New insights into the pathogenesis of idiopathic hypercalciuria

Metabolic Evaluation and Recurrence Prevention for Urinary Stone Patients: An EAU Guidelines Update

BACKGROUND AND OBJECTIVE

The aim of this review was to define patients who are at high risk of recurrence of urolithiasis, to delineate diagnostic and therapeutic algorithms for each type of stone, and to clarify general guidelines and recommendations for prevention of recurrence.

METHODS

A professional research librarian carried out literature searches for all sections of the urolithiasis guidelines, covering the timeframe between 1976 and June 2023.

KEY FINDINGS AND LIMITATIONS

For every patient with urolithiasis, an attempt should be made to analyse the stone. Patients should be given general instructions on how to prevent recurrence, including adequate fluid and calcium intake, and low consumption of sodium and protein. Identifying and correcting the causative factors is a cornerstone in preventing the recurrence of urolithiasis. Diagnostic and therapeutic algorithms by stone composition are available. Every patient should undergo baseline metabolic screening, while patients with calcium stones, who are at high risk of relapse and complications, should undergo extensive metabolic screening with two 24-h urine collections and should receive targeted therapy. Patients with uric acid, infection, or cystine stones are at high risk of relapse. All patients at high risk of recurrence should be closely monitored, especially those not complying with therapy in the long term.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Metabolic stone evaluation and patient follow-up are highly recommended to prevent urolithiasis recurrence.

PATIENT SUMMARY

We reviewed the evidence for proper evaluation of patients with urinary and stones and the treatment options for preventing stone recurrence. It is essential to determine the type of stone and to carry out specific blood and urine tests for planning the best treatment course for each patient.

Effects of thiazides and new findings on kidney stones and dysglycemic side effects

Thiazide and thiazide-like diuretics (thiazides) belong to the most frequently prescribed drugs worldwide. By virtue of their natriuretic and vasodilating properties, thiazides effectively lower blood pressure and prevent adverse cardiovascular outcomes. In addition, through their unique characteristic of reducing urine calcium, thiazides are also widely employed for the prevention of kidney stone recurrence and reduction of bone fracture risk. Since their introduction into clinical medicine in the early 1960s, thiazides have been recognized for their association with metabolic side effects, particularly impaired glucose tolerance, and new-onset diabetes mellitus. Numerous hypotheses have been advanced to explain thiazide-induced glucose intolerance, yet underlying mechanisms remain poorly defined. Regrettably, the lack of understanding and unpredictability of these side effects has prompted numerous physicians to refrain from prescribing these effective, inexpensive, and widely accessible drugs. In this review, we outline the pharmacology and mechanism of action of thiazides, highlight recent advances in the understanding of thiazide-induced glucose intolerance, and provide an up-to-date discussion on the role of thiazides in kidney stone prevention.

Normocalcemic hyperparathyroidism after successful parathyroidectomy for single parathyroid adenoma: Prevalence, etiological factors, predictive markers, treatment and evolution

BACKGROUND AND OBJECTIVE

Postparathyroidectomy normocalcemic hyperparathyroidism (PPNCHPPT) is a frequent situation for which we have no information in our country. The objective is to know our prevalence of PPNCHPPT, the associated etiological factors, the predictive markers, the treatment administered and the evolution.

PATIENTS AND METHOD

Retrospective observational cross-sectional study on 42 patients. Twelve patients with PPNCHPPT and 30 without PPNCHPPT are compared.

RESULTS

HPPTNCPP prevalence: 28.6%. Etiological factors: vitamin D deficiency: 75%; bone remineralization: 16.7%; renal failure: 16.7%; hypercalciruria: 8.3%. No change in the set point of calcium-mediated parathormone (PTH) secretion was observed, but an increase in the preoperative PTH/albumin-corrected calcium (ACC) ratio was observed. Predictive markers: PTH/ACC ratio (AUC 0.947; sensitivity 100%, specificity 78.9%) and PTH (AUC 0.914; sensitivity 100%, specificity 73.7%) one week postparathyroidectomy.

EVOLUTION

follow-up 30 ± 16.3 months: 50% normalized PTH and 8.3% had recurrence of hyperparathyroidism. Patients with PPNCHPPT less frequently received preoperative treatment with bisphosphonates and postoperative treatment with calcium salts.

CONCLUSIONS

This is the first study in our country that demonstrates a mean prevalence of PPNCHPPT, mainly related to a vitamin D deficiency and a probable resistance to the action of PTH, which can be predicted by the PTH/ACC ratio and PTH a week post-intervention and often evolves normalizing the PTH. We disagree with the etiological effect of hypercalciuria and the change in the PTH/calcemia regulation set point, and we acknowledge the scant treatment administered with calcium salts in the postoperative period.

2022 Recommendations of the AFU Lithiasis Committee: Medical management - from diagnosis to treatment

The morphological-compositional analysis of urinary stones allows distinguishing schematically several situations: dietary, digestive, metabolic/hormonal, infectious and genetic problems. Blood and urine testing are recommended in the first instance to identify risk factors of urinary stone disease in order to avoid recurrence or progression. The other objective is to detect a potential underlying pathology associated with high risk of urinary stone disease (e.g. primary hyperparathyroidism, primary or enteric hyperoxaluria, cystinuria, distal renal tubular acidosis) that may require specific management. Lifestyle-diet measures are the basis of the management of all stone types, but pharmacological treatments may be required. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context.

Association between urinary phthalate metabolites and nephrolithiasis in adults: A cross-sectional analysis with NHANES 2007-2018

Nephrolithiasis is highly prevalent and brings health and economic burdens to patients. The augmentation of nephrolithiasis may be associated with exposure to phthalate metabolites. However, few studies investigated the effect of various phthalates exposure on nephrolithiasis. We analyzed data from 7139 participants aged 20 years or above from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. Serum calcium level-stratified univariate and multivariate linear regression analyses were performed to explore the relationship between urinary phthalate metabolites and nephrolithiasis. As a result, the prevalence of nephrolithiasis was approximately 9.96%. After adjusting for confounding factors, associations were found between serum calcium concentration with monoethyl phthalate (P = 0.012) and mono-isobutyl phthalate (P = 0.003) compared with tertile 1 (T1). In adjusted analysis, nephrolithiasis was positively associated with middle and high tertiles of mono benzyl phthalate (P < 0.05) compare with low tertile group. Furthermore, high-level exposure to mono-isobutyl phthalate had a similar positive association with nephrolithiasis (P = 0.028). Our findings provide evidence that exposure to certain phthalate metabolites (i.e. MiBP and MBzP) may be associated with a high risk of nephrolithiasis depending on serum calcium level.

Risk Profile of Patients with Brushite Stone Disease and the Impact of Diet

This study examined the profile of patients and the impact of diet on the risk of brushite stone formation under controlled, standardized conditions. Sixty-five patients with brushite nephrolithiasis were enrolled in the study. Metabolic, dietary, and 24 h urinary parameters were collected under the habitual, self-selected diet of the patients and the balanced mixed, standardized diet. The [13C2]oxalate absorption, ammonium chloride, and calcium loading tests were conducted. All patients had at least one abnormality on the usual diet, with hypercalciuria (84.6%), increased urine pH (61.5%), and hyperphosphaturia (43.1%) being the most common. Absorptive hypercalciuria was present in 32.1% and hyperabsorption of oxalate in 41.2%, while distal renal tubular acidosis (dRTA) was noted in 50% of brushite stone formers. The relative supersaturation of brushite did not differ between patients with and without dRTA. Among all recent brushite-containing calculi, 61.5% were mixed with calcium oxalate and/or carbonate apatite. The relative supersaturation of brushite, apatite, and calcium oxalate decreased significantly under the balanced diet, mainly due to the significant decline in urinary calcium, phosphate, and oxalate excretion. Dietary intervention was shown to be effective and should be an integral part of the treatment of brushite stone disease. Further research on the role of dRTA in brushite stone formation is needed.

