Modern India and Dietary Calcium Deficiency-Half a Century Nutrition Data-Retrospect-Introspect and the Road Ahead.

Calcium and vitamin D are inseparable nutrients required for bone health. In the past half a century, the dietary calcium intake of rural, tribal, and urban India has declined. Though India is the largest producer of milk and cereals, the major source of calcium in India is through non-dairy products. The highest intake of cereals and lowest intake of milk & milk products was observed in rural and tribal subjects whereas, the intake of cereals, milk & milk products were similar in both urban and metropolitan subjects. One of the reasons for lower calcium intake was the proportion of calcium derived from dairy sources. Over the past half a century, the average 30-day consumption of cereals in the rural and urban population has declined by 30%. The Per Capita Cereal Consumption (PCCC)has declined despite sustained raise in Monthly Per capita Consumption Expenditure (MPCE) in both rural and urban households. The cereal consumption was the highest in the lowest income group, despite spending smaller portion of their income, as cereals were supplied through public distribution system (PDS). About 85% of the Indian population are vitamin D deficient despite abundant sunlight. Dietary calcium deficiency can cause secondary vitamin D deficiency. Though India as a nation is the largest producer of milk, there is profound shortage of calcium intake in the diet with all negative consequences on bone health. There is a decline in dietary calcium in the background of upward revision of RDI/RDA. There is a gap in the production-consumption-supply chain with respect to dietary calcium. To achieve a strong bone health across India, it is imperative to have population based strategies addressing different segments including supplementing dietary/supplemental calcium in ICDS, mid-day-meals scheme, public distribution system, educational strategies. Other measures like mass food fortification, biofortification, bioaddition, leveraging digital technologies, investments from corporate sector are some measures which can address this problem. India is a vast country with diverse social, cultural and dietary habits. No single measure can address this problem and requires a multi-pronged strategic approach to tackle the dietary calcium deficiency to achieve strong bone health while solving the problem of nutritional deficiency.

[Experience with active vitamin D metabolites in phosphorus-calcium metabolic disorders in patients with predialysis chronic kidney disease].

AIM: To evaluate the efficacy and safety of alfacalcidol and paracalcitol used to correct impaired phosphorus-calcium metabolism (PCM) in patients with predialysis chronic kidney disease (CKD). SUBJECTS AND METHODS: Examinations were made in 128 patients with Stages III-V CKD, including 89 (69.5%) patients with chronic glomerulonephritis, 30 (23.4%) with chronic tubulointerstitial nephritis, and 9 (7.1%) with hypertensive nephrosclerosis. Impaired PCM was detected in 90 (70.3%) of the examined patients. According to the pattern of the previous therapy, all the 90 CKD patients with PCM disorders were divided into 3 groups: 1) 32 patients with Stages IIIB-V CKD who had taken oral alfacalcidol 0.25 microg/day; 2) 28 patients with Stages IIIB-V CKD who had used oral paricalcitol 1 microg/day; 3) 30 patients with Stages IIIB-V CKD who had not received, as self- motivated, active vitamin D metabolites at the predialysis stage. RESULTS: Alfacalcidol and paricalcitol were quite satisfactorily tolerated by the patients. After 3 months of initiation of the use of these agents, Groups 1 and 2 patients with predialysis CKD and baseline elevated blood intact parathyroid hormone (iPTH) levels could not only achieve, but also maintain target blood iPTH levels. In the patients taking paricalcitol, the urinary protein level decreased more promptly; moreover, by the end of month 6 the reduction in blood pressure (BP) was more significant than in those using alfacalcidol (p < 0.05). Comparison of the effects of angiotensin-converting enzyme inhibitors in combination with alfacalcidol or paricalcitol on BP changes and left ventricular mass index indicated that the most pronounced positive changes occurred when angiotensin-converting enzyme inhibitors were used in combination with paricalcitol. CONCLUSION: The use of paricalcitol in predialysis CKD with PTH hyperproduction results in not only normalization of the levels of both PTH and osseous isoenzyme of alkaline phosphatase, but also in significantly reduced daily proteinuria and regression of left ventricular hypertrophy and chronic heart failure.

Goldilocks, vitamin D and sarcoidosis.

