Children With Type 1 Spinal Muscular Atrophy Are at Increased Risk for Nephrolithiasis

BACKGROUND

Nephrolithiasis is not a well-documented condition in children with spinal muscular atrophy (SMA). It is possible that this condition was underestimated before the era of nusinersen because of a much shorter life expectancy. We present our observational data on nephrolithiasis and its possible risk factors in children with type 1 SMA.

METHODS

We retrospectively reviewed the charts of 20 children with genetically confirmed type 1 SMA. Thirteen patients (aged 9 to 55 months) who underwent urinary tract ultrasonography were included in the study. Medical records were retrospectively reviewed for demographic and clinical characteristics, ultrasound results, and metabolic abnormalities.

RESULTS

Seven children (54%) had nephrolithiasis; 5 had multiple stones and two had a single stone. Two patients had microlithiasis (<3 mm), three had a stone in the size of 3 to 5 mm, and one had a stone in the size of more than 8 mm. Two patients with nephrolithiasis had urinary tract abnormalities. Patients with nephrolithiasis were more likely to have a history of urinary tract infections (UTIs) (P = 0.048) and higher urine specific gravity (P = 0.014) than patients without nephrolithiasis. Five of seven children with nephrolithiasis had a urine metabolic evaluation; all had hypercalciuria, three had hyperuricosuria, but none had hyperoxaluria, hypocitraturia, or hypomagnesemia.

CONCLUSION

Children with SMA type 1 are at an increased risk for nephrolithiasis. Hypercalciuria and high urine specific gravity appear to be the most common risk factors for the occurrence of nephrolithiasis. In addition, UTI is more common in patients with type 1 SMA with nephrolithiasis.

Childhood nephrolithiasis and nephrocalcinosis caused by metabolic diseases and renal tubulopathy: A retrospective study from 2 tertiary centers

OBJECTIVES

To study childhood nephrolithiasis and nephrocalcinosis caused by metabolic disorders, distal renal tubular acidosis (dRTA), and familial hypomagnesemia, hypercalciuria, and nephrocalcinosis (FHHNC).

METHODS

We retrospectively evaluated 86 children presented over 10 years (2011-2021), with nephrolithiasis (89%) and nephrocalcinosis (11%) caused by metabolic disorders (62%), FHHNC (21%), and dRTA (17%).

RESULTS

The mean age at discovery was 72.7 months. The underlying metabolic etiologies included hyperoxaluria (38%), cystinuria (32%), hypercalciuria (24%), and hyperuricosuria (6%). Genetic testing was carried out for 23 patients. Hyperoxaluria was typically treated medically (75%). However, the majority progressed to end-stage kidney disease (ESKD). Most children with cystinuria, hypercalciuria, and hyperuricosuria required medical and surgical intervention. Patients with FHHNC typically presented with nephrocalcinosis. Genetic testing revealed Claudin-16 mutations in 7 children. Patients often progressed to stage II-IV chronic kidney disease (61%) and ESKD (6%). Patients with dRTA typically presented with nephrocalcinosis (80%), as well as poor weight gain and failure to thrive (86%), and medical treatment included sodium bicarbonate and potassium replacement. Despite nephrocalcinosis progression, most patients had normal renal function (53%), although the remaining 47% progressed to chronic kidney disease (none reached ESKD).

CONCLUSION

Childhood nephrolithiasis is mainly related to metabolic disorders and is associated with poor renal outcomes. Nephrocalcinosis and nephrolithiasis have poor outcomes when associated with FHHNC, while nephrocalcinosis associated with dRTA has relatively good renal outcomes.

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.

A Nationwide Retrospective Study in Turkish Children With Nephrocalcinosis

BACKGROUND

Nephrocalcinosis (NC) is defined as calcium deposition in the kidney parenchyma and tubules. This study aims to determine the etiology, risk factors and follow-up results of patients with NC in Turkey.

MATERIALS AND METHODS

Patients diagnosed with NC in the Pediatric Nephrology Department Units of 19 centers from all geographical regions of Turkey over a 10-year period (2010?2019) were included in the study. The medical records from the centers were reviewed and demographic data, admission complaints, medical history, systemic and genetic disorders, risk factors for NC, treatment details and presence of NC after one year follow-up were recorded retrospectively.

RESULTS

The study sample included 195 patients (88 females, 107 males). The mean age at diagnosis was 39.44±47.25 (0.5?208) months; 82/190 patients (43.2%) were diagnosed incidentally; 46/195 patients (23.6%) had an underlying disease; idiopathic hypercalciuria was detected in 75/195 (38.4%) patients. The most common systemic diseases were distal renal tubular acidosis in 11/46 patients (23.9%), primary hyperoxaluria in 9/46 patients (19.6%) and Bartter syndrome in 7/46 patients (15.3%). After one year of follow-up, NC resolved in 56/159 patients (35.2%) and they all did not have an underlying systemic disease.

CONCLUSION

The most common presentation of NC was incidental. Distal renal tubular acidosis and primary hyperoxaluria were the main systemic diseases leading to NC, while hypercalciuria was the most common metabolic risk factor. Nephrocalcinosis was found to remain in most of the patients at a one year follow-up. It may resolve particularly in patients with no underlying systemic disease.

Hypercalcemia in Children Using the Ketogenic Diet: A Multicenter Study

CONTEXT

The ketogenic diet is associated with progressive skeletal demineralization, hypercalciuria, and nephrolithiasis. Acute hypercalcemia has been described as a newly recognized complication of this treatment.

OBJECTIVE

To describe the clinical characteristics of acute hypercalcemia in children on the ketogenic diet through analysis of the presentation, response to treatment, and natural history in a large cohort of patients.

DESIGN

A multicenter case series was performed including children who developed acute hypercalcemia while treated with the ketogenic diet. Information on clinical presentation, treatment, and course of this complication was collated centrally.

RESULTS

There were 14 patients (median (range) age 6.3 (0.9 to 18) years) who developed hypercalcemia 2.1 (range, 0.2-12) years after starting the ketogenic diet. All had low levels of parathyroid hormone and levels of 1,25-dihydroxyvitamin D were low in all except one. Seven (50%) had impaired renal function at presentation. All except the 2 oldest had low alkaline phosphatase levels for age. Once normocalcemia was achieved, hypercalcemia recurred in only 2 of these patients over observation of up to 9.8 years. One patient discontinued the ketogenic diet prior to achieving normocalcemia while 4 more stopped the diet during follow-up after resolution of hypercalcemia.

CONCLUSIONS

Ketotic hypercalcemia can occur years after starting the ketogenic diet, especially in the setting of renal impairment. The mechanism is unknown but appears to be due to reduced osteoblast activity and impaired bone formation. We recommend close attention to optimizing bone health in these children, and screening for the development of ketotic hypercalcemia.

Hypomagnesuria is Associated With Nephrolithiasis in Patients With Asymptomatic Primary Hyperparathyroidism

CONTEXT

The pathogenesis of nephrolithiasis in primary hyperparathyroidism (PHPT) remains to be elucidated. The latest guidelines suggest parathyroidectomy in patients with asymptomatic PHPT with hypercalciuria (> 400 mg/d) and increased stone risk profile.

OBJECTIVE

The objective of this work is to evaluate the association of urinary stone risk factors and nephrolithiasis in patients with asymptomatic sporadic PHPT and its clinical relevance.

DESIGN

A total of 157 consecutive patients with sporadic asymptomatic PHPT were evaluated by measurement of serum and 24-hour urinary parameters and kidney ultrasound.

