Causes of Struvite Kidney Stones

Bacterial Infection as Primary Cause

Struvite stones are also referred to as "infection stones" due to their strong association with urinary tract infections caused by specific organisms that produce the enzyme urease 1
Urease-producing bacteria split urea into ammonia and hydroxide, creating an alkaline urinary environment that promotes stone formation 2
Unlike other stone types, bacteria reside within struvite stones (not just on the surface), making the stones themselves infected 1

The urease enzyme promotes generation of ammonia and hydroxide from urea, resulting in high ammonia concentration 2
Abundant phosphate and magnesium in urine promote crystallization of magnesium ammonium phosphate (struvite) 1
These conditions promote crystallization of magnesium ammonium phosphate (struvite) 1
Struvite stones often contain calcium carbonate apatite as well 1

Formation of an exopolysaccharide biofilm by bacteria facilitates stone development 1
Incorporation of mucoproteins and other organic compounds into the stone matrix 1
Repeated urinary tract infections with urease-producing organisms increase risk of stone formation 1
Structural abnormalities of the urinary tract may increase risk 3

Struvite stones often grow into a "staghorn" configuration, filling the renal pelvis and branching into several or all of the calices 1
Untreated staghorn calculi can destroy kidney function and/or cause life-threatening sepsis 1
Complete stone removal is crucial to eradicate causative organisms 2
Complete stone removal is crucial to relieve obstruction 2
Complete stone removal is crucial to prevent further stone growth 2
Complete stone removal is crucial to preserve kidney function 1
Residual fragments may grow and be a source for recurrent urinary tract infection 1

E. coli, the most common cause of UTIs, typically does not produce urease and is not associated with struvite stone formation 3
Struvite stones differ from uric acid stones, which form in acidic urine (pH <5.5) 3
Calcium oxalate or phosphate stones rarely grow in a staghorn configuration, unlike struvite stones 1