Applications of Metabolomics in Calcium Metabolism Disorders in Humans

The pathogenesis of the disorders of calcium metabolism is not fully understood. This review discusses the studies in which metabolomics was applied in this area. Indeed, metabolomics could play an essential role in discovering biomarkers and elucidating pathological mechanisms. Despite the limited bibliography, the present review highlights the potential of metabolomics in identifying the biomarkers of some of the most common endocrine disorders, such as primary hyperparathyroidism (PHPT), secondary hyperparathyroidism (SHPT), calcium deficiency, osteoporosis and vitamin D supplementation. Metabolites related to above-mentioned diseorders were grouped into specific classes and mapped into metabolic pathways. Furthermore, disturbed metabolic pathways can open up new directions for the in-depth exploration of the basic mechanisms of these diseases at the molecular level.

Calcium Metabolic Disorders in Pregnancy: Primary Hyperparathyroidism, Pregnancy-Induced Osteoporosis, and Vitamin D Deficiency in Pregnancy

Physiologic changes during pregnancy include calcium, phosphate, and calciotropic hormone status. Calcium metabolic disorders are rare in pregnancy and management with close calcium and vitamin D control and supplementation. Primary hyperparathyroidism is mostly asymptomatic and does not affect conception or pregnancy. It requires control of plasma calcium levels. Surgical intervention may be indicated. Data on severe cases are missing. Osteoporosis in or before pregnancy is rare but usually diagnosed from fractures. Medical treatment other than supplementation is contraindicated. Vitamin D deficiency is common and may affect conception and increase complications. Current evidence does not prove vitamin D supplements effective in improving outcomes.

[Research progress on pharmacotherapy of calcific aortic valve disease]

With the population aging and declining incidence of rheumatic heart disease, calcific aortic valve disease (CAVD) has become the most frequent valve disease and the common cause of aortic valve replacement. Patients with CAVD need to cope with a deteriorating quality of life and valve replacement is the only effective clinical option for the patients. Therefore, early pharmacotherapy is of great significance in prevention or slow-down of the progression of CAVD. For years CAVD was considered to be a passive wear and tear process of valves, but now it is recognized as an active and multi-factorial process. Histopathologic studies have revealed that inflammation, disorder of calcium and phosphorus metabolism and dyslipidemia are involved in the process of CAVD. Clinical trials of CAVD pharmacotherapy have been carried out based on those histopathologic studies. Statin, renin-angiotensin inhibitors and anti-osteoporosis drug are well studied in recent years. This article reviews the recent research progress of the pharmacotherapy for CAVD.

[Cognitive Function and Calcium. The link between dementia and bone and calcium metabolism disorders]

Bone and calcium metabolism disorders are closely linked with dementia. Screening for dementia is important since chronic hypercalcemia and hypocalcemia resulting from parathyroid function abnormalities can become a cause of dementia onset. In recent years, it has become clear that vitamin D deficiencies inducing cardiovascular disease and other factors are involved in the pathogenesis of various diseases that in turn become risk factors in dementia, especially Alzheimer's disease. Moreover, osteoporosis and dementia both commonly occur among the elderly. Treating dementia patients for osteoporosis is important since fragility fractures, especially femoral neck fractures, resulting from osteoporosis greatly affect the prognosis of patients with dementia.

Results of medical treatment and metabolic risk factors in children with urolithiasis

Data on conservative treatment in children with urolithiasis are limited. The aim of the study was to determine the metabolic etiology and results of conservative treatment in children with urolithiasis. We evaluated the clinical presentation and metabolic features of 112 children with urolithiasis. The mean age at diagnosis of urolithiasis was 3.9 (range 0.1-18) years, and follow-up duration was 16.7 (range 1-36) months. The most common presenting symptoms were flank or abdominal pain and restlessness (25%). Urine analysis revealed metabolic abnormalities in 92% of cases, including hypocitraturia (42%), hyperoxaluria (32.1%), hypercalcuria (25%), hyperuricosuria (9.8%), and cystinuria (2.7%). Patients who had metabolic risk factors were treated according to underlying metabolic abnormalities. About half of these patients were stone free or stones were diminished in size. These results showed that early recognition and treatment of urinary metabolic abnormalities will reduce the number of invasive procedures and renal damage in children with urolithiasis.

[Clinical significance of disturbed calcium metabolism]

The authors present literature data on the role of Ca-P metabolism and its regulators in the development of bone and cardiovascular pathology, intrauterine development, organogenesis, cell growth and differentiation. A large number of agents are currently available to modify Ca-P metabolism. (calcium and vitamin Dpreparations, PTH, calcitonin, stimulators of Ca-sensitive receptors, calcitriol receptor ligands, etc.) although their application is hampered by the dificulty of laboratory control and the lack of basic knowledge. It is maintained that raising awareness among practitioners about these issues may improve diagnostics of Ca-P metabolic disorders (in the first place, calcium and vitamin D deficiency, secondary hyperthyroidism) and promote their medicamental and non-medicamental therapy.

