The relationship between urinary calcium, sodium, and potassium excretion in full-term healthy newborns

The objective of this study was to determine the specific reference values for urinary calcium/creatinine (UCA/Cr) (mg/mg) in healthy breast-fed newborns, and to evaluate the relationship between UCa/Cr, urinary sodium/creatinine (UNa/Cr), urinary potassium/creatinine (UK/Cr) and UNa/UK ratios in the same group. A total of 88 infants aged between 0-28 days were enrolled in this study. They were divided into two age groups as follows: Group I: < or = 7 days of age; Group 2 infants aged between 8-28 days. Non-fasting spot urine was analyzed for Ca, Na, K and Cr. Significant differences were observed between the two groups in terms of UCa/Cr (0.11+/-0.10 vs 0.27+/-0.23, p<0.001), UNa/Cr (1.29+/-1.63 vs 5.5+/-4.83, p<0.001), and UK/Cr (0.94+/-0.99 vs 2.82+/-2.3, p<0.001). The data showed positive correlation between UCa/Cr and age (r=0.38, p<0.001) as well as between age and UNa/Cr ratio (r=0.68, p=0.0001) and between age and UK/Cr ratio (r=0.57, p<0.0001). Additionally, there was a positive correlation between UNa/UK and age (r=0.40, p=0.001). The UCa/Cr ratio positively correlated with UNa/Cr whereas no correlation was found between UCa/Cr and UNa/Uk ratio. Our data suggest that the healthy neonates differ from the hypercalciuric patients by exhibiting a linear correlation between Na/K and UCa/Cr. As the normal values of UCa/Cr, UNa/Cr, UK/Cr, UNa/UK ratios in the early neonatal period differ from those in the late neonatal period, these differences should be taken into consideration when assessing urinary excretion of these parameters for diagnostic purposes in the early and late newborn periods.     

Asymptomatic hypercalciuria : Prevalence and metabolic characteristics

Hypercalciuria is of continuing interest as a risk factor for kidney stones in children. We screened 592 healthy Turkish children (308 boys, 284 girls, aged 3 month-16 years) for hypercalciuria by measurement of urinary calcium/creatinine (UCa/Cr) ratio in the second-morning urine samples. Hypercalciuria was noted in 17 children (2.9 %), 9 of them were boy and 8 of them were girl. Oral calcium-loading test could only be done in 7 children who were diagnosed as having hypercalciuria, and it revealed absorptive hypercalciuria in 2 cases and renal hypercalciuria in no cases. The frequency of a family history of urolithiasis in asymptomatic hypercalciuric children was 50%. Median UCa/Cr ratios and urinary magnesium/creatinine (UMg/Cr) ratios were 0.11 and 0.10 and the 97th percentiles were 0.32 and 0.23 respectively. The UCa/Cr ratio in second-morning urine samples was correlated with the UMg/Cr ratio (r = 0.44) and was independent of age and sex.     

Hypercalciuria in chronically institutionalized bedridden children: frequency, predictive factors and response to treatment with thiazides

Calcium and creatinine concentrations were analyzed in urine samples of 42 chronically institutionalized bedridden children, with neurologic disorders. Their ages ranged from 2 to 16 (mean 8.7) years. Hypercalciuria, defined as UCa/UCr ratio greater than 0.21, was recognized in 18 children (42.8%), the mean UCa/UCr ratio of this group was 0.40 +/- 0.18. Twenty-four children were normocalciuric, with a mean UCa/UCr ratio of 0.08 +/- 0.03. There were no significant differences between the two groups with regard to age, sex, length of institutionalization, the basic neurologic disorder, diet, anticonvulsive medications, exposure to sunlight and weekly hours of physiotherapy. Age- and sex-matched percentiles for fat and muscle areas were similar in both groups. Seven limb fractures had occurred in the hypercalciuric group during the last three years, but only in one of the normocalciuric patients (p less than 0.02). The hypercalciuric children were treated with a hydrochlorothiazide-amiloride preparation for three weeks, which resulted in reduction of their mean UCa/UCr ratio by 57.7%, to 0.17 +/- 0.13 (p less than 0.005); only four children remained hypercalciuric. We conclude that resorptive hypercalciuria is common among chronically immobilized bedridden children. Hypercalciuria in such children should be specifically looked for, because of its association with deranged bone metabolism and increased frequency of limb fractures. Treatment with thiazides was found to be efficient in reducing urinary calcium excretion in our hypercalciuric patients. This therapeutic modality for the reduction of morbidity in bedridden chronically immobilized children should be further explored.     

