34 Patho

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Renal Failure: Overview

Definition and Types

Renal failure occurs when the kidneys are unable to remove waste products from the blood or maintain fluid, electrolyte, and pH balance. It is classified into two main types: Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD).

Acute Kidney Injury (AKI): Sudden onset, often reversible if treated early.
Chronic Kidney Disease (CKD): Slow, progressive damage over years, usually irreversible and leads to permanent kidney failure.

Etiology

Renal disease: Damage inside the kidneys.
Systemic disease: Conditions such as diabetes, hypertension, lupus.
Urologic defects: Blockages or obstructions outside the kidneys.

Risk Factors

Pre-existing kidney problems or diabetes.
Elderly patients (reduced kidney reserve with age).

Clinical Approach

Careful assessment and monitoring of at-risk patients.
Early recognition of changes in urine output, laboratory results, or kidney function.

Types and Causes of Renal Failure

Acute Renal Failure (AKI)

Sudden onset, often reversible.
Common causes include hypovolemia, decreased vascular filling, heart failure, and decreased renal perfusion due to drugs or contrast dyes.

Chronic Renal Failure (CKD)

Slow, progressive, irreversible damage.
Leads to permanent kidney failure.

Common Causes of CKD

Hypertension: Long-term high blood pressure damages renal vessels.
Diabetes mellitus: High blood sugar damages kidney filters.
Polycystic kidney disease: Inherited cysts enlarge kidneys.
Urinary tract obstructions: Stones, enlarged prostate, scarring.
Glomerulonephritis: Inflammation of kidney filters.
Kidney or urinary tract cancers.
Autoimmune disorders (e.g., lupus).
Lung disease: Reduces blood/oxygen supply to kidneys.
Pain medication use: Long-term NSAIDs or analgesics.

Classification of Acute Renal Failure Causes

Category	Examples
Pre-renal	Hypovolemia (bleeding, dehydration), decreased vascular filling (shock), heart failure, decreased renal perfusion (drugs, contrast dyes)
Post-renal	Bilateral ureteral obstruction, bladder outlet obstruction (enlarged prostate, stones, tumor)
Intrarenal	Acute Tubular Necrosis (ATN), renal ischemia, toxic exposure (drugs, heavy metals), tubular obstruction (hemoglobinuria, myoglobinuria, myeloma light chains, uric acid crystals), renal disease (inflammation, direct damage)

Stages of Chronic Kidney Disease (CKD) Progression

Stage	Description	GFR (mL/min)
Diminished Renal Reserve	Mild kidney damage	60-89
Renal Insufficiency	Moderate loss of function	30-59
Renal Failure	Severe loss of function	15-29
End-Stage Renal Disease (ESRD)	Kidneys cannot function independently; requires dialysis or transplant	<15

Clinical Manifestations of CKD

Metabolic Waste Buildup

Accumulation of urea and creatinine in the blood.

Electrolyte and Acid-Base Disorders

Imbalances in sodium (affecting body fluid volume).
Potassium retention (90% removed by healthy kidneys).
Acid-base imbalance: Kidneys regulate blood pH by removing hydrogen and reabsorbing bicarbonate ().

Bone and Mineral Disorders

Weak bones due to low calcium and vitamin D.
High phosphorus, low active vitamin D, elevated parathyroid hormone (PTH) leading to bone demineralization.

Hematologic Disorders

Anemia (low RBCs due to decreased erythropoietin production).
Increased bleeding risks (abnormal platelets and clotting).

Cardiovascular Disorders

Hypertension and heart disease (toxin buildup affects heart).
Pericarditis (waste buildup irritates pericardial sac).

Gastrointestinal and Neurological Issues

Nausea, vomiting, loss of appetite.
Confusion, poor concentration, nerve damage.

Dermatologic and Immune System Changes

Itching, dry skin.
Increased risk of infections.

Treatment During Renal Insufficiency Stage

Goals and Strategies

Slow progression of renal damage.
Protect kidney function.
Treat infections promptly (especially urinary tract infections).
Avoid nephrotoxic medications.
Control blood pressure and manage diabetes.
Stop smoking.

Medical Management of Renal Failure

General Principles

Control blood pressure, diabetes, and underlying disease.
Correct fluid, electrolyte, and acid-base imbalances.

Renal Replacement Therapies

Hemodialysis: Blood is filtered through a machine.
Peritoneal dialysis: Fluid in the abdomen filters waste.
Transplantation: Diseased kidney replaced with a donor kidney; best long-term option for ESRD.

Dietary and Medication Management

Limit protein intake to reduce waste buildup.
Provide adequate calories (carbohydrates and fats).
Restrict potassium and sodium to prevent dangerous heart rhythms and reduce swelling/hypertension.
Adjust drug dosages due to altered absorption, distribution, and excretion in CKD.

Special Considerations: Children and Elderly

CKD in Children

Causes: Congenital malformations, inherited disorders, acquired diseases, metabolic syndromes.
Manifestations: Severe growth impairment, developmental delay, delayed sexual maturation, bone abnormalities, psychosocial problems.

CKD in Elderly

Normal decrease in GFR with age.
Increased risk from nephrotoxic drugs.
Greater incidence of cerebrovascular, cardiovascular, and skeletal system effects.

Treatment Options for CKD in Elderly and Children

Treatment	Children	Elderly
Hemodialysis	Effective, but may be challenging for small veins	May be harder due to weaker veins, heart stress
Peritoneal Dialysis	Can be done at home, easier for children	Risk of infection (peritonitis)
Transplantation	Best long-term option	May not qualify due to health problems

Key Equations

Glomerular Filtration Rate (GFR):

Summary Table: Stages of CKD by GFR

Stage	GFR (mL/min)
Mild	60-89
Moderate	30-59
Severe	15-29
ESRD	<15

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