Chronic Kidney Disease I: Introduction

Chronic kidney disease (CKD) involves progressive loss of kidney function due to nephron damage from conditions like diabetes or hypertension. As nephrons are lost, remaining nephrons compensate by increasing their filtration workload. Eventually, this increased demand damages functioning nephrons, reducing the kidneys' ability to filter waste. Without treatment, CKD advances to end-stage renal disease, requiring dialysis or kidney transplant for survival.

In early-stage CKD, symptoms are often absent because healthy nephrons compensate for damaged ones, preserving kidney function. This compensatory mechanism masks damage until the kidneys lose a substantial number of nephrons. Consequently, about 70% of people are unaware they have CKD, and the disease often goes undiagnosed and untreated until significant kidney function is lost.

Diabetes and hypertension are the leading causes of CKD. Diabetes accounts for approximately 50% of cases by damaging kidney blood vessels over time, while hypertension contributes about 25% of cases by increasing pressure within the kidney's filtering units. Additional risk factors include obesity, smoking, aging, and genetic predisposition, all of which raise the likelihood of CKD development or progression.

When nephrons are damaged, remaining nephrons compensate by increasing their filtration workload. Over time, this increased demand damages functioning nephrons, progressively reducing the kidneys' ability to filter metabolic waste products like urea and creatinine. These waste substances accumulate in the blood—a condition called uremia—which impairs multiple organ systems including the heart, lungs, and brain.

Proteinuria, or protein in the urine, indicates glomerular injury and signals further kidney damage. As kidney function declines, the kidneys lose their ability to prevent protein leakage into the urine, worsening glomerular damage. This protein loss accelerates kidney deterioration and represents a critical marker of disease progression that requires clinical attention and management.

Uncontrolled high blood pressure increases pressure within the kidney's filtering units, causing direct damage to glomeruli and accelerating nephron loss. This creates a harmful cycle where kidney damage worsens blood pressure control, which further damages the kidneys. Managing blood pressure is essential to slowing CKD progression and preventing the development of chronic kidney disease clinical manifestations.

At end-stage renal disease, the kidneys can no longer filter waste or maintain essential body functions. Patients require renal replacement therapy through dialysis or kidney transplant for survival. This advanced stage represents the final consequence of progressive nephron loss and represents the point where the kidneys have lost approximately 85-90% of their filtering capacity.