Korean Society of Endourology and Robotics (KSER) recommendation on the diagnosis, treatment, and prevention of urolithiasis

This article provides evidence-based recommendations and expert opinions to aid urologists in making optimal decisions regarding managing urolithiasis in various clinical scenarios. The most frequently asked questions by urologists in their clinical practice have been collected and answered in the form of FAQs; based on the latest evidence and expert opinions. The natural history of urolithiasis is divided into active treatment and silent phases, with the active treatment stage divided into typical and special situations and peri-treatment management. The authors address 28 key questions, offering practical guidance for the proper diagnosis, treatment, and prevention of urolithiasis in clinical practice. This article is expected to be served as a valuable resource for urologists.

Ablation of TRPC3 compromises bicarbonate and phosphate transporter activity in mice proximal tubular cells

Proximal tubular (PT) cells reabsorb most calcium (Ca2+ ), phosphate (PO4 3- ), bicarbonate (HCO3 - ), and oxalate (C2 O4 2- ) ions. We have shown that mice lacking Transient Receptor Potential Canonical 3 (TRPC3-/- ) channel are moderately hypercalciuric with presentation of luminal calcium phosphate (CaP) crystals at the loop of Henle (LOH). However, other predisposing factors for such crystal deposition are unknown. Thus, we examined the distinctions in functional status of HCO3 - , PO4 3- , and C2 O4 2- transporters in PT cells of wild type (WT) and TRPC3-/- mice by whole-cell patch clamp techniques to assess their contribution in the development of LOH CaP crystals. Here we show the development of concentration dependent HCO3 - -induced currents in all PT cells, which was confirmed by using specific HCO3 - channel inhibitor, S0859. Interestingly, such activities were diminished in PT cells from TRPC3-/- mice, suggesting reduced HCO3 - transport in absence of TRPC3. While PO4 3- -induced currents were also concentration dependent in all PT cells (confirmed by PO4 3- channel inhibitor, PF-06869206), those activities were reduced in absence of TRPC3, suggesting lower PO4 3- reabsorption that can leave excess luminal PO4 3- . Next, we applied thiosulfate (O3 S2 2 - ) as a competitive inhibitor of the SLC26a6 transporter upon C2 O4 2- current activation and observed a reduced C2 O4 2- -induced conductance which was greater in TRPC3-/- PT cells. Together, these results suggest that the reduced activities of HCO3 - , PO4 3- , and C2 O4 2- transporters in moderately hypercalciuric (TRPC3-/- ) PT cells can create a predisposing condition for CaP and CaP tubular crystallization, enabling CaP crystal formation in LOH of TRPC3-/- mice.

A case-based review of dietary management of calcium oxalate stones

PURPOSE

The purpose of this paper is to help patients with calcium oxalate stones to access prevention and treatment options with dietary management.

METHODS

Typical cases in our hospital and other hospitals were selected for case review; combined with literature review through PubMed search, comprehensive analysis and suggestions were put forward.

RESULTS

By retrieving the literature with sufficient evidence, selecting, and summarizing, analysis of dietary liquid, oxalate and oxalate precursors, calcium, protein, fruits and vegetables, salt, high dietary fiber, and other content with high evidence index was carried out, respectively.

CONCLUSION

Through the retrospective analysis of typical cases and literature review, the importance of diet management in the prevention and treatment of calcium oxalate stones was emphasized again, and suggestions were put forward to promote the prevention and treatment of calcium oxalate stones.

Pediatric Nephrolithiasis

The prevalence of pediatric nephrolithiasis has increased dramatically in the past two decades for reasons that have yet to be fully elucidated. Workup of pediatric kidney stones should include metabolic assessment to identify and address any risk factors predisposing patients to recurrent stone formation, and treatment should aim to facilitate stone clearance while minimizing complications, radiation and anesthetic exposure, and other risks. Treatment methods include observation and supportive therapy, medical expulsive therapy, and surgical intervention, with choice of treatment method determined by clinicians' assessments of stone size, location, anatomic factors, comorbidities, other risk factors, and preferences and goals of patients and their families. Much of the current research into nephrolithiasis is restricted to adult populations, and more data are needed to better understand many aspects of the epidemiology and treatment of pediatric kidney stones.

The Eucalcemic Patient With Elevated Parathyroid Hormone Levels

Primary hyperparathyroidism (PHPT) is classically characterized by hypercalcemia with elevated or inappropriately normal parathyroid hormone (PTH) levels. Elevated PTH levels in the presence of normal calcium levels are not infrequently found during the evaluation of metabolic bone disorders or kidney stone disease. This can be caused by secondary hyperparathyroidism (SHPT) or normocalcemic primary hyperparathyroidism (NPHPT). NPHPT is due to autonomous parathyroid function whereas SHPT is caused by a physiologic stimulation to PTH secretion. Many medical conditions and medications can contribute to SHPT, and differentiation between SHPT and NPHPT may be difficult. Cases are presented to illustrate examples. In this paper, we review the distinction between SHPT and NPHPT as well as end organ effects of NPHPT and outcomes of surgery in NPHPT. We suggest that the diagnosis of NPHPT be made only after careful exclusion of causes of SHPT and consideration of medications that can increase PTH secretion. Further, we advise a conservative approach to surgery in NPHPT.

Calcium selective channel TRPV6: Structure, function, and implications in health and disease

Calcium-selective channel TRPV6 (Transient Receptor Potential channel family, Vanilloid subfamily member 6) belongs to the TRP family of cation channels and plays critical roles in transcellular calcium (Ca2+) transport, reuptake of Ca2+ into cells, and maintaining a local low Ca2+ environment for certain biological processes. Recent crystal and cryo-electron microscopy-based structures of TRPV6 have revealed mechanistic insights on how the protein achieves Ca2+ selectivity, permeation, and inactivation by calmodulin. The TRPV6 protein is expressed in a range of epithelial tissues such as the intestine, kidney, placenta, epididymis, and exocrine glands such as the pancreas, prostate and salivary, sweat, and mammary glands. The TRPV6 gene is a direct transcriptional target of the active form of vitamin D and is efficiently regulated to meet the body's need for Ca2+ demand. In addition, TRPV6 is also regulated by the level of dietary Ca2+ and under physiological conditions such as pregnancy and lactation. Genetic models of loss of function in TRPV6 display hypercalciuria, decreased bone marrow density, deficient weight gain, reduced fertility, and in some cases alopecia. The models also reveal that the channel plays an indispensable role in maintaining maternal-fetal Ca2+ transport and low Ca2+ environment in the epididymal lumen that is critical for male fertility. Most recently, loss of function mutations in TRPV6 gene is linked to transient neonatal hyperparathyroidism and early onset chronic pancreatitis. TRPV6 is overexpressed in a wide range of human malignancies and its upregulation is strongly correlated to tumor aggressiveness, metastasis, and poor survival in selected cancers. This review summarizes the current state of knowledge on the expression, structure, biophysical properties, function, polymorphisms, and regulation of TRPV6. The aberrant expression, polymorphisms, and dysfunction of this protein linked to human diseases are also discussed.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

European Expert Consensus on Practical Management of Specific Aspects of Parathyroid Disorders in Adults and in Pregnancy: Recommendations of the ESE Educational Program of Parathyroid Disorders

This European expert consensus statement provides recommendations for the diagnosis and management of primary hyperparathyroidism (PHPT), chronic hypoparathyroidism in adults (HypoPT), and parathyroid disorders in relation to pregnancy and lactation. Specified areas of interest and unmet needs identified by experts at the second ESE Educational Program of Parathyroid Disorders (PARAT) in 2019, were discussed during two virtual workshops in 2021, and subsequently developed by working groups with interest in the specified areas. PHPT is a common endocrine disease. However, its differential diagnosing to familial hypocalciuric hypercalcemia (FHH), the definition and clinical course of normocalcemic PHPT, and the optimal management of its recurrence after surgery represent areas of uncertainty requiring clarifications. HypoPT is an orphan disease characterized by low calcium concentrations due to insufficient PTH secretion, most often secondary to neck surgery. Prevention and prediction of surgical injury to the parathyroid glands are essential to limit the disease-related burden. Long-term treatment modalities including the place for PTH replacement therapy and the optimal biochemical monitoring and imaging surveillance for complications to treatment in chronic HypoPT, need to be refined. The physiological changes in calcium metabolism occurring during pregnancy and lactation modify the clinical presentation and management of parathyroid disorders in these periods of life. Modern interdisciplinary approaches to PHPT and HypoPT in pregnant and lactating women and their newborns children are proposed. The recommendations on clinical management presented here will serve as background for further educational material aimed for a broader clinical audience, and were developed with focus on endocrinologists in training.