RESULTS

Urinary parameters were tested in the univariate analysis as continuous and categorical variables. Only hypercalciuria and hypomagnesuria were significantly associated with nephrolithiasis in the univariate and multivariate analysis adjusted for age, sex, body mass index, estimated glomerular filtration rate, parathyroid hormone, 25-hydroxyvitamin D, serum calcium, and urine volume (odds ratio, OR 2.14 [1.10-4.56]; P = .04; OR 3.06 [1.26-7.43]; P = .013, respectively). Hypomagnesuria remained associated with nephrolithiasis in the multivariate analysis (OR 6.09 [1.57-23.5], P = .009) even when the analysis was limited to patients without concomitant hypercalciuria. The urinary calcium/magnesium (Ca/Mg) ratio was also associated with nephrolithiasis (univariate OR 1.62 [1.27-2.08]; P = .001 and multivariate analysis OR 1.74 [1.25-2.42], P = .001). Hypomagnesuria and urinary Ca/Mg ratio had a better, but rather low, positive predictive value compared with hypercalciuria.

CONCLUSIONS

Hypomagnesuria and urinary Ca/Mg ratio are each associated with silent nephrolithiasis and have potential clinical utility as risk factors, besides hypercalciuria, for kidney stones in asymptomatic PHPT patients. The other urinary indices that have been commonly thought to be associated with kidney stones in PHPT are not supported by our results.

Auditing the Efficacy and Safety of Alfacalcidol and Calcium Therapy in Idiopathic Hypoparathyroidism

CONTEXT

Patients with hypoparathyroidism are treated with vitamin D and calcium. PTH is an emerging option because of its physiological action. It is important to assess the efficacy and shortcomings of conventional therapy.

OBJECTIVE

We assessed the efficacy and safety of alfacalcidol in a large cohort of patients with idiopathic hypoparathyroidism (IH) and identified a subset who could be treated without oral calcium.

DESIGN AND SETTING

Observational study at tertiary care center.

SUBJECTS AND METHODS

We assessed 92 patients with IH who were receiving alfacalcidol and oral calcium to maintain an optimal serum total calcium level of 8.0 to 8.5 mg/dL during routine follow-up. Patients with suboptimal control were provided free medicines and followed up frequently. Oral calcium and alfacalcidol doses were titrated sequentially to determine the minimum doses for optimal calcium control. Serum phosphate level, 1,25-dihydroxyvitamin D, fractional excretion of phosphorus (FEPh), and hypercalciuria (urine calcium-to-creatinine ratio, >0.2) were assessed at each step of titration.

RESULTS

Only 38% of patients had optimal calcium control during routine follow-up. With good compliance, all achieved optimal serum calcium and 1,25-dihydroxyvitamin D levels and 43% of patients could stop taking oral calcium. Hyperphosphatemia, hypercalciuria, and low FEPh persisted at all stages of therapy. Serum phosphorus levels normalized when the serum calcium level increased to 9.9 mg/dL, but this level of serum total calcium was associated with hypercalciuria in 90% of patients.

CONCLUSION

Alfacalcidol is effective in achieving calcemic control in IH. Calcemic control without oral calcium was achieved in 43% of patients receiving alfacalcidol. However, optimal calcium control was associated with hyperphosphatemia and hypercalciuria in most patients.

Extreme hypomagnesemia: characteristics of 119 consecutive inpatients

Extreme hypomagnesemia (hypoMg) can be encountered in many situations, but little data currently exist. Our aim is to describe the epidemiological, clinical, etiological characteristics, and the biological abnormalities of consecutive inpatients with extreme hypomagnesemia. In our observational monocentric study, between 1st July 2000 and April 2015, all inpatients with extreme hypomagnesemia, defined by at least one plasma magnesium concentration (P_Mg) below 0.3 mmol/L, were included. Demographic, clinical, biological characteristics and the drugs prescribed before the qualifying P_Mg measurement were retrospectively collected. 41,069 patients had at least one P_Mg assessment. The prevalence of extreme hypomagnesemia is 0.3% (119 inpatients). The median age is 70 years, 52% are women. The patients were mainly hospitalized in intensive care (n = 37, 31.1%), oncology (n = 21, 17.6%), gastroenterology (n = 18, 15.1%) and internal medicine (n = 16, 13.4%) departments. One hundred patients (84%) had a medical history of gastrointestinal disease (39% with bowel resections, 24% with stoma), and 50 (42%) had a cancer history. The drugs most commonly prescribed (known to induce hypoMg) are proton pump inhibitors (PPI) (n = 77, 70%), immunosuppressive regimens (n = 25, 22.5%), platinum salt-based chemotherapies (n = 19, 17.1%), and diuretics (n = 22, 19.8%). The suspected causes of hypomagnesemia are often multiple, but drugs (46%, including PPI in 19%) and chronic gastrointestinal disorders (37%) are prominent. Associated electrolyte disturbances include hypocalcemia (77%) and mild hypokalemia (51%). The 1-month mortality from all causes is 16%. Extreme hypomagnesemia is rare in inpatients, and is frequently associated with severe hypocalcemia. Digestive disorders and drugs are the main contributory causes.

Classical complications of primary hyperparathyroidism

Traditionally, classical complications of primary hyperparathyroidism are mainly represented by skeletal, kidney and gastrointestinal involvement. The old picture of osteitis fibrosa cystica is no longer commonly seen, at least in the western world. However, new imagining techniques have highlighted deterioration of skeletal tissue in patients with primary hyperparathyroidism not captured by traditional DXA measurement. Concerning the kidney, the most common consequences of excessive parathyroid hormone secretion are hypercalciuria and kidney stones; however, the exact pathogenesis of urinary stone formation is still unknown. The 2013 International Congress on the management of Asymptomatic Primary Hyperparathyroidism, emphasized the role of imaging techniques for early discovery of both skeletal and renal complications in asymptomatic patients. Gastrointestinal manifestations include acid-peptic disease, constipation, pancreatitis and gall stone disease. More studies are needed in this area to find the exact pathophysiological mechanism underlying these manifestations and the effect of parathyroid surgery.

Calcifediol (25-hydroxyvitamin D) improvement and calcium-phosphate metabolism of alendronate sodium/vitamin D3 combination in Chinese women with postmenopausal osteoporosis: a post hoc efficacy analysis and safety reappraisal

BACKGROUND

Vitamin D (VD) insufficiency or deficiency is a frequent comorbidity in Chinese women with postmenopausal osteoporosis (PMO). The present study aimed to investigate 25-hydroxyvitamin D [25(OH) D] improvement and calcium-phosphate metabolism in Chinese PMO patients treated with 70 mg of alendronate sodium and 5600 IU of vitamin D₃ (ALN/D5600).

METHODS

Chinese PMO women (n = 219) were treated with 12-month ALN/D5600 (n = 111) or calcitriol (n = 108). Changes in 25(OH) D at month 12 were post hoc analyzed by the baseline 25 (OH) D status using the longitudinal analysis. The main safety outcome measures included serum calcium and phosphate and 24-h urine calcium, and the repeated measures mixed model was used to assess the frequencies of the calcium-phosphate metabolic disorders.

RESULTS

Absolute change in mean serum 25(OH) D level was the greatest in VD-deficient patients and least in VD-sufficient patients at months six and 12 (both, P < 0.01). Serum calcium level remained significantly lower in the ALN/D5600 treatment group than in the calcitriol treatment group throughout the 12 months. Mean 24-h urine calcium slightly increased in the ALN/D5600 treatment group and significantly increased in the calcitriol treatment group (+ 1.1 and + 0.9 mmol/L at months six and 12; both, P < 0.05). Calcitriol treatment was associated with more frequent hypercalciuria at month six (9.4% vs. 18.5%, P = 0.05), but not at month 12 (12.3% vs. 13.0%).

CONCLUSION

Baseline VD status predicted 25(OH) D improvement in PMO patients on 12-month ALN/D5600 treatment. The daily use of 0.25 μg of calcitriol was associated with more frequent hypercalciuria at month six, compared to ALN/5600 treatment, necessitating the safety re-evaluation of calcitriol at a higher dosage.

