Bone Disease in Patients With Primary Hypercalciuria and Calcium Nephrolithiasis

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.

Bone resorption in dogs with calcium oxalate urolithiasis and idiopathic hypercalciuria

People with calcium oxalate (CaOx) urolithiasis and idiopathic hypercalciuria (IH) often have evidence of increased bone resorption, but bone turnover has not previously been investigated in dogs with these conditions. The aim of this study was to determine whether a marker of bone resorption, β-crosslaps, differs between dogs with CaOx urolithiasis and IH compared to controls. This retrospective, cross-sectional study used a canine specific ELISA to measure β-crosslaps concentrations in stored frozen serum samples from 20 dogs with CaOx urolithiasis and IH and 20 breed-, sex-, and age-matched stone-free controls (18 Miniature Schnauzers, 14 Bichons Frise, and 8 Shih Tzus). Dogs with CaOx urolithiasis and IH had lower β-crosslaps concentrations relative to controls (P = .0043), and β-crosslaps had a moderate negative correlation with urinary calcium-to-creatinine ratios (r = -0.44, P = .0044). Miniature Schnauzers had lower β-crosslaps concentrations than the other two breeds (P = .0035). The ELISA had acceptable intra-assay precision, but concentrations decreased when samples were repeatedly assayed over time. Assay recovery rates were also below acceptance criteria. In conclusion, Miniature Schnauzers, Bichons Frise, and Shih Tzus with CaOx urolithiasis and IH have evidence of decreased bone resorption compared to stone-free controls. This suggests that other causes of IH, such as intestinal hyperabsorption of calcium, underlie risk for CaOx urolithiasis in these breeds. Results should be confirmed in larger populations and with other β-crosslaps assays and additional biomarkers of bone turnover. The stability of canine serum β-crosslaps after freeze-thaw cycles and storage at various temperatures requires investigation.

Defining metabolic activity of nephrolithiasis - Appropriate evaluation and follow-up of stone formers

Considering the variation in metabolic evaluation and medical management of kidney stone disease, this consensus review was created to discuss the metabolic activity of nephrolithiasis, define the difference between single and recurrent stone formers, and develop a schema for metabolic and radiologic follow-up. A systematic review of the literature was performed to identify studies of metabolic evaluation and follow-up of patients with nephrolithiasis. Both single and recurrent stone formers share many similarities in metabolic profiles. The study group determined that based on an assessment of risk for stone recurrence and metabolic activity, single and recurrent stone formers should be evaluated comprehensively, including two 24 h urine studies on a random diet. Targeted medication and dietary recommendations are effective for many patients in reducing the risk of stone recurrence. Follow-up of those with stone disease should be obtained depending on the level of metabolic activity of the patient, the risk of chronic kidney disease and the risk of osteoporosis/osteopenia. A standard scheme includes a baseline metabolic profile, a repeat study 3-6 months after initiation of treatment, and then yearly when stable, with abdominal imaging obtained every 1-2 years.

Nephrolithiasis and Osteomalacia associated with adefovir-induced Fanconi syndrome in a patient with hepatitis B

Background

An increasing number of case reports suggest that acquired renal Fanconi syndrome may be associated with prolonged use of adefovir against hepatitis B virus. Renal Fanconi syndrome is an uncommon disease, and its complication with nephrolithiasis is quite rare. Herein, we report a rare coexistence of nephrolithiasis and acquired renal Fanconi syndrome in a chronic hepatitis B-positive patient with prolonged adefovir therapy.

Case presentation

The patient presented with osteomalacia and nephrolithiasis. Consequently, extracorporeal shock-wave lithotripsy and left double-J ureteral stent insertion were considered for obstructive nephropathy, which was caused by nephrolithiasis. However, osteomalacia had been misdiagnosed as osteoporosis before admission to our hospital. On admission, a complexity of multiple fractures, hypophosphataemia, glycosuria without hyperglycaemia and non–anion-gap metabolic acidosis indicated a diagnosis of acquired renal Fanconi syndrome induced by adefovir. After switching from adefovir to entecavir, the patient’s symptoms and laboratory findings improved significantly.