Beyond kidney stones: Why pediatricians should worry about hypercalciuria

The incidence of urolithiasis (UL) is increasing, and it has become more common in children and adolescents over the past few decades. Hypercalciuria is the leading metabolic risk factor of pediatric UL, and it has high morbidity, with or without lithiasis as hematuria and impairment of bone mass. The reduction in bone mineral density has already been described in pediatric idiopathic hypercalciuria (IH), and the precise mechanisms of bone loss or failure to achieve adequate bone mass gain remain unknown. A current understanding is that hypercalciuria throughout life can be considered a risk of change in bone structure and low bone mass throughout life. However, it is still not entirely known whether hypercalciuria throughout life can compromise the quality of the mass. The peak bone mass is achieved by late adolescence, peaking at the end of the second decade of life. This accumulation should occur without interference in order to achieve the peak of optimal bone mass. The bone mass acquired during childhood and adolescence is a major determinant of adult bone health, and its accumulation should occur without interference. This raises the critical question of whether adult osteoporosis and the risk of fractures are initiated during childhood. Pediatricians should be aware of this pediatric problem and investigate their patients. They should have the knowledge and ability to diagnose and initially manage patients with IH, with or without UL.

Evaluation and Management of Elevated Parathyroid Hormone Levels in Normocalcemic Patients

Primary hyperparathyroidism is a common endocrine disorder. It used to present as a highly symptomatic disease before the advent of the multichannel autoanalyzer, now usually presenting as mild asymptomatic hypercalcemia. A newer presentation has been increasingly identified in the past two decades, normocalcemic primary hyperparathyroidism, presenting with elevated parathyroid hormone concentrations and consistently normal serum calcium. These patients are usually symptomatic, with parathyroid hormone levels measured in the evaluation for kidney stones or osteoporosis. It is important to exclude causes of secondary hyperparathyroidism. This review will focus on the evaluation and management of elevated parathyroid hormone levels in normocalcemic patients.

Advances in the diagnosis and the management of primary hyperparathyroidism

The parathyroid glands, one of the last organs to be discovered, are responsible for maintaining calcium homeostasis, and they continue to present the clinician with diagnostic and management challenges that are reviewed herein. Primary hyperparathyroidism (PHPT) comprises the vast majority of pathology of the parathyroid glands. The classic variant, presenting with elevated calcium and parathyroid hormone levels, has been studied extensively, but the current body of literature has added to our understanding of normocalcemic and normohormonal variants of PHPT, as well as syndromic forms of PHPT. All variants can lead to bone loss, kidney stones, declining renal function, and a variety of neurocognitive, gastrointestinal, and musculoskeletal complaints, although the majority of PHPT today is asymptomatic. Surgery remains the definitive treatment for PHPT, and advances in screening, evolving indications for surgery, new imaging modalities, and improvements in intra-operative methods have greatly changed the landscape. Surgery continues to produce excellent results in the hands of an experienced parathyroid surgeon. For those patients who are not candidates for surgery, therapeutic advances in medical management allow for improved control of the hypercalcemic state. Parathyroid cancer is extremely rare; the diagnosis is often made intra-operatively or on final pathology, and recurrence is common. The mainstay of treatment is normalization of serum calcium via surgery and medical adjuncts.

Prevention and management of urinary stone

The prevalence of urolithiasis is increasing not only in South Korea but also around the world. Urolithiasis has a high recurrence rate, therefore, reducing it is very important in the quality of life for stone formers. For this purpose, dietary modifications and drug therapy can be performed through stone analysis and 24-hour urine collection. Stone analysis is recommended for all stone formers, and the 24-hour urine collection is usually recommended for recurrent stone formers or high-risk groups. A general dietary modification for all stone formers includes a sufficient fluid intake, low levels of sodium, sugar, and animal protein, a normal calcium diet, as well as a high amount of citrate intake. Drug therapy should be performed in cases such as the recurrence of stones or increase of the existing ones, even after the application of preservation therapy, such as dietary modification. The ideal drug therapy should prevent the occurrence of urolithiasis, have no side effects, and have a suitable patientsʼ compliance. Follow-up should be performed periodically, through 24-hour urine collections and imaging studies. For follow-up imaging studies, a lowdose non-enhanced computed tomography is recommended, and it can be performed once a year if the patient is in a stable state. To control various and complex metabolic abnormalities in recurrent stone formers, multiple approaches may be required through diet modifications, drug therapy, treatment of the metabolic syndrome, and lifestyle modifications.

Animal models of naturally occurring stone disease

The prevalence of urolithiasis in humans is increasing worldwide; however, non-surgical treatment and prevention options remain limited despite decades of investigation. Most existing laboratory animal models for urolithiasis rely on highly artificial methods of stone induction and, as a result, might not be fully applicable to the study of natural stone initiation and growth. Animal models that naturally and spontaneously form uroliths are an underused resource in the study of human stone disease and offer many potential opportunities for improving insight into stone pathogenesis. These models include domestic dogs and cats, as well as a variety of other captive and wild species, such as otters, dolphins and ferrets, that form calcium oxalate, struvite, uric acid, cystine and other stone types. Improved collaboration between urologists, basic scientists and veterinarians is warranted to further our understanding of how stones form and to consider possible new preventive and therapeutic treatment options.

Possible Associations of Disturbed Neurometals and Ammonia with Glycaemic Control in Type 1 Diabetic Children with Attention Deficit Hyperactivity Disorder

The chronicity of type 1 diabetes mellitus (T1DM) is reported to be associated with various psychological disorders. The current study aimed to evaluate the levels of serum ammonia and various neurometals (zinc, copper, and magnesium) in patients with T1DM with and without ADHD and to correlate their levels with glycaemic status. A prospective case-control study was conducted with 60 diabetic children with T1DM (allocated into a group of 20 patients with a diagnosis of ADHD and a group of 40 patients without ADHD) who were comparable to 60 matched controls. Assays of glucose, glycated haemoglobin (HbA1c), ammonia, zinc, copper, and magnesium were performed. Overall, ammonia and copper levels were significantly higher in the diabetic patients especially those with ADHD than in the control group (p ˂ 0.05 for all). The calculated copper/zinc ratio was significantly higher in the diabetic patient group than in the control group and higher in diabetic children with ADHD than in diabetic children without ADHD (p ˂ 0.05 for all). Diabetic children had significantly lower magnesium levels than the controls (p ˂ 0.05), but no significant difference between the diabetic subgroups was detected. A positive correlation between glycaemic control (HbA1c %) and ammonia level was found in the diabetic group and subgroups, and a positive correlation was found between HbA1c % and the Cu/Zn ratio in diabetic children with ADHD (p ˂ 0.05 for all). The current study confirms an association of elevated ammonia and copper/zinc ratio with poor glycaemic control and ADHD development among children with T1DM.