Purkinje cell calcium dysregulation is the cellular mechanism that underlies catecholaminergic polymorphic ventricular tachycardia

BACKGROUND

Inherited arrhythmias can be caused by mutations in the cardiac ryanodine receptor (RyR2). The cellular source of these arrhythmias is unknown. Isolated RyR2(R4496C) mouse ventricular myocytes display arrhythmogenic activity related to spontaneous Ca(2+) release during diastole. On the other hand, recent whole-heart epicardial and endocardial optical mapping data demonstrate that ventricular arrhythmias in the RyR2(R4496C) mouse model of catecholaminergic polymorphic ventricular tachycardia (CPVT) originate in the His-Purkinje system, suggesting that Purkinje cells, and not ventricular myocytes, may be the cellular source of arrhythmogenic activity. The relative effect of the RyR2(R4496C) mutation on calcium homeostasis in ventricular myocytes versus Purkinje cells is unknown.

OBJECTIVE

This study sought to determine which cardiac cell type is more severely affected, in terms of calcium handling, by expression of the RyR2(R4496C) mutant channel: the ventricular myocytes or the Purkinje cells.

METHODS AND RESULTS

To discriminate Purkinje cells from ventricular myocytes, we crossed the RyR2(R4496C) mouse model of CPVT with the Cx40(EGFP/+) transgenic mouse. This genetic cross yields Purkinje cells that express eGFP, and therefore fluoresce green when excited by the appropriate wavelength; ventricular myocytes, which do not express connexin 40, are not green. Intracellular calcium was measured in each cell type using calcium-sensitive probes. Purkinje cells of the RyR2(R4496C) mouse model of CPVT show an approximately 2x greater rate (P < .05) and approximately 2x to 3x greater amplitude (P < .000001) of spontaneous calcium release events than ventricular myocytes isolated from the same heart.

CONCLUSION

These results demonstrate that focally activated arrhythmias originate in the specialized electrical conducting cells of the His-Purkinje system in the RyR2(R4496C) mouse model of CPVT.

Thirty-month follow-up of coronary artery calcification in hemodialysis patients: different roles for inflammation and abnormal calcium-phosphorous metabolism?

BACKGROUND

Cardiovascular disease is the leading cause of death in hemodialysis (HD) patients. Coronary artery calcification (CAC) is considered a marker of atherosclerosis and coronary artery disease (CAD). The CAC progression and factors that influence it were evaluated during a 30-month period.

METHODS

Forty HD patients without a history of CAD were enrolled into the study. CAC score was assessed with conventional CT repeated every six months. The circulating factors of phosphorous, calcium, calcium-phosphorous product, intact parathyroid hormone, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, lipoprotein-alpha, albumin, high sensitivity C-reactive protein, and fibrinogen were measured monthly. Hypertension and calcium intake during the study period were taken into account as well.

RESULTS

At baseline, CAC score was correlated with age and duration of HD therapy. From all evaluated factors, CAC initiation was influenced only by older age and C-reactive protein. CAC, when it was started, was aggravated continuously and was influenced only by elevated serum phosphorous and calcium-phosphorous product. Hypertension, lipid profile, and calcium intake did not affect CAC initiation or progression.

CONCLUSIONS

Once CAC progression starts, it is an uninterrupted process. The roles of inflammation and abnormal calcium-phosphorous metabolism in CAC differ. Inflammation is the major factor that contributes in CAC initiation. Elevated serum phosphorous and calcium-phosphorous product accelerates CAC progression.

Abnormal Circadian Rhythm of Diuresis or Nocturnal Polyuria in a Subgroup of Children With Enuresis and Hypercalciuria is Related to Increased Sodium Retention During Daytime

PURPOSE

In a subgroup of children with enuresis an increase in nighttime water and solute excretion has been documented. To investigate if modifications in renal function are involved in nocturnal enuresis, we assessed circadian variation in natriuresis and tubular sodium handling in polyuric hypercalciuric children.

MATERIALS AND METHODS

A total of 10 children with proved hypercalciuria and nocturnal polyuria and 10 age matched controls were included in the study. A 24-hour urine collection was performed in 8 sampling periods for measurement of urinary sodium excretion. Segmental tubular sodium transport was investigated during a daytime oral water load test and calculated according to standardized clearance methodology.

RESULTS

The children with enuresis showed a marked increase in the fractional excretion of sodium during the night (0.93% +/- 0.36%), while daytime sodium excretion was decreased (0.84% +/- 0.23%). Analysis of segmental tubular sodium transport revealed decreased delivery of sodium to distal tubule (C(H2O) + C(Na) = 10.7 ml/100 ml glomerular filtration rate), indicating increased proximal tubular sodium reabsorption but also stimulation of distal sodium reabsorption as demonstrated by increased fractional distal sodium reabsorption (92.9% +/- 2.2%, controls 90.5% +/- 2.9%). Increased distal reabsorption was associated with increased fractional potassium excretion (17.5% +/- 2.7%, controls 13.6% +/- 6.4%), indicating increased distal tubular sodium/potassium exchange.

CONCLUSIONS

No intrinsic defect in renal tubular sodium transport was found, but during the day increased sodium reabsorption in proximal and distal tubules was observed, suggesting extrarenal factors to be involved in altered circadian variation in solute and water excretion by the kidney.

Medical evaluation and treatment of urolithiasis

Nephrolithiasis is responsible for 1 in 1000 to 1 in 7600 pediatric hospital admissions annually throughout the United States. Seventy-five percent of children with nephrolithiasis have an identifiable predisposition to stone formation. This article reviews the different causes and disease states associated with nephrolithiasis in the pediatric population. The initial evaluation and the metabolic evaluation of children with nephrolithiasis are reviewed. Treatment modalities for the different stone types are also described.