While low levels of vitamin D can increase the risk for osteoporosis, excessive amounts of vitamin D may also be problematic. Hypercalcemia and hypercalcuria due to increased vitamin D activity occur in a significant proportion of sarcoidosis patients. Saidenberg-Kermanac'h and colleagues compared vitamin D levels with bone fragility fractures in their sarcoidosis clinic.They found that a 25-(OH) vitamin D level between 10 and 20 ng/ml was associated with the lowest risk of bone fractures and paradoxically higher levels increased the risk of bone fractures. Using less vitamin D supplementation may simultaneously lower the risk for bone fracture and hypercalcemia in sarcoidosis.

Vitamin D and calcium abnormalities in the HIV-infected population.

The prevalence of vitamin D deficiency among HIV-infected persons is substantial and comparable to the general population. The factors associated with vitamin D deficiency are similar for both populations but additional factors (ie, use of certain antiretroviral agents) also contribute to vitamin D deficiency among HIV-infected persons. The adverse outcomes associated with vitamin D deficiency considerably overlap with non-AIDS defining illnesses (NADIs) that are increasingly becoming widespread in the aging HIV-infected population. However, there is scant evidence to support any causal inference. Further studies are warranted as efforts to identify and address modifiable risk factors contributing to NADIs continue.

Bone fragility in sarcoidosis and relationships with calcium metabolism disorders: a cross sectional study on 142 patients.

INTRODUCTION: The prevention of fragility fractures in patients with sarcoidosis is a serious concern and the potential risk of hypercalcemia limits vitamin D and calcium supplementation. The objective of this study was to evaluate the risk factors for low bone mineral density (BMD) and fractures in sarcoidosis. In particular, we aimed to determine the link among bone fragility and calcium and vitamin D metabolism in this population. METHODS: We performed a cross-sectional analysis on 142 consecutive patients with histologically proven sarcoidosis. BMD and prevalence of vertebral fractures on X-rays were assessed and the association with potential risk factors was studied by regression analysis. RESULTS: Fragility fractures occurred in 23.5% of patients, despite a normal mean BMD in the study population. In a multivariate analysis, low dietary calcium, fracture, age, gender and menopause were associated with increased risk of low BMD. Low dietary calcium, high current corticosteroid dose and low creatinine clearance were associated with increased risk of fracture. Serum 25(OH)D between 10 and 20 ng/ml was significantly associated with higher BMD. Conversely, values greater than 20 ng/ml were associated with increased risk of fracture. Serum 25(OH)D level was inversely correlated with disease activity. Of note, vitamin D supplements increased serum 25(OH)D in a dose-dependent manner but had no effect on serum calcium level. CONCLUSIONS: Sarcoidosis patients have a high risk of fracture despite not having a lowered BMD suggesting that other independent factors are involved. Current corticosteroid dose, low dietary calcium and serum 25(OH)D levels are associated with bone fragility. In sarcoidosis, calcium and vitamin D supplementation might be warranted, but desirable 25(OH)D serum levels might be lower than those advised for the general population.

Parathyroid and calcium metabolism disorders during pregnancy.

Parathyroid disorders are not common among pregnant women, but harbor a significant morbidity and mortality potential if they remain unrecognized and untreated. The symptoms caused by abnormally low or high blood free calcium level are mostly non-specific in the initial stages, thus when recognized might pose a real danger. Here we will survey the alterations in calcium metabolism induced by pregnancy, and describe the clinical manifestations, diagnosis and treatment of parathyroid and other calcium metabolism disorders during pregnancy. The current literature on the impact of calcium and vitamin D deficiency during pregnancy will also be reviewed.

[Prevalence and quality of control of calcium and phosphorus metabolism disorders among Lithuanian hemodialysis patients in 2004 and 2005]. / Kalcio ir fosforo apykaitos sutrikimu paplitimas, pobudis bei kontroles kokybe tarp Lietuvos hemodializuojamu ligoniu (2004-2005 metu duomenimis).