Study of Urine Composition of Patients With Recurrent Nephrolithiasis in Lorestan, Iran

INTRODUCTION

Nephrolithiasis is one of the most common urinary tract diseases. After the first episode of urinary calculus, the risk of recurrence is nearly 40% to 50% at 5 years. Nephrolithiasis is a systemic disease that is associated with some metabolic disorders. This study aimed to provide a picture of the frequency of metabolic abnormalities in patients with nephrolithiasis from west part of Iran.

MATERIALS AND METHODS

Patients with recurrent urinary tract calculi referred to the Nephrology-Urology Clinics in Khorramabad city were recruited. After collection of demographic data of all the patients, 24-hour urine and blood samples were taken to measure biochemical factors.

RESULTS

Of the 232 participants, 125 were males and 107 were females. Hyperoxaluria was seen in 93 (40.1%) of the participants, hypercalciuria in 55 (23.7%), hypocitraturia in 58 (25%), and hyperuricosuria in 33 (14.9%). Hyperoxaluria in the males was significantly more frequent than in the female patients. There were no significant differences between the two groups in other urinary metabolic disorders.

CONCLUSIONS

Patients with nephrolithiasis from Lorestan province may have metabolic characteristics varying from those of regions; ethnicity may be a possible reason. Variation of dietary regimens, such as the amount of meat or vegetable in the diet that can change oxalate, calcium, or citrate of urine, might have influenced the results. Time of sampling is another factor. Population-specific studies are helpful to health care providers for preventive planning for nephrolithiasis.

Mineral Disorders in Adult Inpatients Receiving Parenteral Nutrition. Is Older Age a Contributory Factor?

BACKGROUND

Parenteral nutrition (PN)-dependent adults and elderly individuals who are admitted to hospital treatment are potentially susceptible to mineral disorder complications due to depleted physiological reserves, loss of lean body mass, and increased fat mass, thus worsening inflammation.

AIM

The purpose of this study is to evaluate the prevalence of hypophosphatemia, hypokalemia, and hypomagnesaemia prior and within the first 7 days of PN infusion. Furthermore, whether malnutrition and old age are associated with these disorders was also investigated.

METHODS

This study included a historical cohort of adult patients, and 1,040 patients whose information was prospectively entered in the database were evaluated.

RESULTS

Of the 781 patients, 27.3% were ≥65 years, 80.9% had undergone surgical treatment, 74.3% were in the intensive care unit, and 17.9% died during the hospitalization period. About 17.1% patients were malnourished. Protein energy malnutrition (PEM) was observed in 31.9% of the elderly patients and 27.1% of adults in general. Hypophosphatemia, hypokalemia, and hypomagnesemia were more prevalent before the start of PN infusion (D0: 214 [18.4%]), and new events were more common during the first 2 days of PN infusion (D1: 283 [23.1%]; D2: 243 [20.1%]. Elderly patients were more susceptible to developing hypophosphatemia (odds ratio [OR]: 1.69; 95% confidence interval [CI]: 1.29-2.19; p<0.001). Patients with PEM were also more susceptible to hypophosphatemia (OR: 3.75; 95% CI: 1.13-12.47; p=0.036).

CONCLUSION

Hypophosphatemia, hypokalemia, and hypomagnesemia were frequently observed in hospitalized adults and elderly patients before and particularly during the first 2 days of PN infusion. Elderly patients and patients with PEM are more susceptible to developing hypophosphatemia.

Kidney Calculi: Pathophysiology and as a Systemic Disorder

The pathophysiology of urinary stone formation is complex, involving a combination of metabolic, genetic, and environmental factors. Over the past decades, remarkable advances have been emerged in the understanding of the pathogenesis, diagnosis, and treatment of calcium kidney calculi. For this review, both original and review articles were found via PubMed search on pathophysiology, diagnosis, and management of urinary calculi. These resources were integrated with the authors' knowledge of the field. Nephrolithiasis is suggested to be associated with systemic disorders, including chronic kidney insufficiency, hematologic malignancies, endocrine disorders, autoimmune diseases, inflammatory bowel diseases, bone loss and fractures, hypertension, type 2 diabetes mellitus, metabolic syndrome, and vascular diseases like coronary heart diseases and most recently ischemic strokes. This is changing the perspective of nephrolithiasis from an isolated disorder to a systemic disease that justifies further research in understanding the underlying mechanisms and elaborating diagnostic-therapeutic options.

Blood pressure and urolithiasis in children

INTRODUCTION

Urolithiasis is a condition that is most commonly found in adults, but is becoming increasingly prevalent in children. Little is known about the relationship between blood pressure (BP) and urolithiasis in children.

OBJECTIVES

The aim was to evaluate the relationship between urolithiasis and BP, and to determine the association of BP with 24-h urine parameters in children.

METHODS

We retrospectively analyzed BP and 24-h urine data from children <18 years with and without urolithiasis from 2004 to 2015 at a single tertiary center. Children with a diagnosis of non-glomerular hematuria without history of urolithiasis were chosen as the control group. Non-stone formers were excluded if they presented with any abnormal 24-h urine data or kidney disease. Casual BP, BP index (BPi), and 24-h urine parameters were compared between groups using t-tests. Multiple regression analyses adjusting for age, sex and body mass index (BMI) z-score evaluated the association of BP with urolithiasis and urine electrolytes.

RESULTS

The urolithiasis group (N = 71) was significantly older, taller and heavier than the non-stone former group (N = 53) (Table). Systolic BP and diastolic BP in stone formers were significantly greater than in non-stone formers, respectively (p = 0.019). Additionally, systolic BPi was significantly higher in the urolithiasis group (p = 0.03) but there was no significant difference in diastolic BPi (p = 0.45). Urolithiasis was a significant predictor of systolic BPi in the adjusted model (β = 0.04, 95% CI 0.001-0.07). In stone formers, systolic BP and systolic BPi were directly associated with 24-h urine sodium, oxalate/1.73 m², and uric acid (all p < 0.05). Urine calcium was not associated with any BP parameter.

DISCUSSION

The findings are consistent with previous studies in adults that examined the correlation between blood pressure and kidney stones. The results of this study also showed that blood pressure was positively associated with urine sodium, oxalate, and uric acid. Interestingly, contrary to adult literature, our hypothesis which postulated that blood pressure would be associated with an increase in urine calcium was not supported by our findings. The small sample size is a study limitation and the use of healthy controls as a comparison would have been ideal.

CONCLUSIONS

Blood pressure was directly associated with urolithiasis children. Greater BP values were also associated with abnormalities in 24-h urine oxalate, uric acid, and sodium values. Interestingly, BP was not associated with urine calcium in this population.

Calcium and bone homeostasis in heterozygous carriers of CYP24A1 mutations: A cross-sectional study

BACKGROUND

Bi-allelic CYP24A1 mutations can cause idiopathic infantile hypercalcemia (IIH), adult-onset nephrocalcinosis, and possibly bone metabolism disturbances. It is currently unclear if heterozygous carriers experience clinical problems or biochemical abnormalities. Our objective is to gain insight in the biochemical profile and health problems in CYP24A1 heterozygotes.

STUDY DESIGN

Cross-sectional evaluation of participants. Data of previously reported carriers are reviewed.

SETTING AND PARTICIPANTS

Outpatient clinic of a tertiary care hospital. Participants were eight family members of an infant with a well-characterized homozygous CYP24A1 mutation c.1186C>T p.(Arg396Trp).

OUTCOMES

Serum vitamin D metabolites. Symptoms or biochemical signs of hypercalcemia, hypercalciuria or nephrocalcinosis. Bone health in heterozygous as compared to wild type (WT) subjects.

MEASUREMENTS

Genotyping by Sanger sequencing; vitamin D metabolites by liquid chromatography tandem mass spectrometry; renal, calcium and bone markers by biochemical analyses; presence of nephrocalcinosis by renal ultrasound; bone health by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography.