Hypocitraturia: a risk factor for reduced bone mineral density in idiopathic hypercalciuria?

The association between idiopathic hypercalciuria (IH) and reduced bone mineral density (BMD) has been described in adults and children. Frequently, hypocitraturia (HC) is an associated condition. To determine the effect that HC may have on bone metabolism of these patients, we studied 88 children with IH at diagnosis, divided into the following groups: group 1-44 (50%) patients with associated HC; group 2-44 (50%) patients without HC; group 3 (29 subjects), a healthy control group. Urinary and blood electrolytes, as long as urinary N-telopeptide, were measured. Lumbar spine (L2-L4) and femoral neck bone mineral density (BMD) and bone mineral content (BMC) were measured by dual energy X-ray absorptiometry. There was no difference in age between the three groups (P=0.80), but weight, height, body mass index, and bone age were lower (P<0.01) and serum intact parathyroid hormone (iPTH) was higher (P<0.05) in group 1 than in groups 2 and 3. N-telopeptide, measured in urine, did not differ between groups. The following bone densitometry parameters: lumbar spine BMC, BMC adjusted for height (BMCh), BMC adjusted for width of vertebrae (BMCw) and BMD, as well as femoral neck BMD, were significantly lower in group 1 than in groups 2 and 3 (P<0.01). When we corrected densitometry parameters for height, BMC was lower in group 1 and not in group 2 when compared with controls.

CONCLUSIONS

Children with IH and associated HC may have a higher risk of bone mass loss and consequent osteopenia. Further studies are needed to assess the role that hypocitraturia may have in this form of bone disease.

Fatty acids and idiopathic calcium nephrolithiasis

Clinical and experimental investigations seem to underline the important role of fatty acids in the pathogenesis of hypercalciuria, a well-known risk factor for lithogenesis. To evaluate the relationships between the previously reported increase in plasma phospholipid arachidonic acid level and the factors responsible for calcium metabolism in idiopathic calcium nephrolithiasis, a best-fit model was constructed. This new statistical application shows a causal relationship between plasma phospholipid arachidonic acid content, intestinal calcium absorption, biochemical markers of bone turnover, urinary calcium excretion and bone mineral density at the lumbar spine. This model suggests that a defect in the phospholipid fatty acid composition could represent the primary event responsible for the mosaic of metabolic and clinical alterations that are distinctive features of renal stone formers, such as kidney, intestine, and bone calcium metabolism, and several forms of idiopathic hypercalciuria.

Bone disease in primary hypercalciuria

Primary hypercalciuria (PH) is very often accompanied by some degree of bone demineralization. The most frequent clinical condition in which this association has been observed is calcium nephrolithiasis. In patients affected by this disorder, bone density is very frequently low, and increased susceptibility to fragility fractures is reported. The very poor definition of this bone disease from a histomorphometric point of view is a crucial aspect. At present, the most common finding seems to be a low bone turnover condition. Many factors are involved in the complex relationships between bone loss and PH. Since bone loss was mainly reported in patients with fasting hypercalciuria, a primary alteration in bone metabolism was proposed as a cause of both hypercalciuria and bone demineralization. This hypothesis was strengthened by the observation that some bone resorbing-cytokines, such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor nechrosis factor-alpha (TNF-alpha), are high in hypercalciuric patients. An excessive response to the acid load induced by dietary protein intake seems to be an additional factor explaining a primitive alteration of bone. The intestine plays a major role in the clinical course of bone disease in PH. Patients with absorptive hypercalciuria less frequently show bone disease, and a reduction in dietary calcium greatly increases the probability of bone loss in PH subjects. It has recently been reported that greater bone loss is associated with a larger increase in intestinal calcium absorption in PH patients. Considering the absence of parathyroid hormone (PTH) alterations, it was proposed that this is not a compensatory phenomenon, but probably the marker of disturbed cell calcium transport, involving both intestinal and bone tissues. While renal hypercalciuria is rather uncommon, the kidney still seems to play a role in the pathogenesis of bone loss in PH patients, possibly via the effect of mild-to-moderate urinary phosphate loss with secondary hypophosphatemia. In conclusion, bone loss is very common in PH patients. Even if most of the factors involved in this process have been identified, many aspects of this intriguing clinical condition remain to be elucidated.

Hypercalciuria and recurrent urinary tract infections: incidence and symptoms in children over 5 years of age

Hypercalciuria is an important and common risk factor in the formation of renal stones. In this study we evaluated the incidence and the clinical presentation of hypercalciuria in 75 children over 5 years of age with the diagnosis of recurrent urinary tract infection (UTI). We measured random urinary calcium/creatinine value (three times), 24-h urinary calcium excretion, serum calcium, phosphorus, electrolytes, blood gas, blood urea nitrogen and creatinine levels. Hypercalciuria was found in 32 patients (43%). The mean urinary calcium/creatinine ratio for hypercalciuric patients was 0.50+/-0.21 mg/mg (min: 0.24, max: 2.60). The mean urinary calcium/creatinine ratio for the rest of the study population--those without hypercalciuria--was 0.10+/-0.04 mg/mg (min: 0.01, max: 0.18). Presenting symptoms of the hypercalciuric patients and normocalciuric patients were similar. History of familial urolithiasis was positive in 19 patients (59%). Predisposing urinary tract abnormalities in recurrent UTI was shown in 12 of the hypercalciuric patients (12/32, 37.5%) and 8 of the normocalciuric patients (8/43, 19%) without a statistically significant difference between. We conclude that hypercalciuria is not a rare finding among recurrent UTI cases in Turkish children. Hypercalciuria does not modify the clinical presentation of UTI, and we suggest the investigation of urinary calcium excretion in children with recurrent UTI.