Hypercalciuria in children with juvenile rheumatoid arthritis: association with hematuria

After discovering juvenile rheumatoid arthritis (JRA), hematuria, and urolithiasis associated with hypercalciuria in two children, urinary calcium excretion was examined in 38 patients with JRA. Fasting urine calcium/creatinine (mg/mg) (UCa/UCr) ratios were increased (greater than 0.21) in 12 patients, who had a mean UCa/UCr ratio of 0.34 +/- 0.14, compared with 0.09 +/- 0.06 in 26 normocalciuric patients with JRA. Increased UCa/UCr ratios were found more frequently in patients with systemic JRA (P less than 0.05); however, no relationship between UCa/UCr ratios and either functional classification or drug therapy was observed. Four children with increased urine calcium to creatinine ratios were examined more extensively. Twenty-four-hour urine calcium excretion ranged from 4.0 to 7.2 mg/kg/24 hours. An orally administered calcium loading test demonstrated fasting hypercalciuria after dietary calcium restriction in these four patients. Serum calcium, bicarbonate, phosphorus, and parathyroid hormone values were normal. Hematuria was found in six of 12 hypercalciuric patients with JRA but in only three of 26 normocalciuric patients (P less than 0.016). We conclude that urinary calcium excretion is frequently increased in patients with JRA and that hypercalciuria may be related to the pathogenesis of hematuria in some of them.     

Increased urinary excretion of renal N-acetyl-beta-glucosaminidase in hypercalciuria

Urinary excretion of N-acetyl-beta-glucosaminidase (NAG), a lysosomal enzyme, was examined in 33 children with hypercalciuria. Urinary NAG excretion in 13 healthy children was 5.84 +/- 9.35 nmole/hr/mg of creatinine (NAG/Cr) (mean +/- SD) compared with 35.61 +/- 42.04 nmole/hr/mg of creatinine in 23 children with renal hypercalciuria, and 28.99 +/- 13.69 nmole/hr/mg of creatinine in ten children with absorptive hypercalciuria. In children with renal hypercalciuria, NAG/Cr excretion was not statistically different between children with either urolithiasis or hematuria without calculi. In six children with renal hypercalciuria, no significant change in NAG/Cr excretion occurred after a mean duration of 25 weeks of hydrochlorothiazide therapy although urinary calcium to creatinine ratios (UCa/Cr) decreased from 0.24 +/- 0.11 to 0.16 +/- 0.11. We conclude that increased urinary calcium excretion produces renal tubular injury and that the renal injury may not be reversed by short-term alterations in urinary calcium excretion.     

Studies on the urinary calcium excretion in children with hematuria of postglomerular origin: effects of the variation of dietary calcium and sodium intake

The effect of different dietary regimens and of an oral calcium (Ca) load was studied in 30 children with postglomerular hematuria, 8 of whom were renal stone formers. In addition we investigated the urinary inorganic phosphate complex composition in 12 of them, based on the principles of complex equilibria. Twenty-one of the 30 hematuric children with a urinary Ca/creatinine (Ca/cr) ratio of greater than or equal to 0.6 (mmol/mmol) were regarded as hypercalciuric. Low calcium intake normalised the ratio in 11 patients, fulfilling the definition of absorptive hypercalciuria, but not in the other 10 patients with renal hypercalciuria. Sodium restriction combined with low calcium diet induced a further significant decrease of the urinary Ca/cr ratio to a normal range in both forms of hypercalciuria (mean +/- SD: 0.325 +/- 0.112 in absorptive hypercalciuria; 0.533 +/- 235 in renal hypercalciuria). There was a significant difference in the composition of phosphate complexes between the 6 normocalciuric patients and the 6 children with renal hypercalciuria investigated. Lithogenic urinary phosphate complexes (CaHPO4, MgHPO4) were excreted by the latter group in a significantly higher amount under basal conditions. On the basis of these data sodium restriction added to low calcium diet could represent a dietary approach in preventing excessive calcium excretion in idiopathic hypercalciuria, and therefore renal stone formation.     

