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Renal & Urinary

Renal & Urinary System Review

Educational Use Only. This app is not intended to replace instructor guidance, institutional policies, clinical judgment, or professional medical training.

Overview

The renal system regulates fluid, electrolytes, and waste excretion. NCLEX covers acute/chronic kidney disease, dialysis, urinary tract infections, and electrolyte imbalances. Fluid management and recognizing renal failure are critical.

Key Concepts

  • 1

    Acute kidney injury: prerenal (decreased perfusion), intrarenal (kidney damage), postrenal (obstruction)

  • 2

    Chronic kidney disease stages 1-5 based on GFR; stage 5 (GFR <15) requires dialysis

  • 3

    BUN/Creatinine ratio: normal 10:1 to 20:1; >20:1 suggests prerenal cause

  • 4

    Dialysis types: hemodialysis (3x/week, vascular access), peritoneal dialysis (daily, peritoneal membrane)

  • 5

    Electrolyte shifts in AKI: hyperkalemia, hyperphosphatemia, hypocalcemia, hyponatremia

  • 6

    UTI: dysuria, frequency, urgency; pyelonephritis adds flank pain, fever, chills

  • 7

    Nephrotic syndrome: massive proteinuria (>3.5 g/day), hypoalbuminemia, edema, hyperlipidemia

Nursing Interventions

  • Monitor intake and output strictly; report output <30 mL/hr or <0.5 mL/kg/hr

  • Daily weights at same time, same scale, same clothing to track fluid status

  • Monitor serum electrolytes: potassium, sodium, calcium, phosphorus, magnesium

  • For hyperkalemia: restrict potassium, administer kayexalate, insulin+glucose, calcium gluconate (cardiac protection)

  • Assess vascular access for dialysis: check bruit and thrill, do not take BP or draw blood from access arm

  • Restrict fluid, sodium, potassium, and phosphorus in CKD as ordered

  • Monitor for signs of fluid overload: edema, crackles, JVD, hypertension

Critical Red Flags

  • Serum potassium >6.5 mEq/L — risk of fatal cardiac dysrhythmias

  • Oliguria or anuria with rising BUN/creatinine — acute kidney injury

  • Sudden weight gain with edema and crackles — fluid overload

  • Hematuria with flank pain and fever — possible pyelonephritis or kidney stones

  • Altered mental status with asterixis — uremic encephalopathy

  • Absent bruit or thrill at dialysis access — access failure

Key Lab Values

BUN: 7-20 mg/dL (elevated in renal dysfunction)

Creatinine: 0.6-1.2 men, 0.5-1.1 women (more specific for kidney function)

GFR: >90 normal, <15 indicates renal failure

Serum potassium: 3.5-5.0 mEq/L (critical >6.0 or <2.5)

Serum sodium: 135-145 mEq/L

Serum calcium: 8.5-10.5 mg/dL (low in CKD due to high phosphorus)

Urine specific gravity: 1.005-1.030

Patient Teaching

  • Follow prescribed fluid restriction; spread fluids throughout the day

  • Avoid high-potassium foods: bananas, oranges, tomatoes, potatoes, salt substitutes

  • Avoid high-phosphorus foods: dairy, nuts, colas; take phosphate binders with meals

  • Protect dialysis access: no BP cuffs, IVs, or blood draws on access arm

  • Report signs of infection at access site: redness, warmth, drainage, fever

  • Maintain adequate protein intake (1.0-1.2 g/kg/day for dialysis patients)

Educational Use Only — Not a substitute for professional training.