Alterations in Kidney Function and Elimination

Overview of Kidney Function and Laboratory Assessment

• Major Role of the Kidneys: The kidneys serve as the primary regulator of fluid output in the human body. Their functions include:

  • Removal of Waste Products: Filtering metabolic byproducts from the blood.
  • Fluid and Electrolyte Balance: Maintaining homeostatic levels of water and essential ions.
  • Acid-Base Balance: Regulating blood pH within the narrow range of $7.35$ to $7.45$.
  • Bone Integrity: Facilitating the conversion of Vitamin D into its active form.
  • Hemodynamic Stability: Regulating blood pressure through the secretion of Renin.
  • Red Blood Cell Production: Secretion of Erythropoietin to stimulate the production of RBCs.

• Primary Laboratory Assessments:

  • Blood Urea Nitrogen (BUN): Normal range is $7-20\,mg/dL$.
  • Serum Creatinine (Cr): A byproduct of muscle waste used to determine kidney function. Normal range is typically $< 1.2\,mg/dL$ (or specifically $0.5-1.3\,mg/dL$).
  • Glomerular Filtration Rate (GFR): Indicates how well the kidneys filter waste and fluid. Normal is $> 90\,mL/min$.

Clinical Grading and Staging of Chronic Kidney Disease (CKD)

• CKD Definition: An irreversible, gradual loss of kidney function, common in older adults, progressing through five stages based on eGFR results:

• Stage 1:

  • eGFR Result: Greater than $90\,mL/min$.
  • Conclusion: Kidneys are functioning within normal range; little kidney damage is present.

• Stage 2:

  • eGFR Result: $60$ to $89\,mL/min$.
  • Conclusion: Kidneys still functioning within normal range; mild kidney damage present.

• Stage 3a:

  • eGFR Result: $45$ to $59\,mL/min$.
  • Conclusion: Kidneys not functioning within normal range; mild to moderate damage evident.

• Stage 3b:

  • eGFR Result: $30$ to $44\,mL/min$.
  • Conclusion: Kidneys not functioning within normal range; moderate to severe damage present.

• Stage 4:

  • eGFR Result: $15$ to $29\,mL/min$.
  • Conclusion: Kidneys not functioning within normal range and at risk of total failure; severe damage evident.

• Stage 5 (End-Stage Kidney Failure):

  • eGFR Result: Less than $15\,mL/min$.
  • Conclusion: Kidneys have stopped functioning or are very close to it; severe and significant damage.

Comparison of Normal vs. Abnormal Renal Values

• Urinalysis:

  • Normal: Clear, yellow to deep amber.
  • Abnormal: Hematuria (blood), proteinuria (protein), presence of particles, foamy appearance, or high concentration.

• Glomerular Filtration Rate (GFR):

  • Normal: $> 90\,mL/min$.
  • Abnormal: Trends showing values less than $90\,mL/min$ down to less than $15\,mL/min$.

• Complete Blood Count (CBC):

  • Normal: Hemoglobin (Hgb) $12-16\,g/dL$; Hematocrit (Hct) $36-48\%$.
  • Abnormal: Decreased values (anemia related to low Erythropoietin).

• Blood Urea Nitrogen (BUN):

  • Normal: $7-20\,mg/dL$.
  • Abnormal: Ranges from $80$ to $> 100\,mg/dL$, occurring either quickly or gradually.

• Serum Creatinine (Cr):

  • Normal: $0.5-1.3\,mg/dL$.
  • Abnormal: Values between $> 2$ and $5\,mg/dL\,mL^{-1}$.

• Renal Ultrasound:

  • Normal: Healthy structural appearance.
  • Abnormal: Evidence of scarring or structural damage.

Acute Kidney Injury (AKI) and Multi-System Impact

• Etiology: AKI can result from trauma, drug use, infection, or renal artery blockage. It is categorized into Prerenal, Intrarenal (including Acute Tubular Necrosis), and Postrenal types.

• Pathophysiological Complications by System:

  • Cardiovascular: Increased blood pressure, edema, dysrhythmias (due to high $K+$), and chest pain.
  • Respiratory: Shortness of breath (SOB), low oxygen saturation, crackles in lungs, and metabolic imbalance (acidosis) reflected in Arterial Blood Gases (ABGs).
  • Renal: Low urine output, low eGFR, increased BUN, and reduced $Ca+$ levels.
  • Neurological: Lethargy, confusion, muscle twitching, and seizures.
  • Integumentary: Itching (pruritus), dry skin, and edema in the lower extremities (LE).

