What Factors Drive Staghorn vs Nonstaghorn Pattern Growth in Patients with Metabolic Stones?

Purpose: There has been an increase in the number of staghorn calculi that form in the absence of infection (metabolic staghorns). It is unknown why some large metabolic calculi form as solitary or multiple separate, nonbranching caliceal stones, whereas others develop as staghorn stones forming a cast of the collecting system. We sought to compare these two groups of metabolic stone formers (SFs) in an attempt to shed light on these disparate stone-forming phenomena. Materials and Methods: From January 2017 to September 2018, 190 patients underwent percutaneous nephrolithotomy for stones >2 cm. We identified 86 (45%) patients with a metabolic stone, defined as ≥80% calcium oxalate monohydrate or dihydrate and/or calcium phosphate. Exclusion criteria included stones composed of cystine, >20% uric acid, or any infectious element (struvite or carbonate apatite). Metabolic staghorn and nonstaghorn SFs were compared with respect to medical comorbidity, 24-hour urine parameters, stone and urine microbiology, stone compositions, and intraoperative findings. Statistical differences were assessed using chi-square analysis, Fisher's exact test, and Student's t-test. Results: In total, 25 (29%) staghorn and 61 (71%) nonstaghorn SFs were included for analysis. The groups were statistically similar in age, sex, body mass index, and medical comorbidity. Staghorn SFs had larger stone burdens (p < 0.0001), but did not require more punctures (p = 0.783). Staghorn SFs were more likely to have hyperoxaluria (p = 0.041) and higher mean 24-urine oxalate levels (p = 0.040). There were no other significant differences in 24-hour urine profiles, rates of metabolic abnormalities, stone compositions, stone or urine cultures, presence of collecting system obstruction, or pelvicaliceal anatomy. Conclusions: Although potentially driven by urinary oxalate, whether a metabolic stone will form into a staghorn configuration or not does not appear significantly influenced by standard determinants of stone development, including metabolic profile, cultures, hydronephrosis, and pelvicaliceal anatomy, among others. Further work is needed to elucidate the physicochemical factors that govern the pathogenesis of this increasingly prevalent entity.

Renal stone composition does not affect the outcome of percutaneous nephrolithotomy in children.

PURPOSE: We sought to investigate the association between renal stone composition and percutaneous nephrolithotomy outcomes in pediatric patients and define the characterization of the stone composition. METHODS: The data of 1157 children who underwent percutaneous nephrolithotomy between 1991 and 2012 were retrieved from the multicenter database of the Turkish Pediatric Urology Society. The study population comprised 359 children (160 girls, 199 boys) with stone analyses. Patients were divided into five groups according to the stone composition [group 1: calcium oxalate; group 2: calcium phosphate; group 3: infection stones (magnesium ammonium phosphate, ammonium urate); group 4: cystine; group 5: uric acid, xanthine stones]. RESULTS: Patient characteristics, perioperative, postoperative, and stone characteristics were compared considering the stone composition. There were no significant differences between the groups concerning age, sex, side involved, preoperative hematocrit levels, and solitary renal unit. Patients with cystine stones were more likely to have a history of stone treatment. Groups 2 and 5 had mostly solitary stones. However, group 3 had staghorn stone more often, and group 4 frequently had multiple stones. Overall stone-free rate (79.4%) was similar among the groups. Although stone composition was related to blood transfusion and prolonged operative and fluoroscopy screening times on univariate analysis, it was not a significant predictor of them on multivariate analysis. CONCLUSIONS: Stone composition was not a predictor of outcomes of pediatric percutaneous nephrolithotomy. However, cystine and infection stones, which are larger and filled multiple calyxes due to the nature of stone forming, were more challenging cases that need multiple tracts.

No stone unturned: The presence of kidney stones in a skeleton from 19th century Peoria, Illinois.

During the excavation of the 19th century Peoria City Cemetery (Peoria, Illinois), a skeleton of a female, aged 20-30 years old, was found with large, bilateral calcified masses in the abdominal region. The masses were analyzed by Fourier transform infrared (FTIR) spectroscopy, and the results compared to published clinical data in an effort to determine the etiology of the stones. The calcified masses were determined to be staghorn struvite uroliths, which commonly result from chronic urinary tract infection and likely impacted the overall health of this individual.

Infrared spectroscopic analysis of staghorn calculi obtained after open renal surgery in a urology unit of Sri Lanka.

The composition of renal stones varies widely among populations. The aim of our study was to determine the composition of staghorn renal stones using Fourier transform infrared (FTIR) spectroscopy in a cohort of Sri Lankan patients. Forty two staghorn calculi removed from kidneys of adult patients during open surgery were analysed. There were 32 men. Nineteen (45%) were calcium oxalate monohydrate (whewellite) stones. Stones containing a mixture of calcium oxalate and calcium hydroxyl phosphate (apatite) were found in 16 (38%). Only 4 (10%) staghorn calculi were coposed of struvite. Three (7%) were uric acid stones. So most staghorn renal stones in Sri Lanka are calcium oxalate. Contrary to the traditional view based on studies done in the western world, only 10% of staghorn calculi removed from patients in Sri Lanka are struvite or infection stones. This could be the reason for kidneys with staghorn calculi in Sri Lanka to retain their function.