Double jeopardy: a patient's tale of two concurrent hypercalcaemic syndromes

Primary hyperparathyroidism (PHPT) is the most common cause of parathyroid hormone (PTH) dependent hypercalcaemia, however there are few reported cases of its co-occurrence in patients with familial hypocalciuric hypercalcaemia (FHH). This case highlights the challenges in managing a rare case of dual pathology. A 49-year-old Caucasian woman with symptoms of hypercalcaemia presented with an adjusted serum calcium of 2.77 mmol/L and PTH of 11.5 pmol/L. Neck ultrasound and sestamibi scan were concordant with a left lower parathyroid adenoma, and a preoperative dual-energy X-ray absorptiometry scan confirmed osteopenia. Parathyroidectomy resulted in a PTH reduction from 11.5 pmol/L to 2.7 pmol/L. Interestingly, her lowest pre-operative adjusted serum calcium of 2.67 mmol/L remained unchanged 14 months post-parathyroidectomy. Twenty-four hours urine calcium:creatinine clearance ratio performed postoperatively was low and sequencing analysis of the calcium-sensing receptor gene confirmed the coexistence of FHH. Although surgery is not indicated in FHH, parathyroidectomy may help reduce hypercalcaemia and its associated complications if there is coexistent PHPT.

Effect of Vitamin D Treatment on Dynamics of Stones Formation in the Urinary Tract and Bone Density in Children with Idiopathic Hypercalciuria

Vitamin D supplementation in patients with urolithiasis and hypercalciuria is considered to be unsafe. We analyzed the impact of vitamin D supplementation on selected health status parameters in children with idiopathic hypercalciuria. The study included 36 children with urolithiasis resulting from excessive calcium excretion. The level of calcium and 25(OH)D (hydroxylated vitamin D - calcidiol) in serum, urinary calcium excretion and the presence of stones in urinary tract were assessed prospectively. Blood and urine samples were collected at the time when the patient was qualified for the study and every three months up to 24 month of vitamin D intake at a dose of 400 or 800 IU/day. At time zero and at 12, and 24 months of vitamin D supplementation, densitometry was performed. Supplementation with vitamin D caused a statistically significant increase in the concentration of 25(OH)D in serum. There were no significant changes in calcium concentration in serum, excretion of calcium in urine but also in bone density. There was no significant increase in the risk of formation or development of stones in the urinary tract. Supplementation with vitamin D (400–800 IU/day) in children with idiopathic hypercalciuria significantly increases 25(OH)D concentration, does not affect calciuria, but also does not improve bone density.

The effect of an oral sodium phosphate load on parathyroid hormone and fibroblast growth factor 23 secretion in normo- and hypercalciuric stone-forming patients

BACKGROUND & AIMS

Abnormalities of parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) secretion may cause calcium-phosphate (Ca-P) metabolism disorders in nephrolithiasis. Post-phosphate-load alterations in serum Ca, P and PTH, phosphaturia and calciuria enable monitoring hormonal regulation of Ca-P homeostasis. Our study aimed to determine differences in: 1.selected Ca-P metabolism parameters between healthy and kidney-stone-forming individuals, 2.PTH and FGF23 secretion induced by sodium-phosphate-load(NaP-load) in patients with/without hypercalciuria, 3.secretion of Ca-P related hormones in patients with low and normal/high serum concentrations of 25-hydroxyvitamin D₃ (25OHD₃).

METHODS

Sodium phosphates NaH₂PO₄/Na₂HPO₄-100mmol were administered orally for five days in 19 hypercalciuric [urinary Ca(U-Ca) 6.5 ± 1.7 mmol/d]-HSF, 35 normocalciuric (2.5±1 mmol/d)-NSF stone-forming patients and 19 controls (U-Ca 2.5 ± 1.4 mmol/d)-CG. On days 1 and 5 PTH-,FGF23-,Ca-,P were determined before and after NaP-load. The areas under PTH, FGF23 curves (AUC) were calculated. U-Ca, urinary phosphate (U-P) and sodium (U-Na) were also determined.

RESULTS

Following NaP-load, patients and controls exhibited expected alterations in Ca-P homeostasis. Despite changes in phosphate and PTH, no differences in FGF23 concentrations were observed. Patients differed from controls in having higher AUCPTH, calciuria and natriuresis, taking longer for PTH and P to normalize and lack of correlation between AUCPTH and phosphaturia. Post-NaP-load hypocalciuric effect of PTH secretion in NSF was less pronounced than in CG. In the HSFs, the hypocalciuric effect was more pronounced than in NSFs, but insufficient to correct hypercalciuria. In all stone-formers with low 25OHD₃ concentrations, the AUCFGF23 was significantly increased on first (1215 ± 605vs766 ± 315 p = 0.0457) and fifth days (1211 ± 641vs777 ± 299 p = 0.041) of NaP-load, compared to normal/high 25OHD₃-patients. Hypercalciuric patients with low 25OHD₃ concentrations had greater AUCPTH5 than those with normal/high 25OHD₃ (1005 ± 401vs835 ± 220 p = 0.0341).

CONCLUSIONS

Compared to controls, kidney-stone-forming patients exhibited enhanced PTH secretion after NaP-load. The HSFs showed a more pronounced hypocalciuric effect than NSFs, but insufficient to correct hypercalciuria. In hypercalciuric stone-formers with low 25OHD₃, FGF23 engagement in hyperphosphatemia reduction increased.

Metabolic effects of cholecalciferol supplementation in patients with calcium nephrolithiasis and vitamin D deficiency

INTRODUCTION

In this paper, we investigated whether cholecalciferol supplementation may increase the risk of stone recurrence in patients with calcium nephrolithiasis and Vitamin D deficiency.

METHODS

Thirty-three stone formers (56 ± 17 years old, 12 males) with 25(OH)D < 20 ng/mL were considered. Calcium excretion and urine supersaturation with calcium oxalate (ßCaOx) and brushite (ßbsh) were evaluated, both before and after cholecalciferol supplementation. Values of ß > 1 mean supersaturation. Cholecalciferol was prescribed as oral bolus of 100,000-200,000 IU, followed by weekly (5000-10,000 IU) or monthly (25,000-50,000 IU) doses. Calcium intake varied between 800 and 1000 mg/day. In urine, total nitrogen (TNE) was taken as an index of protein intake, sodium as a marker of dietary intake, and net acid excretion (NAE) as an index of acid-base balance.

RESULTS

TNE, sodium, and NAE did not change during the study (p = ns). Compared to baseline values, after cholecalciferol, both serum calcium and phosphate did not vary (p = ns); 25(OH)D increased from 11.8 ± 5.5 to 40.2 ± 12.2 ng/mL (p < 0.01); 1.25(OH)₂D increased from 41.6 ± 17.6 to 54 ± 16 pg/mL (p < 0.01); PTH decreased from 75 ± 27.2 to 56.7 ± 21.1 pg/mL (p < 0.01); urinary calcium increased from 2.7 ± 1.5 to 3.6 ± 1.6 mg/Kg b.w. (p < 0.01); ßbsh increased from 0.9 ± 0.7 to 1.3 ± 1.3 (p = 0.02); whereas ßCaOx varied but not significantly. Before cholecalciferol supplementation, 6/33 patients were hypercalciuric (i.e., urine Ca ≥ 4 mg/Kg b.w.) and increased to 13/33 after cholecalciferol supplementation (pX² = 0.03).

CONCLUSIONS

Cholecalciferol supplementation may increase calcium excretion, or reveal an underlying condition of absorptive hypercalciuria. This may increase both urine supersaturation with calcium salts and stone-forming risk.

