Renal Calculi (Kidney stones)

urinary/renal calculi

-frequent cause of hospitalization

-affects men more than women

-50% recurrence rate

condition necessary for stone formation

-supersaturation of urine with stone components (high mineral levels)

-higher concentration of minerals in the urine that the urine can dissolve

condition that suppresses stone formation

-presence of citrate in the urine(normal by-product of citric acid cycle in kidney)

-prevents clumping of minerals

-citrate binds to calcium cyrstals

-citrate levels decreased with metabolic acidosis and hypokalemia

Factors that contribute to stone formation

-dehydration

-urinary stasis

-hypercalcemia

-idiopathic

Hypercalcemia

-excessive calcium in the blood

-9.0 to 10.5 mg/dL

-causes: hyperparathyroidism, cancers, excessive vitamin D

urinary stones clinical presentation

-pain/renal colic (pain from obstructed urine flow)

-stone in renal pelvis: pain in back or flank

-stone in ureter: wave-like pain in flank radiating to groin

-hematuria

urinary stones complications

-infection

-hydronephrosis (kidney expands from blockage)

-renal failure

medical managment

-CT is test of choice

-CBC to look at WBC count

-Chemistries to look at BUN and creatinine

-urinanalysis C+S

kidney stones treatment

-pain meds (IV narcotics or NSAID)

-fluids (more than 2L a day to flush out)

-stone analysis (strain urine)

-less than 7mm = stone can pass

-more than 7mm requires intervention

Interventions for large stones

-extracorpeal shock wave lithotripsy (ESWL)

-percutaneous nephrolithotomy

-ureterscopy

extracorporeal shockwave lithotripsy (ESWL)

use of ultrasound waves to break up renal calculi (best for stones in upper ureter or kidney)

percutaneous nephrolithotomy

the surgical removal of a nephrolith through a small incision in the back

urteroscopy

used to remove a distal stone

medications for large stones

1. alpha blockers (tamsulosin (Flomax)) relaxes ureter

2. calcium channel blockers (Nifedipine (procardia))

Types of kidney stones

calcium, struvite, uric acid, cystine

Calcium phosphate stone

-results from high urinary calcium concentration

-manangment:

-high fluid intake

-treat underlying cause for serum calcium

-low sodium diet

-restricted animal protein

-thiazide diuertic (decreases calcium excretion in urine)

-calcium restriction NOT recommended

Calcium oxalate stone

-results from high urinary oxalate levels

-treat with low oxalate diet (avoid spinach, strawberries, tea, rhubarb, peanuts, chocolate, wheat bran)

Uric acid stones

- associated with increased uric acid levels

-treat with low purine diet (organ meats, shellfish, alcohol, fatty food

-allupurinol (Zlyoprim), decreases uric acid production

-potassium citrate can alkalinize the urine

Struvite stone

-associated with chronic UTI

-bacteria split urea into ammonia --> binds to phosphate and magnesium

-associated w/ proteus, klebsiella, and pseudomonias, NOT E.COLI

-treat chronic UTI and acidify urine w/ cranberry juice