Normal urinary calcium/creatinine ratios in Turkish children

A random urine calcium/creatinine ratio (UCa/Cr) is of practical use in screening for hypercalciuria. However, due to worldwide variations, reference values for the pediatric population are not yet well established. Furthermore, no study has been conducted to establish normal UCa/Cr values in Turkish children. The objectives of the present study were to set normal values of random UCa/Cr by age in the pediatric population of Istanbul City. A total of 324 healthy children of both genders were enrolled in the study. They were divided into four age groups as follows: (1) < 7 months, (2) 8-18 months, (3) 19 months to 6 years, and (4) 7-14 years. A non-fasting random urine specimen from each subject was analyzed for calcium and creatinine. The median UCa/Cr values were 0.19, 0.20, 0.14 and 0.10 respectively. The data showed a strong inverse relationship with age. The age-dependent 95th percentiles of UCa/Cr values were 0.76, 0.60, 0.69 and 0.24 respectively. The child's age and geographic location should be taken into consideration when interpreting UCa/Cr ratio.     

Hypercalciuria and postglomerular hematuria in children. The effects of thiazide on calcium excretion, urine saturation with respect to calcium-hydrogenphosphate and hematuria

Calcium-hydrogenphosphate was considered as one of the main factors governing renal calculus formation. The degree of saturation (expressed as activity product = AP) with respect to this phase was therefore calculated in urines of 36 hypercalciuric children (20 absorptive, 16 renal subtype) with isolated hematuria and 30 healthy controls. The effect of thiazide treatment on the urine saturation and on the evolution of hematuria was also investigated. The results were compared to the urinary calcium excretion (expressed as Ca/cr ratio). Urines of both hypercalciuric groups were saturated on basal conditions (AP above 3.5 x 10-6 mol2/l2; -lgAP below 6.4), the values differed significantly from those of the controls (-lgAP = 6.78 +/- 0.4 in the control-; 6.1 +/- 0.25 in absorptive-, 6.03 +/- 0.34 in renal hypercalciuria; p less than 0.001). Thiazide normalized the activity product in all groups. During thiazide therapy significant decrease in the occurrence of hematuria was noted (p less than 0.001 in both hypercalciuric groups). These data furnish further evidence on the relation of hypercalciuria and postglomerular hematuria. Simultaneous determinations of the state of saturation may provide further information on the "stone forming potential" of the urines investigated.     

Longitudinal changes in insulin sensitivity, insulin secretion, and beta-cell function during puberty

OBJECTIVE: To determine longitudinal changes in insulin sensitivity (SI), insulin secretion, and beta-cell function during puberty in white and black youth. STUDY DESIGN: The tolbutamide-modified frequently sampled intravenous glucose tolerance test and minimal modeling were used to measure SI, the acute insulin response to glucose (AIRg), and beta-cell function (disposition index, DI) in white (n = 46) and black (n = 46) children (mean [+/-SD] age at baseline = 10.2 +/- 1.7 years). Growth curve models (including 272 observations) with SI, AIRg, and DI regressed on Tanner stage were run after adjusting for covariates. RESULTS: After adjusting for covariates, growth curve models revealed that SI decreased and subsequently recovered by the end of puberty in whites and blacks (both p < .05), AIRg decreased linearly across Tanner stages in both races (both p < .001), and DI decreased across puberty in blacks (p = .001) but not in whites (p = .2). CONCLUSIONS: White and black youth exhibited transient insulin resistance and diminished AIRg during puberty. The progressive decline in DI among blacks versus whites may reflect a unique effect of puberty on beta-cell compensation in blacks. Future studies are needed to identify whether this difference contributes to the increased risk of type II diabetes in young blacks.     

Urinary calcium excretion in Swedish children

Urinary calcium excretion was measured in an unselected population of 153 healthy Swedish children aged 2–18 years. Urine was collected after an ordinary meal. Urinary calcium excretion was measured as the calcium/creatinine concentration ratio (UCa/Cr) and expressed in mmol/1 per mmol/1. UCa/Cr was 0.44 ± 0.379 (mean ±SD). As the UCa/Cr in this childhood population was not distributed in a normal manner, the results are more correctly presented as the 50th (0.33) and 97th (1.5) centiles. There was a weak but significant correlation between UCa/Cr and age, with higher values in the lower age groups. There was no correlation between UCa/Cr and the anamnestic intake of cow's milk. Repeated samples from some children showed a coefficient of variation between days of 30–40%. The upper limits of normal UCa/Cr (97th centile = 1.5; +2 SD = 1.2) in this investigation were higher than what is considered normal by others. In spite of this, none of the children had a history of renal stone disease or any other symptoms of hypercalciuria. Renal stone disease is thought to be rare in Swedish children although the real incidence is not known. The diagnosis of hypercalciuria should be based on repeated samples from an individual with symptoms and related to age-related reference values from the same population group.     