Metabolic abnormalities and the medical management of calcium oxalate nephrolithiasis

The lifetime prevalence of urolithiasis is approximately 12% for men and 7% for women in the United States and seems to be increasing; the cost of managing kidney stones continues to escalate. The most common kidney stones continue to be composed primarily of calcium and are an admixture of phosphate and oxalate. Of these, calcium oxalate stones are the most predominant. This review will focus only on the pathogenesis and medical management of calcium oxalate stones.

[Hypocalciuria during pregnancy as a risk factor of preeclampsia]

BACKGROUND

Although preeclampsia has been studied thoroughly, its origin is still unknown. However, there are various factors that strive to explain its cause. Some of them are: the genetic, placenta and immunological aspects, endothelial damage, hormonal and autoimmunological alterations, deficit of essential fatty acids, and the ion disorder theory.

OBJECTIVE

To evaluate if hypocalciuria is a factor related to the development of preeclampsia or transitory hypertension during pregnancy.

MATERIAL AND METHOD

A cohort study of 63 women was performed. Serum calcium levels and calcium in 24 hours urine collection were assessed in women with 32 to 36 weeks of pregnancy. Patients were selected by sampling of consecutive cases.

RESULTS

Twenty-four patients had hypocalciuria (group I) and 39 normocalciuria (group II). Calcium serum levels were of 8.05 +/- 0.22 mg/ dL and of 8.22 +/- 0.36 for group I and II, respectively (t=1.25, p=0.21). Of the 24 patients with hypocalciuria, 5 (20.83%) had preeclampsia compared to 2 (5.12%) of the 39 with normocalciuria (RR= 4.06; 95% CI 3.29, 7.20). We did not find correlation between preeclampsia and the risk factors. When considering hypocalciuria as a prognosis test, we obtained 0.71 of sensitivity and 0.66 of specificity; the exactitude of the test was of 0.66.

CONCLUSIONS

Hypocalciuria could be considered as a risk factor for the development of preeclampsia and transitory hypertension during pregnancy.

Examination of megalin in renal tubular epithelium from patients with Dent disease

Dent disease is characteristic for the urinary loss of low-molecular-weight proteins and calcium, leading to renal calcification and, in some patients, chronic renal failure. This disorder is caused by loss-of-function mutations in the renal chloride channel gene, CLCN5. The animal model of this disease has demonstrated the possible role of disturbed megalin expression, which is a member of the low-density lipoprotein receptor family and is associated with renal reabsorption of a variety of proteins, in Dent disease. We examined the expression of megalin in the renal tubular epithelium of two unrelated patients with Dent disease. One patient, whose CLCN5 gene was completely deleted, showed significantly decreased staining of megalin compared with controls, while there was no change in another patient with partial deletion of the gene. These results demonstrated that mutation of CLCN5 in some patients with Dent disease may impair the expression of megalin, resulting in abnormal calcium metabolism, manifested as hypercalciuria and nephrocalcinosis.

Hypercalciuria is a common and important finding in postmenopausal women with osteoporosis

OBJECTIVE AND DESIGN

The prevalence and the effects of hypercalciuria on bone in patients with primary osteoporosis are poorly defined. We therefore retrospectively analyzed the data of 241 otherwise healthy women. They were 45-88 years of age and had been referred for their first visit to our Unit for Metabolic Bone Diseases over a 2-year period because of primary osteoporosis (bone density T-score < -2.5).

METHODS

The main parameters of calcium and skeletal metabolism had been analyzed in all subjects. This population was then divided into two groups, according to the presence (HC+) or absence (HC-) of hypercalciuria.

RESULTS

Elevated urinary calcium was present in 19% of the subjects. Due to the selection criteria, spinal and femoral bone loss was similar in the two groups. Urinary calcium, phosphate and fractional calcium excretion were higher in hypercalciuric patients. In a logistic regression model, the higher the Tm of phosphate, the lower the risk of hypercalciuria (odds ratio 0.33, confidence interval 0.18-0.62). On the contrary, hypercalciuria was the most important predictor of low bone mass in HC+ (accounting for more than 50% of the variance in spinal bone density).

CONCLUSIONS

Hypercalciuria is a common feature in postmenopausal bone loss. Since increased urinary calcium excretion and low bone mass appear to be linked, hypercalciuria seems to be an important determinant of reduced bone density in this setting as well.

Successful pregnancy in a woman with congenital "Swiss-cheese" platelets. A case report

BACKGROUND

Congenital "Swiss-cheese" platelets are a rare disorder of platelet function due to impaired calcium mobilization. Management of pregnancy in patients with this disorder had not been reported previously.

