Nephrology and Renal Disorders Lecture Notes

General Kidney Physiology and Function

• NCLEX Relevance: Nephrology is considered a high-yield NCLEX topic.

• Filtration Capacity: The kidneys contain approximately $1,000,000$ nephrons responsible for removing toxins from the blood.

• Normal Urine Output: A normal adult output ranges between $25\,ml/hr$ to $50\,ml/hr$.

  • The speaker notes a calculation equivalent to $180$ bags of saline in an hour of filtration work.

• Blood Pressure Regulation: Beyond filtration, the kidneys control blood pressure via the Renin-Angiotensin System (RAS).

  • Aldosterone: Controls blood pressure levels.

• Erythropoietin (EPO): This hormone is produced by the kidneys to drive red blood cell production in the bone marrow in response to low oxygen levels.

• Systemic Connections: Kidney disease frequently leads to secondary hypertension and anemia due to the failure of these systems.

Polynephritis (Pyelonephritis)

• Definition: The primary exemplar for kidney disease in this module is polynephritis. It is a bladder infection that ascends into the kidney.

  • If the infection is in the urethra, it is urethritis.

  • If the infection climbs to the kidney, it is polynephritis.

• Mechanism of Injury: Bacteria cause inflammation in the kidneys, leading to scarring.

  • Scarring results in the death of nephrons, hindering the kidney's ability to filter, absorb, and secrete.

  • While Acute Kidney Injury (AKI) involves immediate damage, scarring often makes the condition permanent or chronic.

• Risk Factors:

  • UTIs: Chronic or severe urinary tract infections are the primary precursor.

  • Pregnancy: Hormonal changes and uterine compression slow urine flow, increasing risk. It is also associated with preterm labor.

  • Miscellaneous: Overuse of NSAIDs, chemotherapy, cancer, and the use of chronic catheters or presence of stones.

• Clinical Manifestations:

  • Systemic: Fever, chills, tachycardia, and tachypnea (fast breathing).

  • Local: Flank pain (kidney pain), and tenderness at the costometibial angle (CVA tenderness).

  • Urinary: Specific symptoms include burning and urgency, which are more amplified than a standard UTI.

  • GI: Nausea and vomiting (indicative of a systemic inflammatory response, usually absent in simple UTIs).

  • Psychosocial: Patients may feel embarrassed, "dirty," or cognitively scared.

  • Older Adults: Geriatric patients, especially women, may present with aggression and delirium ("throwing fists") rather than standard symptoms.

• Diagnostics:

  • Urinalysis (UA): Look for positive leukocyte esterase, nitrites, presence of white blood cells (WBCs), and bacteria.

  • Urine Culture: Identifying the specific organism (e.g., $E.\,coli$) to guide antibiotic therapy.

  • Blood Cultures: Necessary if sepsis is suspected; normal growth should be zero.

  • Inflammatory Markers: Elevated WBC count, C-Reactive Protein (CRP), and Erythrocyte Sedimentation Rate (ESR).

  • Kidney Function Tests: Monitoring BUN, Creatinine, and Glomerular Filtration Rate (GFR).

  • Imaging: KUB (Kidneys, Ureters, Bladder) X-ray or a CAT scan. The CAT scan is the standard for identifying stones or scarring.

• Management:

  • Antibiotics: Start with broad-spectrum and narrow down after culture results.

  • Hydration: Goal of $2\,L/day$ to help filter toxins.

  • Catheter Management: If a catheter has been in for more than $2$ weeks, it must be replaced before starting new antibiotics.

Urosepsis

• Pathophysiology: Occurs when the kidney infection spreads into the bloodstream, triggering a systemic inflammatory response that can lead to septic shock.

• Risk Factors: Delayed treatment, urinary obstructions (stones/strictures), diabetes, immunosuppression, and indwelling catheters in older adults.

• Signs of Sepsis:

  • Hypotension (caused by vasodilation).

  • Tachycardia.

  • Fever or hypothermia (in severe/late stages).

• Sepsis Bundle/Emergency Action:

  • Requires blood cultures and lactic acid tests.

  • Broad-spectrum antibiotics (e.g., Rocephin, Ventevice) must be administered within $1$ hour of the sepsis alert.

  • Caution: Cultures must be obtained before the first dose of antibiotics.

  • Fluids: IV fluid resuscitation to support blood pressure and perfusion.

  • Vasopressors: Use of medications like Levo (Levophed) if blood pressure does not respond to fluids.

  • Nursing Caveat: Do not provide warm blankets to febrile patients as the body needs to naturally lower its temperature.

Glomerulonephritis (GN)

• Definition: Inflammation of the glomerulus (the filtrate unit).

• Acute GN: Comes on suddenly, often occurring approximately $10$ days after a strep throat infection. Most patients recover quickly.

• Chronic GN: Develops over years and always progresses to End-Stage Kidney Disease (ESKD). It involves nephron atrophy and permanent scarring.

• Hallmark Finding: A fixed urine specific gravity of $1.01$. This indicates the kidneys have lost the ability to concentrate or dilute urine regardless of fluid intake.

• Primary vs. Secondary:

  • Primary: The disease originates in the kidney itself.