RESULTS

Six participants were heterozygous carriers of the mutation. None of the heterozygous subjects had experienced IIH. One had a documented history of nephrolithiasis, two others had complaints compatible with this diagnosis. No major differences between WT and heterozygous subjects were found regarding bone health, serum or urinary calcium or 25OHD/24,25(OH)2D ratio. Literature reports on three out of 33 heterozygous cases suffering from IIH. In all three, the 25OHD/24,25(OH)2D ratio was highly elevated. Nephrocalcinosis was frequently reported in family members of IIH cases.

LIMITATIONS

Small sample size, lack of a large control group.

CONCLUSIONS

Our and literature data suggest that most heterozygous CYP24A1 mutation carriers have a normal 25OHD/24,25(OH)2D ratio, are usually asymptomatic and have a normal skeletal status but may possibly be at increased risk of nephrocalcinosis. A review of the available literature suggests that an elevated 25OHD/24,25(OH)2D ratio may be associated with symptoms of IHH, irrespective of carrier status.

Hypercalciuria May Persist After Successful Parathyroid Surgery and It Is Associated With Parathyroid Hyperplasia

CONTEXT

Hypercalciuria is frequently found in primary hyperparathyroidism (1HPT) and, although it generally normalizes after successful parathyroidectomy, may persist in some patients. The factors associated with persistent calcium renal leak (cRL) have not been clarified.

OBJECTIVE

The purpose of this study was to determine the prevalence of cRL in our 1HPT population and investigate cRL-related factors.

DESIGN

This was a retrospective longitudinal study.

SETTING

The study was conducted in an outpatient setting.

PATIENTS/INTERVENTION

The participants were 95 patients with 1HPT successfully operated on who had a normal estimated glomerular filtration rate.

MAIN OUTCOME MEASURES

The biochemical parameters of calcium metabolism and bone mineral density (BMD) measured by dual-X-ray absorptiometry before and 24 months after surgery were assessed. All histological findings were recorded.

RESULTS

The prevalence of hypercalciuria before and after surgery was 74% and 32%, respectively. Before, surgery patients with cRL showed lower calcium and higher phosphate levels than those without cRL (10.9 ± 0.6 vs 11.4 ± 0.8 mg/dL [2.7 ± 0.2 vs 2.8 ± 0.2 mmol/L], P = .01 and 2.6 ± 0.5 vs 2.4 ± 0.4 mg/dL [0.84 ± 0.2 vs 0.77 ± 0.1 mmol/L], P = .04, respectively), whereas 24-h calciuria levels and the prevalence of 1HPT complications (osteoporosis, renal stones, and hypertension) were comparable. After surgery, serum calcium, phosphate, and PTH levels were comparable between patients with and without cRL. The prevalence of the histological finding of parathyroid hyperplasia was higher in patients with cRL (50%) than in patients without cRL (22%) (P = .01). The presence of cRL was independently associated with presurgery hypercalciuria (odds ratio, 4.71; 95% confidence interval, 1.18-18.8; P = .03) and parathyroid hyperplasia (odds ratio, 3.52; 95% confidence interval, 1.31-9.43; P = .01). Only patients without cRL had improved BMD at the spine (P = .04), total femur (P = .01), and femoral neck (P = .01).

CONCLUSIONS

cRL is present in 30% of patients with 1HPT after successful surgery, and it is associated with parathyroid hyperplasia before surgery and the lack of improvement in BMD after surgery.

A London experience 1995-2012: demographic, dietary and biochemical characteristics of a large adult cohort of patients with renal stone disease

BACKGROUND

Kidney stone disease has an estimated prevalence of around 10%. Genetic as well as environmental factors are thought to play an important role in the pathogenesis of renal stones.

AIM

The aim of our study was to analyse and report the main characteristics of patients with kidney stones attending a large UK metabolic stone clinic in London between 1995 and 2012.

DESIGN

A cross-sectional study.

METHODS

Analysis of data from stone formers attending the University College and Royal Free Hospitals' metabolic stone clinic from 1995 to 2012. Demographic, clinical, dietary and biochemical characteristics have been summarized and analysed for men and women separately; trends over time have also been analysed.

RESULTS

Of the 2861 patients included in the analysis, 2016 (70%) were men with an average age of 47 years (range 18-87 years) and median duration of disease of 6 years (range 0-60 years). The prevalence of low urine volume, hypercalciuria, hyperoxaluria, hyperuricosuria and hypocitraturia was 5.6%, 38%, 7.9%, 18% and 23%, respectively. The prevalence of several risk factors for stones increased over time. The majority of stones were mixed, with around 90% composed of calcium salts in varying proportion.

CONCLUSION

Our findings in a large cohort of patients attending a London-based stone clinic over the past 20 years show differences in distributions of risk factors for stones for men and women, as well as metabolic profiles and stone composition. The impact of most risk factors for stones appeared to change over time.

Proton pump inhibitors and hospitalization with hypomagnesemia: a population-based case-control study

BACKGROUND

Some evidence suggests that proton pump inhibitors (PPIs) are an under-appreciated risk factor for hypomagnesemia. Whether hospitalization with hypomagnesemia is associated with use of PPIs is unknown.

METHODS AND FINDINGS

We conducted a population-based case-control study of multiple health care databases in Ontario, Canada, from April 2002 to March 2012. Patients who were enrolled as cases were Ontarians aged 66 years or older hospitalized with hypomagnesemia. For each individual enrolled as a case, we identified up to four individuals as controls matched on age, sex, kidney disease, and use of various diuretic classes. Exposure to PPIs was categorized according to the most proximate prescription prior to the index date as current (within 90 days), recent (within 91 to 180 days), or remote (within 181 to 365 days). We used conditional logistic regression to estimate the odds ratio for the association of outpatient PPI use and hospitalization with hypomagnesemia. To test the specificity of our findings we examined use of histamine H2 receptor antagonists, drugs with no causal link to hypomagnesemia. We studied 366 patients hospitalized with hypomagnesemia and 1,464 matched controls. Current PPI use was associated with a 43% increased risk of hypomagnesemia (adjusted odds ratio, 1.43; 95% CI 1.06-1.93). In a stratified analysis, the risk was particularly increased among patients receiving diuretics, (adjusted odds ratio, 1.73; 95% CI 1.11-2.70) and not significant among patients not receiving diuretics (adjusted odds ratio, 1.25; 95% CI 0.81-1.91). We estimate that one excess hospitalization with hypomagnesemia will occur among 76,591 outpatients treated with a PPI for 90 days. Hospitalization with hypomagnesemia was not associated with the use of histamine H2 receptor antagonists (adjusted odds ratio 1.06; 95% CI 0.54-2.06). Limitations of this study include a lack of access to serum magnesium levels, uncertainty regarding diagnostic coding of hypomagnesemia, and generalizability of our findings to younger patients.

CONCLUSIONS

PPIs are associated with a small increased risk of hospitalization with hypomagnesemia among patients also receiving diuretics. Physicians should be aware of this association, particularly for patients with hypomagnesemia. Please see later in the article for the Editors' Summary.

Hypercalciuria in school-aged children of Rasht: a single-center study

Hypercalciuria is the most common identifiable metabolic cause of calcium kidney calculus disease. Idiopathic hypercalciuria is defined as hypercalciuria with normal serum electrolytes levels in the absence of any known underlying disease responsible for increased urinary calcium excretion. The aim of the present survey was to study the prevalence of urinary tract signs and symptoms of idiopathic hypercalciuria in a healthy group of primary school children living in Rasht, a city in north of Iran. The prevalence of idiopathic hypercalciuria in our study was estimated to be 5.6%. This is a first report of idiopathic hypercalciuria in Guilan province.

