Objective 6: Discuss Pathophysiology of Decreased Renal Reserve, Renal Insufficiency and End-Stage of Chronic Renal Failure

Decreased Renal Reserve

The early stage of CKD in which some nephrons are destroyed, but remaining nephrons compensate and maintain relatively normal function.

Renal Reserve

Remaining kidney function that allows the kidneys to compensate for the loss of functioning nephrons.

Compensatory Hyperfiltration

Increased filtration by remaining nephrons to compensate for destroyed nephrons.

GFR During Decreased Renal Reserve

Slightly decreased, but often sufficient to maintain relatively normal homeostasis.

Creatinine During Decreased Renal Reserve

May become higher than normal as kidney filtration begins declining.

Symptoms During Decreased Renal Reserve

Usually absent or minimal because remaining nephrons compensate.

Renal Insufficiency

The stage of CKD in which kidney function declines significantly and compensation is no longer adequate.

GFR During Renal Insufficiency

May decrease to approximately 20% of normal according to the study guide.

Azotemia

Accumulation of nitrogen-containing waste products, particularly urea and creatinine, in the blood.

Impaired Urine Concentration

Inability of damaged renal tubules to adequately conserve water and concentrate urine.

Polyuria During Renal Insufficiency

Increased urine production caused by impaired tubular water reabsorption.

Nocturia

Frequent urination during the night, often associated with impaired urine concentration.

Erythropoietin (EPO)

A hormone produced by the kidneys that stimulates red blood cell production in the bone marrow.

Decreased Erythropoietin Production

Occurs as kidney tissue becomes damaged, reducing stimulation of red blood cell production.

Erythropoiesis

The process of producing red blood cells in the bone marrow.

Anemia in CKD

Decreased red blood cell production caused partly by reduced erythropoietin production.

Anemia Manifestations

Fatigue, weakness, reduced exercise tolerance, and decreased energy.

Uremic Waste Accumulation

Retention of metabolic waste products that can contribute to nausea, anorexia, and other systemic symptoms.

End-Stage Renal Disease (ESRD)

The final stage of CKD in which kidney function becomes severely diminished.

GFR During ESRD

Negligible or severely reduced, indicating minimal remaining filtration capacity.

Oliguria in ESRD

Severely decreased urine production due to advanced kidney failure.

Anuria

Almost complete absence of urine production.

Fluid Retention in ESRD

Accumulation of sodium and water causing edema, hypertension, and possible heart failure.

Hyperkalemia in ESRD

Excessive potassium accumulation due to severely impaired renal excretion.

Metabolic Acidosis in ESRD

Acid accumulation caused by impaired hydrogen ion elimination and bicarbonate regulation.

Uremia in ESRD

Severe accumulation of waste products that affects multiple body systems.

ESRD Treatment

Generally requires regular dialysis or kidney transplantation to sustain life.

What are the three stages of chronic renal failure in this study guide?

Decreased renal reserve, renal insufficiency, and end-stage renal failure.

What happens during decreased renal reserve?

Some nephrons are destroyed, but remaining nephrons compensate to maintain relatively normal function.

How do remaining nephrons compensate during decreased renal reserve?

They increase their individual filtration activity.

What happens to GFR during decreased renal reserve?

It decreases slightly but may remain sufficient to maintain homeostasis.

What symptoms occur during decreased renal reserve?

Usually few or no noticeable symptoms.

Why can patients have no symptoms during early CKD?

Remaining nephrons compensate for the loss of functioning kidney tissue.

What laboratory finding may appear during decreased renal reserve?

Slightly elevated serum creatinine.

What happens during renal insufficiency?

Kidney function declines significantly and remaining nephrons cannot compensate adequately.

Approximately how low can GFR fall during renal insufficiency according to the study guide?

Approximately 20% of normal.

What is azotemia?

Accumulation of nitrogen-containing waste products, particularly BUN and creatinine, in the blood.

Why does polyuria occur during renal insufficiency?

Damaged tubules cannot adequately reabsorb water or concentrate urine.

What is nocturia?

Frequent urination during the night.

Why does nocturia occur during renal insufficiency?

The kidneys lose their ability to properly concentrate urine.

What hormone do healthy kidneys produce to stimulate red blood cell production?

Erythropoietin (EPO).

What happens to erythropoietin production during CKD?

It decreases as kidney tissue becomes damaged.

Why does anemia develop during renal insufficiency?

Reduced erythropoietin decreases stimulation of red blood cell production in the bone marrow.

What is erythropoiesis?

The production of red blood cells in the bone marrow.

What are common manifestations of anemia in CKD?

Fatigue, weakness, reduced exercise tolerance, and decreased energy.

What happens during end-stage renal failure?

Kidney function becomes severely diminished and the kidneys cannot maintain normal homeostasis.

What happens to GFR during ESRD?

It becomes negligible or severely reduced.

What happens to urine output during ESRD?

Oliguria or anuria may develop.

What is oliguria?

Severely decreased urine production.

What is anuria?

Almost complete absence of urine production.

Why does fluid overload develop during ESRD?

The kidneys cannot adequately eliminate sodium and water.

What complications can result from fluid retention during ESRD?

Edema, hypertension, and congestive heart failure.

Why does hyperkalemia occur during ESRD?

The kidneys cannot adequately eliminate potassium.

Why does metabolic acidosis occur during ESRD?

The kidneys cannot adequately eliminate hydrogen ions or maintain bicarbonate.

What causes severe uremia during ESRD?

Extensive accumulation of metabolic waste products in the bloodstream.

What treatments are generally required during ESRD?

Regular dialysis or kidney transplantation.

How does urine output differ between renal insufficiency and ESRD?

Renal insufficiency commonly causes polyuria, while ESRD may cause oliguria or anuria.