Hematuria and hypercalciuria in children with diabetes mellitus

Hematuria of unknown origin occurs in 30% of patients with diabetic nephropathy. In nondiabetic persons, hematuria may be caused by hypercalciuria with or without nephrolithiasis. Eight children with type I diabetes mellitus, hematuria, and hypercalciuria were observed in our clinic during a 1-year period. Two of these also had evidence of renal papillary necrosis. To assess the importance of hypercalciuria in the pathogenesis of hematuria in children with diabetes mellitus, we measured urinary calcium excretion in a large population of such patients. The calcium to creatinine ratio in the urine of diabetic children (0.21 +/- 0.01) was greater than that of nondiabetic children (0.12 +/- 0.01). A calcium to creatinine ratio of 0.28 was established as the upper limit of normal in our nondiabetic population, and 27% of the diabetic children were hypercalciuric on this basis. The diabetic children with hypercalciuria also had hyperphosphaturia and a urinary CaHPO4 X 2H2O molar ion product three times that found in the nondiabetic control population. These data suggest that many children with diabetes are at risk for renal damage due to hypercalciuria. Because hypercalciuria is more common in diabetic than nondiabetic children, it may play a previously unrecognized role in the renal disease associated with diabetes mellitus.     

Health-related quality of life in overweight and nonoverweight black and white adolescents

OBJECTIVES: To assess the impact of obesity on quality of life (QOL) in black and white adolescents. STUDY DESIGN: One hundred ten overweight (body mass index [BMI], 41.7 +/- 8.9 kg/m2) and 34 nonoverweight adolescents (BMI, 20.6 +/- 2.9 kg/m2) and their parents completed measures of QOL. RESULTS: Overweight was associated with poorer adolescent-reported QOL and parent reports of their children's QOL. Examining groups by weight status and race, overweight whites reported the greatest impairment on Social/Interpersonal, Self-Esteem, and Physical Appearance QOL (all P < .01), whereas parents of overweight blacks reported the poorest General Health Perceptions scores regarding their children. Interactions between BMI z-score and race were detected for Social/Interpersonal, Self-esteem, Daily Living, Self-Efficacy, Self-regard, and Physical Appearance QOL (all P < .05): Higher BMI in whites was associated with greater impairments in QOL than in blacks. Parents reported similar relations for their children. CONCLUSIONS: According to adolescent and parent reports, overweight is associated with poorer QOL in adolescence, regardless of race; however, compared with overweight white adolescents, blacks report less impairment in QOL. Future research is required to determine whether differences in QOL are predictive of treatment success.     

The urinary sodium/potassium ratio in children from southern Italy living in Cimitile: a case for concern

The urinary sodium/potassium (Na/K) ratio was evaluated in 220 children aged 3-16 years living in Cimitile, a small town near Naples in Southern Italy by utilizing 24 hour urinary collections. The Na/K ratio averaged 3.79 +/- 1.68 and correlated significantly (p less than 0.001) with age, body weight and height but not with Body Mass Index (BMI). No difference was seen when data were analyzed by sex. Mean daily sodium excretion averaged 3.91 +/- 1.52 mM/Kg while potassium excretion averaged 1.17 +/- 0.54 mM.Kg. The Na/K ratio was higher than that observed in children studied in Israel, United Kingdom, USA, and the Federal Republic of Germany and is of the same magnitude of that previously reported in children born in Japan. This high Na/K ratio is a case for concern because of the risks connected with high Na/K ratio in urine.     