Association of elevated urinary cadmium with urinary stone, hypercalciuria and renal tubular dysfunction in the population of cadmium-contaminated area

Excessive urinary calcium is the major risk of renal tubular dysfunction and urinary stone formation. We examined the association of elevated urinary cadmium with urinary stones and chronic kidney disease (CKD) in 1,085 study residents of 13 cadmium-contaminated villages. Elevated urinary cadmium was significantly correlated with urinary stone and CKD. Elevated urinary cadmium appeared to increase risk of urinary stone and CKD; ORs and 95 % CIs were 2.73 (1.16, 6.42) and 3.73 (2.50, 5.57) after adjusting for other co-variables. This study revealed that elevated urinary stone and CKD induced by cadmium might increase the risk of urinary stone and CKD.

Incidence of hypercalcemia, hypercalciuria and related factors in patients treated with recombinant human parathyroid hormone (1-84)

AIM

The aim of this paper was to determine the incidence of hypercalcemia and hypercalciuria (and related factors) in 22 postmenopausal women with osteoporosis treated with PTH (1-84) in daily practice.

METHODS

Osteoporosis was defined as history of osteoporotic fracture or a T score less than -3 SD on bone densitometry. Patients were treated with PTH (1-84), 100 mcg/daily, for 12 months. Clinical and laboratory data at baseline and after 6 months of treatment were assessed.

RESULTS

The mean age was 71.9 years. The incidence of hypercalcemia and the hypercalciuria were 6 events. Increase in serum calcium levels showed a statistically significant correlation with 24-hour urinary calcium (rho [ρ]=0.83, P<0.001), serum alkaline phosphatase (ρ=0.76, P=0.001), total proteins (ρ=0.77, P=0.005), and β-CTx (ρ=0.82, P=0.002). On the other hand, 24-hour urinary calcium excretion correlated significantly with β-CTx (ρ=0.83, P=0.002), alkaline phosphatase (ρ=0.73, P=0.005), total proteins (ρ=0.73, P=0.02), and serum phosphate (ρ=0.58, P=0.04). When the group of patients with and without hypercalcemia were compared, there were statistically significant differences in increases of β-CTx and baseline β-CTx values, whereas the group of patients with and without hypercalciuria showed significant differences in serum calcium increases and baseline values of T score at the femoral neck.

CONCLUSION

The incidence of hypercalcemia and hypercalciuria after treatment with PTH (1-84) is similar to that expected according to the product's technical specifications. There was a significant correlation between increases of serum calcium, urinary calcium excretion, serum alkaline phosphatase, and β-CTx after treatment with PTH (1-84). Baseline β-CTx values were significantly lower in patients who developed hypercalcemia than in those with normal serum calcium levels.

Biochemical risk factors for stone formation in healthy school children

Prevalence of urolithiasis in childhood is increasing. The wide geographic variation in the incidence of lithiasis in childhood is related to climatic, dietary, and socioeconomic factors. Many children with stone disease have a metabolic abnormality. In Southeast Asia, urinary calculi are endemic and are related to dietary factors. The main aim of this study was to determine the prevalence of renal stone, urine metabolic abnormality, control of blood pressure and demographic character in elementary school children of Qom. A cross sectional study was performed on 110 primary school children (56 girls and 54 boys) aged 7 to 11 years old. Demographic data such as age, height, weight were gathered, and systolic and diastolic blood pressure, Urine analysis and culture, urinary levels of calcium, creatinine, phosphorus, magnesium, sodium, potassium, uric acid, cystine, citrate, oxalate, protein and sonographic findings were evaluated. The mean (±SD) of age was 8.85±1.51 years. Only one child had renal stone (1%), but the prevalence of abnormal renal sonography was 7%. The most prevalent urine metabolic abnormalities were hypercalciuria (23%) and hypocitraturia (100%). 11.2% of children had positive urine culture that all were female. The prevalence of high blood pressure was 7.1% for girls and 11.1% for boys. The prevalence of renal stone in children in this study was 1%, which means the accurate judgment about the prevalence of renal stone in Qom city needs more comprehensive studies. Similar to other studies in Iran this study shows that the prevalence of hypercalciuria is significantly higher comparing to other countries, it may be associated with excessive intake of sodium.

Clinical correlation between hypercalciuria and nocturnal enuresis

Hypercalciuria may present with dysuria, urinary incontinence and nocturnal enuresis (NE). To determine the frequency of hypercalciuria in NE patients and normally continent children, we studied 122 consecutive pre- school children with NE referred to our nephrology clinic during two years, from September 2007 to August 2009. We measured the 24- hour urinary calcium. Furthermore, we compared the response to nasal desmopressin in hypercalciuric and normocalciuric patients. Hypercalciuria was found in 26 (21.3 %) of the NE patients as compared with five (4.5%) of 110 continent children [(P < 0.001), OR = 5.68 (95% CI, 2.1-15.4)]. In addition, the mean 24- hour urine calcium/body weight ratio (24h- U- Ca/Bw) was higher in NE patients, 3.04 ± 1.54 vs. 2.57 ± 0.9, respectively (P = 0.005). Wet nights per week in both NE patients with and without hypercalciuria at the first visit ranged from two to seven (median: 6 and 7, respectively), and the mean overall success rate of the nasal desmopressin therapy was 83.3% and 90%, respectively (P > 0.05). The response to desmopressin above 90% occurred within one month of therapy without a significant change in the levels of hypercalciuria. We conclude that these results suggest that hypercalciuria has a significant association with NE and does not interfere with the desmopressin therapy.

Nutritional aspects of idiopathic nephrolithiasis in Tunisian children

OBJECTIVE

We evaluated the metabolic and the nutritional aspects of 134 urolithiasic children, in order to outline the risk factors that contribute to idiopathic stone formation in children.

MATERIAL AND METHODS

In this prospective study 134 children (56 females, 78 males) with renal calculi were evaluated. The age of the patients ranged 6 months to 16 years. A dietary survey was performed on every child. All patients were investigated with respect to stone localization, serum and urine risk factors. Statistical analysis of data was carried out using software SPSS 11.0 for Windows. Statistical significance was determined using chi-square test.

RESULTS

Hypercalciuria was the commonest risk factor detected in this group (28.3%). A decrease of water intake was noted in all age group specially in the rural area (549.6 vs 1150.6 ml/day), and an increase in animal protein intake in 17 cases (mean 1.9 g/kg). In addition, increased intake of starchy foods and food with high oxalate content (sorgum) was observed in our 10-16 years group (51%). Calcium oxalate monohydrate represents the principal component of idiopathic stone (58.2%), which is more frequent in children (68%) than infants (51.7%) (P < 0.02).

CONCLUSIONS

The high frequency of idiopathic urolithiasis highlights the influence of dietary habit in stone formers in our country. The increase in calcium oxalate stones in school-age children confirms the change in the etiology of urolithiasis according to age.

Hypercalciuria in Jahrom's school-age children: what is normal calcium-creatinine ratio?

INTRODUCTION

The purpose of this study was to determine normal reference values for urine calcium-creatinine (Ca/C) ratio in Iranian children of Jahrom, in south-east of Iran.

MATERIALS AND METHODS

A total of 1068 school-age children were included by stratified clustered random sampling from primary schools of Jahrom, Iran, between March 2008 and May 2008. Nonfasting random urine specimens from each subject were analyzed for calcium and creatinine concentrations.

RESULTS

The mean ratio of urine Ca/C in all children was 0.123 +/- 0.106 (range, 0.01 to 2.25), and the 95th percentile value was 0.25. Nonfasting Ca/C ratios were not significantly different between the boys and the girls. The Ca/C ratio was highest in 9-year-old children (mean, 0.132 +/- 0.11). Based on the 95 percentile value of urine Ca/C (> 0.25) in the present study, 5.1% of the children in Jahrom were hypercalciuric. The prevalence of hypercalciuria differed with age (P = .06), and the most prevalent rate was observed in 9-year-old group (9.3%).

CONCLUSIONS

We provided a reference value for urine Ca/C ratio in south-east Iranian children. A child's age and ethnicity should be taken into consideration when assessing the urinary solute-creatinine ratios.

