The kidneys filter waste products from the blood and regulate fluid and electrolyte balance, managing the body’s internal environment. When kidney function declines to the point where these essential processes cease, a patient has kidney failure. If not treated by mechanical or surgical intervention, this condition initiates a sequence of events where the body’s systems become overwhelmed by toxicity and imbalance. This explains the physiological progression toward death when treatment options, such as dialysis or transplantation, are unavailable or withdrawn.
Understanding End-Stage Renal Disease
Dying from kidney failure occurs when the condition reaches its most severe stage, known as End-Stage Renal Disease (ESRD). This corresponds to Stage 5 Chronic Kidney Disease, where the kidneys function at less than 15% of their normal capacity. This loss of filtration means the body can no longer maintain the necessary fluid, acid-base, and electrolyte balance required for survival.
For a patient with ESRD, life must be maintained artificially, typically through regular dialysis treatments or a successful kidney transplant. When a patient chooses to forgo these interventions, or when treatments fail, the body’s internal systems begin to break down. The decision to pursue comfort-focused care marks the point where the physiological decline becomes irreversible and leads directly to death.
How Toxins Accumulate and Systemic Balance Fails
The decline begins with the loss of the kidneys’ primary role: waste removal. Nitrogenous waste products, the byproducts of protein metabolism, accumulate in the bloodstream, creating a toxic state known as uremia. The buildup of substances like urea and creatinine causes widespread systemic poisoning, affecting nearly every organ system.
The inability to excrete acid leads to a severe condition called metabolic acidosis. The body continuously produces metabolic acids, and without the kidneys to eliminate them, the blood’s pH level drops dangerously low. This acidemia can cause symptoms like hyperventilation as the body attempts to compensate, and it diminishes the heart’s pumping ability.
Fluid retention is also a major factor, as the kidneys lose their ability to regulate water and sodium levels. This leads to fluid overload, causing visible swelling, or edema, in the extremities. This excess fluid places significant strain on the cardiovascular system and precedes the most severe life-ending events.
The Final Physiological Events Leading to Death
The most acute cause of death in untreated kidney failure is often an electrolyte derangement known as hyperkalemia. Without kidney function, potassium—a mineral normally tightly controlled—rises to critically high levels in the blood. Potassium regulates the electrical signals that control muscle and nerve function, particularly within the heart.
Potassium levels exceeding approximately 6.5 milliequivalents per liter (mEq/L) can interfere with the heart’s electrical stability, disrupting the normal cardiac rhythm. This interference leads to fatal arrhythmias, such as ventricular fibrillation or asystole, where the heart stops beating effectively. This results in sudden cardiac arrest and can occur with little warning, representing a rapid systemic shutdown.
Simultaneously, the unchecked fluid overload progresses to a severe state of pulmonary edema. The retained fluid backs up into the lungs, flooding the air sacs and severely impairing the ability to breathe. This causes a profound sensation of drowning and acute respiratory distress. Combined with the decreased function of the heart, this causes the body to shut down irreversibly.
Managing Symptoms and Ensuring Comfort
When a patient chooses conservative management without dialysis, the focus shifts entirely to comfort, typically under the guidance of palliative or hospice care. Medical teams manage the distressing symptoms that arise from circulating toxins and fluid imbalances. This includes controlling nausea, vomiting, and generalized itching, which are common manifestations of uremia.
A high priority is placed on managing pain, anxiety, and restlessness, often requiring careful selection of medications due to the body’s inability to clear them. As uremia progresses, the accumulation of toxins in the brain causes a progressive change in mental status, starting with confusion and drowsiness. This ultimately progresses to unconsciousness and coma, which provides a natural physiological pathway for a peaceful passing.