CASE

Successful pregnancy occurred in a woman with congenital Swiss-cheese platelets. Neither the mother nor neonate experienced any hemorrhagic complications.

CONCLUSION

Successful pregnancy is possible in women with congenital Swiss-cheese platelets. The lack of hemorrhagic complications may be due to the increase in platelet intracellular free calcium concentration during pregnancy.

[Bone loss in type 2 diabetes mellitus--diabetic osteopenia]

Loss of bone mineral content has been recognized as one of the chronic complications of type 2 diabetes mellitus, although its mechanism is not fully documented. A negative calcium balance due to both enhanced urinary calcium excretion and decreased intestinal calcium absorption has been occurred because of alteration of vitamin D metabolism and/or decreased parathyroid function. From the view point of bone cell metabolism, osteoblastic bone formation is suppressed by alternation of vitamin D metabolism, hypoparathyroidism, chronic hyperglycemia and insufficient insulin action. On the other hand, osteoclastic bone resorption is rather enhanced. The functional bone uncoupling system between osteoblast and osteoclast in type 2 diabetes mellitus could result in loss of bone density.

[Calcium homeostasis disorders in children with multiple caries]

A saliva of the examined children of 3, 6, 12 years old with intensive caries are characterized by a changing of calcium homeostasis which is accompanied with redistribution of calcium fractions in a mixed nonstimulation saliva. In this case the concentration of Ca2+ is raisign considerably while the concentration of general calcium is raising slightly.

Bone alterations in patients with idiopathic hypercalciuria and calcium nephrolithiasis

OBJECTIVES

To verify whether alterations in bone density and turnover in patients with calcium nephrolithiasis and hypercalciuria are observable in various subgroups of patients divided according to the pathogenesis of the hypercalciuria.

METHODS

Seventy patients with calcium nephrolithiasis and idiopathic hypercalciuria, 19 to 64 years old, were assessed for spine and femur mineral metabolism and bone density using a Dexa evaluation system. After a low calcium diet, the subjects were classified into two groups: fasting hypercalciuria (FH, 39 patients) and absorptive hypercalciuria (AH, 31 patients).

RESULTS

Only in the patients with FH was the lumbar spine bone density lower than in the controls (P <0.001). Also, only the patients with FH had higher bone alkaline phosphatase and urinary hydroxyproline levels than the control group (P <0.005 and <0.015, respectively). The blood pH levels were lower, even though within the normal range, in the hypercalciuric patients than in the controls (P <0.01). There was a negative correlation between the urinary hydroxyproline level and lumbar spine and femoral neck density in patients with FH (P <0.001 and <0.005, respectively), and the blood pH correlated positively with the lumbar spine bone density.

CONCLUSIONS

Altered bone metabolism and overall bone loss were found only in the patients with FH. Overloading of acid valences, perhaps of dietary origin, could be the pathogenic factor responsible.

Idiopathic external root resorption associated to hypercalciuria

Although external root resorption (ERR) is a physiological process in deciduous dentition, it is very infrequent in permanent dentition - where the phenomenon is related to the existence of inadequate occlusal forces, periodontal pathology and microtraumatisms, etc. However, in many cases root resorption cannot be attributed to any concrete cause; such cases are defined as idiopathic external root resorption (IERR). Epidemiological studies have found that the underlying cause can only be established in 5% of all ERR. The present study describes three cases of IERR with different degrees of involvement and associated to mild calciuria and a history of nephrolithiasis. Hypercalciuria with normal blood calcium levels is usually idiopathic and exhibits a familial trait, with a prevalence of 20-40 cases per 1,000 individuals in adults. A form of hypercalciuria associated to nephrolithiasis with a mutation of the CLCN5 gene has been identified, involving low molecular weight proteinuria - though this mutation has not been uniformly demonstrated in most cases of idiopathic hypercalciuria. The peculiarity of the cases described in the present study is attributable to the coexistence of IERR with normocalcemic hypercalciuria and nephrolithiasis - thus pointing to the need for in-depth evaluation of the possible association of these three clinical situations.

Enamel hypomineralization in permanent first molars. A clinical, histo-morphological and biochemical study

Hypomineralization in the permanent first molars was common in a group of 516 Swedish 8-year-old children. Ninety-five children (18.4%) had at least one molar with demarcated opacity. The incisors frequently displayed opacities concomitantly. The mean number of hypomineralized teeth of the affected children was 3.2 (SD 1.8), of which 2.4 were first molars. Six and a half percent of the children had severe defects, 5% had moderate defects, while 7% had only mildly hypomineralized teeth. Fifteen percent had more than one tooth affected, indicating systemic causation. The affected children, especially the boys, were reported to have had more health problems, asthma in particular (but only 4 cases), during the first year of life. Breast feeding history was similar in children with and without enamel defects. The children with severely defected enamel had undergone dental treatment of their first molars nearly ten times as often as the children in the healthy control group at the age of nine. Behavior management problems and dental fear and anxiety were common compared to the controls. Undemineralized sections from 73 permanent first molars, extracted due to severe hypomineralization of the enamel, were examined in polarized light. The hypomineralized areas extended from the cusps cervically comprising about half of the buccal and lingual sides. The cervical border to normal enamel was well defined and mainly followed the lines of Hunter-Schreger. The hypomineralized zones were covered by thin well-mineralized enamel. The concentration gradients for F, Cl, Na, Mg, K and Sr in hypomineralized enamel were analyzed by means of Secondary Ion Mass Spectrometry (SIMS), and completed with an analysis of the main matrix elements O, P and Ca by means of X-ray microanalysis (XRMA). Hypomineralized enamel had a higher content of C. Ca and P concentration were lower compared with normal enamel. The mean Ca/P ratio in hypomineralized areas was significantly lower (1.4) than the mean Ca/P ratio in the adjacent normal enamel (1.8).