[Long term renal outcome of children born preterm: a regular follow-up is needed]

Most of the published studies evaluating renal prognosis of children born very preterm found asymptomatic abnormalities (blood pressure, glomerular filtration rate GFR, hypercalciuria, decreased renal size, microalbuminuria...) during childhood or early adulthood. The objective of this study was to assess renal function (inulin clearance) in a prospective single-center cohort of children born preterm between 1998 and 2001 (< 30 GW,<1000 g) and to identify neonatal risk factors for renal abnormalities during childhood. Fifty children were included in the final part of the study. At a mean age of 7.6 years, no patient had arterial hypertension or chronic kidney disease, but mean centile for diastolic blood pressure was higher than expected and ultrasounds revealed small-sized kidneys compared to controls. The average GFR was 112 ml/min per 1.73 m(2) (91-158). Two children had microalbuminuria, two had hypercalciuria and one had nephrocalcinosis. Children with intra- or extra-uterine growth retardation had an impaired GFR compared to children with appropriate pre- and post-natal growth (107 vs. 110 vs. 125 ml/min per 1.73 m(2), p<0.05). Children with bronchopulmonary dysplasia had a significant higher microalbuminuria. In conclusion, findings of borderline blood pressure and reduced kidney size in children born preterm can be regarded as markers of reduced nephron number. Long term renal follow-up (blood pressure, serum creatinine, urine albumin / creatinine ratio) should be performed in all children born very preterm, with an early referring when abnormalities are highlighted.

Metabolic factors associated with urinary calculi in children

INTRODUCTION

We aimed to identify metabolic and anatomical abnormalities present in children with urinary calculi.

MATERIALS AND METHODS

Metabolic evaluation was done in 142 pediatric calculus formers. Evaluation included serum biochemistry; measurement of daily excretion of urinary calcium, uric acid, oxalate, citrate, and magnesium (in older children); and measurement of calcium, uric acid, oxalate, and creatinine in random urine samples in nontoilet-trained patients. Urinary tests for cystinuria were also performed. All of the patients underwent renal ultrasonography.

RESULTS

Sixty-one patients (42.7%) had metabolic abnormalities. Anatomical abnormalities were found in 12 patients (8.4%). Three children (2.1%) had infectious calculi, and 3(2.1%) had a combination of metabolic and anatomic abnormalities. In 66 children (46.2 %) we did not find any reasons for calculus formation (idiopathic). Urinalysis revealed hypercalciuria in 25 (17.6%), hyperuricosuria in 23 (16.1%), hyperoxaluria in 17 (11.9%), cystinuria in 9 (6.3%), hypocitraturia in 3 (2.1%), and low urinary magnesium level in 1 (0.7%) patients. Sixteen patients (11.2%) had mixed metabolic abnormalities.

CONCLUSIONS

Metabolic abnormalities are common in pediatric patients with urinary calculi. In our study, calcium and uric acid abnormalities were the most common, and vesicoureteral reflux seemed to be the most common urological abnormality which led to urinary stasis and calculus formation.

The effect of recombinant PTH(1-34) and PTH(1-84) on serum ionized calcium, 1,25-dihydroxyvitamin D, and urinary calcium excretion: a pilot study

We investigated the frequency of hypercalcemia and/or hypercalciuria following parathyroid hormone (PTH) 1-34 and 1-84 administration in a crossover trial. Ten postmenopausal osteoporotic women previously treated with bisphosphonates were subdivided into two groups of five patients each. A 24-h urine collection to determine baseline calcium (Ca) and creatinine (Cr) the day before administration of PTH was followed by determination of serum ionized Ca (Ca(2+)), Cr, 25(OH)D, and 1,25(OH)(2)D at baseline. Thereafter, 100 mcg of PTH(1-84) or 20 mcg of PTH(1-34) was administered. A 24-h urinary collection and blood samples 2, 4, and 24-h after each PTH administration were again taken. One week after the first PTH administration patients were rechallenged with the second PTH. The PTH peptides did not differ with respect to changes in Ca(2+) at 2, 4, and 24 h postinjection; at the last time point the values were virtually identical to the initial values. There was no difference in urinary Ca on the day following PTH injection compared to baseline, in terms both of Ca/Cr and of Ca excretion. The two PTH peptides did not differ with respect to changes in 1,25(OH)(2)D at 2, 4, and 24 h considering both the absolute values and the percent changes with respect to baseline (24-h 1-84 = 125.6 + or - 58.6 pg/ml, 153% increase; 1-34 = 124.1 + or - 64.7, 130%). Our results indicate no difference in postinjection serum Ca(2+), 1,25(OH)(2)D, or urinary Ca excretion after a single dose of either PTH(1-84) or PTH(1-34) in patients previously treated with bisphosphonates.

Spontaneous urinary calcium oxalate crystallization in hypercalciuric children

Idiopathic hypercalciuria is the most important predisposing risk factor for calcium oxalate (CaOx) renal stone formation. We assessed the associations between spontaneous CaOx crystallization based on the Bonn Risk Index (BRI), urinary pH, calciuria, oxaluria, and citraturia in 140 Caucasian patients with hypercalciuria, aged 4-17 years, and compared the findings with those in 210 normocalciuric controls. Of the 140 hypercalciuric patients, 58 had renal stones, and 82 had recurrent erythrocyturia, renal colic, or urinary obstructive symptoms-but without stones. Urinary ionized calcium ([Ca(2+)]) levels were measured using a selective electrode, while the onset of crystallization was determined using a photometer and titration with 40 mmol/L ammonium oxalate (Ox(2-)). The calculation of the BRI was based on the [Ca(2+)]:Ox(2-) ratio. The BRI values were 12-fold higher in hypercalciuric children than in healthy controls, but no differences were found in the BRI between subjects with urinary stones and those with urolithiasis-like symptoms. An increased BRI suggested an association with hypercalciuria, lower urinary pH, hypocitraturia, and hypooxaluria. These data indicate that hypercalciuria is an important factor associated with increased urinary CaOx crystallization, although the causal pathways need further investigation. Determination of the BRI in children with hypercalciuria may improve the risk assessment of kidney stones.

Hypercalciuria in pediatric patients with ureteropelvic junction obstruction is of genetic origin

OBJECTIVE

Genitourinary tract malformations are associated with urolithiasis. Hypercalciuria has been described in children with ureteropelvic junction obstruction (UPJO), although the etiology of this metabolic abnormality remains unknown. This study was conducted to find out whether children with UPJO have a higher prevalence of hypercalciuria and whether their family members are affected by hypercalciuria and/or urolithiasis.

MATERIAL AND METHODS

We studied the prevalence of hypercalciuria and urolithiasis in 27 children (14 males, 13 females) with UPJO and their parents.

RESULTS

One patient had a history of renal colic, whereas imaging studies showed macroscopic renal lithiasis in two patients and calyceal microlithiasis in four. Hypercalciuria was found in 17/27 children (63%), 15 of whom (88%) had a familial history of urolithiasis: seven families in first-degree relatives, six in second-degree relatives and two in other relatives. Concerning the 10 children without hypercalciuria, seven of them (70%) had a family history of urolithiasis: four in first-degree relatives and three in second-degree relatives. The prevalences of both urolithiasis and hypercalciuria were not influenced by gender.

CONCLUSIONS

Urolithiasis is associated with hypercalciuria in patients with UPJO. In accordance with previous data, our results show that the prevalence of hypercalciuria is greater in pediatric patients with UPJO than in the general population. Likewise, the prevalence of urolithiasis in the families of these children is also higher than that in the general population. Hypercalciuria was inherited as an autosomal dominant trait.