UNLABELLED: The aim of the study was to determine the prevalence and quality of control of disorders of calcium and phosphorus metabolism among patients on hemodialysis in Lithuania during the period of 2004-2005 and to assess rarely used methods of treatment such as parathyroidectomy and administration of calcimimetics. MATERIAL AND METHODS: All Lithuanian hemodialysis centers were visited, and data on disorders of calcium-phosphorus metabolism were collected in December 2004 and 2005. The quality of control was evaluated according to Kidney Disease Outcome Quality Initiative recommendations. RESULTS: According to Kidney Disease Outcome Quality Initiative guidelines, normal parathyroid hormone levels were found in 20.4% of hemodialysis patients in 2004 and 18.8% of hemodialysis patients in 2005; normal levels of phosphate were in 41.9% and 39.4%, respectively; normal levels of calcium were observed in 44.7% of patients in 2004 and in 42.3% of patients in 2005. In 2005 as compared to 2004, there were statistically significantly more patients with low parathyroid hormone level (39.9% and 45.8%, respectively, P<0.05). Only in 5.6% of patients in 2004 and 3.9% of patients in 2005, all four parameters of calcium-phosphate metabolism (calcium, phosphate, and of parathyroid hormone levels and calcium-phosphate product) were within the normal range. No parameters in the normal range were found in 17-20% of patients. The use of alfacalcidol significantly increased: 316 (30.8%) patients in 2004 and 388 (35.7%) patients in 2005 were treated with alfacalcidol (P<0.05). Alfacalcidol was prescribed for 16.5% of patients in 2004 and for 17% of patients in 2005, in whom parathyroid hormone level was below the normal range in the presence of hypercalcemia and hyperphosphatemia. The use of calcimimetics was considered rational in 142 (13.8%) patients in 2004 and 119 (10.9%) patients in 2005. According to the data of our study, parathyroidectomy was indicated in 19 (1.85%) patients in 2004 and 17 (1.56%) patients in 2005. CONCLUSIONS: According to Kidney Disease Outcome Quality Initiative recommendations, the control of disorders of calcium-phosphate metabolism in Lithuanian hemodialysis patients was insufficient in 2004 and 2005. One-third of the patients were treated with alfacalcidol when parathyroid hormone level was low and hypercalcemia and hyperphosphatemia persisted. Calcimimetics for the treatment of secondary hyperparathyroidism were administered in about 10% of patients.

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.

Bone mineral density and urinary N-acetyl-beta-D-glucosaminidase activity in paediatric patients with idiopathic hypercalciuria.

BACKGROUND: Idiopathic hypercalciuria (IH) is defined as hypercalciuria that persists after correction of dietary inbalances and has no detectable causes. Patients with IH have a higher prevalence of osteoporosis. Defective reabsorption of calcium by the renal tubule is considered a likely mechanism of IH. N-acetyl-beta-D-glucosaminidase (NAG) is a lysosomal enzyme that is a very sensitive marker of renal tubular impairment. METHODS: Fifteen patients (nine boys and six girls, mean age 12.4 +/- 4.0 years) with IH (urinary calcium excretion >0.1 mmol/kg per 24 h) had their bodyweight, height, body mass index (BMI), urinary NAG/creatinine ratio (U-NAG/Cr) and 24-h urinary calcium excretion (U-Ca/24 h) assessed. L1-L4 bone mineral density (BMD) was measured by dual energy X-ray absorptiometry and volumetric BMD (BMDvol) was calculated. The obtained results were expressed as Z-scores. RESULTS: The values of basic anthropometric parameters did not differ significantly from the values of the reference population and there was a tendency to short stature, which did not reach statistical significance (P = 0.08). The values of calciuria and U-NAG/Cr were significantly higher while BMD was significantly lower when compared to the reference values (P < 0.0006, P < 0.006 and P < 0.001, respectively). Inverse and significant correlations were found between U-Ca/24 h and BMD, U-Ca/24 h and body height, and U-Ca/24 h and BMDvol (r = -0.64 and -0.70, respectively, P < 0.01; r = -0.55, P < 0.05), while there was no correlation between U-NAG/Cr and U-Ca/24 h, nor between BMD and weight or BMD and BMI. CONCLUSION: Tubular impairment is highly probable in children with IH, but there is a poor relationship with the degree of calcium leakage. Idiopathic hypercalciuria should be considered as a risk factor for stunted growth and low bone mass.

Clinical and laboratory features of calcium-sensing receptor disorders: a systematic review.