Normocalcemic Hyperparathyroidism: Study of its Prevalence and Natural History

CONTEXT

Normocalcemic hyperparathyroidism (NPHPT) is characterized by persistently normal calcium levels and elevated parathyroid hormone (PTH) values, after excluding other causes of secondary hyperparathyroidism. The prevalence of the disease varies greatly and the data on the natural history of this disease are sparse and inconclusive.

OBJECTIVES

The objectives of this study are to describe the prevalence of NPHPT and its natural history in a referral population and to compare the variability of serum calcium with a group of patients with primary hyperparathyroidism (PHPT).

DESIGN

A retrospective study was conducted over 5 years.

SETTING

The setting for this study was a metabolic bone referral center.

PATIENTS

A total of 6280 patients were referred for a bone mineral density measurement (BMD).

MAIN OUTCOME MEASURES

The prevalence and natural history of NPHPT and variability of calcium were the main outcome measures.

RESULTS

We identified NPHPT patients using data from the day of the BMD measurement. We excluded patients with low estimated glomerular filtration rate (eGFR) or vitamin D, or with no measurements available. Based on the evaluation of their medical files, we identified 11 patients with NPHPT (prevalence 0.18%). Only 4 patients had consistent normocalcemia throughout their follow-up, with only 2 also having consistently high PTH. None had consistently normal eGFR or vitamin D.Intermittent hypercalcemia was present in 7 of the 11 NPHPT patients. The mean adjusted calcium was found to be significantly lower in the NPHPT group compared with the PHPT group but higher than the control group. PTH was similar for NPHPT and PHPT. These 2 groups had similar variability in serum calcium.

CONCLUSIONS

NPHPT patients often have episodes of hypercalcemia. We believe that NPHPT is a mild form of PHPT.

Vitamin D and Kidney Stones

This review explores the relationship between vitamin D supplementation and lithogenesis. A causal relationship has been assumed despite myriad studies demonstrating that therapeutic doses of vitamin D do not increase lithogenic risk. Select stone formers may be at increased risk for recurrence with vitamin D supplementation, possibly from CYP24A1 gene mutations. Additionally, the evidence for who is vitamin D deficient, and the benefits of supplementation in those not at risk for rickets, is sparse. Concerns may be avoidable as vitamin D screening appears unnecessary in most patients, and superior pharmacology is available which increases bone density, while decreasing stone formation.

LIFESTYLE RISK FACTORS AND BONE MASS IN RECURRENT STONE-FORMING PATIENTS: A CROSS-SECTIONAL STUDY IN 144 SUBJECTS

Patients with urolithiasis, particularly hypercalciuria, may have reduced bone mineral density (BMD). There are numerous risk factors contributing to reduction of BMD such as advanced age, sedentary lifestyle, smoking, low calcium intake, etc. The aim of our study was to investigate the association of lifestyle risk factors and daily intake of milk and dairy products with determinants of BMD in a group of recurrent calcium stone formers (RSF) compared with healthy subjects (HS). The study was carried out at the Department of Mineral Research, Faculty of Medicine in Osijek, Croatia. The study included 144 subjects, i.e. 56 RSF and 78 HS. BMD was assessed by dual-energy x-ray absorptiometry. A standard self-reported questionnaire was used to collect data on lifestyle risk factors. Current dietary intake was assessed by personal interview that included questions about milk and dairy product intake. Low BMD was observed in 44.64% of RSF and 35.90% of HS. RSF consumed significantly less milk and dairy products than HS. Calcium restriction in dietary recommendations might be unnecessary due to the impact on bone mineral loss in RSF and dual-energy x-ray absorptiometry should be included in the routine evaluation of RSF.

TRPV5 in renal tubular calcium handling and its potential relevance for nephrolithiasis

Nephrolithiasis or renal stone disease is an increasingly common problem, and its relatively high recurrence rate demands better treatment options. The majority of patients with nephrolithiasis have stones that contain calcium (Ca²⁺), which develop upon "supersaturation" of the urine with insoluble Ca²⁺ salts; hence processes that influence the delivery and renal handling of Ca²⁺ may influence stone formation. Idiopathic hypercalciuria is indeed frequently observed in patients with kidney stones that contain Ca²⁺. Genetic screens of nephrolithiasis determinants have identified an increasing number of gene candidates, most of which are involved in renal Ca²⁺ handling. This review provides an outline of the current knowledge regarding genetics of nephrolithiasis and will mainly focus on the epithelial Ca²⁺ channel transient receptor potential vanilloid 5 (TRPV5), an important player in Ca²⁺ homeostasis. Being a member of the TRP family of ion channels, TRPV5 is currently part of a revolution in structural biology. Recent technological breakthroughs in the cryo-electron microscopy field, combined with improvements in biochemical sample preparation, have resulted in high-resolution 3-dimensional structural models of integral membrane proteins, including TRPV5. These models currently are being used to explore the proteins' structure-function relationship, elucidate the molecular mechanisms of channel regulation, and study the putative effects of disease variants. Combined with other multidisciplinary approaches, this approach may open an avenue toward better understanding of the pathophysiological mechanisms involved in hypercalciuria and stone formation, and ultimately it may facilitate prevention of stone recurrence through the development of effective drugs.

Evidence for a regulated Ca2+ entry in proximal tubular cells and its implication in calcium stone formation

Calcium phosphate (CaP) crystals, which begin to form in the early segments of the loop of Henle (LOH), are known to act as precursors for calcium stone formation. The proximal tubule (PT), which is just upstream of the LOH and is a major site for Ca²⁺ reabsorption, could be a regulator of such CaP crystal formation. However, PT Ca²⁺ reabsorption is mostly described as being paracellular. Here, we show the existence of a regulated transcellular Ca²⁺ entry pathway in luminal membrane PT cells induced by Ca²⁺-sensing receptor (CSR, also known as CASR)-mediated activation of transient receptor potential canonical 3 (TRPC3) channels. In support of this idea, we found that both CSR and TRPC3 are physically and functionally coupled at the luminal membrane of PT cells. More importantly, TRPC3-deficient mice presented with a deficiency in PT Ca²⁺ entry/transport, elevated urinary [Ca²⁺], microcalcifications in LOH and urine microcrystals formations. Taken together, these data suggest that a signaling complex comprising CSR and TRPC3 exists in the PT and can mediate transcellular Ca²⁺ transport, which could be critical in maintaining the PT luminal [Ca²⁺] to mitigate formation of the CaP crystals in LOH and subsequent formation of calcium stones.

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.

Phosphaturia in kidney stone formers: Still an enigma

Calcium kidney stones are common worldwide. Most are idiopathic and composed of calcium oxalate. Calcium phosphate is present in around 80% and may initiate stone formation. Stone production is multifactorial with a polygenic genetic contribution. Phosphaturia is found frequently among stone formers but until recently received scant attention. This review examines possible mechanisms for the phosphaturia and its relevance to stone formation from a wide angle. There is a striking lack of clinical data. Phosphaturia is associated, but not correlated, with hypercalciuria, increased 1,25 dihydroxy-vitamin D [1,25 (OH)₂D], and sometimes evidence of disturbances in proximal renal tubular function. Phosphate reabsorption in the proximal renal tubules requires tightly regulated interaction of many proteins. Paracellular flow through intercellular tight junctions is the major route of phosphate absorption from the intestine and can be reduced therapeutically in hyperphosphatemic patients. In monogenic defects stones develop when phosphaturia is associated with hypercalciuria, generally explained by increased 1,25 (OH)₂D production in response to hypophosphatemia. Calcification does not occur in disorders with increased FGF23 when phosphaturia occurs in isolation and 1,25 (OH)₂D is suppressed. Candidate gene studies have identified mutations in the phosphate transporters, but in few individuals. One genome-wide study identified a polymorphism of the phosphate transporter gene SLC34A4 associated with stones. Others did not find mutations obviously linked to phosphate reabsorption. Future genetic studies should have a wide trawl and should focus initially on groups of patients with clearly defined phenotypes. The global data should be pooled.