Alendronate/vitamin D3 70 mg/2800 IU with and without additional 2800 IU vitamin D3 for osteoporosis: results from the 24-week extension of a 15-week randomized, controlled trial

Although vitamin D supplementation is a fundamental part of osteoporosis treatment, many patients do not regularly take adequate amounts. A once-weekly (OW) alendronate (ALN) preparation that includes 2800 IU of vitamin D3 in a single combination tablet (ALN+D2800) is available for treating patients and ensuring intake of vitamin D that is consistent with existing guidelines. This randomized, double-blind study extension was conducted to evaluate the safety and tolerability of ALN+D2800 and ALN+D2800 plus an additional 2800 IU vitamin D3 single tablet supplement (ALN+D5600) administered for 24 weeks in men and postmenopausal women with osteoporosis previously treated OW for 15 weeks with either ALN or ALN+D2800. The primary endpoint was the proportion of participants who developed hypercalciuria (defined as a 24-hour urine calcium >300 mg in women or >350 mg in men and an increase of >25% versus randomization baseline) at week 39. The key secondary endpoint was the proportion of participants with vitamin D insufficiency (serum 25(OH)D <15 ng/mL [37.4 nmol/L]) at the end of the study. Hypercalciuria incidence (4.2% [ALN+D5600] vs. 2.8% [ALN+D2800]), did not differ between groups (p = 0.354). No participants developed hypercalcemia. Among the participants with vitamin D insufficiency at the week 0 baseline, the prevalence of insufficiency at the end of the study was reduced by 92% in the ALN+D5600 group and by 86% in the ALN+D2800 group. The incidences of clinical adverse experiences, including drug-related adverse experiences, were similar in both groups. In subjects previously treated with ALN+D2800 for 15 weeks, the addition of 2800 IU D3 for 24 weeks did not produce hypercalcemia nor increase the risk of hypercalciuria.

Hypercalciuria and recurrent urinary tract infections among children in Zahedan, Iran

OBJECTIVES

To evaluate the association of idiopathic urinary tract infection (UTI) and hypercalciuria in Iranian children.

METHODS

Seventy children with episodes of UTI, and 70 healthy controls were studied. Random urine calcium-creatinine ratio (UCa/Cr) and plasma calcium were measured.

RESULTS

Hypercalciuria was found significantly higher (p<0.05) in UTI patients (30%) than normal subjects (11.4%). The results showed that frequency of hypercalciuria is higher in females (42.9%) than males (17.1%).

CONCLUSION

The investigation of urinary calcium excretion in children with recurrent UTI is recommended.

Idiopathic osteoporosis in premenopausal women. Clinical characteristics and bone remodelling abnormalities

OBJECTIVE

Osteoporosis is infrequent in young premenopausal women and is often associated with secondary disorders. However, idiopathic osteoporosis may be found in this setting and few data are known on this condition. Therefore, the aim of this study was to analyse the clinical characteristics and bone remodelling abnormalities in premenopausal women with idiopathic osteoporosis.

METHODS

28 premenopausal women with idiopathic osteoporosis (aged 38.3+/-7.6 years) were included. The patients had one or more fragility fractures and/or decreased bone mass (z-score <-2 in the lumbar spine or femur). In all patients, secondary causes of osteoporosis were excluded and previous skeletal fractures, family history and risk factors for osteoporosis were recorded. In addition, bone mineral density at the lumbar spine and hip, spinal x-rays, and laboratory tests including PTH, 25-hydroxyvitamin D, 1,25 (OH)<inf>2</inf> vitamin D and urinary calcium excretion were measured. Bone markers such as serum bone alkaline phosphatase (bone AP) and P1NP, and urinary hydroxyproline (HYP), NTx and CTx were measured and results were compared with those observed in a control group of 28 healthy premenopausal women.

RESULTS

46% of the patients had previous fragility fractures, 53% had family history of osteoporosis, 36% had associated hypercalciuria and 30% had a BMI <20 Kg/m². Patients with idiopathic osteoporosis had increased bone resorption markers (NTx and HYP) but normal bone formation markers when compared with healthy controls. No significant differences in the clinical and biochemical parameters were observed between patients with or without hypercalciuria.

CONCLUSION

Young women with idiopathic osteoporosis have an increased bone resorption without changes in bone formation when assessed by biochemical markers.

Risk factors for nephrolithiasis in children

OBJECTIVE

The aim of this study is to evaluate the clinical outcome in children with urinary calculi, to detect risk factors for nephrolithiasis in childhood.

MATERIAL AND METHODS

This retrospective study comprised 62 pediatric nephrolithiasis patients who have come for routine follow-up visits between the dates of January 2002-August 2006 (48% girls and 52% boys).

RESULTS

The mean age of the patients was 8.8 +/- 4.5 years (1-16 years). Hypercalciuria was found in 25 (40%) patients. The mean urinary calcium excretion for hypercalciuric patients was 5.7 +/- 1.2 mg/kg (4.8 mg/kg per day). In our hypercalciuric patients 15 (60%) children had abdominal or flank pain, seven (28%) patients macroscopic hematuria and three (12%) dysuria. Hypocitraturia is the second important risk factor for nephrolithiasis. Urinary calcium excretion showed a positive correlation with the stone size (r = 0.482, P = 0.043). A positive correlation was found between recurrent urinary tract infection (UTI) and hypercalciuria (r = 0.528, P = 0.017). Urinary citrate excretion showed a negative correlation with recurrent UTI (r = -0.503, P = 0.024). Hyperuricaciduria, hyperoxaluria were found to have no effect on the stone size and UTI of the patients. Stones were disintegrated with ESWL in two patients, endoscopic interventions were used in one patient and two underwent an open surgical procedure.

CONCLUSION

All children with nephrolithiasis should have a metabolic screen. Children with a positive family history and consanguinity should be followed carefully with respect to metabolic abnormalities.

Hypercalciuria is the main renal abnormality finding in Human Immunodeficiency Virus-infected children in Venezuela

Kidney involvement in children with Human Immunodeficiency Virus (HIV) infection is increasing in prevalence in parallel with the longer survival of HIV-infected patients and the side-effects of new antiretroviral drugs. However, there are only a few reports describing renal tubular disorders in HIV+ children. This is a cross-sectional, case series study evaluating kidney disease in 26 Venezuelan HIV-infected children. The study cohort consisted of 15 girls and 11 boys, with a median age of 5.9 years (25-75th percentile: 3.6-7.8), who had been treated with antiretrovirals for 2.8 +/- 0.4 years, Overall, the patients were short for their age and gender (Z-height: -3.1; 25-75th percentile: -4.94 to -1.98), and 15 showed signs of mild to moderate malnutrition. All of the children had a normal estimated glomerular filtration rate (136 +/- 22.6 ml/min/1.73 m2), and glomerular involvement was only observed in one patient with isolated proteinuria. None had nephromegaly. In contrast, tubular disorders were commonly found. Hypercalciuria was detected in 16 of the patients (UCa/Cr = 0.28; 25-75th percentile: 0.17-0.54 mg/mg), with five of these showing crystalluria. Eight children showed hyperchloremia, and three had frank metabolic acidosis. Kidney stones were absent in all, but one boy had bilateral medullary nephrocalcinosis. Conclusion, in Venezuelan children, HIV infection per se, or its specific treatment, was commonly associated with renal tubular dysfunction, especially hypercalciuria and acidosis, potentially leading to nephrocalcinosis and growth impairment. We recommend renal tubular evaluation during the follow-up of children with HIV infection.

Occurrence of hypercalciuria in patients with osteoporosis treated with teriparatide

CONTEXT

Teriparatide (TPTD) [recombinant human PTH(1-34)] given sc once daily transiently increases serum calcium concentrations at 4-6 h after dosing, but its effects on urinary calcium excretion are less well studied.

OBJECTIVE

Our objective was to evaluate urinary calcium excretion, a prespecified safety endpoint, for up to 12 months of TPTD treatment.

DESIGN

This study included two prospective, randomized, double-blind placebo-controlled clinical trials.

PARTICIPANTS

A total of 2074 participants with osteoporosis or low bone mass (study 1, 1637 postmenopausal women; study 2, 437 men) were included.