Conclusions

The mechanism responsible for nephrolithiasis in renal Fanconi syndrome is still unclear. We recommend regularly monitoring renal function and serum calcium and serum phosphate to prevent renal Fanconi syndrome during the prolonged use of adefovir for hepatitis B virus.

Metabolic diagnosis and medical prevention of calcium nephrolithiasis and its systemic manifestations: a consensus statement

BACKGROUND

Recently published guidelines on the medical management of renal stone disease did not address relevant topics in the field of idiopathic calcium nephrolithiasis, which are important also for clinical research.

DESIGN

A steering committee identified 27 questions, which were proposed to a faculty of 44 experts in nephrolithiasis and allied fields. A systematic review of the literature was conducted and 5216 potentially relevant articles were selected; from these, 407 articles were deemed to provide useful scientific information. The Faculty, divided into working groups, analysed the relevant literature. Preliminary statements developed by each group were exhaustively discussed in plenary sessions and approved.

RESULTS

Statements were developed to inform clinicians on the identification of secondary forms of calcium nephrolithiasis and systemic complications; on the definition of idiopathic calcium nephrolithiasis; on the use of urinary tests of crystallization and of surgical observations during stone treatment in the management of these patients; on the identification of patients warranting preventive measures; on the role of fluid and nutritional measures and of drugs to prevent recurrent episodes of stones; and finally, on the cooperation between the urologist and nephrologist in the renal stone patients.

CONCLUSIONS

This document has addressed idiopathic calcium nephrolithiasis from the perspective of a disease that can associate with systemic disorders, emphasizing the interplay needed between urologists and nephrologists. It is complementary to the American Urological Association and European Association of Urology guidelines. Future areas for research are identified.

Nephrolithiasis, bone mineral density, osteoporosis, and fractures: a systematic review and comparative meta-analysis

Our meta-analysis demonstrates that people with nephrolithiasis have decreased bone mineral density, an increased odds of osteoporosis, and potentially an elevated risk of fractures.

INTRODUCTION

People with nephrolithiasis might be at risk of reduced bone mineral density (BMD) and fractures, but the data is equivocal. We conducted a meta-analysis to investigate if patients with nephrolithiasis have worse bone health outcomes (BMD), osteoporosis, and fractures versus healthy controls (HCs).

METHODS

Two investigators searched major databases for articles reporting BMD (expressed as g/cm² or a T- or Z-score), osteoporosis or fractures in a sample of people with nephrolithiasis, and HCs. Standardized mean differences (SMDs), 95 % confidence intervals (CIs) were calculated for BMD parameters; in addition odds (ORs) for case-control and adjusted hazard ratios (HRs) in longitudinal studies for categorical variables were calculated.

RESULTS

From 1816 initial hits, 28 studies were included. A meta-analysis of case-control studies including 1595 patients with nephrolithiasis (mean age 41.1 years) versus 3402 HCs (mean age 40.2 years) was conducted. Patients with nephrolithiasis showed significant lower T-scores values for the spine (seven studies; SMD = -0.69; 95 % CI = -0.86 to -0.52; I ² = 0 %), total hip (seven studies; SMD = -0.82; 95 % CI = -1.11 to -0.52; I ² = 72 %), and femoral neck (six studies; SMD = -0.67; 95 % CI = --1.00 to -0.34; I ² = 69 %). A meta-analysis of the case-controlled studies suggests that people with nephrolithiasis are at increased risk of fractures (OR = 1.15, 95 % CI = 1.12-1.17, p < 0.0001, studies = 4), while the risk of fractures in two longitudinal studies demonstrated trend level significance (HR = 1.31, 95 % CI = 0.95-1.62). People with nephrolithiasis were four times more likely to have osteoporosis than HCs (OR = 4.12, p < 0.0001).

