Introduction: Who Should Undergo Diagnostics and When to Seek Them

If you have been living with kidney problems, knowing when you might need hemodialysis starts with understanding how your kidney function is being monitored. Your doctor will help determine when hemodialysis becomes necessary based on several important factors. These include your overall health, how well your kidneys are working, the signs and symptoms you experience, your quality of life, and your personal preferences.^[5]

The decision to begin hemodialysis typically comes when your kidneys can no longer support your body’s needs. This usually happens when you have only 10% to 15% of your kidney function remaining. At this stage, your kidneys cannot effectively remove toxins and excess fluid from your blood, and dangerous waste products begin to build up in your body.^[1][13] This condition is known as kidney failure, which is the final stage of long-term kidney disease.

You might notice certain warning signs that suggest your kidneys are failing. These can include feeling sick to your stomach, throwing up, swelling in your body, or feeling extremely tired. These symptoms occur because waste products are accumulating in your blood, a condition called uremia.^[5] If you experience these symptoms, it is important to talk to your doctor right away about whether you need to begin hemodialysis.

Sometimes hemodialysis is needed suddenly if your kidneys stop working due to an injury or acute illness. This is called acute kidney injury. In these cases, dialysis may be temporary while your kidneys heal. For most people, however, hemodialysis becomes a long-term or lifelong treatment, especially if they have end-stage kidney disease or are waiting for a kidney transplant.^[1][3]

Your healthcare team will work closely with you to determine the right time to start hemodialysis. This team typically includes a nephrologist, a doctor who specializes in kidney problems, along with nurses, technicians, and other professionals experienced in managing dialysis. Starting dialysis is a significant step, but you do not have to face it alone. Your medical team will guide you through every stage of the process and help you understand what to expect.^[5]

Diagnostic Methods to Identify the Need for Hemodialysis

To understand whether you need hemodialysis, doctors use several tests and measurements that show how well your kidneys are functioning. These diagnostic methods help distinguish kidney failure from other conditions and track the progression of kidney disease over time. The goal is to catch problems early and determine the best time to start treatment.

Estimated Glomerular Filtration Rate (eGFR)

One of the most important tests your doctor will use is called the estimated glomerular filtration rate, or eGFR. This measurement tells your doctor how much blood your kidneys can filter each minute. It is not a test you take directly. Instead, your doctor calculates your eGFR using the results of a blood test that measures a waste product called creatinine. The calculation also considers your sex, age, and other factors.^[5]

The eGFR is expressed as a number. A normal eGFR is usually around 90 or higher. As kidney disease progresses, this number drops. When your eGFR falls below 15, it means your kidneys are functioning at less than 15% of their normal capacity. At this stage, you are considered to have kidney failure, and your doctor will likely discuss starting hemodialysis with you.^[3][14]

Blood Tests for Kidney Function

Blood tests are essential tools for diagnosing kidney problems and monitoring how your kidney disease is progressing. These tests measure the levels of waste products and other substances in your blood that healthy kidneys would normally remove.

The serum creatinine test measures the amount of creatinine, a waste product from muscle activity, in your blood. When your kidneys are not working properly, creatinine builds up instead of being filtered out. Higher levels of creatinine in your blood indicate that your kidneys are struggling to do their job.^[3]

Another common blood test is the blood urea nitrogen (BUN) test. Urea is a waste product formed when your body breaks down protein from the food you eat. Like creatinine, urea is normally removed by the kidneys. If your BUN level is high, it suggests that your kidneys are not filtering waste effectively.^[1]

Your doctor may also check for other substances in your blood, such as potassium, sodium, and calcium. These minerals, called electrolytes, need to be balanced in your body. When kidneys fail, these balances can be disturbed, leading to serious health problems. Hemodialysis helps restore these balances by removing excess minerals and fluids from your blood.^[1]

Monitoring Signs and Symptoms

In addition to laboratory tests, your doctor will pay close attention to the symptoms you experience. As kidney function declines, you may develop signs of uremia. These can include nausea, vomiting, loss of appetite, tiredness, difficulty sleeping, swelling in your hands or feet, itching, trouble concentrating, and changes in how much you urinate.^[5]

Your doctor will also monitor your blood pressure regularly. Kidney disease often causes high blood pressure, and high blood pressure can further damage your kidneys. This creates a cycle that can worsen kidney failure. Hemodialysis helps control blood pressure by removing excess fluid and balancing minerals in your body.^[1][3]

Additional Diagnostic Tests

Sometimes your doctor may order additional tests to understand the cause or extent of your kidney damage. A urine test can reveal whether there is protein or blood in your urine, both of which are signs of kidney problems. Your doctor may also use imaging tests like ultrasound to see the size and shape of your kidneys and check for blockages or other abnormalities.