INTERVENTIONS

Participants were given calcium (1000 mg/d) and vitamin D (400-1200 IU/d) supplements, and were randomized to placebo, TPTD 20 mug/d, or TPTD 40 mug/d.

MAIN OUTCOME MEASURES

Urinary calcium excretion was measured in 24-h collections at baseline, 1, 6, and 12 months.

RESULTS

In each study, baseline urinary calcium excretion was similar among groups. All groups had significantly increased urinary calcium excretion, compared with baseline, at most post-baseline time points. Post-baseline urinary calcium excretion was increased in the TPTD 20 microg/d group by up to 32 mg/d compared with placebo at the same time point (P < 0.05) in study 1. A total of seven participants (0.3%), of which three and four were in the placebo and TPTD groups, respectively, discontinued study drug due to repeated hypercalciuria (>300 mg/d).

CONCLUSION

Urinary calcium excretion was increased with TPTD treatment for up to 12 months, compared with placebo and baseline values, but the magnitude of these changes is unlikely to be clinically relevant or warrant urinary calcium monitoring for most patients.

Etiology of nephrocalcinosis in northern Indian children

This retrospective survey examines the etiology of nephrocalcinosis (NC) in 40 patients (26 boys), over an 8-year period. The median age at onset of symptoms and presentation was 36 months and 72 months, respectively. Clinical features included marked failure to thrive (82.5%), polyuria (60%) and bony deformities (52.5%). The etiology of NC included distal renal tubular acidosis (RTA) in 50% patients and idiopathic hypercalciuria and hyperoxaluria in 7.5% each. Other causes were Bartter syndrome, primary hypomagnesemia with hypercalciuria, severe hypothyroidism and vitamin D excess. No cause for NC was found in 12.5% patients. Specific therapy, where possible, ameliorated the biochemical aberrations, although the extent of NC remained unchanged. At a median (range) follow up of 35 (14-240) months, glomerular filtration rate (GFR) had declined from 82.0 (42-114) ml/min per 1.73 m2 body surface area to 70.8 (21.3-126.5) ml/min per 1.73 m2 body surface area (P = 0.001). Our findings confirm that, even with limited diagnostic facilities, protocol-based evaluation permits determination of the etiology of NC in most patients.

Urinary risk factors for recurrent calcium stone formation in Thai stone formers

OBJECTIVE

To survey the urinary risk factors associated with recurrent calcium stone and the contribution of renal tubular acidosis to the prevalence of recurrent calcium stone formation in Thai recurrent stone formers.

MATERIAL AND METHOD

There were 86 consecutive recurrent calcium stone formers. Three-day dietary record, serum biochemical parameters, first morning urine pH, and two 24-hour urine collections were obtainedfrom each subject. Urinary risk factors for calcium stone formation were determined from the average of the 2-day urine collection. Normal controls were 34 subjects matched for aged, sex, and weight, and without a history of renal stone formation.

RESULTS

Seven patients (8.1%) were diagnosed as incomplete renal tubular acidosis (iRTA). Among the 79 idiopathic calcium stone formers (ISF), 69.6%, 15.2%, 10.1%, 7.2% and 1.3% of patients were hypocitraturia, hypercalciuria, low urinary volume, hyperuricosuria and hyperoxaluria, respectively. The common combinations of risk factors were hypocitraturia plus low urine output (8.9%) or plus hypercalciuria (7.6%). There were significant differences between ISF and normal controls in urinary oxalate excretion (0.16 +/- 0.01 vs 0.12 +/- 0.01, p < 0.05), urinary calcium/citrate ratio (4.49 +/- 0.50 vs 2.83 +/- 0.34, p < 0.01) and ion activity product for calcium oxalate stone (0. 46 +/- 0.03 vs 0. 33 +/- 0.03, p < 0. 05). Urinary citrate in ISF varied directly with net alkaline absorption (r = 0.34, p < 0.005) and urinary potassium (r = 0.54, p < 0.001). There were significant correlations between urinary calcium excretion and both sodium excretion (r = 0.42, p < 0.001) and urea excretion (r = 0.41, p < 0.001) in ISE There were seven (8.1%) with incomplete renal tubular acidosis. Patients with iRTA tended to have less urinary citrate and higher calcium/citrate ratio than did ISF, but hypercalciuria was uncommon.

CONCLUSIONS

Hypocitraturia was the most common urinary risk factor found in Thai recurrent idiopathic calcium stone formers followed by hypercalciuria and low urinary volume. Almost one-fourth of the stone formers had multiple risk factors. Hypocitraturia might result from low potassium and low alkaline intake. iRTA was common among recurrent calcium stone formers. Determination of morning urine pH should be a part of the investigations for urinary risk factors to avoid overlooking the diagnosis of iRTA.

Immobilization and hypercalciuria in children

Intermediate-term immobilization may lead to an increase in serum and urinary calcium. In order to test this hypothesis, we evaluated 46 children, 21 with Legg-Calvé-Perthes disease (LCP; 7.2+/-1.8 years old) and 25 with developmental dysplasia of the hip joint (DDH; 10+/-5 months of age), submitted to immobilization for up to 16 weeks. These two conditions require intermediate-term immobilization as treatment modality, and no studies evaluating calcium metabolism in these groups of patients have been conducted. In LCP patients, blood and 24-h urine samples were obtained before the beginning of treatment and after 1, 6, 8, 14 and 16 weeks of immobilization, while in DDH patients, blood and spot urine samples were collected before treatment and after 6 and 14 weeks of treatment. Urinary calcium, creatinine, potassium and sodium as well as serum calcium, phosphorus, parathyroid hormone, creatinine and alkaline phosphatase were determined in those samples. Renal ultrasound was performed before and after treatment. A mean increase of 2.3 times baseline values of urinary calcium was observed in 40% of previously normocalciuric LCP patients after only 1 week of immobilization. Among the DDH children, who had never previously ambulated, there was no significant variation in the urinary calcium excretion. None of the serum parameters changed in either group throughout the study. Urinary stones were not evidenced by renal ultrasound. Therefore, the present data suggested that intermediate-term immobilization led to a transient increase in urinary calcium in 40% of LCP patients. Complications such as urinary stones were not observed. In conclusion, this modality of treatment does not impose an increased risk of urinary stone formation in LCP and DDH patients.

High Urinary Calcium Excretion and Genetic Susceptibility to Hypertension and Kidney Stone Disease

Increased urinary calcium excretion commonly is found in patients with hypertension and kidney stone disease (KSD). This study investigated the aggregation of hypertension and KSD in families of patients with KSD and hypercalciuria and explored whether obesity, excessive weight gain, and diabetes, commonly related conditions, also aggregate in these families. Consecutive patients with KSD, aged 18 to 50 yr, were recruited from a population-based Kidney Stone Center, and a 24-h urine sample was collected. The first-degree relatives of eligible patients (n = 333) and their spouse were interviewed by telephone to collect demographic and health information. Familial aggregation was assessed using generalized estimating equations. Multivariate-adjusted odds ratios (OR) revealed significant associations between hypercalciuria in patients and hypertension (OR 2.9; 95% confidence interval 1.4 to 6.2) and KSD (OR 1.9; 95% confidence interval 1.03 to 3.5) in first-degree relatives, specifically in siblings. No significant associations were found in parents or spouses or in patients with hyperuricosuria. Similarly, no aggregation with other conditions was observed. In an independent study of siblings of hypercalciuric patients with KSD, the adjusted mean fasting urinary calcium/creatinine ratio was significantly higher in the hypertensive siblings compared with normotensive siblings (0.60 +/- 0.32 versus 0.46 +/- 0.28 mmol/mmol; P < 0.05), and both sibling groups had significantly higher values than the unselected study participants (P < 0.001). Urinary sodium/creatinine and uric acid/creatinine ratios were not different among the groups. Although an environmental effect cannot be excluded fully, our findings suggest that the disturbance in calcium metabolism in hypertension and KSD has a genetic basis.