CONCLUSIONS

Nephrolithiasis is associated with lower BMD, an increased risk of osteoporosis, and possibly, fractures. Future screening/preventative interventions targeting bone health might be indicated.

Calcium nephrolithiasis and bone demineralization: pathophysiology, diagnosis, and medical management

PURPOSE OF REVIEW

To establish the relationship between calcium nephrolithiasis, bone densitometry scoring, and bone mineral density (BMD) loss according to bone turnover markers (BTMs) and urinary metabolites.

RECENT FINDINGS

Patients with recurrent calcium nephrolithiasis and idiopathic fasting hypercalciuria (urinary calcium/creatinine ratio >0.11) are more likely to have BMD loss that may lead to osteopenia or osteoporosis. In these patients, BTMs may be used as a surrogate for both bone health and stone recurrence. Suspect higher lithogenic states when calcium stone formers have serum beta-crosslaps (resorptive marker) greater than 0.311 ng/ml, serum osteocalcin (formative marker) greater than 13.2 ng/ml, and beta-crosslaps/osteocalcin ratio greater than 0.024.

SUMMARY

Patients with recurrent calcium nephrolithiasis and fasting hypercalciuria have a higher incidence of osteopenia and osteoporosis, measured by the dual-energy X-ray absorptiometry. These patients present not only with hypercalciuria and increased BTMs (mainly resorptive), but also up to 30% have hypocitraturia and increased urinary calcium/citrate ratio (>0.25). On the basis of these results, a diagnostic algorithm was created, classifying hypercalciurics according to their fasting calcium/creatinine and calcium/citrate ratio. Medical therapy for these patients is aimed at improving the dietary habits (normocalcemic, low salt, low animal protein diet), prescribing combinations of potassium citrate, thiazides, and bisphosphonates, and correcting bone and urinary abnormalities that may lower future skeletal and kidney stone risk.

Retrospective review of serum and urinary lithogenic risk factors in patients with osteoporosis and osteopenia

OBJECTIVE

To analyze differences in bone remodeling markers, lithogenic factors and bone densitometry among the 3 groups of patients (controls, patients with relapsing calcium renal lithiasis, and patients with loss of bone mineral density without lithiasis).

MATERIAL AND METHODS

This is a cross-sectional study including 203 patients who were divided in 3 groups: group 1 (controls), group 2 (patients with relapsing calcium renal lithiasis), and group 3 (patients with osteopenia and/or osteoporosis in the lumbar spine or hip). Bone densitometry, calcium-phosphorous and bone metabolism analysis, and analysis of lithogenic risk factors in fasting urine samples and 24-hour urine samples were performed. Statistical analysis was performed with SPSS 17.0. A P ≤.05 was considered statistically significant.

RESULTS

Patients in group 2 presented greater calcium excretion and a lower citrate excretion in 24-hour urine samples as compared with the other 2 groups. The proportion of hypercalciuria and hypocitraturia was higher in group 2. In addition, patients in group 2 presented a lower loss of bone mineral density as well as altered bone remodeling markers as compared with those in group 1. Patients in group 3 also presented alterations in urine calcium and citrate excretion with respect to the control group, with elevated fasting calcium and citrate levels and calcium-to-citrateratio.

CONCLUSION

Lithogenic risk factors are altered in patients with osteopenia and/or osteoporosis without renal lithiasis although to a lesser extent than patients with calcium renal lithiasis.