Hypercalciuria in children with febrile convulsions

BACKGROUND

The purpose of the present study was to investigate whether idiopathic hypercalciuria may be implicated in the pathogenesis of febrile convulsions.

METHODS

We studied 38 children (22 boys) with febrile convulsions (mean (+/- SD) age 3.25 +/- 1.09 years) and 45 healthy children (28 boys) of similar age who served as controls. Twenty-four hour urine calcium and phosphate, as well as serum calcium, phosphate, alkaline phosphatase and intact parathyroid hormone (PTH) concentrations were determined.

RESULTS

Hypercalciuria (urine Ca >4.0 mg/kg bodyweight per 24 h) was found in nine children with febrile convulsions (23.7%) and in three controls (6.7%). Hypercalciuric children excreted significantly more phosphate in their urine (37.0 +/- 11.6 mg/kg bodyweight per 24 h) than normocalciuric children (18.7 +/- 8.7 mg/kg bodyweight per 24 h) and controls (20.2 +/- 7.6 mg/kg bodyweight per 24 h). They also had higher serum intact PTH concentrations (49.87 +/- 15.36 pg/mL) than normocalciuric (35.39 +/- 15.67 pg/mL) and control children (28.21 +/- 14.00 pg/mL). According to the calcium-loading test, eight of nine children with hypercalciuria had the renal type of the disorder. Furthermore, hypercalciuric children had significantly more convulsive episodes (2.77 +/- 1.98) than normocalciuric children (1.86 +/- 1.24).

CONCLUSIONS

Our results suggest that renal hypercalciuria may be implicated in the pathogenesis of febrile convulsions.

[Importance of dietary sodium in the hypercalciuria syndrome and nephrolithiasis]

The studies involved 20 children with idiopathic hypercalciuria (IH). An influence of urinary sodium excretion, and reflection of its intake, on urinary calcium excretion has been assessed. Children who were normocalciuric had significancy lower values of urine sodium excretion when compared with those with persisting hypercalciuria. The main factor responsible for hypercalciuria in children seemed to be urine sodium excretion. As urine sodium excretion reflects its intake, reduction dietary salt, rather than calcium intake, may be useful in the management of children with hypercalciuria and nephrolithiasis.

Genetic hypercalciuric stone-forming rats

In humans, idiopathic hypercalciuria is associated with stone formation. In order to study the mechanisms that are responsible for excess urine calcium excretion, in ways that are difficult or impossible in humans, we have developed a rat model of hypercalciuria. Spontaneously hypercalciuric rats have been successively inbred for over 50 generations to produce a strain in which urine calcium excretion is over 10 times greater than that of controls, and all rats form kidney stones. Analysis of the model has revealed that the rats not only exhibit increased intestinal calcium reabsorption but an independent defect in renal tubular calcium resorption and an increased tendency for bone resorption. These findings closely parallel those in patients with idiopathic hypercalciuria. In the intestine, bone and kidney there is an increased number of vitamin D receptors which are hyperresponsive to 1,25-dihydroxyvitamin D3. Whether the increased number of vitamin D receptors is directly responsible for the hypercalciuria and whether the same abnormality is present in humans with idiopathic hypercalciuria is under investigation. Hypercalciuric rats appear to be an excellent model to provide insights into the mechanisms causing hypercalciuria, and to delineate treatments for stone disease.

Renal granulomatous sarcoidosis in childhood: a report of 11 cases and a review of the literature

We analysed retrospectively 11 children with renal granulomatous sarcoidosis confirmed by renal histology in order to describe the course and prognosis of the disease. Symptomatic sarcoidosis was diagnosed at a mean age of 10.1 years. Nine children had renal involvement at the time of diagnosis. In the course of the disease, nine patients developed renal failure and mild proteinuria, seven had transient sterile leukocyturia, four showed microscopic haematuria, seven had a urinary concentrating defect, and enlarged kidneys were seen in three patients. One child had hypercalcaemia and hypercalciuria, none had hypertension. Light microscopy of the kidney showed interstitial infiltration by mononuclear cells in all children, interstitial fibrosis in nine patients, epithelioid granulomas in seven, tubular involvement in eight, and mild glomerular involvement in seven patients. Renal immunofluorescence was negative. Ten children received prednisone for 1-11 years. After a mean follow up of 5.5 years, three patients had entered end-stage renal failure and one had chronic insufficiency after interruption of medical supervision and prednisone therapy.

CONCLUSION

Renal failure, proteinuria, leukocyturia, haematuria, and concentration defect are the prominent features of renal granulomatous sarcoidosis in children. Steroid therapy, adjusted according to disease activity, may prevent end-stage renal failure.