Efficacy of standard and low dose hydrochlorothiazide in the recurrence prevention of calcium nephrolithiasis (NOSTONE trial): protocol for a randomized double-blind placebo-controlled trial

Background

Nephrolithiasis is a global healthcare problem with a current lifetime risk of 18.8% in men and 9.4% in women. Given the high cost of medical treatments and surgical interventions as well as the morbidity related to symptomatic stone disease, medical prophylaxis for stone recurrence is an attractive approach. Thiazide diuretics have been the cornerstone of pharmacologic metaphylaxis for more than 40 years. However, evidence for benefits and harms of thiazides in the prevention of calcium containing kidney stones in general remains unclear. In addition, the efficacy of the currently employed low dose thiazide regimens to prevent stone recurrence is not known.

Methods

The NOSTONE trial is an investigator-initiated 3-year prospective, multicenter, double-blind, placebo-controlled trial to assess the efficacy of standard and low dose hydrochlorothiazide treatment in the recurrence prevention of calcium containing kidney stones. We plan to include 416 adult (≥ 18 years) patients with recurrent (≥ 2 stone episodes in the last 10 years) calcium containing kidney stones (containing ≥50% of calcium oxalate, calcium phosphate or a mixture of both). Patients will be randomly allocated to 50 mg or 25 mg or 12.5 mg hydrochlorothiazide or placebo.

The primary outcome will be incidence of stone recurrence (a composite of symptomatic or radiologic recurrence). Secondary outcomes will be individual components of the composite primary outcome, safety and tolerability of hydrochlorothiazide treatment, changes in urinary biochemistry elicited by hydrochlorothiazide treatment and impact of baseline disease severity, biochemical abnormalities and stone composition on treatment response.

Discussion

The NOSTONE study will provide long-sought information on the efficacy of hydrochlorothiazide in the recurrence prevention of calcium containing kidney stones. Strengths of the study include the randomized, double-blind and placebo-controlled design, the large amount of patients studied, the employment of high sensitivity and high specificity imaging and the exclusive public funding support.

Trial registration

ClinicalTrials.gov, NCT03057431. Registered on February 20 2017.

Management of normocalcemic primary hyperparathyroidism

Traditional hypercalcemic primary hyperparathyroidism is a common endocrine disease. Patients with a history of nephrolithiasis or a suspected metabolic bone disease are increasingly being identified with elevated PTH concentrations in the setting of consistently normal serum and ionized calcium concentrations. In the absence of secondary causes of hyperparathyroidism, a diagnosis of normocalcemic primary hyperparathyroidism is reasonable. As most cohorts described in the literature are from referral populations, involvement of the skeleton and the kidneys is common, two traditional target organs of primary hyperparathyroidism. Data from small cohorts show patients with normocalcemic disease respond similarly to hypercalcemic primary hyperparathyroidism with regard to medical and surgical approaches. In normocalcemic patients, multiglandular disease may be more common. In this article, we review the available literature on the epidemiology, diagnosis, clinical features, medical and surgical management of this newer phenotype of primary hyperparathyroidism.

Pathophysiology and symptoms of renal colic in children - a case report

Urolithiasis is a disease characterized by the presence of stones in the kidney or urinary tract. It is often detected accidentally during an ultrasound or an abdominal x-ray performed for other reasons. However, the first symptom of kidney stone disease can be severe pain called renal colic. Pain caused by a colic attack is characterized by sudden onset. In half of the cases it is associated with nausea or vomiting and can lead to hypotension and fainting. The exact location and radiation of the pain depends on the location of the stone in the urinary tract. The first most commonly performed study is abdominal ultrasound with estimation of the deposit size and evaluation of urinary tract obstruction. Alternative or complementary studies are: an abdominal x-ray where radiopaque deposits can be shown, or unenhanced helical computed tomography of the abdomen. The severity of pain depends on the individual pain threshold and on the change in hydrostatic pressure in the part of the urinary system above the obstruction. Prolonged deposition of the stone in one place causes the activation of autoregulatory mechanisms to lower the pressure of the upper urinary tract, which limits the pain. The basic treatment for renal colic is analgetic therapy. The most commonly used drugs are NSAIDs and opiates. Another important component of renal colic treatment are medications that facilitate urinary stone passage by reducing oedema or limiting urethral contractions, such as: calcium channel blockers, alpha blockers, phosphodiesterase inhibitors. Intensive hydration is not currently recommended. Patients who are unlikely to spontaneously excrete the stone are eligible for minimally invasive treatment. The risk of urolithiasis recurring is high, reaching up to 40% in 5 years and up to 50% in 10 years. However, it can be reduced by proper prevention. The paper describes the pathophysiology of pain in renal colic, the treatment methods, and the case of a boy with recurrent renal colic.

Medical therapy for nephrolithiasis: State of the art

The prevalence of nephrolithiasis is increasing worldwide. Understanding and implementing medical therapies for kidney stone prevention are critical to prevent recurrences and decrease the economic burden of this condition. Dietary and pharmacologic therapies require understanding on the part of the patient and the prescribing practitioner in order to promote compliance. Insights into occupational exposures and antibiotic use may help uncover individual risk factors. Follow-up is essential to assess response to treatment and to modify treatment plans to maximize therapeutic benefit.

Effect of phyllanthus niruri on metabolic parameters of patients with kidney stone: a perspective for disease prevention

Phyllanthus niruri (P.niruri) or stone breaker is a plant commonly used to reduce stone risk, however, clinical studies on this issue are lacking.

OBJECTIVE

To prospectively evaluate the effect of P. niruri on the urinary metabolic parameters of patients with urinary lithiasis.

MATERIALS AND METHODS

We studied 56 patients with kidney stones <10mm. Clinical, metabolic, and ultrasonography assessment was conducted before (baseline) the use of P. niruri infusion for 12-weeks (P. niruri) and after a 12-week (wash out) Statistical analysis included ANOVA for repeated measures and Tukey's/McNemar´s test for categorical variables. Significance was set at 5%.

RESULTS

Mean age was 44±9.2 and BMI was 27.2±4.4kg/m2. Thirty-six patients (64%) were women. There were no significant changes in all periods for anthropometric and several serum measurements, including total blood count, creatinine, uric acid, sodium, potassium, calcium, urine volume and pH; a significant increase in urinary potassium from 50.5±20.4 to 56.2±21.8 mg/24-hour (p=0.017); magnesium/creatinine ratio 58±22.5 to 69.1±28.6mg/ gCr24-hour (p=0.013) and potassium/creatinine ratio 39.3±15.1 to 51.3±34.7mg/gCr24- hour (p=0.008) from baseline to wash out. The kidney stones decreased from 3.2±2 to 2.0±2per patient (p<0.001). In hyperoxaluria patients, urinary oxalate reduced from 59.0±11.7 to 28.8±16.0mg/24-hour (p=0.0002), and in hyperuricosuria there was a decrease in urinary uric acid from 0.77±0.22 to 0.54±0.07mg/24-hour (p=0.0057).

CONCLUSIONS

P.niruri intake is safe and does not cause significant adverse effects on serum metabolic parameters. It increases urinary excretion of magnesium and potassium caused a significant decrease in urinary oxalate and uric acid in patients with hyperoxaluria and hyperuricosuria. The consumption of P.niruri contributed to the elimination of urinary calculi.

The Impact of Vitamin D Supplementation on Vitamin D Level, Urinary Calcium Excretion and Bone Density in Patients with Hypercalciuria and Vitamin D Deficiency − Preliminary Report

Aim

To study the impact of vitamin D supplementation on vitamin D concentration in plasma, calcium urinary excretion and bone density in patients with urolithiasis in the course of idiopathic hypercalciuria and with a low vitamin D level.

