Metabolic abnormalities in patients with nephrolithiasis: comparison of first-episode with recurrent cases in Southern Iran

An Increase Incidence in Uric Acid Nephrolithiasis: Changing Patterns

INTRODUCTION

Nephrolithiasis is a complex disease affecting all age groups globally. As the causative factors for nephrolithiasis rises significantly, its incidence, prevalence and recurrence continues to baffle clinicians and patients.

AIM

To study the prevalence of different types of renal stones extracted by Percutaneous Nephrolithotomy (PCNL) and open surgical procedures.

MATERIALS AND METHODS

Renal stones from 50 patients were retrieved by Percutaneous Nephrolithotomy (PCNL), Ureterorenoscopy (URS) and open surgical techniques for qualitative tests for detection of calcium, oxalate, uric acid, phosphate, ammonium ion, carbonate, cystine and xanthine.

RESULTS

Three patients had stone removed by open surgery and rest had undergone PCNL. Nine of the stones were pure of calcium oxalate, 9 were of pure uric acid and 32 were mixed stones. Forty one stones had calcium. Among the mixed stones, oxalate was present in 25 samples (39 of total), uric acid was seen in 17 (25 of total stones), phosphate was present in 23 (23 of total) and carbonate was present in 4 stones (4 of total). Only 1 patient had triple phosphate stone. 12 were of staghorn appearance of which 6 were of struvite type, 6 were pure uric acid and remaining were mixed oxalate-phosphate stones.

CONCLUSION

Our study, though in a small number of hospital based patients, found much higher prevalence of uric acid stones and mixed stones than reported by previous hospital based studies in north India (oxalate stones~90%, uric acid~1% and mixed stones~3%). Biochemical analysis of renal stones is warranted in all cases.

Metabolic abnormalities in patients treated with percutaneous nephrolithotomy

Objectives:

To assess metabolic abnormalities in patients with percutaneous nephrolithotomy (PCNL) that could pose a risk for stone recurrence.

Materials and methods:

The data was collected retrospectively on all patients who had PCNL and metabolic studies, between January 2000 and September 2012.

Results:

There were 144 patients; median age and follow up were 49.5 (15– 4) years and 80.2 (16–180) months, respectively. Nearly half of the patients had staghorn calculus. Metabolic abnormalities (MAs) were found in 55 (38.2%). The 31 (21.5%) of these had multiple metabolic abnormalities (MMA) while 24 (16.6%) had a single metabolic abnormality (SMA). Uricosuria was found in 24 (16.6%), hyperoxaluria in 22 (15.3%), hyperphosphaturia in 18 (12.5%), hypercalciuria in 10 (7%), hypomagnesuria in 6 (4.2%), cystinuria in 5 (3.5%) and hypocitraturia in 5 (3.5%). Hyperuricaemia was present in 10 (7%), hypercalcaemia in 5 (3.5%), hyperphosphataemia in 7 (5%) and renal tubular acidosis in 1 (0.7%). In non-staghorn, MAs were found in 25 (35.2%) and 16 (64%) of these had MMA. In patients with staghorn, MAs were present in 30 (41%) patients. Half of the patients 15 (50%) in this group had MMA. A high proportion of the first time stone formers requiring surgical treatment had MAs and 57% of these had MMA. Stone analysis was available for 69 (48%) and 37 (53.6%) of these had mixed composition. The highest proportion of patients with uric acid stones had MA 89% followed by cystine stones 80%, matrix stones 50%, calcium oxalate 36.6%, carbonate apatite 36.4% and triple phosphate 33.3% .

Conclusion:

A high proportion of first time stone formers, staghorn and non-staghorn stone formers with PCNL had MA. These findings suggest that the treatment of metabolic abnormalities can play an important role in reducing the risk of stone recurrences and management may include referral to dedicated metabolic stone clinics.

Risk factors for urinary stones in healthy schoolchildren with and without a family history of nephrolithiasis

BACKGROUND

The prevalence of lithiasis is increasing at all ages. This study aimed to assess the crystallization risk in urine from healthy school children and to determine urinary parameters that are most associated with it.