Think of genetic hypercalciuria when a child has urinary tract findings

Genetic hypercalciuria, one of the most common mineral disorders in childhood, is frequently associated with a variety of urinary tract problems. Identifying and treating genetic hypercalciuria alleviates urinary tract problems and optimizes peak bone mass growth in affected children. Advanced practice pediatric nurses play a key role in identifying and coordinating care for children with genetic hypercalciuria.

Subtle psychiatric presentations of endocrine diseases

Endocrine disorders frequently present initially to psychiatrists. This article reviews the differential diagnosis of psychiatric and endocrine disorders. The range of endocrinopathies is presented, with emphasis placed on the common psychiatric symptomatology associated with these conditions. Various signs and symptoms that might stimulate a psychiatrist to pursue a work-up for each endocrine disorder are also emphasized.

Hypercalciuria and hematuria in juvenile rheumatoid arthritis

OBJECTIVE

To investigate the frequency of hypercalciuria and the relationship between hypercalciuria and hematuria in patients with juvenile rheumatoid arthritis (JRA).

METHODS

Twenty-eight children with JRA were studied, as well as 10 patients with acute arthritis unrelated to JRA and 14 healthy children as control groups. Cases with urinary calcium excretion (UCE) >4 mg/kg/day were considered hypercalciuric. Urinalysis was performed for detecting hematuria in all cases.

RESULTS

UCE was 4.19 +/- 2.9 mg/kg/day in patients with JRA, 1.94 +/- 1.57 mg/kg/day in children with acute arthritis, and 2.0 +/- 1.45 mg/kg/day in healthy children. UCE was significantly higher in JRA compared with the other study groups. Of the 28 patients with JRA, 13 (46.4%) had hypercalciuria and 6 (21.4%) had hematuria. UCE was significantly higher in hematuric patients with JRA than in those with no hematuria (p<0.05). UCE in patients with JRA without hematuria was also higher than the UCE values detected in the disease and healthy control groups (p<0.05).

CONCLUSION

Hypercalciuria is a frequent finding in patients with JRA [13/28 (46.4%)] and should be considered during the investigation of hematuria in patients with JRA.

[Incidence and development of aortic stenosis in chronic hemodialysis. An ultrasonographic and biological study of 112 patients]

Valvular calcification in chronic haemodialysis patients has already been reported in the literature, particularly the abnormally high incidence of aortic stenosis. In this study, 112 haemodialysis patients were followed up by Doppler echocardiography for a period of 36 months. Sixteen patients developed aortic valvular calcification with aortic stenosis over an 18.7 +/- 7.5 months period. The indexed aortic valve surface area decreased from 1.24 +/- 0.9 cm2/m2 to 0.66 +/- 0.21 cm2/m2 with abnormally rapid progression. Eight patients with aortic stenosis died during the 3 year study period. These results reflect the abnormal extra-skeletal calcification of chronic haemodialysis patients. Several predisposing factors were demonstrated: age (68.5 +/- 11.1 years versus 57.1 +/- 16.3 years in patients without calcifications), male gender, a longer period of dialysis than the patients without aortic stenosis (8.1 +/- 5.3 versus 5.9 +/- 5.7 years), abnormalities of calcium and phosphate metabolism, increased of the phosphocalcic product by hyperphosphoraemia and not by hypercalcaemia, hypoparathyroidism in 62% and hyperparathyroidism in 38% an increase in vitamin D 3 (19.7 +/- 14 ng/ml versus 9.6 +/- 6.3 ng/ml) biological signs of adynamic osteodystrophy. Calcific aortic stenosis is a commonly observed valvular lesion in haemodialysis patients: its progression may be very rapid, associated with a poor prognosis. Old age, male gender, duration of haemodialysis, hyperphosphataemia associated with hypoparathyroidism and raised Vitamin D3 are predisposing factors.

Non-malignant complications of coeliac disease

Patients with coeliac disease are at increased risk of developing complications which increase morbidity and mortality. Emphasis on malignant complications has often overshadowed the non-malignant risks, which have received relatively little attention, although some of these can be very troublesome and even life-threatening. This article points out that a large population of unidentified or neglected coeliac patients is at potential risk. The challenge is to identify this group by case-finding or screening programmes in selected populations, so that they can be offered a gluten-free diet and other treatments which will not only improve general health but may also prevent or reduce the development of health problems. The non-malignant risks are outlined and bone and neuropsychiatric disturbances considered in more detail because of recent developments in these areas.

Hypercalciuria and ultrasound abnormalities in children with cystinosis

We noted microscopic haematuria in children with cystinosis. To investigate this we studied urinary calcium excretion and undertook renal ultrasound scans. Most patients had elevated urinary calcium excretion and all had abnormal appearances on ultrasound scan, ranging from increased cortical echogenicity only to those with increased cortical and medullary echogenicity. The ultrasound scan appearance was graded and correlated with laboratory parameters. It remains unclear as to the aetiology of the ultrasound findings and whether they are a consequence of treatment or a hitherto unrecognised feature of the disease.