Materials and method

Prospective analysis concerning 28 patients (16 boys, 12 girls) aged 6-14 years (average 10.4) in terms of urinary calcium excretion (mg/kg/day and Ca/Creatinine ratio in morning urine sample), 25OHD blood level after 3, 6, 9 and 12 months of individually recommended doses of vitamin D supplementation (400 IU or 800 IU). The doses were determined on the basis of 25 (OH) D deficiency. The children were on a normocalcemic diet.

The bone mineral density of the patients was assessed before and after 12 months of vitamin D use at the aforementioned doses.

Results

There was no statistically significant correlation between 25 (OH) D plasma concentration and urinary calcium excretion measured on Ca /Creatinine ratio in daily urine collection and Ca/Creatinine ratio in the morning urine sample.

No statistically significant change in calcium excretion was noted (measured by calciuria in daily urine collection and the calcium to creatinine ratio in the morning urine sample). A statistically significant increase in vitamin D plasma concentration was observed. Improvement in bone mineral density was not statistically significant.

Conclusions

Supplementation of vitamin D in the children with idiopathic hypercalciuria and urolithiasis who were examined seems to be safe. The decision to start treatment and the selection of the vitamin D dose should be considered individually.

Patients with urolithiasis should be carefully monitored for calcium/phosphate metabolism parameters and the activity of the disease.

Supplementation of low doses vitamin D in the children examined did not improve bone mineral density.

Renal stones

Renal stone disease is a worldwide problem which carries significant morbidity. It frequently requires specialist urology intervention. Patients with recurrent disease and those at high risk require specialist investigations and review. Certain cases benefit from medical and surgical intervention. In this review, we discuss the pathophysiology, risk assessment, specialist investigations and various interventions, their rationale and evidence base. This review aims to provide an update of the previous publication in 2001 in this journal on this topic.

Role of FGF23 in Pediatric Hypercalciuria

Background

This study explored the possible role of FGF23 in pediatric hypercalciuria.

Methods

Plasma FGF23 was measured in 29 controls and 58 children and adolescents with hypercalciuria: 24 before treatment (Pre-Treated) and 34 after 6 months of treatment (Treated). Hypercalciuric patients also measured serum PTH hormone, 25(OH)vitD, phosphate, calcium, creatinine, and 24 h urine calcium, phosphate, and creatinine.

Results

There were no differences in age, gender, ethnicity, or body mass index either between controls and patients, or between Pre-Treated and Treated patients. Median plasma FGF23 in controls was 72 compared with all patients, 58 RU/mL (p = 0.0019). However, whereas FGF23 in Pre-Treated patients, 73 RU/mL, was not different from controls, in Treated patients it was 50 RU/mL, significantly lower than in both controls (p < 0.0001) and Pre-Treated patients (p = 0.02). In all patients, there was a correlation between FGF23 and urinary calcium (r = 0.325; p = 0.0014). Treated patients had significantly lower urinary calcium (p < 0.0001), higher TP/GFR (p < 0.001), and higher serum phosphate (p = 0.007) versus Pre-Treated patients.

Conclusions

Pharmacological treatment of hypercalciuric patients resulted in significantly lower urinary calcium excretion, lower serum FGF23, and elevated TP/GFR and serum phosphate concentration, without significant changes in PTH. Further studies are indicated. This trial is registered with Clinical Registration Number RBR 8W27X5.

Changes in urinary risk profile after short-term low sodium and low calcium diet in recurrent Swiss kidney stone formers

Background

Kidney stone disease is common in industrialized countries. Recently, it has attracted growing attention, because of its significant association with adverse renal outcomes, including end stage renal disease. Calcium-containing kidney stones are frequent with high recurrence rates. While hypercalciuria is a well-known risk factor, restricted intake of animal protein and sodium, combined with normal dietary calcium, has been shown to be more effective in stone prevention compared with a low-calcium diet. Notably, the average sodium intake in Switzerland is twice as high as the WHO recommendation, while the intake of milk and dairy products is low.

Methods

We retrospectively analyzed Swiss recurrent kidney stone formers (rKSF) to test the impact of a low-sodium in combination with a low-calcium diet on the urinary risk profile. In patients with recurrent calcium oxalate containing stones, we investigated both, the consequence of a low-sodium diet on urinary volume and calcium excretion, and the influence of a low-sodium low-calcium diet on urinary oxalate excretion.

Results

Of the 169 patients with CaOx stones, 49 presented with hypercalciuria at baseline. The diet resulted in a highly significant reduction in 24-h urinary sodium and calcium excretion: from 201 ± 89 at baseline to 128 ± 88 mmol/d for sodium (p < 0.0001), and from 5.67 ± 3.01 to 4.06 ± 2.46 mmol/d (p < 0.0001) for calcium, respectively. Urine volume remained unchanged. Notably, no increase in oxalate excretion occurred on the restricted diet (0.39 ± 0.26 vs 0.39 ± 0.19 mmol/d, p = 0.277). Calculated Psf (probability of stone formation) values were only predictive for the risk of calcium phosphate stones.

Conclusion

A diet low in sodium and calcium in recurrent calcium oxalate stone formers resulted in a significant reduction of urinary calcium excretion, but no change in urine volume. In this population with apparently low intake of dairy products, calcium restriction does not necessarily result in increased urinary oxalate excretion. However, based on previous studies, we recommend a normal dietary calcium intake to avoid a potential increase in urinary oxalate excretion and unfavorable effects on bone metabolism in hypercalciuric KSFs.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0755-7) contains supplementary material, which is available to authorized users.

Primary aldosteronism as a cause of secondary osteoporosis

OBJECTIVE

Patients with primary aldosteronism (PA) have a high prevalence of osteoporosis (OP) and fractures (Fx). We evaluated the presence of PA in patients admitted to our metabolic bone disease outpatient clinic.

DESIGN

Study conducted on an in- and outpatient basis in a referral Italian endocrinology unit.

METHODS

A total of 2632 patients were evaluated. 2310 were excluded because they were taking drugs known to affect bone or mineralocorticoids metabolism or were diagnosed to have a secondary cause of osteoporosis. The remaining 322 subjects (304 females, 18 males) took part in the study. Bone mineral density (BMD) and thoracic and lumbar spine vertebral morphometry were performed by dual X-ray absorptiometry. All patients were screened for PA with aldosterone-to-renin ratio. In those who had positive results, confirmatory tests were performed.

RESULTS

Among 322 subjects, 213 were osteoporotics and 109 were not. PA was diagnosed in eleven out of 213 osteoporotic patients (5.2%) and one out of 109 non-osteoporotic subjects (0.9%, P = 0.066). PA was observed in the 26.1% of patients with the concomitant presence of osteoporosis, hypertension and hypercalciuria. Compared with patients without PA, patients with PA had mean values of urinary calcium excretion, 4.8 ± 2.5 mmol/day vs 7.6 ± 3.2 mmol/day, P < 0.001 and serum PTH levels, 5.4 pmol/L vs 7.3 pmol/L, P < 0.01, significantly higher.

CONCLUSIONS

PA should be considered among the causes of secondary OP.

Urinary metals in a spontaneous canine model of calcium oxalate urolithiasis

Calcium oxalate urolithiasis is a common and painful condition in people. The pathogenesis of this disease is complex and poorly understood. Laboratory animal and in vitro studies have demonstrated an effect of multiple trace metals in the crystallization process, and studies in humans have reported relationships between urinary metal concentrations and stone risk. Dogs are a spontaneous model of calcium oxalate urolithiasis, and the metal content of canine calcium oxalate stones mirrors that of human stones. The aim of this study was to test for a relationship between urinary metals and calcium oxalate urolithiasis in dogs. We hypothesized that urinary metals would differ between dogs with and without calcium oxalate urolithiasis. Urine from 122 dogs (71 cases and 51 stone-free controls) was analyzed for calcium and 12 other metals. The cases had higher urinary calcium, copper, iron, and vanadium and lower urinary cobalt. Higher urinary vanadium in the cases was associated with being fed a therapeutic stone-prevention diet. Urinary calcium had a strong positive correlation with strontium and moderate positive correlations with chromium, nickel, and zinc. The results of this study complement the findings of similar human studies and suggest a potential role of trace metals in calcium oxalate urolithiasis. Further investigation into how trace metals may affect stone formation is warranted.

