Bone mineral density status in urolithiasis patients with vitamin D inadequacy followed at a tertiary stone centre

Comparison of the bone mineral density status of patients with kidney stones stratified by stone composition

PURPOSE

Bone loss has been found to occur frequently in patients with particular metabolic disorders that are likely associated with certain kidney stone composition. Thus, we compared the bone mineral density (BMD) of patients with different kidney stone compositions.

PATIENTS AND METHODS

A total of 204 consecutive patients who exhibited stone formation with calcium oxalate (CaOx), calcium phosphate (CaP), uric acid (UA), and magnesium ammonium phosphate (MAP) underwent 24 h urine test and BMD measurement. BMD was measured by dual X-ray absorptiometry at the lumbar spine (LS) and femoral neck (FN). The Z-score was used to express BMD. A BMD Z-score ≤  - 2 was defined as a diagnostic threshold for bone loss.

RESULTS

Amongst the patients, 38 had an LS BMD Z-score of ≤  - 2, but only 2 had FN BMD Z-score of ≤  - 2. The group with an LS BMD Z-score of ≤  - 2 exhibited significantly larger male - female ratio, higher frequency of hypercalciuria and CaP, and lower frequency of MAP than the group with an LS BMD Z-score of >  - 2. Reduced LS BMD was most remarkable in the CaP group, followed by the CaOx, UA, and MAP groups. The LS BMD Z-score of hypercalciuric patients was significantly lower than that of normocalciuric patients only in the CaP group.

CONCLUSION

Patients with different kidney stone compositions presented different BMD status. Using this information may facilitate medical decision-making in patients with kidney stone who should undergone BMD earlier.

Supine Versus Prone Percutaneous Nephrolithotomy (PCNL): A Single Surgeon's Experience

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is one of the greatest advances in the field of urology and has been considered the gold standard in the treatment of renal calculi of more than 2 cm in size. While both the supine and prone positions offer their unique advantages, it is still being debated which position offers the most in terms of surgical outcomes. We have evaluated the two approaches in terms of operative time, success rate, stone clearance rate, safety, and complications.

METHODS

This prospective cohort study was done in the urology department of a tertiary care center in South India between January 2018 and October 2020. A total of 166 patients, with 83 in supine and 83 in prone positions, were included in the study.

RESULTS

Both groups were matched in terms of age, body mass index, stone size and location, co-morbidities, medications taken, presence of diverticular stone, history of surgery, and baseline creatinine level. Mean operative time and pain scores were noted to be less in supine position as compared to prone. Ease of puncture was superior in supine position. Stone residue was noted to be higher in supine PCNL as well.

CONCLUSION

Supine PCNLs are preferred in high-risk patients while the prone position is preferred in bilateral PCNLs, complex anatomy, or larger stone burden.

Analysis of vitamin D deficiency in calcium stone-forming patients

PURPOSE

The aim of this study is to analyse the percentage of hypovitaminosis D, as well as its relationship with the various parameters of calcium-phosphate metabolism.

METHODS

A case control study was conducted on 366 patients, divided into two groups: Group 1: 127 non-stone-forming patients, and Group 2: 239 calcium stone forming. A study was performed on calcium-phosphate metabolism and urinary lithogenic factors. The percentage of vitamin D deficiency (25-OH-vitamin D levels <20 ng/ml) between the groups was analysed and compared. The SPSS 20.0 statistics program was used for the analysis, with a p ≤ .05 being considered significant.

RESULTS

The mean age of Group 1 was 52.1 years compared to 49.6 years in Group 2, with no significant differences (p = .07). Vitamin D levels were lower in Group 2 compared to Group 1 (25.7 vs. 28.4 ng/ml, p = .02). A vitamin D deficiency was observed in 28 % of the Group 2 stone-forming patients versus 15.7 % in Group 1 (p = .009), with an odds ratio (OR) of 2.09 (95 % CI; 1.19-3.63). In the stone-forming patients with a vitamin D deficiency, the only difference observed was the higher levels of iPTH compared to those stone-formers with a normal vitamin D (56.9 vs. 45.5 pg/ml, respectively; p = .0001).

