk factors
Some people have a higher chance of developing kidney problems and may benefit from regular screening. Important risk factors include:
- Diabetes (type 1 or type 2).
- High blood pressure.
- Heart and blood vessel disease.
- Obesity and metabolic syndrome.
- A family history of kidney disease or polycystic kidney disease.
- Autoimmune diseases such as lupus.
- Recurrent urinary tract infections or kidney stones.
- Long-term use of certain pain medicines or other drugs can affect the kidneys.
Older age also increases risk, and many people over 60 have some degree of reduced kidney function.
Lifestyle and environmental factors
Dehydration, repeated severe infections, and exposure to toxins can strain the kidneys over time. Smoking, a high-salt diet, and a sedentary lifestyle worsen blood pressure and cardiovascular health, indirectly harming kidney function. Paying attention to these modifiable risk factors can significantly reduce the chance of developing advanced kidney disease.
How Are Kidney Problems Diagnosed?
Initial assessment and medical history
A nephrology evaluation usually begins with a detailed discussion of symptoms, medical history, and medications. The doctor asks about blood pressure, diabetes control, recurrent infections, family history, and any previous kidney issues. A physical examination assesses for swelling, changes in blood pressure, and signs of fluid overload or other organ involvement.
Key laboratory tests
Several routine tests help assess kidney health:
- Blood tests: Creatinine and blood urea nitrogen (BUN) are measured to estimate how well the kidneys are filtering waste. From creatinine, doctors calculate the estimated glomerular filtration rate (eGFR), which indicates the stage of kidney function.
- Urine tests: A simple urine dipstick can show protein, blood, sugar, or signs of infection. More detailed tests measure the amount of protein or albumin leaking into the urine, which is an early marker of kidney damage.
- Electrolyte and mineral tests: Levels of potassium, sodium, bicarbonate, calcium, and phosphate help evaluate the kidneys’ ability to maintain balance.
Imaging and specialized tests
Depending on the situation, additional tests may be needed:
- Ultrasound to visualize the size, shape, and structure of the kidneys, detect cysts, tumors, or urine flow obstruction.
- CT or MRI in selected cases for more detailed imaging.
- A kidney biopsy, in which a tiny piece of kidney tissue is taken with a needle under imaging guidance and examined under a microscope, is especially useful for glomerular diseases or unexplained rapid kidney decline.
These tests help determine the cause and severity of kidney damage and guide the treatment plan.
Treatment Options in Nephrology
Treating the underlying cause
The first goal in nephrology is to identify and treat the underlying cause of kidney damage whenever possible. This may include:
- Tight control of blood sugar in people with diabetes.
- Aggressive treatment of high blood pressure with medications, diet changes, and exercise.
- Stopping or adjusting medications that injure the kidneys.
- Treating infections or obstructions in the urinary tract.
- Using immunosuppressive medications in autoimmune kidney diseases.
In many patients, these steps can slow or even halt further damage.
Medications and supportive care
Nephrologists often prescribe medications to support kidney function and protect other organs:
- Blood pressure drugs such as ACE inhibitors or ARBs, which also help reduce protein loss in the urine.
- Diuretics (“water tablets”) to manage swelling and fluid overload.
- Medications to control potassium, phosphate, and acid–base balance.
- Erythropoiesis-stimulating agents and iron therapy to treat kidney-related anemia.
- Vitamin D analogs and other treatments to protect bone health.
Regular follow-up visits and blood tests are essential to adjust doses and monitor side effects.
Dialysis and kidney transplantation
When kidney function declines to a very low level, the body cannot keep up with waste removal and fluid balance, leading to serious complications. At that point, a nephrologist will discuss renal replacement therapy, which includes:
- Hemodialysis: Blood is filtered through a machine, usually three times a week in a dialysis center or sometimes at home, through a specialized access in the arm or via a catheter.
- Peritoneal dialysis: A cleansing fluid is instilled into the abdomen through a soft tube, where it absorbs waste and excess fluid before being drained and replaced; this can often be done at home, including overnight.