Late-onset hereditary hypophosphatemic rickets with hypercalciuria (HHRH) due to mutation of SLC34A3/NPT2c

OBJECTIVE

To identify a genetic basis for markedly reduced bone density and multiple fractures in an adult patient with hypophosphatemia and hypercalciuria.

SUBJECTS

A 54-year-old Vietnamese man, his unaffected two daughters and wife.

METHODS

We performed biochemical studies and sequenced the SLC34A3 gene using genomic DNA from peripheral blood mononuclear cells.

RESULTS

Biochemical evaluation of the proband revealed hypophosphatemia with increased renal phosphate wasting, hypercalciuria, low serum parathyroid hormone (PTH) and an elevated serum 1,25(OH)2D level. Mutation analysis of SLC34A3 gene revealed that the patient was a compound heterozygote for two nonsynonymous nucleotide substitutions: a novel c.571G>A (p.G191S) damaging mutation and the previously reported c.200G>A (p.R67H) polymorphism, consistent with the clinical diagnosis of late-onset hereditary hypophosphatemic rickets with hypercalciuria (HHRH). His wife and older daughter both carried the p.R67H polymorphism, while his younger daughter was compound heterozygous for p.R67H and p.G191S.

CONCLUSIONS

HHRH is an uncommon autosomal recessive disease that generally manifests in childhood as rickets or nephrolithiasis, but an adult onset phenotype may occur in heterozygous carriers of SLC34A3 mutations. The severe presentation of this proband in adulthood with marked nephrolithiasis, multiple fractures and low bone density emphasizes the importance of measuring the serum phosphorus level in patients with suspected but unexplained osteoporosis and/or recurrent renal stones. The recognition of late-onset HHRH facilitates timely institution of appropriate therapy.

FGF23 Is Not Associated With Age-Related Changes in Phosphate, but Enhances Renal Calcium Reabsorption in Girls

CONTEXT

Fibroblast growth factor (FGF)23 is a critical determinant of phosphate homeostasis. The role of FGF23, however, in regulating physiologic changes in serum phosphate and renal phosphate handling across childhood is not well described. In addition, animal models have suggested a role for FGF23 in regulating renal calcium excretion.

OBJECTIVE

To assess changes in FGF23 concentrations across childhood in relation to changes in mineral ions and hormones of mineral ion homeostasis.

DESIGN

This was a cross-sectional study.

SETTING

The study was conducted at a Clinical Research Center at a tertiary care hospital.

PATIENTS OR OTHER PARTICIPANTS

Ninety healthy girls ages 9 to 18 years were recruited from the surrounding community.

MAIN OUTCOME MEASURES

The associations of intact and C-terminal FGF23 concentrations with measures of mineral ion homeostasis were determined by univariable and multivariable linear regression.

RESULTS

Serum phosphate and renal phosphate excretion varied with age, as expected (R = -0.49, P < 0.001 and R = -0.48, P < 0.001, respectively). Neither intact nor C-terminal FGF23 varied with age, and FGF23 was not correlated with serum or urinary phosphate. Intact FGF23 was positively correlated with serum calcium (R = 0.39, P < 0.001) and negatively correlated with urinary calcium/creatinine ratio (R = -0.27, P = 0.011).

CONCLUSIONS

The changes in serum and urinary phosphate handling across childhood do not appear to be determined by alterations in FGF23 concentrations. These data may point to a role for FGF23 in calcium regulation in human physiology.

Pathogenesis of calcium oxalate urinary stone disease: species comparison of humans, dogs, and cats

Idiopathic calcium oxalate nephrolithiasis is a highly recurrent disease that is increasing in prevalence. Decades of research have not identified effective methods to consistently prevent the formation of nephroliths or induce medical dissolution. Idiopathic calcium oxalate nephroliths form in association with renal papillary subepithelial calcium phosphate deposits called Randall's plaques (RPs). Rodent models are commonly used to experimentally induce calcium oxalate crystal and stone formation, but a rodent model that conclusively forms RPs has not been identified. Both dogs and cats form calcium oxalate uroliths that can be recurrent, but the etiopathologic mechanisms of stone formation, especially renal pathologic findings, are a relatively unexploited area of study. A large animal model that shares a similar environment to humans, along with a shorter lifespan and thus shorter time to recurrence, might provide an excellent means to study preventative and therapeutic measures, along with enhancing the concepts of the one health initiative. This review article summarizes and compares important known features of idiopathic calcium oxalate stone disease in humans, dogs, and cats, and emphasizes important knowledge gaps and areas for future study in the quest to discover a naturally occurring animal model of idiopathic calcium oxalate stone disease.

Medical management of urinary calculi: up to date 2016

Nephrolithiasis (NL) is one of the most prevalent nontransmissible diseases in western countries. It is being associated with other frequent diseases, including osteoporosis, cardiovascular disease, hypertension, diabetes mellitus, through a putative common link with metabolic syndrome and insulin resistance or altered mineral metabolism. This review will focus on classification, physicochemical basis, risk factors, laboratory and imaging investigations, medical management.Classification as to stone composition includes calcium, uric acid (UA), cystine (Cys), infected, 2-8 dihydroxyadenine and rare NL. According to pathophysiology, NL is classified as primary, secondary to systemic diseases or drugs, caused by renal or metabolic hereditary disorders.A stone can only form in supersaturated environment, and this is sufficient in UA, Cys and infected NL, but not in Ca-NL, which results from the imbalance between supersaturation and inhibition. All types are characterized by derangements of peculiar risk factors. Laboratory investigations aim at identifying type of NL, underlying risk factors and state of saturation, and pathophysiology. This justifies a rationale therapy able to dissolve some types of stones and/or produce reduction in recurrence rate in others.Medical management includes alkali and allopurinol for UA nephrolithiasis (UA-NL), thiols and alkali in Cys-NL, dietary and pharmacological intervention for Ca-NL. Thiazides and alkaline citrate salts are the most widely used drugs in Ca-NL, where they proved efficient to prevent new stones. Other drugs have only been used in particular subsets.Proper medical management and modern urological approaches have already notably improved clinical outcomes. Future studies will further clarify mechanisms of NL with expected new and targeted therapeutic options.

Idiopathic hypercalciuria and formation of calcium renal stones

The most common presentation of nephrolithiasis is idiopathic calcium stones in patients without systemic disease. Most stones are primarily composed of calcium oxalate and form on a base of interstitial apatite deposits, known as Randall's plaque. By contrast some stones are composed largely of calcium phosphate, as either hydroxyapatite or brushite (calcium monohydrogen phosphate), and are usually accompanied by deposits of calcium phosphate in the Bellini ducts. These deposits result in local tissue damage and might serve as a site of mineral overgrowth. Stone formation is driven by supersaturation of urine with calcium oxalate and brushite. The level of supersaturation is related to fluid intake as well as to the levels of urinary citrate and calcium. Risk of stone formation is increased when urine citrate excretion is <400 mg per day, and treatment with potassium citrate has been used to prevent stones. Urine calcium levels >200 mg per day also increase stone risk and often result in negative calcium balance. Reduced renal calcium reabsorption has a role in idiopathic hypercalciuria. Low sodium diets and thiazide-type diuretics lower urine calcium levels and potentially reduce the risk of stone recurrence and bone disease.