[Nephrolithiasis: metabolic defects and terapeutic implications]

Over the past 10 years, major progress has been made in the knowledge of urinary lithogenesis, including the potential pathogenetic role of Randall's plaques and renal tubular crystal retention. Urine supersaturation is the driving force of this process and can be induced by some risk factors, including low urine volume, high urinary excretion of calcium oxalate and uric acid and low urinary excretion of citrate. Primary hypercalciuria can be due to intestinal overabsorption renal leak and bone reabsorption of calcium. Prophilaxis is mainly conducted with thiazides and low calcium diet which is indicated only in the intestinal form. Primary hyperoxaluria is treated with pyridoxine and may require in the severe forms simultaneous renal and liver transplantation. Enteric hyperoxaluria is secondary to fatty acids malabsorption and requires diet, oral calcium and cholestiramine. Hyperuricosuria is caused by diet endogenous overproduction, mainly due to enzymatic defects or high renal excretion of uric acid. Urine alkalinization with K or K and Mg citrate can prevent stone formation even in idiopathic uric acid nephrolithiasis, in which a defect of urine acidification is supposed to be the main abnormality, and in hypocitraturic patients. Cystinuria is a rare inherited defect with an intense clinical impact. It can be classified in three forms and urinary stone formation is the role. Increased solubility and conversion of cystine in a more soluble form are the main goals of the prophylaxis which includes K citrate and thiol agents administration. Tiopronin is preferred to D-penicillamine due to its lower side effects.

Association of severe calcium lithogenic activity and bone remodeling markers

OBJECTIVE

To establish cutoff points for markers of bone remodeling that allow for screening of patients at risk for serious lithogenic activity.

MATERIALS AND METHODS

We conducted a cross-sectional study with 182 patients (aged between 25 and 60 years) divided into 3 groups: group 1, 56 patients without lithiasis; group 2, 67 patients with light calcium lithiasis; and group 3, 59 patients with severe calcium lithiasis. The criteria for inclusion in and exclusion from the study were established, and light and severe lithogenic activity were defined. Metabolic variables in blood and urine, along with bone densitometry, were studied for the groups. Statistical analysis of the results and preparation of receiver operating characteristic curves to establish optimal cutoff points were performed.

RESULTS

The patients in group 3 showed the greatest bone mineral density loss and the highest values for markers of bone remodeling, together with increased 24-hour calciuria. Using the receiver operating characteristic curves developed and based on statistical significance (P = .0001), the following cutoff points for severe lithogenic activity, with a sensitivity between 75% and 85%, were established: β-crosslaps >0.331 ng/mL; osteocalcin >13.2 ng/mL; β-crosslaps/osteocalcin >0.024; 24-hour calciuria >306.6 mg; and fasting urine calcium/creatinine >0.105.

CONCLUSION

Patients with calcium lithiasis and elevated values for osteocalcin, β-crosslaps, β-crosslaps/osteocalcin, 24-hour calciuria, and fasting urine calcium/creatinine may present a high risk of severe lithogenic activity.

Plasma and urinary levels of cytokines in patients with idiopathic hypercalciuria

BACKGROUND

Recent studies suggest that cytokines modulate bone turnover. Idiopathic hypercalciuria (IH) seems to be associated with bone mineral loss. Therefore, the aim of this study was to assess cytokines involved in bone turnover in patients with IH.

METHODS

Plasma and spot-urine levels of interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor alpha (TNF-α), transforming growth factor β1 (TGF-β1), and monocyte chemoattractant protein (MCP-1) were measured in 70 children and adolescents with IH and in 37 healthy controls. Patients with IH were subdivided according to their calciuria at the time of sample collection: ≥4 mg/kg/day (persistent IH, n=27) and below 4 mg/kg/day (controlled IH, n=43). Cytokines were determined by enzyme-linked immunoassay.

RESULTS

Plasma and urinary concentrations of IL-1β, IL-6, IL-8, and TNF-α were undetectable in all groups. No differences were found between controlled and persistent hypercalciuria for plasma and urinary levels of MCP-1 and TGF-β1. On the other hand, MCP-1 levels were significantly higher in both subgroups of IH in comparison to healthy controls. Furthermore, urinary MCP-1 levels of IH patients correlated positively with bone mineral content (p=0.013).

CONCLUSION

Although cytokine measurements did not allow the differentiation between persistent and controlled IH, our findings suggest that MCP-1 might play a role in patients with IH.