Mutations in the calcium-sensing receptor gene (CaSR) may result in disorders of calcium homeostasis manifesting as familial benign hypocalciuric hypercalcaemia (FBHH), neonatal severe hyperparathyroidism (NSHPT) or autosomal dominant hypocalcaemia with hypercalciuria (ADHH). FBHH may have a population prevalence as high as one in 16 000, and ADHH one in 70 000. NSHPT is very rare. The FBHH condition is usually asymptomatic. Parathyroidectomy does not result in normal serum calcium, and no active treatment is indicated. To differentiate FBHH from primary hyperparathyroidism (PHPT), a guideline which includes measurement of serum calcium, intact parathyroid hormone (PTH), magnesium and fasting urinary calcium excretion is proposed. Screening of family members for hypercalcaemia, and occasionally a search for mutations in the CaSR gene, may be required. The NSHPT condition may manifest with hypercalcaemia, (usually) very elevated serum PTH concentration, subperiosteal erosions and fractures. Milder cases may be managed medically, but respiratory failure, extreme hypercalcaemia and failure to thrive are indications for early parathyroidectomy. The ADHH condition may result in asymptomatic hypocalcaemia, but some affected family members have minor symptoms, and a minority experience seizures in infancy which can recur into adulthood. A significant proportion of cases previously reported as idiopathic hypoparathyroidism (IHP) may in fact be due to mutations in the CaSR gene. In a moderately hypocalcaemic patient with no other clearly discernible cause, an elevated urine calcium:creatinine ratio is suggestive of ADHH, as is the presence of a first-degree relative with hypocalcaemia. If treatment with vitamin D analogues is undertaken, serum and urine calcium should be monitored, advice which applies equally to ADHH and IHP.

Childhood idiopathic hypercalciuria--clinical significance of renal calyceal microlithiasis and risk of calcium nephrolithiasis.

OBJECTIVE: To evaluate the clinical significance of renal calyceal microlithiasis (RCM) in children with idiopathic hypercalciuria (IHC). MATERIAL AND METHODS: RCM is a renal echographic finding defined as the presence of hyperechogenic spots < 3 mm in diameter in the renal calyces. These spots have been associated with the presence of nephrourological symptoms in children and are considered to represent a stage prior to urolithiasis. We reviewed the medical records of 103 children (63 girls, 40 boys; age range 1-14 years; mean age 6.57 years) referred for various complaints who had IHC. Renal echography was routinely performed. At diagnosis, 52 children had RCM, 35 showed normal echography, 14 had calculi and two presented nephrocalcinosis. A long-term follow-up study was carried out to compare the clinical manifestations, analytic data and renal echographic findings of patients with RCM and those with normal echography. RESULTS: The clinical manifestations and the results of biochemical studies did not differ significantly between the two groups. Renal sonographic findings during the follow-up period revealed that, of patients with initial RCM, 35 showed normalized sonographic findings, two developed calculi and 36 developed recurrent RCM. Of the children with normal initial echography, 17 developed RCM and three developed calculi. The risk of developing lithiasis was less in children with RCM than in those with normal initial renal echography (0.04 vs 0.09), the relative risk being 0.45 (95% CI 0.08-2.55). The clinical and analytic differences between the group of 14 children with initial lithiasis and the other two groups previously described were also analyzed and no significant differences were found. An ongoing echographic study of these patients showed that the echograph was normalized in 10 children at some point or other, while seven developed RCM (four unilateral, three bilateral). In 13 cases the lithiasis reappeared, and the relative risk of recurrent lithiasis compared with those who initially showed no lithiasis was 16.16 (CI 95% 6.81-38.31). CONCLUSION: Our results indicate that up to 85% of children with IHC presented RCM in follow-up sonographies. This echographic finding, which may appear and disappear at different points during follow-up, does not seem to indicate an increased risk of lithiasis.

Bone mass loss in calcium stone disease: focus on hypercalciuria and metabolic factors.

