Acute Renal Problems

Acute Renal Problems
Leonard C. Hymes, M.D.
Division of Nephrology   Department of Pediatrics-Emory
  1. Acute Renal Failure
    Definition: Sudden decrease in GFR as demonstrated by a rise in serum creatinine and BUN

    Pathogenesis   Diagnosis   Management
    • Acute Renal Failure Pathogenesis
      • Pre Renal Azotemia
        • Renal parenchymal injury and acute renal failure have not occurred
        • Physiologic response to reduced renal perfusion: Dehydration, heart failure, septic shock
        • Mediated by ADH, aldosterone and prostaglandins
      • Obstructive Uropathies
        • Hydronephrosis by imaging studies
        • Frequently associated with U.T.I.
        • Examples: Posterior urethral valves, ureterocele, VUR, urolithias, tumors
      • Tubular-Interstital Disease
        • Injury to renal interstitium and tubules
        • Ischemic: ATN, vasomotor
        • Infiltration: Leukemia
        • Toxic: Myoglobinuria, antibiotics
      • Glomerular-Vascular
        • Usually associated with hematuria and hypertension
        • Acute Glomerulonephritis: PSAGN, SLE, Henoch-Schonlein Purpura
        • Vascular: HUS, DIC
    • Acute Renal Failure Management
      • Hypervolemia
        • Fluid restriction to IWL
        • IWL = 400 cc/meter sq
        • Electrolyte free
      • Diuretics: Usually ineffective
    • Nutrition
      • Acute renal failure is a catabolic event
      • Daily restrictions: Na and K = 2 grams and Protein = 2 grams / kg
      • Renal supplements: Suplena ; Low Na, K and P; high caloric density 500 cal/8oz
      • Ca Carbonate or Ca Acetate
      • Cacitriol (Rocatrol or Calcijex IV)
    • Infection
      • Primary infections: Post-strep AGN, hemolytic uremic syndrome, pyelonephritis
      • Secondary infections: In-dwelling catheters- bladder, central venous, peritoneal: Staph aureas, fungal
      • Antibiotics should be chosen very carefully
      • Dose modification for renal failure
      • Monitor peak and trough levels
      • Removal by dialysis
    • Uremia
      • Symptomatic azotemia
      • Encephalopathy
      • Platelet dysfunction and bleeding
      • Peripheral neuropathy
      • Pericarditis
      • Absolute indication for dialysis
      • Peritoneal
      • Hemodialysis
      • CVVH (ICU)
  2. Electrolyte Disturbances
    Hyonatremia   Hypernatremia   Hyperkalemia   Hypocalcemia
    • Hyponatremia
      Dilution: Acute renal failure, nephrotic syndrome, SIADH
      Depletion: AGE, Na wasting nephropathy
      Spurious: Hyperlipidemia, hyperglycemia
      • Dilutional Hyponatremia
        • Fluid restriction
        • Nephrotic Syndrome - 25% albumin + furosemide
        • SIADH - Furosemide + replace 1/2 urine output with 3% saline
        • Renal failure: dialysis
      • Hyponatremic Dehydration
        • Calculation of Na deficit = (140-Na) * TBW where TBW = 0.6 * kg
        • Isotonic losses = 140 meq/L
        • Example: Na 125 meq/L, weight 5 kg with 5% dehydration (.250 L)
        • Na deficit = (140-125) * 0.6 * 5= 45meq
        • Isotonic losses .250 * 140 = 35 meq
        • Total Na needs = 35 + 45 = 80 meq
        • Fluids = maintenance + deficit = 500 + 250 cc
        • Totals: 750 cc + Na 80 meq
      • Hyponatremia: Seizures
        • Seizures may occur when Na < 120 meq/L
        • Emergency management: 3% Saline 10cc/kg will raise serum Na by 13 meq/L
        • Example: Na 110 meq/L, weight 3 kg Raise serum Na to 130 meq/L= 76 cc of 3% saline
    • Hypernatremia
