Week 7- Renal Disorders

Renal System Overview

• Components of the Renal System

  

  • Kidneys

  • Ureters

  • Bladder

  • Urethra

  • Prostate Gland (in males)

• Blood Flow and Purpose

  • Blood flows from the kidneys through multiple arteries surrounding the nephrons, aiding in the reabsorption of ions before returning deoxygenated blood to the inferior vena cava.

• Functions of the Kidneys

  • Removal of waste from the body.

  • Regulation of:

  • Blood pressure

  • Blood volume

  • Blood glucose

  • Blood osmolarity

Nephron Structure

• Comprised of:

  • Renal Corpuscles:

    • Glomerulus

    • Bowman’s Capsule

  • Renal Tubules:

    • Proximal Convoluted Tubule

    • Loop of Henle

    • Distal Convoluted Tubule

    • Collecting Duct

• Glomerular Filtration Rate (GFR)

  • Definition: The volume of blood filtered per minute by the glomeruli.

  • Normal GFR: approximately $125 ext{ mL/min}$.

  • Influenced significantly by blood pressure.

Renal System Anatomy and Physiology

• Key Organs

  • Kidneys

  • Ureters

  • Bladder

  • Urethra

  • Prostate Gland (in males)

Functions of the Kidneys

• Regulating Ion Concentration

• Regulating Blood pH Levels

• Regulating Blood Volume

• Regulating Blood Pressure

• Managing Blood Osmolarity

• Hormone Production

• Excreting Waste and Foreign Substances

Nephrons

• Filtration

  • Glomerular Capsule

  • Filtration of plasma, including glucose.

  • Contains the Glomerulus, surrounded by the Bowman’s capsule, located in the renal cortex.

Renal Tubule Functions

• Proximal Convoluted Tubule

  • Function:

    • Reabsorption of 80% of electrolytes, water, glucose, amino acids, and bicarbonate.

    • Secretion of hydrogen ions and creatinine.

  • Location: Renal cortex

• Loop of Henle

  • Function:

    • Reabsorption of sodium and chloride in the ascending limb, water in the descending loop.

  • Location: Inner renal medulla

• Distal Convoluted Tubule

  • Function:

    • Secretion of potassium, hydrogen, and ammonia.

    • Reabsorption of water influenced by antidiuretic hormone and bicarbonate.

    • Regulation of sodium and potassium by aldosterone.

  • Location: Renal cortex

Glomerular Filtration Rate (GFR)

• Definition: The volume of blood filtered per minute by the glomeruli.

• Normal GFR: $125 ext{ mL/min}$

• Factors Influencing GFR:

  • Net filtration pressure

  • Total surface area for filtration

  • Filtration membrane permeability

• Tests to Assess GFR:

  1. Creatinine Clearance: An assessment method involving a 24-hour urine collection based on body surface area.

  2. Serum Creatinine Levels: Normal ranges are:

  • Males: $60-110 ext{ µmol/L}$

  • Females: $45-90 ext{ µmol/L}$

Renal Assessment

• Concept: A combination of subjective and objective patient information.

• Purpose: To analyze kidney function and diagnose issues.

Urinalysis

• Objective Measures:

  • Vital Signs

  • Inspection

  • Palpation

  • Percussion

  • Auscultation

  • Urine Analysis: Color, clarity, odour

  • Weight

• Subjective Measures:

  • Frequency and urgency

  • Nocturia: Urinating once or more per night

  • Dysuria: Painful, burning sensation during urination

  • Hesitancy: Difficulty urinating

  • Incontinence: Leakage of urine

  • History of urinary conditions

• Significance of Urinalysis:

  • Establishes baseline information and aids in diagnosis

  • Optimal Timing: Morning sample best for reliability

Components of Urinalysis

• Chemical and Microscopic Findings:

  • Specific Gravity

  • pH level

  • Protein levels

  • Leucocytes

  • Nitrites

  • Blood

  • Ketones

  • Glucose

  • Bilirubin

  • Urobilinogen

Abnormal Findings and Their Significance

• Hematuria: Blood in urine indicates potential kidney injury or disease.

• Color Changes:

  • Dark, smoky color indicates excessive bilirubin.

• Odor: Ammonia-like odour can indicate infection (UTI).

• Cloudiness: Linked with urinary tract infections (UTI).

• pH Levels: Can indicate diabetes insipidus or dehydration.

Renal Serology and Procedures

Serum Levels

• Serum Urea: A byproduct of protein metabolism, normal range: $3-8 ext{ mmol/L}$.

• Creatinine: Removed by kidneys, reliable indicator of GFR, normal range: $53-115 ext{ µmol/L}$.

• eGFR: Estimates kidney filtering capability, normal: <$90 ext{ mL/minute}/1.73 ext{ m}^2$.