In some cases, a kidney biopsy may be performed. This involves taking a small sample of kidney tissue to examine under a microscope. A biopsy can help identify the specific disease affecting your kidneys and guide treatment decisions. However, this test is not always necessary for determining whether you need hemodialysis.^[14]

Tracking Disease Progression

Kidney disease is often divided into stages based on your eGFR and other factors. In the earlier stages, you may not need dialysis. Instead, your doctor will focus on treatments to slow the progression of kidney disease, such as controlling blood pressure, managing diabetes, and making dietary changes. As kidney disease advances to stage 5, also known as end-stage kidney disease, hemodialysis or a kidney transplant becomes necessary to sustain life.^[14]

Your healthcare team will monitor your kidney function over time through regular blood tests and checkups. This allows them to identify when your kidney function is declining and plan ahead for starting dialysis. Beginning dialysis in a planned way, rather than in an emergency, gives you time to prepare physically and emotionally. It also allows your medical team to create a vascular access, a special site on your body where blood can be removed and returned during hemodialysis treatments.^[3][14]

Diagnostics for Clinical Trial Qualification

If you are considering participating in a clinical trial related to kidney disease or hemodialysis, there are specific diagnostic tests and criteria that researchers use to determine whether you are eligible. Clinical trials are research studies that test new treatments, devices, or approaches to care. They play an important role in advancing medical knowledge and improving treatments for kidney failure.

The tests used to qualify patients for clinical trials are often similar to those used in regular clinical practice, but they may be more detailed or frequent. Researchers need to carefully document your kidney function and overall health to ensure that the study results are accurate and meaningful.

Kidney Function Measurements

For clinical trials involving hemodialysis, one of the first things researchers will assess is your level of kidney function. This is typically measured using your eGFR. Many trials specify a minimum eGFR level for enrollment. For example, a trial might only accept patients whose eGFR is below 15, indicating advanced kidney failure. This ensures that all participants in the study are at a similar stage of kidney disease.^[14]

Researchers will also review your history of kidney disease. They may ask about how long you have had kidney problems, what caused your kidney disease, and whether you have experienced episodes of acute kidney injury. This information helps researchers understand whether you are a good fit for the study and whether the treatment being tested is likely to benefit you.

Blood and Urine Tests

Clinical trials often require detailed blood and urine tests before you can enroll. These tests measure a wide range of substances in your body, including creatinine, urea, electrolytes, and proteins. They provide a baseline snapshot of your health that researchers can compare to later results after you begin the treatment being studied.

For example, if a clinical trial is testing a new type of dialysis solution or a new dialysis machine, researchers will want to know your starting levels of waste products in your blood. After you use the new treatment, they will repeat these tests to see if the treatment is more effective at removing waste compared to standard hemodialysis.^[14]

Assessment of Health Status and Comorbidities

Clinical trials often have strict criteria about other health conditions you may have. Researchers need to ensure that the study treatment is safe for participants and that any health changes observed are due to the treatment being tested, not other diseases. For this reason, you may undergo tests to check for conditions like diabetes, heart disease, infections, or other complications related to kidney failure.

Your doctor may also assess your nutritional status, blood pressure, and weight. These factors can affect how well you tolerate hemodialysis and how you respond to the treatment being studied. Some trials may exclude patients who have certain complications, while others may specifically seek out patients with those conditions to test whether the new treatment can help.^[14]

Monitoring During the Trial

Once you are enrolled in a clinical trial, you will undergo regular diagnostic tests throughout the study. These tests are more frequent and detailed than what you would typically receive during routine care. Researchers use these tests to monitor your progress, detect any side effects or complications, and gather data about how well the treatment is working.

You may have blood tests before and after each dialysis session, imaging tests to check your vascular access, and questionnaires to assess your quality of life and symptoms. This close monitoring is a key part of clinical research and helps ensure that new treatments are both safe and effective before they are made available to the wider public.