Nephrolithiasis Flashcards
What is Nephrolithiasis?
Precipitation of urinary solute as a stone.
What are risk factors for Nephrolithiasis?
- High concentration of solute in the urinary filtrate
2. Low urine volume
What is the classic presentation for Nephrolithiasis?
Presents as (1) Colicky pain with (2) hematuria and (3) unilateral flank tenderness.
How long does it usually take a stone to pass? What happens if the stone remains lodged?
- Stone is usually passed within hours
- If not, surgical intervention may be required
What is the most common type of Nephrolithiasis?
Calcium oxalate and/or calcium phosphate
What is the most common cause of Calcium oxalate/Calcium phosphate Nephrolithiasis?
Idiopathic hypercalciuria
What do you have to exclude (what could be the cause of) with Calcium oxalate/Calcium phosphate stones?
Hypercalcemia and its related causes
What disease is associated with Calcium oxalate stones?
Crohn disease
How does Crohn disease form calcium oxalate stones?
Small bowel damage –> Inc. resorption of oxalate –> Binds to calcium –> Forms Calcium oxalate stone
How do you treat calcium oxalate/calcium phosphate stones?
Hydrochlorothiazide (Ca2+ sparing diuretic)
What is the second most common type of Nephrolithiasis?
Ammonium magnesium phosphate
What is the most common cause of an ammonium magnesium phosphate stone?
Infection with Urease-positive organisms
What are urease-positive organisms?
- Proteus vulgaris
- Klebsiella
What leads to the formation of a stone with urease-positive organisms?
Alkaline urine leads to formation of stone
What does an ammonium magnesium phosphate stone classically result in?
Staghorn calculi in renal calyces –> acts as deposition site for UTIs
How do you treat ammonium magnesium phosphate stones?
Surgical removal of stone (due to size) and eradication of pathogen (to prevent recurrence).
What is the third most common form of Nephrolithiasis? What percentage of all Nephrolithiasis does it represent?
Uric acid
5%
What do uric acid stones look like?
Radiolucent (as opposed to other types of stones which are radiopaque)
What are risk factors for uric acid stones?
- Hot, arid climates
- Low urine volume
- Acidic pH
What is the most common stone seen in patients with gout?
Uric acid stone
What increases one’s risk for a uric acid stone?
Hyperuricemia (e.g. leukemia or myeloproliferative disorders)
How do you treat uric acid Nephrolithiasis?
-Hydration
-Alkalinization of urine (potassium bicarbonate)
[Allopurinol is also administered in patients with gout]
What is a rare cause of Nephrolithiasis?
Cystine
What populations are Cystine Nephrolithiasis commonly seen in?
Children!
What cause are Cystine stones associated with?
Cystinuria (a genetic defect of tubules that results in decreased reabsorption of cysteine)
–> then cystine piles up in the filtrate and this increases the risk for a kidney stone
What might cystinuria of nephrolithiasis cause?
It may form Staghorn calculi
How do you treat Cystine Nephrolithiasis?
- Hydration
- Alkalinization of urine
