End-Stage Kidney Disease (ESKD) is the final, permanent stage of chronic kidney failure. At this stage, the kidneys have lost the ability to filter waste and maintain the body’s internal balance. Kidney replacement therapy, such as a transplant or dialysis, is required to sustain life. The decision to begin this therapy involves a careful assessment of laboratory results and the patient’s physical well-being, not just a single piece of information.
How Kidney Function Is Measured
The primary measure used to assess kidney function is the Glomerular Filtration Rate (GFR). This rate estimates the volume of blood filtered by the kidney’s glomeruli each minute. GFR is calculated using a blood test that measures creatinine, a waste product from muscle metabolism, in the bloodstream. A higher level of creatinine in the blood indicates a lower GFR, as the kidneys are failing to remove it efficiently.
A normal GFR in a healthy adult is approximately 100 milliliters per minute per 1.73 square meters of body surface area (mL/min/1.73m²). This value is used to categorize the progression of Chronic Kidney Disease (CKD) into five distinct stages. These stages standardize diagnosis and treatment planning for patients with diminishing kidney function.
CKD progression begins with Stage 1 (GFR 90 mL/min/1.73m² or higher), indicating damage despite normal function. Function declines through Stage 2 (60–89 mL/min/1.73m²) and Stage 3 (30–59 mL/min/1.73m²). Stage 4 signifies a severe reduction in function, with a GFR between 15 and 29 mL/min/1.73m².
The final classification is Stage 5, defined as kidney failure, where the GFR falls below 15 mL/min/1.73m². This stage indicates the kidneys are functioning at 10 to 15 percent of normal capacity or less. At this point, the kidneys can no longer adequately balance fluids, electrolytes, and waste products in the body.
The Quantitative Threshold for Dialysis Initiation
The established quantitative guideline for considering dialysis is when the estimated GFR (eGFR) drops below 15 mL/min/1.73m², corresponding to Stage 5 kidney failure. This benchmark signifies that the body’s ability to clear toxins is severely compromised. However, in many asymptomatic patients, the actual initiation of dialysis may be safely delayed until the eGFR falls lower, often into the range of 5 to 10 mL/min/1.73m².
The eGFR of 15 mL/min/1.73m² is generally the point where physicians begin intensive pre-dialysis care and planning. This preparation includes educating the patient about options and ensuring vascular access, such as a fistula or graft, is created for hemodialysis. This necessary preparation often takes months and prevents an emergency start to treatment.
The numerical threshold alone is not considered a trigger to immediately start treatment. Studies have shown that initiating dialysis too early, when the GFR is higher than 10 mL/min/1.73m², does not offer a survival benefit compared to a later start. Therefore, the numerical guideline primarily functions as a marker for when dialysis becomes a serious and necessary consideration.
When Clinical Symptoms Override the GFR Number
While GFR measures kidney function numerically, the patient’s physical condition and severe symptoms are often the true determinants for starting dialysis. When waste products accumulate due to kidney failure, a condition known as uremia develops. This syndrome causes symptoms that negatively impact quality of life and pose serious health risks.
One of the most pressing symptoms is fluid overload, which can lead to pulmonary edema, a dangerous buildup of fluid in the lungs causing shortness of breath. Uncontrolled fluid accumulation and severe hypertension that does not respond to medication are clear signs that immediate dialysis is needed to remove excess volume. Another serious concern is hyperkalemia, a dangerously high level of potassium in the blood, which can cause abnormal heart rhythms and lead to cardiac arrest.
Neurological symptoms are also a powerful indication for treatment, as toxin buildup can affect the brain, leading to uremic encephalopathy. This manifests as confusion, difficulty concentrating, memory loss, and potentially seizures or coma. Other debilitating symptoms include intractable nausea, vomiting, and appetite loss, resulting in severe malnutrition.
Dialysis is initiated immediately if these uremic symptoms cannot be managed through diet changes or medication, regardless of the 15 mL/min/1.73m² GFR threshold. The primary goal is to alleviate suffering and prevent life-threatening complications. Ultimately, the decision is a shared one between the patient and the care team, balancing the GFR number with the patient’s overall health, quality of life, and personal preferences.