Effect of race on outcome of white and black children with acute myeloid leukemia: the St. Jude experience

BACKGROUND: The association between race and outcome of treatment for childhood acute myeloid leukemia (AML) has not been adequately studied. PROCEDURE: We compared the clinical characteristics, biological features, and outcomes between white and black children with AML who were treated on five consecutive clinical protocols (1980-2002) at St. Jude Children's Research Hospital. We used proportional hazards modeling to investigate the relation between race and outcome. RESULTS: We observed no statistically significant differences between the 229 white and 58 black patients in clinical characteristics, FAB subtype, cytogenetic features, or outcome. There were no significant differences in event-free survival (EFS) or overall survival (OS) between the two race groups in individual clinical trials or in all studies combined. For the study group as a whole, the 5-year survival estimate was 39.2% +/- 3.6% for white patients and 33.8% +/- 6.5% for black patients. However, on our most recent trial (AML-97), there was a trend towards inferior outcome among black patients: the 5-year survival estimates were 55.6% +/- 12.3% and 27.3% +/- 13.5% for whites and blacks, respectively. CONCLUSIONS: Although we detected no differences in treatment outcome between white and black children with AML over the entire study period, black children appear to have worse outcomes than white children during more recent studies. Improved treatment is needed for all children with AML.     

Screening for Hypercalciuria

Reference values for the urinary calcium/creatinine ratio (Ca/Cr ratio) in the first morning urine were established in 361 healthy children aged 5 to 15 years, on unrestricted diets. The urinary Ca/Cr ratio in the urine upon arising was independent of sex but dependent upon age. The measurement of the urinary Ca/Cr ratio in the urine upon arising while on unrestricted diets may be a reasonable screening test for elevated calcium excretion. On the basis of the urinary Ca/Cr ratios in the urine upon arising during unrestricted diets and the calciuric response to calcium restricted diets and the oral calcium loading test, idiopathic hypercalciuria (IH) was subclassified into three groups: (1) absorptive hypercalciuria; (2) renal hypercalciuria; (3) dietary hypercalciuria. The pathogenesis of IH is controversial. Our data suggest that disordered 1,25 (OH)₂ vitamin D metabolism with excessive urinary phosphate excretion occurs in absorptive hypercalciuria.     

Extremely high prevalence of hypercalciuria in children living in the Aral Sea region

The Aral Sea region is a natural area seriously polluted by human activities. In addition to the increased prevalence of diverse chronic diseases in children, the risk of developing urolithiasis is reported to be high in this region. This study was undertaken to clarify the prevalence of hypercalciuria in children of the Aral Sea region. A group of 205 children living in Kazalinsk, close to the Aral Sea, and a group of 187 children living in Zhanakorgan, far from the Aral Sea, were screened for hypercalciuria. Urinary sodium excretion (sodium per creatinine, uNa/Cr) in addition to calcium excretion (calcium per creatinine, uCa/Cr) was also calculated for each subject. Mean uCa/Cr (mmol/mmol) and uNa/Cr (mmol/mmol) excretions were significantly higher in Kazalinsk than in Zhanakorgan (uCa/Cr: 0.75 +/- 0.74 and 0.33 +/- 0.30; uNa/Cr: 3.54 +/- 2.27 and 2.89 +/- 1.69, respectively, mean +/- SD, p < 0.01). Hypercalciuria regarded as an uCa/Cr of more than 0.703 was observed in 79 out of 205 Kazalinsk children (38.6%) while this was seen in only 24 out of 187 Zhanakorgan children (12.8%). Linear regression analysis revealed a direct positive correlation between urinary calcium and sodium excretion (p < 0.01) in Kazalinsk children. Conclusion: The prevalence of hypercalciuria in children around the Aral Sea region is extremely high. This may be associated with excessive intake of calcium and sodium, or due to impaired renal tubular function caused by toxic chemicals. Therefore, hypercalciuria that may lead to urolithiasis should be taken into account when considering the health problems of this area.     

