What is the primary characteristic of chronic kidney disease as it progresses?

The primary characteristic of chronic kidney disease (CKD) as it progresses is the progressive decline in renal function. CKD is characterized by a gradual loss of kidney function over time, which can lead to an inability to effectively filter waste products and excess fluids from the blood. This decline is typically measured in terms of the glomerular filtration rate (GFR), with stages of CKD classified based on this measurement.

As CKD advances, patients may experience a variety of complications, including electrolyte imbalances, metabolic acidosis, and ultimately, meaningful alterations in urine output. Unlike in acute kidney injury, where sudden changes can occur, CKD is a more insidious process and the decline in kidney function is usually progressive and sustained. Thus, monitoring GFR and recognizing its decline are crucial for managing the disease and its complications.

In this context, options like increased urine output, stable creatinine levels, and frequent urination do not accurately reflect the key features of CKD progression. In fact, as kidney function deteriorates, patients often experience a decrease in urine output and may also see rising creatinine levels, which indicate worsening renal function. Therefore, recognizing the progressive decline in renal function is essential for understanding the trajectory of chronic kidney disease.