BACKGROUND: Several authors have observed that idiopathic calcium stone formers show a bone mass reduction, which is more evident in those with idiopathic hypercalciuria. The aim of this work was the evaluation of osteopenia and osteoporosis rate in a group of idiopathic calcium stone formers. The influence of hypercalciuria, nutritional factors and anthropometric parameters on bone mass was evaluated in these patients as well. METHODS: We enrolled 196 idiopathic calcium stone formers; 102 males, and 94 females. All subjects underwent a metabolic study. BMC and BMD were evaluated as well as QUS. RESULTS: Males showed greater weight, height, BMI, densitometric values and plasma creatinine, uric acid, urea, sodium, magnesium, GFR and urinary osmolarity than females. Moreover males excreted more uric acid, urea, creatinine, sulphate, phosphate, oxalate and citrate than females. The prevalence of osteopenia and osteoporosis, according to T-score, was 54% and 14% respectively. Hypercalciuria was demonstrated in 21.7% of the patients. Hypercalciuric men showed a higher excretion of urea, phosphate, sulphate and magnesium. CONCLUSIONS: Our results confirm the importance of QUS in the evaluation of stone formers' bone mass. Anthropometric characteristics and dietary habits seem to play a role in bone loss. We did not demonstrate any influence of hypercalciuria on bone mass. Although the pathogenesis of bone loss in stone formers still remains unclear, it can be hypothesized that a slight degree of metabolic acidosis, probably of alimentary origin, may be involved in the reduction of bone mass.

Genetic renal disorders with hypomagnesemia and hypocalciuria.

The combination of hypomagnesemia and hypocalciuria is the phenotypic signature of two distinct genetic renal tubular transport disorders: Gitelman's syndrome and autosomal dominant isolated renal magnesium wasting. In the past 5 years the genetic defects underlying these disorders have been elucidated through positional candidate cloning approaches. The defective proteins involved in both diseases are located within the distal convoluted tubule (DCT), a segment of the nephron known to play an important role in active magnesium reabsorption in the nephron. The introduction outlines the magnesium handling in the body in general and, in particular, in the kidney, followed by a detailed discussion of Gitelman's syndrome and isolated renal magnesium wasting, including the clinical and biochemical symptoms, genetic aspects and pathophysiology.

Hypercalciuria in Beckwith-Wiedemann syndrome.

We determined the incidence of hypercalciuria (HC) and its association with nephrocalcinosis and nephrolithiasis in 18 consecutive patients with Beckwith-Weidemann syndrome (BWS). Random, nonfasting urine samples were obtained from each patient. All patients had abdominal ultrasonography, most on several occasions. Four patients (22%) had HC. Of these, 2 had nephrocalcinosis, one had hyperechoic kidneys, and one had normal renal imaging. Serum calcium was normal in all patients with HC. Because we found that an increased prevalence in the occurrence of HC and its complications in a group of children with BWS, any child with BWS should be evaluated for HC.

[Inheritance and prevalence of hypercalciuria in the children from the island of La Gomera]. / Herencia y prevalencia de hipercalciuria en la población infantil de la isla de La Gomera.

The urinary elimination of calcium has been studies in 549 school children from the island of La Gomera (Canary Islands) and in 100 children of a control group from the capital of the Canaries, Santa Cruz de Tenerife. The diet was not manipulated and it was proven that the water that they consumed was of characteristic equal. The 95th centile for the distribution of the calcium/creatinine index was 0.2 in the control group, we calculated the prevalence of hypercalciuria of this group (3.8%) and of the study group (16%). The prevalence was analyzed by areas of the island and it this showed that it was higher (28.4%) in those from isolated communities and therefore, with history of more inbreeding that in those with good communications (10.6%). It was observed that the risk of suffering hypercalciuria among the children that have four grand-parents who are natives of the island of La Gomera is 2.85 times higher than in those that don't have any grand-father/mother coming from the island. Hypercalciuria siblings of children with hypercalciuria found in 50%.

High prevalence of bone disorders after gastrectomy.

BACKGROUND: Studies indicate that gastrectomy might alter calcium and bone metabolism, resulting in bone disorders. No data are currently available on the prevalence of bone disorders after gastrectomy. METHODS: Sixty gastrectomy patients were investigated for serum parameters of calcium and bone metabolism 5 to 20 years postoperatively and compared to an age- and sex-matched healthy control population. Forty patients agreed to a radiological investigation of the spine by anterior-posterior and lateral radiographs of the thoracic and lumbar spine and by computed tomography (CT) osteodensitometry. RESULTS: Serum calcium and 25-(OH)-vitamin D were decreased in gastrectomized patients, while parathyroid hormone and 1,25-(OH)2-vitamin D were increased. Serum parameters of calcium metabolism were altered in as many as 68% of patients. We found 31 vertebral fractures in 13 patients, 30 grade 2 vertebral deformities in 18 patients, and osteopenia in 15 patients, corresponding to a prevalence of 33%, 45%, and 37% in gastrectomized patients, respectively. The overall rate of gastrectomy patients having vertebral fractures and/or osteopenia was 55%. The risk of having a vertebral deformity was increased by more than sixfold after gastrectomy. Our study is the first report evaluating vertebral deformities in gastrectomized patients, and the largest series of gastrectomized patients investigated by CT osteodensitometry. CONCLUSION: We found a high prevalence of bone disorders in gastrectomized patients, possibly resulting from disorders in calcium metabolism. Postgastrectomy bone disease might derive from a calcium deficit, which increases calcium release from bone and impairs calcification of newly build bone matrix.