• Blood Urea Nitrogen (BUN): Normal range: $3-8 ext{ mmol/L}$.

Diagnostic Imaging and Procedures

• Renal Ultrasound: Evaluates kidneys.

• Bladder Scan: Determines bladder volume.

• Cystoscopy: Visualizes the bladder.

• Intravenous Pyelogram: Imaging of kidney structures.

Age-related Changes

• Impacts of Aging on the Renal System:

  • Decreased renal tissue

  • Decreased function of Loop of Henle

  • Weakening urinary sphincter

  • Decrease in nephrons and renal blood vessels

  • Decreased bladder capacity and sensory receptors

Urinary Tract Infection (UTI)

• Types:

  • Upper UTIs (pyelonephritis): Kidney level infection.

  • Lower UTIs (cystitis, urethritis): Bladder or urethra infection.

Risk Factors

• Anatomical Factors: Women are at higher risk due to shorter urethra distance to the anus.

• Functional Disorders: Constipation, voiding dysfunction can increase risk.

• Immune system conditions: Diabetes, HIV increases susceptibility.

Pathophysiology of UTI

• General Cause: Bacteria, primarily E. coli, enter through the urethra → ascends to the bladder. → bacteria adheres to urothelium → bacteria multiply → causes infection + inflammation → WBCs + Cytokines + other pro-inflammatory markers reach the site of infection 

  • Cystitis occurs = irritation and swelling of bladder

  • pyelonephritis = inflammation of kidneys (if infection spreads) 

• Symptoms of a UTI:

  • Hesitancy: Difficulty starting urination

  • Dysuria: Painful or difficult urination

  • Frequency and Urgency: Urine loss and strong urge to void

• Clinical Manifestations:

Diagnosis and Management

• Medications:

  • Antibiotics (e.g., Trimethoprim; Nitrofurantoin)

  • Trimethoprim

    • MOA: Selectively interferes with bacterial biosynthesis of the nucleic acids and the proteins of the organism

    • Broad spectrum antibiotic

    • Contraindicated in pregnancy

  • Nitrofurantoin

    • MOA: Bacteriostatic and bactericidal as interferes with the bacterial enzymes

    • Broad spectrum affecting both gram-positive and gram-negative bacteria

    • Can be used in caution in pregnancy

  • First generation cercosporin

    • MOA: Bactericidal as inhibit cell wall synthesis

      • i.e. Cephalexin

    • Can be used with caution in pregnancy

    • Broad spectrum mainly used for gram-positive bacteria

  • Other medication

    • Antipyretics

    • Analgesia

  • Avoid unnecessary cauterization

  • Sepsis

    • If patient is acutely unwell then fluid resuscitation would be appropriate management to stabilize the patient

  • Patient education

    • Instructions on antibiotic therapy

    • Drinking more fluids

    • Encourage urination once feel the urge

    • Urination after intercourse

    • Cleansing of genitals

    • Avoiding constipation

    • Avoidance of spermicides

Acute Kidney Injury (AKI)

The sudden impaired functioning of the kidneys. 

Pathophysiology

• Categories of AKI:

  

  • Prerenal: Caused by factors outside the kidney (e.g., dehydration, hemorrhage).

  • Intrinsic/Intrarenal: Due to direct damage to kidneys (e.g., nephrotoxins).

  • Postrenal: Due to obstructions (e.g., benign prostatic hyperplasia).

Clinical Features

• Oliguria

• Hypovolemia

• Fluid retention

• Severe acidosis

• Decreased sodium levels

• Increased potassium levels

• Increased urea and creatine levels

• Neurological changes

Risk Factors:

• Hypertension, hypercholesterolemia, infection/sepsis, nephrotoxic agents.

Clinical Phases (RIFLE Classification)

Stages of AKI

Patient Management

• General Monitoring: Vital signs, fluid intake/output, lab values.

• Management Strategies:

  • Dietary restrictions, IV fluid therapy, medication administration, hemodialysis as a last resort.

• Prerenal: Provide Intravenous therapy to increase blood volume and perfusion to kidneys

  Intrinsic renal: Remove the cause of damage for example nephrotoxic medication or treat the infection such as glomerulonephritis

  Postrenal: Remove the obstruction through surgery or by providing urinary catheter

Nursing Management Priorities

• Pain management, monitoring for changes in vital signs, monitoring at-risk patients.

Chronic Kidney Disease (CKD)

• Pathophysiology:

  • Progressive, irreversible decline in kidney function.

  • Signs include increased workload on remaining nephrons leading to damage.

  • Duration: More than 3 months with eGFR <$60 ext{ mL/min}/1.73 ext{ m}^2$.

Nursing Diagnoses for CKD

• Fluid Volume Excess: Due to oliguria characterized by edema, weight gain, and hypertension.

• Fatigue: Related to uremia and anemia, marked by pallor and low hemoglobin levels.