METHODS

Urine samples were obtained from 184 children aged 5-12 years: a spot sample collected in the afternoon, and a 12-h overnight sample. Information was obtained regarding family histories of lithiasis. Urine volume, pH, and biochemical parameters of stone risk were measured. Crystallization risk was defined by the presence of specific urine conditions that had previously been associated with stone formation in vitro.

RESULTS

Crystallization risk was observed in 15 % of spot urine samples and 54 % of 12-h samples. Metabolic abnormalities and a low urinary volume were more frequently detected in children with crystallization risk. Calcium excretion and calcium/citrate ratio were higher in children with a family history of lithiasis.

CONCLUSIONS

We observed a high prevalence of crystallization risk in urine, especially in children with a family history of the disease. Low urinary volume was the factor most associated with increased risk. Adequate fluid intake at an early age may be a simple and effective measure to reduce the incidence of nephrolithiasis.

Metabolic evaluation in patients with nephrolithiasis: A report from Isfahan, Iran

Background:

Nephrolithiasis is a major public health problem worldwide. In recent years, growing evidence suggest that this disease may originate from underlying metabolic disorders. This is the first study that reports the frequency of different metabolic abnormalities among patients with nephrolithiasis in Isfahan, a large central province of Iran.

Materials and Methods:

From the time period between March 2009 and August 2010, 437 nephrolithiasis patients in Isfahan province enrolled in this study. Metabolic evaluation was performed by obtaining a 24-hours urine sample and fasting venous blood draw. We analyzed urine samples for volume, creatinine, calcium, citrate, oxalate, uric acid, sodium, and cystine. Fasting blood samples were assessed for serum calcium, phosphorus, sodium, potassium, uric acid, albumin, creatinine and blood urea nitrogen.

Results:

The mean age was 46 ± 13.8 years (rang: 18-87). Nearly 50% were first time stone formers. The most common metabolic abnormalities were hypocitraturia (40.5%) and hypernatriuria (31.8%) that was followed by hyperoxaluria (28.8%). Hypercalciuria was detected only in 9.2% of the cases.

Conclusion:

Although, high calcium excretion was the most frequent metabolic derangement in several similar studies, in our province with considerably high prevalence of vitamin D deficiency, it is not frequent among nephrolithiasis patients. Instead, other metabolic risk factors were in higher frequencies.

Phosphaturia as a promising predictor of recurrent stone formation in patients with urolithiasis

Purpose

Recent studies have suggested that renal phosphate leakage and the associated phosphaturia are significant underlying causes of calcium urolithiasis. The aims of this study were to assess whether phosphaturia relates to urinary metabolic abnormalities and recurrent stone formation.

Materials and Methods

A database of patient histories and urine chemistries was analyzed for 1,068 consecutive stone formers (SFs) and 106 normal controls. Urine values for phosphaturia that were higher than 95% of the normal control values were defined as indicating hyperphosphaturia, and the effect of phosphaturia on urinary metabolites and stone recurrence was determined. Of these patients, 247 patients (23.1%) who had been followed up for more than 36 months or had a recurrence of stones during follow-up (median, 46.0 months; range, 5-151) were included in the analyses for stone recurrence.

Results

Of the SFs, 19.9% (212/1,068) had increased urinary phosphate excretion. SFs with hyperphosphaturia had a greater urinary volume and higher levels of calcium, uric acid, oxalate, and citrate than did SFs with normophosphaturia. A multivariate Cox regression model, stratified by stone episodes, revealed that hyperphosphaturia was an independent predictor of recurrent stone formation in first-time SFs (hazard ratio [HR]: 2.122; 95% confidence interval [CI]: 1.100-4.097; p=0.025). No association was detected between hyperphosphaturia and recurrent stone formation in recurrent SFs. Kaplan-Meier curves showed identical results.

Conclusions

This study demonstrates that hyperphosphaturia is closely associated with urinary metabolic abnormalities. Furthermore, hyperphosphaturia is a significant risk factor for stone recurrence in first-time SFs.