Pathophysiology Dr. Aya M. Serry

Renal Failure

2015

Renal Failure

• Renal failure is defined as a significant loss of renal function in both kidneys to the point where less than 10 to 20% of normal GFR remains

• Renal failure may occur as an acute and rapidly progressing process or may present as a chronic form in which there is a progressive loss of renal function over a number of years

Pathophysiology of Renal Failure

• In renal failure there is either glomerular or tubular dysfunction

• Glomerular dysfunction- As the main function of glomeruli is filtration, glomerular dysfunction leads to fall in GFR with retention of those substances usually cleared by filtration, including water.

• Tubular Dysfunction- As the main function of tubules is re-absorption tubular failure results in the voiding of large volumes of dilute urine (polyuria) of low specific gravity, along with electrolytes and nutrients.

Renal Failure

Acute Chronic

A. Acute Renal Failure

• Acute renal failure means that your kidneys have suddenly stopped working.

• Sudden decrease in renal function. • Acute renal failure may be pre-renal, intra-renal or post-renal in nature. Acute renal failure is often reversible as long as permanent injury to the kidney has not occurred.

• Manifestations - Oliguria (reduced urine output) Possible edema and fluid

retention - Elevated blood urea nitrogen levels (BUN) and serum

creatinine - Alterations in serum electrolytes

A. Acute Renal Failure

A. Acute Renal Failure.. Causes

Acute renal failure has three main causes:

1. A sudden, serious drop in blood flow to the kidneys.

Examples: Heavy blood loss, an injury, or a bad infection Not enough fluid in the body (dehydration) also can harm the kidneys

2. Damage from some medicines, poisons, or infections.

Examples of medicines that can sometimes harm the kidneys include:

-Antibiotics, such as gentamicin-Pain medicines, such as aspirin and ibuprofen-Some blood pressure medicines, such as ACE inhibitors.-The dyes used in some X-ray tests..

A. Acute Renal Failure.. Causes

3. A sudden blockage that stops urine from flowing out of the kidneys.

Examples: Kidney stones, a tumor, an injury, or an enlarged prostate gland (men) can cause a blockage.

A. Acute Renal Failure.. Risk Factors

Age

History of kidney or liver disease

Diabetes

High blood pressure

Heart failure

Obesity

Illness (Hospital or intensive care (ICU))

Heart or belly surgery or a bone marrow transplant

A. Acute Renal Failure.. Symptoms

Urine retention

Swelling, especially in your legs and feet

Decreased appetite

Nausea and vomiting

Feeling confused, anxious and restless, or sleepy

Some people may not have any symptoms

A. Acute Renal Failure.. Diagnosis

• Routine laboratory test (creatinine and blood urea nitrogen)

• Ultrasound of the kidney helps to determine whether kidney problem is acute or chronic.

• kidney biopsy

• computed tomography scan

A. Acute Renal Failure.. Treatment

Treatment can vary widely, depending on the cause. For example, your doctor may need to restore blood flow to the kidneys, stop any medicines that may be causing the problem, or remove or bypass a blockage in the urinary tract.

At the same time, the doctor will try to:

Stop wastes from building up in your body (Dialysis)-a machine that filters blood and returns it to the body

Antibiotics to prevent or treat infections

Diuretics

limiting sodium, potassium, and phosphorus intake

Renal Dialysis

B. Chronic Renal Failure

•Chronic renal failure is the end result of progressive kidney damage and loss of function. •Chronic renal failure is often classified into four progressive stages based on the loss of GFR.

• Stages of Chronic Renal Failure:

• Diminished renal reserve — GFR decreased to 35 to 50%• Renal insufficiency — GFR decreased to 20 to 35% • Renal failure — GFR reduced to less than 20% • End-Stage Renal Disease — GFR is less than 5%

Chronic Renal Failure CausesHypertension

Glomerulonephritis

Diabetic Nephropathy

HIV nephropathy

Reflux nephropathy in children

Polycystic kidney disease

Kidney infections & obstructions

B. Chronic Renal Failure… Causes

MalaiseWeaknessFatigueNeuropathyCHFAnorexiaNauseaVomiting

SeizureConstipationPeptic ulcerationDiverticulosisAnemiaPruritusJaundiceAbnormal hemostasis

B. Chronic Renal Failure… Symptoms

• Careful management of fluids and electrolytes

• Careful use of diuretics

• Careful dietary management; restriction of dietary protein intake

• Recombinant erythropoietin to treat anemia

• Renal dialysis

• Renal transplantation

B. Chronic Renal Failure… Treatment