CONCLUSION

Calcium stone-forming patients have lower mean levels of vitamin D and a higher percentage of hypovitaminosis D than in non-stone-forming patients. This was only related to increased iPTH levels, with urine calcium and other lithogenic parameters having no obvious effect.

Combined vitamin D and calcium supplementation in vitamin D inadequate patients with urolithiasis: Impact on hypercalciuria and de novo stone formation

INTRODUCTION

We examined the effect of combined vitamin D and calcium supplementation (VDCS) on urinary calcium excretion and de novo stone formation in vitamin D inadequate (VDI) urolithiasis patients.

METHODS

We retrospectively reviewed the data of VDI patients (serum 25-hydroxyvitamin D <75 nmol/L) followed at a tertiary stone centre between September 2009 and December 2014. VDI patients with history of urolithiasis, who were placed on VDCS for abnormal bone mineral density or hyperoxaluria, were included. Hypercalciuric patients and patients on thiazide diuretics were excluded. Metabolic stone workup and two 24-hour urine collections were performed before and after VDCS.

RESULTS

In total, we included 34 patients, with a mean age of 54.8 years and a mean body mass index of 25.7 kg/m(2). After VDCS, there was a significant increase in the mean serum 25-hydroxyvitamin D (52.0 vs. 66.4 nmol/L, p < 0.001) and the mean urinary calcium excretion (3.80 vs. 5.64 mmol/d, p < 0.001). Eight (23.5%) patients developed de novo hypercalciuria. After a median follow-up of 39 (range: 7-60) months, 50% of hypercalciuric patients developed stones compared with 11.5% of non-hypercalciuric patients (p = 0.038).

CONCLUSION

This study showed a significant effect of combined VDCS on mean urinary calcium excretion, de novo hypercalciuria, and stone development in VDI patients with history of urolithiasis. Therefore, VDI urolithiasis patients receiving VDCS are advised to have monitoring with 24-hour urine collections and imaging studies. Although small, our sample size was good enough to validate the statistical outcomes. Prospective studies are needed to confirm these results.

Leisure time physical activity, smoking and risk of recent symptomatic urolithiasis: Survey of stone clinic patients

INTRODUCTION

We explore relationships between selected lifestyle factors and recent (≤6 months) symptomatic urolithiasis (RSU).

METHODS

Surveys querying socio-demographic, medical history, physical activity, diet and smoking were administered to a convenience sample of stone clinic patients at a tertiary care hospital. Leisure time physical activity (LTPA) was assessed with the International Physical Activity Questionnaire (long form). Multivariate logistic regression was used to identify associations between risk factors and RSU.

RESULTS

Of the 163 participants, most were male (64%) and white (78%), with a mean (standard deviation) age of 56.3 (14.2) years. The mean body mass index (BMI) was 27.3 (5.4) kg/m(2) and 57 (35%) patients reported RSU. No significant (p < 0.05) differences were observed between participants with and without RSU in age, sex, ethnicity, BMI, or diet. Of the cohort, 52 (35%) participants met physical activity guidelines for walking (29%), moderate (27%) or vigorous activity (29%). LTPA did not differ significantly by RSU status. Compared to those without RSU, participants with RSU had higher rates of smoking (7% vs. 21%, p = 0.02 and had 8.5 (95% confidence interval 2.2-32.2) times the odds of being current smokers after controlling for sex, diet, and LTPA.

CONCLUSIONS

Physical inactivity and smoking are common among stone clinic patients, though LPTA was not associated with RSU. Study limitations include its small sample size, selection bias, and reliance on self-reported RSU (recall bias). In addition, participants may have already been following dietary recommendations to prevent urolithiasis recurrence. Nonetheless, current smoking was a potent predictor of RSU. When desired, smokers should be referred for smoking cessation.