• Organ-Specific Impacts of AKI:

  • Brain: Uremic encephalopathy causing confusion (late stage); long-term risk of dementia and stroke.
  • Heart: Congestive heart failure, arrhythmias, and ischemic heart disease.
  • Lungs: Acute lung injury and pulmonary edema.
  • Liver: Altered hepatic metabolism and synthesis.
  • Intestines: Altered gut microbiota causing nausea and vomiting; uremic toxin accumulation.
  • Immune System: Systemic inflammation affecting the heart and lungs.

Diagnostic Procedures for Renal Disorders

• 24-Hour Urine Collection: Discard the first void of the day, then collect all subsequent urine for a full 24-hour period.
• KUB (Kidney, Ureters, Bladder): X-ray imaging; ensure the client is not pregnant before performing.
• CT Scan: Provides 3D images. Nursing considerations include checking for iodine allergies, holding Metformin, and encouraging water intake afterward to flush contrast.
• MRI: Less risk than CT but requires the client to remain perfectly still.
• VCUG (Voiding Cystourethrogram): Contrast dye injected into a catheter to visualize urinary tract infections (UTIs) or bladder trauma.
• Kidney Biopsy: Performed under sedation. Monitor the dressing for bleeding and the urine for traces of blood post-procedure.

Urinary Tract Infections (UTI) and Incontinence

• Urinary Tract Infections:

  • Symptoms: Frequency, urgency, bladder spasms, fever, and small amounts of urine.
  • Diagnosis: Urine Culture and Sensitivity (C&S).
  • Treatment (Antibiotics):
    • Sulfonamides: Trimethoprim/sulfamethoxazole (first-line treatment).
    • Nitrofurantoin
    • Fluoroquinolones
    • Phenazopyridine: Used specifically to treat discomfort, burning, and dysuria.
  • Patient Education: Increase fluid intake and be aware of sun sensitivity caused by some antibiotics.

• Urinary Incontinence:

  • Definition: Involuntary loss of urine or sudden leakage with the desire to void.
  • Assessments: Stress test (client coughs with full bladder while standing), Urinalysis (rules out infection), and Bladder scan (measures post-void residual).
  • Safety: Incontinence is strongly correlated with an increased risk for falls.

Urinary Retention and Benign Prostatic Hyperplasia (BPH)

• Urinary Retention:

  • Causes: Obstructive (pelvic organ prolapse, BPH, renal stones), Infectious (prostatitis, urethritis, UTI), or Other (childbirth complications, neurological disorders).
  • Diagnosis: Urine culture (may require catheterization), bladder scan for post-void residual, and cystoscopy.

• Benign Prostatic Hyperplasia (BPH) Surgical Management:

  • TURP: Transurethral Resection of Prostate.
  • TUNA: Transurethral Needle Ablation.
  • TUIP: Transurethral Incision of Prostate.
  • PVP: Photoselective vaporization of the prostate.
  • Prostatectomy: Full or partial removal of the prostate.

Specialized Renal Conditions and Care

• Hepatorenal Syndrome (HRS):

  • Definition: A multiorgan condition affecting both kidneys and the liver, often occurring in patients with decompensated cirrhosis.
  • Features: Reduced GFR without pathological changes to the kidney tissue; associated with multiorgan dysfunction.
  • Reversal: Can be reversed using vasopressors, plasma expanders (Albumin), or liver transplant.
  • Labs: Shows elevated $Cr+$ and $BUN$.

• Polycystic Kidney Disease (PKD):

  • Clinical Presentation: Flank pain, polyuria, nocturia, hematuria, hypertension, proteinuria, and palpable kidney masses.

• Renal Calculi:

  • Requires management based on size and clinical presentation; etiology includes risk factors and comorbidities.

• Acute Renal Failure (ARF) Treatment:

  • Prerenal Treatment: Fluid challenge to restore perfusion.
  • Elimination of Nephrotoxic Medications: Avoid agents like Vancomycin, Tetracycline, and Acetaminophen.
  • Manifestations Management: Addressing electrolyte disturbances like Hyperkalemia and Hypokalemia.

Questions & Discussion

• What would be early signs of electrolyte imbalance with CKD? (Audience/Self-study Prompt).
• What clinical manifestations should prompt the nurse to prioritize assessment of cardiac and respiratory systems in clients with AKI? (Fatigue, dyspnea, hypotension, bradycardia, increased work of breathing, and edema around eyes/hands).
• Discussion Question regarding TURP:
  • What is a TURP? A Transurethral Resection of the Prostate to treat BPH obstruction.
  • Complications: Potential for bleeding, infection, and transurethral resection syndrome.
  • Nursing Care: Monitoring for hematuria, managing continuous bladder irrigation (CBI), and tracking intake and output.
• Scenarios for Reflection:
  • Client with pulmonary edema, hypertension, and SOB: This client is at high risk for AKI/CKD due to fluid overload and poor renal perfusion. Diagnostic tests are ordered to determine if the kidney's inability to regulate fluid is causing the systemic symptoms.