questions 5

Nephrolithiasis

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Topic updated on 11/28/16 1:37am

Snapshot
  • A 30-year-old man presents to the ER with acute onset of severe, colicky left flank pain, with radiation of the pain down the abdomen into the groin. He has increases frequency of urination and dysuria. PE shows tenderness in the costovertebral angle. Dipstick is positive for blood. Sediment examination shows blood and the presence of square crystals that look like the back of an envelope.
Introduction
  • Epidemiolgoy
    • incidence
      • most often in males in third and fourth decade of life
    • risk factors
      • low fluid intake
      • enzyme disorders
      • RTA
      • hyperparathyroidism
      • medications
      • Crohn's disease due to increased reabsorption of oxalate
      • decreases urine citrate levels because citrate is essential to bind stone constituents and prevent aggregation.
  • Pathophysiology
    • cause
      • idiopathic hypercalcemia is the ost common cause
Classification
  • Types of stones
Calcium oxalate 75% Radiopaque Idiopathic hypercalcemia 
Calcium phosphate 8% Radiopaque primary hyperparathyroidism
Struvite (Ammonium-Mg-Phos) 9% Radiopaque Often staghorn calculi. Associated with urease positive Proteus orStaph. saprophyticus
Uric acid 7% Radiolucent Gout and high purine turnover states
Cysteine 1% Radiopaque Often staghorn calculi. Associated with amino acid transport defects.

 

Presentation
  • Symptoms
    • pain
      • abrupt onset of 10/10 flank pain
      • radiates toward the abdomen and groin
      • patients move around and are unable to get comfortable
    • urinary track symptoms
      • urinary frequency
      • dysuria
  • Physical exam
    • hematuria
Imaging
  • Radiographs
    • abdominal X-rays
      • only stones that contain calcium oxalate or calcium phosphate are radiopaque
      • stones of uric acid, xanthine, ammonium nitrate are radiolucent
      • show up as a filling defect
      • therefore an AXR is only useful if it is positive.
    • with IV pyelogram to rule out staghorn calculi in the renal pelvis
  • CT of the abdomen and pelvis  
  • Renal ultrasound 
    • should be performed to rule out hydronephrosis
Studies
  • Urinalysis
    • urine should always be strained for stones
      • stones should be analyzed by X-ray diffraction
        • gold standard for stone analysis
Differential
  • Urinary tract obstruction:
    • congenital defects most common cause in children
    • BPH and nepthrolithiasis most common cause in adults
Treatment
  • Medical treatment
    • analgesia, aggressive hydrationwait for spontaneous passage 
      • indications
        • first line of treament stones < 2cm
      • technique
        • hydration should include 2.5-3 liters/day
    • extracorpeal and percutaneous lithotripsy
      • indications
        • stones > than 2 cm
    • thiazides (hydrochlorothiazide)
      • indications
        • useful for calcium pyrophosphate stones
    • treat underlying infection
      • indications
        • struvite stones
    • alkalinizing the urine pH
      • indications
        • uric acid stones
        • oxalate stones
        • cystine stones
  • Surgical treatment
    • surgical resection
      • indications
        • staghorn calculi are best removed by surgery


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Qbank (3 Questions)

TAG
(M2.RL.6) A 54-year-old male presents to the emergency department with sudden-onset, excruciating left flank pain radiating to his groin. A CT scan is ordered and shown in Image A. Which of the following best justifies the use of CT in the diagnosis of this patient's condition? Topic Review Topic
FIGURES: A          

1. KUB radiographs have a higher sensitivity but CT scan has a higher specificity and should be used in cases of high positive suspicion
2. Radiolucent stones can be visualized that are missed on KUB radiographs
3. The use of IV contrast can highlight the anatomy of the urinary system
4. CT scans provide additional information for a planned percutaneous nephrostomy placement
5. CT scan should not have been used here for this indication

PREFERRED RESPONSE ▶
TAG
(M2.RL.54) A 45-year-old woman presents to the ED with sharp, severe, colicky right flank pain radiating to the groin that she reports started suddenly several hours ago. She also reports discolored urine when she last voided. Vital signs are within normal limits. On exam, the patient is visibly in pain and shifts positions every few minutes. Costovertebral tenderness is elicited on percussion. Her abdominal radiograph is shown in Figure A. Past medical history is significant for type II diabetes mellitus, fibromyalgia, gout, and depression. What additional information about the patient’s history would likely explain the radiographic findings? Topic Review Topic
FIGURES: A          

1. Recent diagnosis of parathyroid adenoma
2. Frequent Gram-negative bacilli urinary tract infections
3. Recent diagnosis of acute myeloid leukemia
4. Prior history of calcium stones
5. Renal tubular acidosis

PREFERRED RESPONSE ▶
TAG
(M2.RL.88) A 39-year-old male presents with acute-onset, severe right-sided flank pain that radiates to his groin. He has never experienced an episode like this before. CT abdomen and pelvis (Figure A) as well as urine sediment analysis showing envelope-shaped crystals confirm the most-likely diagnosis. Conservative treatment is pursued and the issue resolves spontaneously within a 36-hour waiting period. Which of the following is the next best step in management on discharge of the patient from the hospital? Topic Review Topic
FIGURES: A          

1. Recommend in-depth metabolic evaluation as outpatient
2. Encourage increased hydration
3. Initiate furosemide
4. Recommend 10-day course of prophylactic antibiotics
5. Schedule periodic renal ultrasounds to monitor for recurrence

PREFERRED RESPONSE ▶


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