      • Calculation of free water deficit (L) = Na - 150 * TBW/150 (TBW=0.60*kg)
      • or 4 cc/kg to lower Na by 1 meq/L
      • Example: Weight 5 kg, Na 160 meq/L
      • Correct to Na 150 meq/L, free water deficit = 4cc*5kg*(160-150) = 200cc
      • Correct water deficit over 48 hrs
    • Hyperkalemia
      • Hyperkalemia: Etiology
        • Renal failure
        • Primary hypoaldosterone
        • Congenital adrenal hyperplasia
      • Hyperkalemia: Nonurgent
        • Nonurgent: Normal ECG - Kayexalate (Sodium polystyrene resin)
        • Dose 0.5 to 1.0 gram/kg q 6-12 h po/pr
        • May cause hyperNa
        • Cardiac monitoring +/-
        • May require elective dialysis
      • Hyperkalemia: Urgent
        • Urgent: ECG widened qrs and peaked T waves: Cardiac monitoring essential
        • NaBicarbonate 1-3 meq/kg IV
        • CaGluconate 10% 0.2-0.5 cc/kg IV
        • Glucose 25% 2cc (0.5gm) per kg IV + insulin 0.3u per gm glucose
        • Must follow with Kayexalate or dialysis
    • Hypocalcemia
      • Clinical findings: tetany, carpal pedal spasms, + Chevostek sign
      • Treatment: IV Ca Gluconate 9% 1cc/ kg: Very dangerous drug
      • Oral Ca Carbonate or Acetate
      • Vit D: Calcitriol
  3. Hypertension
    • Malignant hypertension
      • Malignant hypertension: seizure, coma, cerebral infarction
      • Treatment: Diazoxide 2-5 mg/kg IV or Sodium Nitroprusside continuous IV infusion
      • Cranial MRI or CT
    • Mild to Moderate Hypertension: Step-wise approach
      • 1st Ca Channel blockers: procardia, norvasc or Diuretics: lasix, zaroxolyn
      • 2nd ACE inhibitors: enalapril, prinivil, captopril
      • 3rd Beta blockers: labetalol, atenalol
      • 4th Angiotensin receptor blocker: losartan or Vasodilators: minoxidil
  4. Nephrotic Syndrome
    Definition: hypoalbunemia, proteinuria, hyperlipidemia, edema Urgent problems: anasarca and infections
    • Infection
      • Strep pneumonia peritonitis and pneumonia. Also gram neg rods
      • Antibiotics: Cefotaxime or Vancomycin and Aminoglycoside
      • Risk for infections related to multiple factors: Ascitic fluid, hypo IgG, immunosuppreesion, decreased macrophage activity
    • Anasarca
      • 25% Albumin 0.5 to 1.0 grams/kg q8h
      • Lasix 1.0 mg/kg IV q 8h
      • Monitor Na and K
      • Other indication for albumin: Vascular contraction - hypotension, tachycadia, hemoconcentration, azotemia
  5. Gross Hematuria
    • Urgent
      • Trauma
      • AGN with hypertension or renal failure
      • Bleeding disorders
      • Pain (stones, U.T.I)
    • Nonurgent
      • Isolated: Normal BP, renal function
      • Asymptomatic: Painless, no edema
      • Examples: IgAN, idiopathic hypercalciuria, thin membrane disease
    • Evaluation of Gross Hematuria
      • Serum electrolytes, C3C4, ASO, ANA, renal US, Urine Ca/creat
      • Urinalysis with microscopic: Hematuria vs Myoglobinuria,RBC morphology
      • Renal biopsy for renal failure, HBP, proteinuria, or family history.
  6. Urinary Tract Infections
    • Cystitis vs Pyelonephritis
      • Cystitis: Suprapubic pain, dysuria, afebrile, gross hematuria (Adenovirus)
      • Pyelonephritis: Septic, flank pain, WBC casts , gram neg enteric organisms
      • Criteria for admission based on symptoms
    • Urinary Tract Infections: Evaluation
      • Imaging studies in all preadolescent children after first infection:
      • Renal US, VCUG
      • Adolescent female: Sexual activity, pregnancy test, STD
      • Adolescent male: Very rare infection, accounting for only 0. 3% of all U.T.I.