[Renal manifestations in sarcoidosis]

Clinically distinct renal disease is said to be rare in sarcoidosis, but autopsy reveals an incidence of renal involvement is 23 or 26% in Japanese studies. There are three categories of renal disease in sarcoidosis: 1) renal changes by abnormal calcium metabolism, 2) interstitial nephritis or granulomatous nephritis and 3) glomerulonephritis. Some investigators add renal angiitis to the three categories. In some patients without clinical renal disorders, renal involvement is discovered by chance at the time of autopsy or renal biopsy. Renal disease may develop during the course of sarcoidosis, preceding the diagnosis of sarcoidosis, or may be found simultaneously with extrarenal involvements at the time of diagnosis. Renal involvement should always be considered for exact diagnosis and appropriate treatment.

Tumoral calcinosis. Controversies in the etiology and alternatives in the treatment

OBJECTIVE

To examine our experience and review the literature concerning the diagnosis, origin, and treatment of tumoral calcinosis (TC).

DESIGN/SETTING

Case series based on patients with TC treated in University of California-San Francisco hospitals from 1981 to 1992 and the review of the patients described in the English-language literature.

PATIENTS

The study included a total of 17 patients: 10 women and seven men.

MAIN OUTCOME MEASURES

Sex, age, origin, symptoms, localization, treatment, and morbidity.

RESULTS

Seven men and six women, from 32 to 62 years of age, had known disorders of calcium metabolism, and four women, from 37 to 84 years of age, did not. The main causes of the calcium metabolic disorder were secondary hyperparathyroidism in 11 patients (85%) and primary hyperparathyroidism in two patients. In three patients there was a history of trauma at the involved site and in one patient the origin was unknown. Swelling and pain are the most common presenting complaints. Generalized pruritus was observed in 54% of the patients with metabolic disorders (P < .001) but not in patients without metabolic disorders. Among our patients with metabolic disorders, TC occurred most frequently at the shoulder (46%) and elbow (31%). Eleven patients with secondary hyperparathyroidism had received calcium carbonate to bind phosphate, a high level of calcium in the dialysate, and calcitriol (1,25-vitamin D) either orally, intravenously, or both, and three received epoetin alfa (Epogen). Following parathyroidectomy, the patients with hyperparathyroidism improved symptomatically, although calcifications did not change in size. One patient had the calcifications resected and did well, whereas another was treated by subtotal resection and had a recurrence 3 years later. All four of our patients without a metabolic disorder had complete resection of TC with no recurrence.

CONCLUSION

We believe TC is becoming more common in uremic patients with secondary hyperparathyroidism because of recent changes in the medical treatment of these patients. The increased use of calcium carbonate to bind phosphate as well as calcitriol and calcium to suppress parathyroid function and possibly epoetin alfa are causing more patients to develop TC.

[Hypercalciuria]

Hypercalciuria is the cause of almost 20% of all secondary osteoporoses and in 23% these cases are associated with calcium urolithiasis. It is therefore necessary to search for these patients actively because their treatment with hydrochlorothiazide and amiloride is easy and highly effective. We must not be satisfied with the finding of hypercalciuria as the only cause of demineralization of bone, as several causes may combine in a single patient. Comprehensive treatment of osteopenia associated with hypercalciuria is relatively shorter and more successful than in other forms of secondary osteopenias.

[The eye manifestations in phosphorus-calcium metabolic disorders]

The investigation of a number of 286 patients having disorders of binocular seeing shows a very frequent association of these to spasmophilia, especially for persons of feminine sex during their third or fourth decades of life. The medicamentous treatment of spasmophilia has ameliorated the disturbing binocular seeings, which had appeared again after stopping the treatment for a long time. The authors recommend the cover-test end the examination using Maddox's experiment for tracing rapidly out the binocular seeing disturbings. In order to stimulate the movements of the ocular globe in an reverse sense to the deviation formed by the oculomotor existed lack of poise, it had been used the prescription of classes with prisms assembled conversely to the classic rules, having the indication of wearing them for 3-4 hours a day.

[Bone density in idiopathic hypercalciuria in men. Study by dual photon absorptiometry, X-ray computed tomography and histomorphometry]

Lumbar bone mineral density (BMD) of the L3 vertebra was evaluated by double photon absorptiometry or tomodensitometry (TDM) in 55 hypercalciuric individuals in two separate studies. In the first, in a department of nephrology, 29 lithiasis patients were studied by TDM of L3. By this technique, trabecular density was 75 +/- 23% of normal. It was lower in the 17 patients in whom hypercalciuria persisted after calcium restriction (66 +/- 15% of normal and below the "fracture threshold" in 9 cases) than in the 12 patients in whom it disappeared after the prescription of such a diet (88 +/- 26%, below the "fracture threshold" in 3 cases), this difference being significant (p less than 0.01). In another 26 patients, seen in a department of rheumatology, three of whom had osteoporosis with vertebral fracture, density was measured in 21 cases by double photon absorptiometry (mean Z score -1.9 +/- 1.0) and in 5 cases by TDM (mean BMD of L3 69 +/- 21% of normal). Mean iliac trabecular volume, measured in 8 cases only, was 70 +/- 25% of normal and was below the "fracture threshold" in 3 cases. Comparison of the two study groups was not possible because of differences in recruitment and methods of investigation. These two studies nevertheless show the existence of significant vertebral bone rarefaction during hypercalciuria in the young man. Confirmed and quantified in patients in whom the metabolic disturbance was discovered as a result of radiological abnormalities, this quantitative abnormality was also seen in patients in whom hypercalciurie was found because of renal lithiasis.(ABSTRACT TRUNCATED AT 250 WORDS)