nephrolithiasis; kidney stone

Introduction

see urinary calculus.

Etiology

• see urinary calculus
• staghorn calculus
• oral antibiotics increase risk
• risk factors for recurrent stones
  • younger age
  • higher body-mass index
  • male sex
  • family history of stones
  • pregnancy at last stone episode
  • stone composition other than calcium oxalate
  • asymptomatic stones noted incidentally on previous imaging
  • additional stones in the kidney (especially in the renal pelvis or lower pole) at the time of a symptomatic episode

Clinical manifestations

• presents as colicky flank pain with radiation to groin or lower quadrant pain*
  • does not present as upper quadrant pain
• hematuria*
• nausea/vomitng & dysuria may be present*

* if the stone is stable & not moving, may be asymptomatic

Laboratory

• serum chemistries
  • basic metabolic panel*
  • serum calcium, serum albumin, serum phosphate, serum uric acid
  • serum PTH
• 24 hour urine*:
  • 24 hour urine calcium
  • 24 hour urine creatinine
  • 24 hour urine uric acid
    • increased risk of uric acid stones if > 1000 mg/24 hrs
  • phosphorous, citrate, oxalate, cystine
• stone profile*
  • calculus composition analysis
  • inhibitor content
  • 75-85% of stones contain calcium
• urinalysis: hematuria*
  • urine microscopy: non-dysmorphic erythrocytes*

* hematuria may not be present if stone is stable

Radiology

• renal ultrasound (preferred modality in pregnant women)
• non-contrast CT of kidneys, ureters, bladder (initial test of choice)

Complications

• recurrent stones
• hypercalcemia, hyperparathyroidism

• disease interaction of diabetes mellitus type-2 with familial nephrolithiasis

Management

prognosis:

• kidney stone < 5-6 mm usually pass sponataneously
• passage of stones 4-10 mm may be facilitated by tamsulosin, nifedipine, silodosin, or tadalafil; efficacy is controversial (see urinary calculus)
• thiazide diuretics have been recommended to decrease recurrent nephrolithiasis in people with calcium stones; a randomized trial failed to find benefit
• NEJM recommends thiazide diuretics for hypercalciuria & alkaline urine
• 28% of asymptomatic renal stones will become symptomatic in 3.5 years
• removal of small asymptomatic stones when removing a larger symptomatic stone prevents subsequent symptomatic renal colic
• increase calcium & magnesium intake to bind oxalate in the gut & prevent its absorption (calcium oxalate most common stones)
• replacement of inhibitor substances
  • potassium citrate* 10-30 meq BID
    • reduces risk of calcium, uric acid, & cystine stones
      • NEJM claims potassium citrate may increase risk of calcium phosphate stones in alkaline urine
  • pyrophosphate
  • magnesium oxide
• in patients with diabetes mellitus type 2, SGLT-2 inhibitors associated with lower risk for kidney stones vs GLP-1 receptor agonists or DPP-4 inhibitors
• urology consultation
  • pyelonephritis or urosepsis (associated with nephrolithiasis)
  • acute kidney injury
  • large stone (> 1 cm) requiring surgical removal
  • bilateral urinary obstruction
  • urinary obstruction of a solitary kidney

More general terms

• urinary calculus (stone, nephrolithiasis, urolithiasis)
• kidney disease; renal disease

More specific terms

• staghorn calculus

Patient information

nephrolithiasis patient information