  • Secondary: Kidney damage is a casualty of a systemic illness (HIV, Lupus, Hepatitis).

• Treatment: Antibiotics for underlying infection, corticosteroids or cytotoxic drugs to suppress the immune response (increases infection risk), and sodium/fluid restriction.

Nephrotic Syndrome vs. Nephrosclerosis

• Nephrotic Syndrome: The glomerular filter holes become too large (like a pasta strainer with seeds).

  • Proteinuria: Loss of more than $3.5\,g$ of protein in $24\,hours$.

  • Clinical Picture: Low blood albumin, periorbital edema (around eyes/face), and hyperlipidemia (liver increases lipid production to compensate).

  • Urine: May contain fat.

  • Common Cause: Minimal change disease (especially in children).

• Nephrosclerosis: A vascular problem where kidney blood vessels thicken and narrow (similar to atherosclerosis).

  • Causes: Hypertension (second leading cause of ESKD) and diabetes.

  • Management: Use of ACE inhibitors or ARBs to protect the kidneys.

Health Equity and Genetics

• APOL1 Gene Variant: Found in approximately $13\%$ of Black Americans.

• Risk: Raises the lifetime risk of ESKD to $15\%$ to $30\%$.

• Management: Manageable with sodium restriction, diuretics, and ACE inhibitors.

Obstructions: Hydronephrosis and Hydroureter

• Hydronephrosis: Blockage at or near the renal pelvis. The renal pelvis normally holds only $5\,ml$ to $8\,ml$ of urine.

• Hydroureter: Blockage lower in the ureter.

• Pathophysiology: Back pressure builds in the kidney tissue. Permanent damage can occur in under $48\,hours$.

• Management (Nephrostomy Tubes):

  • Monitor output hourly.

  • Normal Findings: Some blood in the first $12$ to $24\,hours$; diuresis (high output) immediately after placement.

  • Abnormal Findings: Absent drainage (clogged/dislodged), foul-smelling/cloudy drainage (infection), or persistent bleeding after $24\,hours$.

Polycystic Kidney Disease (PKD)

• Definition: Overproduction of cysts that replace functional kidney tissue.

• Pathophysiology: Cysts compress blood vessels and nephrons, causing hypertension and kidney failure.

• Assessment:

  • Visible abdominal distension.

  • Palpable, tender kidneys.

  • Dull Aching Pain: Simple cyst growth or low-grade infection.

  • Sharp Sudden Pain: Cyst rupture or stone movement.

• Cyst Rupture Signs: Bright red or cola-colored urine.

• Associated Risks: Higher incidence of cerebral aneurysms (watch for severe headaches/vision changes).

• Management:

  • Goal BP: $130/80\,mmHg$.

  • Sodium restriction under $2\,g/day$.

  • Drug Therapy: Tolvaptan (slows growth but requires liver monitoring).

  • Contraindication: Avoid Aspirin (bleeding risk).

Renal Artery Stenosis (RAS)

• Pathophysiology: Atherosclerotic plaque narrows the renal artery, leading to chronic underperfusion and triggering the RAAS system.

• Clinical Presentation: New onset of difficult-to-control hypertension in patients aged $40$ to $60$ with no prior history.

• Diagnostics: MRA, renal ultrasound, or arteriography.

• Treatment: Endovascular stenting or renal arterial bypass surgery.

Renal Cell Carcinoma (RCC)

• Characteristics: Highly vascular tumor.

• Paraneoplastic Syndromes: Systemic effects like anemia or erythrocytosis (the tumor affects EPO production).

• Staging: Stage 1 (confined) to Stage 4 (spread to lungs, liver, long bones, adrenal glands).

• Signs: Dull aching pain and late-stage hematuria (blood in urine).

• Treatment: Nephrectomy is the primary treatment. Traditional chemo is ineffective; immunotherapy/targeted therapy are used for metastatic disease.

• Post-Op Monitoring: Priority is watching for hemorrhage and Adrenal Insufficiency (both cause hypotension, low output, and altered consciousness).

Kidney Trauma

• Grading: Grade 1 (bruising) to Grade 5 (shattered kidney/torn blood supply).

• Cause: Blunt trauma (e.g., motor vehicle accidents) is most common.

• Nursing Safety Alert: If there is bleeding at the urethral opening, never attempt a urinary catheter without provider approval.

• Output Goal: The goal for all trauma/post-op patients is urine output above $0.5\,ml/kg/hr$.

  • Output below $25\,ml$ to $30\,ml$ per hour indicates high risk for AKI.

Questions & Discussion

• Question 1: Which clinical findings are associated with acute polynephritis?

  • Response: Urinary frequency, dysuria, tachycardia, and costovertebral tenderness.

  • Note: Oliguria (reduced urine output) is a trap answer; it usually indicates advanced failure or obstruction, not simple acute polynephritis where the kidney is still filtering.

• Question 2: The nurse is caring for a client 8 hours after nephrectomy. Which assessment finding requires immediate intervention?

  • Response: Abdominal distension.

  • Rationale: Abdominal distension is an early sign of internal bleeding/hemorrhage pooling blood in the cavity.