Renal function in children with hypercalciuria.

Hypercalciuria is a common problem causing symptoms such as abdominal pain, hematuria and enuresis, and leading to stone formation. It results from a renal tubular calcium "leak" or intestinal hyper-reabsorption of calcium. This study was performed to determine whether renal functional impairment was present in children with hypercalciuria. The study group comprised 298 children who were screened for hypercalciuria by means of urinary calcium/creatinine (UCa/UCr) ratio. The renal functions of 18 children (6.4%) detected as having hypercalciuria with Ca/Cr ratios of greater than 0.18 in their spot urines were evaluated. Results were compared with those of the healthy control group. The rate of hypercalciuria did not very significantly between the boys and girls (p > 0.05). The mean value of daily calcium excretion was 6.42 + 3.93 mg/kg/day in the children with hypercalciuria, which was significantly different from that of the control group (p < 0.01). When the values of creatinine, osmolar and free water clearances, fractional excretion of sodium and tubular reabsorption of phosphorus were compared between the patient and control groups, the difference was not significant (p > 0.05). Urinary N-acetyl-beta-D-glucosaminidase (NAG) excretion, which was described as the creatinine ratio, was significantly higher in the children with hypercalciuria. These findings suggest that in the presence of normal renal functional studies in children with hypercalciuria, tubular injury can be detected by NAG, which is a more sensitive marker of renal tubular injury.

[Incidence of the different types of hypercalciuria in Spain]. / Incidencia de los diferentes tipos de hipercalciuria en España.

OBJECTIVE: To carry out a comparative biochemical study of primary hyperparathyroidism, the different types of hypercalciuria and a healthy population. METHODS: Fourteen patients with primary hyperparathyroidism and 103 patients with idiopathic hypercalciuria were studied under conditions of restricted calcium intake and following a calcium load; the results were compared to those of 18 healthy controls. RESULTS: The patients with hyperparathyroidism showed high parathormone concentrations. Sixty-nine patients with idiopathic hypercalciuria had normal parathormone levels and were considered suffering from absorptive hypercalciuria. Those patients with high urinary calcium excretion under restricted calcium intake and normal urinary phosphate threshold were considered as being absorptive hypercalciuria type I, those with normal urinary calcium as absorptive hypercalciuria type II, and those with low urinary phosphate threshold constituted a renal phosphate leakage group. Thirty-four patients had normal serum calcium, elevated parathormone, hypophosphatemia and high calcium excretion under all dietary conditions, and were considered undergoing renal hypercalciuria. Patients with renal hypercalciuria had increased urine hydroxyproline and low serum calcium compared with the controls after an oral calcium load. This biochemical behaviour is compatible with secondary hyperparathyroidism caused by renal calcium leakage. CONCLUSIONS: In summary, the biochemical parameters: parathormone, urinary phosphate threshold and urinary calcium excretion, measured in fasting conditions, allowed classification of patients with idiopathic hypercalciuria.

Urinary calcium creatinine ratio and hypercalciuria.

Random urine samples of 352 children in the age group of 5-12 yrs were studied for urinary calcium-creatinine ratio (Uca/Ucr mg/mg). None had any predisposing factor for secondary hypercalciuria. Calcium and creatinine both were estimated by colorimetric method. We observed that Uca/Ucr in the general pediatric population was skewed, the pattern was similar to that described in western children and it was independent of age and sex. The mean and standard deviation (SD) of Uca/Ucr was 0.10 +/- 0.094. Considering mean +2SD as the upper limit of normal, which was 0.29 in this series, the prevalence of hypercalciuria was 6.5%.