Idiopathic hypercalciuria in children: pathophysiologic considerations of renal and absorptive subtypes

Sixteen children with idiopathic hypercalciuria and seven control children were observed. Patients were classified into two groups by means of an orally administered calcium loading test. Individuals with renal hypercalciuria (five children) had a high fasting urinary calcium/creatinine concentration ratio (0.27 +/- 0.05), a mild increase of this value after calcium administration (0.29 +/- 0.07, P less than 0.05), and elevated mean serum parathyroid hormone (PTH) concentrations (0.95 +/- 1.14 ng/ml). Patients with absorptive hypercalciuria (11 children) had fasting urinary calcium/creatinine concentration ratio of 0.11 +/- 0.04, a large increase of this index after calcium loading (0.25 +/- 0.06, P less than 0.0005), and normal levels of serum PTH (0.29 +/- 0.10 ng/ml). Next, we examined the effects of two different calcium intakes on urinary calcium excretion, serum calcium, PTH, and 1,25-dihydroxyvitamin D3 concentrations. In patients with absorptive hypercalciuria, the increased calcium intake resulted in significant increments of calciuria (P less than 0.0005), mild elevation of serum calcium concentration (P less than 0.05), and reduction of serum 1,25-dihydroxyvitamin D3 concentrations (P less than 0.005). By contrast, these values were not modified in children with renal hypercalciuria. Serum PTH did not change within each group. After dietary calcium supplementation, serum ratios of 1,25-dihydroxyvitamin D3 to calcium, phosphate, and PTH concentrations decreased significantly only in the group of children with absorptive hypercalciuria. Our data support the contention that 1,25-dihydroxyvitamin D3 metabolism is different in the two groups of patients with hypercalciuria.     

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.     

Use of the calcium-creatinine ratio in diagnosis and therapy

Hypercalciuria is a major cause of urolithiasis in adults and has reached increasing attendance in childhood. Traditionally urinary excretion of calcium is evaluated by 24-hour urine collection. Previous reports proposed the urinary calcium/urinary creatinine ratio (Ca/Cr-ratio) to diagnose hypercalciuric states. In 10 children with normocalciuria and 8 children with hypercalciuria the values of calcium excretion and Ca/Cr-ratio in a 24-hour urine collection were compared. 40 analyses showed a significant correlation (p = 0.001, r = 0.91) and hypercalciuria (urinary calcium greater than 4 mg/kg/day) is present if the Ca/Cr-ratio exceeds 0.23 (mg/mg). In 10 of the 18 patients the Ca/Cr-ratio of the 24-hour collection was compared with the Ca/Cr-ratio of a random urine sample collected 3 hours after breakfast. No significant difference was present. In 9 of 10 patients the correct diagnosis (normocalciuria or hypercalciuria) was possible by evaluation of this random urine sample. Our studies indicate that the evaluation of Ca/Cr-ratio in a random urine sample is a simple and reliable method to detect hypercalciuria and should be performed in all children with urolithiasis or unexplained hematuria. It is also a simple test for early detection of hypercalciuria in patients with long-term administration of vitamin D metabolites.     

Intrauterine programming of urinary calcium and magnesium excretion in children born to mothers with insulin dependent diabetes mellitus

BACKGROUND: Offspring of diabetic rats have reduced urinary calcium and magnesium excretion compared with offspring of controls; these differences persist up to 16 weeks after birth, a time equivalent to young adulthood in humans. OBJECTIVES: To test the hypothesis that urinary calcium and magnesium excretion would be lower in children born to mothers with insulin dependent diabetes mellitus (ChMIDDM) than those born to non-diabetic mothers. METHODS: Concentrations of calcium, magnesium, sodium, and creatinine were measured in first void spot urine samples collected from 45 (28 male; median age 9.6 years) ChMIDDM and 127 (58 male; median age 11.3 years) controls. Analysis of covariance was used to test for differences in urinary calcium to creatinine ratios (UCa/Cr), magnesium to creatinine ratios (UMg/Cr), and log sodium to creatinine ratios (logUNa/Cr) between controls and ChMIDDM after allowing for the effects of sex and age. RESULTS: UCa/Cr (difference -0.10, 95% confidence interval (CI) -0.19 to -0.01; p = 0.03) and UMg/Cr (difference -0.15, 95% CI -0.22 to -0.08; p<0.0001) were lower in ChMIDDM than controls. However, logUNa/Cr did not differ between ChMIDDM and controls (difference -0.14, 95% CI -0.33 to 0.05; p = 0.1). The daily estimated intake of magnesium, sodium, and protein were significantly higher and that of calcium non-significantly higher in ChMIDDM than controls. In ChMIDDM, UCa/Cr and UMg/Cr were not related to diabetic control of mothers. CONCLUSIONS: Results of this study provide the first evidence that in humans, as in rats, there is modification of renal Ca and Mg handling in ChMIDDM, which persists well into childhood.