Nephrolithiasis Flashcards
What is nephrolithiasis?
Formation of all types of urinary calculus in the kidney, which may be deposited along the entire urogenital tract from renal pelvis to urethra
What are the different classifications of nephrolithiasis?
Check amboss notes on urolithiasis classification
What are the clinical features of nephrolithiasis?
Stones usually form in the collecting duct of kidneys but may be deposited along entire urogenital tract
Small stones may be asymptomatic
Severe unilateral and colicky flank pain (renal colic) - radiates anteriorly to lower abdomen, groin, labia, testicles or perineum. Paroxysmal or progressively worsening. Area around the kidneys may be tender on percussion
Hematuria
Nausea, vomiting and reduced bowel sounds
Dysuria, frequency and urgency
Passage of gravel or a stone
Patients are usually unable to sit still and move around frequently
What is the diagnosis for urolithiasis?
Clinical suspicion - consider if patients have unilateral colicky flank pain associated with nausea, vomiting and or Hematuria
Initial diagnostics - lab studies - CBC, BMP, urinalysis, human chorionic gonadotropin (hormone produced by placenta after implantation)
Imaging studies - CT abdomen and pelvis weight out contrast preferred if imaging is indicated
Further testing - determine stone composition, identify metabolic risk factors with a dietary history and lab studies
CBC - increased WBC count
BMP - typically within normal range. elevated BUN and creatinine suggest acute kidney injury
Urinalysis - non specific findings of nephrolithiasis - gross or microscopic Hematuria, Crystalluria. Alkaline urine pH >7.5-8 suggests struvite stones associated with urease producing organisms
Acidic urine pH <4.5-5.5 may indicate urticaria acid stones
What will a CT abdomen and pelvis without IV contrast show? And what are the indications?
Indications - first line for non pregnant patients with suspected nephrolithiasis
Findings - Calculus size, location, density and degree of obstruction. Hydronephrosis and or hydroureter, nephritic fat stranding
What will an ultrasound abdomen and pelvis show? And what are the indications?
Indications - suspected nephrolithiasis in patients for whom radiation exposure should be minimalised eg pregnant patients, paediatric patients
Findings - provides a complete outline of the i urinary tract system, size and location of stone, degree of obstruction
What is the treatment of nephrolithiasis?
Symptomatic treatment prior to confirmatory tests for patients with renal colic
Urology to be consulted in the following cases - large stones (>10mm), infected kidney stones, acute renal failure, solitary kidney or kidney transplant with obstruction
Attempt a trial of conservative treatment for patients with small (<10mm) uncomplicated stones - offer medical expulsive therapy in addition to symptomatic treatment. Treatment concomitant UTI if present. Interventional treatment is indicated if conservative treatment is unsuccessful after 4-6 weeks
What is threw symptomatic management of nephrolithiasis?
Analgesia - first line is NSAID’s, second line is opioids eg morphine
Antiemetics
IV fluids for dehydration
What is the conservative management for nephrolithiasis?
Initiate medical expulsive therapy - first line is an alpha blocker eg tamsulosin - relieves ureter muscle spasms, promotes the passage of ureteral stones <10mm, reduces the need for analgesics
Alternative - calcium channel blocker eg nifedipine (currently not routinely recommended)
Provide antibiotics if UTI is present
What is the interventional management for nephrolithiasis?
Ureteral stones - ureterenoscopy - first line for mid or distal ureter stones
OR extracorporeal shockwave lithiotripsy
Renal stones >20mm or lower renal pole stones >10mm - percutaneous neprholithotomy
What are the complications of nephrolithiasis?
Recurrent UTI -> risk of pyelonephritis, urosepsis and perinephric abscess
Urinary obstruction -> inflammation of the kidney and hydronephrosis -> permanent glomerular damage if left untreated
Acute kidney damage
What is the -prevention of nephrolithiasis?
Hydration - sufficient fluid intake
Diet - for calcium stones - reduced consumption of salt and animal protein, reduced consumption of oxalate rich foods and supplemental vitamin C - for oxalate stones
Calcium intake shouldn’t be restricted (risk of osteoporosis)
For urticaria acid stones - low in purine
For cystine stones - low in sodium
Chemoprophylaxis - for calcium stones - thiazide diuretics - for recurrent calcium containing stones. Allopurinol in the case of high urine urine acid. Urticaria acid stones - allopurinol. Cystine stones - tiopronin. Struvite stones - antibiotic treatment for UTI.
Change urinary pH - depends on stone composition. Urine alkalisation - to raise pH to 6.5-7.5 - diet rich in fruits and vegetables or supplementation of potassium citrate. Used to prevent recurrence of calcium oxalate, uric acid and cystine stones. Urine acidification - to lower pH to <7. Intake of cranberry juice or betaine or diet rich in dairy products, grains or meats. Used to prevent recurrence of calcium phosphate and struvite stones