- Kidney transplantation: A healthy kidney from a living or deceased donor is surgically placed into the patient. Transplantation can offer better quality of life and survival for many people, but requires lifelong follow‑up and medications to prevent rejection.
The choice among these options depends on medical factors, lifestyle, personal preferences, and availability; the nephrology team supports the patient in making an informed decision.
Everyday Kidney Care and Prevention
Healthy lifestyle habits
Many of the same habits that protect the heart also protect the kidneys. Helpful measures include:
- Keeping blood pressure and blood sugar within target ranges with diet, medication, and regular check-ups.
- Maintaining a healthy weight through balanced nutrition and physical activity.
- Limiting salt intake by reducing processed foods and not adding extra salt at the table.
- Drinking enough fluids, especially water, unless a doctor gives specific fluid restrictions.
- Avoiding smoking and moderating alcohol consumption.
Small, consistent changes often matter more than short bursts of intense effort.
Protecting the kidneys from medicines and toxins
Not all medicines are safe for the kidneys, particularly when used long-term or at high doses. Patients are usually advised to:
- Use over‑the‑counter pain relievers (especially some nonsteroidal anti‑inflammatory drugs) with caution and only as directed.
- Inform healthcare providers about all prescription drugs, supplements, and herbal products being taken.
- Have kidney function monitored when taking medications known to affect the kidneys, such as some antibiotics, contrast dyes used in imaging, or certain chemotherapy drugs.
People with kidney disease should always check with their doctor before starting any new medicine or supplement.
When to see a nephrologist
It is reasonable to ask for a nephrology consultation if:
- Blood tests show a low eGFR or rising creatinine over time.
- Urine tests repeatedly show protein or blood.
- Blood pressure is hard to control despite several medications.
- There is a family history of significant kidney disease.
- Swelling, unexplained fatigue, or other symptoms suggest a kidney-related cause.
Early referral to nephrology allows more time to slow disease progression, manage complications, and plan for potential future treatments.
Frequently Asked Questions (FAQ)
1. What is the difference between a nephrologist and a urologist?
A nephrologist is an internal medicine specialist who focuses on kidney function and medical kidney diseases, such as chronic kidney disease, glomerulonephritis, and electrolyte problems. A urologist is a surgical specialist who treats conditions of the urinary tract and male reproductive system, such as kidney stones, prostate enlargement, urinary obstruction, and cancers of the kidneys or bladder. In many patients, nephrologists and urologists work together when both medical and surgical issues are present.
2. How often should kidney function be checked?
For someone with no risk factors and no symptoms, kidney function is often checked as part of routine blood tests during general health visits. People with diabetes, high blood pressure, heart disease, or a family history of kidney problems are usually advised to have kidney tests at least once a year, or more often if values are abnormal or disease is already present. The exact interval is tailored to each person’s situation.
3. Can damaged kidneys recover?
In some cases, especially in acute kidney injury caused by dehydration, infection, or certain medications, kidney function can improve significantly once the underlying problem is treated. However, in chronic kidney disease, much of the damage is permanent. The main goal then is to prevent further decline, manage complications, and maintain quality of life for as long as possible.
4. Is dialysis always permanent?
Not always. When dialysis is started because of an acute, temporary injury to the kidneys, there is a chance that kidney function will recover enough to stop dialysis. In chronic kidney failure, dialysis is usually long-term unless the person receives a successful kidney transplant. The nephrology team explains whether dialysis is likely to be temporary or permanent in each individual case.
5. What can a person do today to protect their kidneys?
The most effective steps are to monitor blood pressure and blood sugar, follow a heart‑healthy and low‑salt diet, stay physically active, avoid smoking, and use medications responsibly under medical guidance. Regular check‑ups with a primary care physician or relevant specialist, and early referral to nephrology when kidney tests are abnormal, give the best chance to preserve kidney function over time.
