Nephrolithiasis

Question 1

1st phenomena of stone formation

Answer 1

Supersaturation of urine by stone-forming constituents, including calcium, oxalate, and uric acid
Crystals or foreign bodies can act as a nidus which ions from supersaturated urine form microscopic crystalline structures

Question 2

2nd phenomena of stone formation

Answer 2

More likely responsible for calcium oxalate stones
Deposition of stone material on a renal papillary calcium phosphate nidus (Randall plaque)
Calcium phosphate precipitates the basement membrane of the thin loops of Henle, and erodes into the interstitium and then accumulates in subepithelial space of the renal papilla

Question 3

The stone clinic effect

Answer 3

Increase fluid intake, regular visits to a provider who advises increase fluids, and dietary modifications can cut stone recurrence by 60%

Question 4

Nephrolithiasis Symptoms

Answer 4

Acute onset sever flank pain radiating into the groin
Gross/microscopic hematuria
Nausea/Vomiting
Fever/Chills (only with infection)

Question 5

Nephrolithiasis Work-UP

Answer 5

UA: Can have hematuria (gross/microscopic)..No hematuria does not reduce chance of stone
Always look for bacteria (nitrites) or leukocytes
Infection is more serious if a lot of epithelial cells, probably a contaminated specimen

CBC: Looking for elevated WBC
Usually >15,000

Question 6

Gold standard imaging for stones

Answer 6

CT scan

Question 7

Nephrolithiasis Medications

Answer 7

Flomax 0.4mg one PO qday
Ketorolac 30mg IM/IV single dose
Hydrocodone or Oxycodone
Metoclopramide 10mg IM/IV q4-6 hours prn
Morphine 1-2mg IV q2-4 hours prn

Question 8

Calcium oxalate stones

Answer 8

most common, caused by high calcium and high oxalate excretion
green leafy vegetables, tea, chocolate

Question 9

Uric acid stones

Answer 9

Most common radiolucent stone

Low urine volume and acidic urine pH promote precipitation of uric acid

Question 10

Cystine stones

Answer 10

A genetic cause of kidney stones
Patients with cystinuria have impairment of renal cystine transport with decreased proximal tubular reabsorbtion of filtered cystine resulting in increased urinary cystine excretion and stone formation

Question 11

Struvite stones

Answer 11

Can grow rapidly over weeks or months
Can grow into staghorn calculus
Caused by UTI

Question 12

Xanthine stones

Answer 12

Rare!
Caused by inborn defect of xanthine oxidase
Xanthine cannot be oxidized to uric acid