Beta-thalassaemia major: Prevalence, risk factors and clinical consequences of hypercalciuria.

Regular transfusion and chelation therapy produces increased life expectancy in thalassaemic patients who may develop new complications. Since few data are available regarding hypercalciuria in ß-thalassaemia major (TM), the aim of our study was to evaluate its prevalence, risk factors and clinical consequences. We enrolled 176 adult TM patients followed at the Center of Thalassemia of Ferrara. Hypercalciuria was defined by a calciuria of 4 mg/kg/day or more in a 24-h urine sample. Anamnestic, biochemical and radiological data were collected. Hypercalciuria prevalence was reported in 69.3% of patients (females 52.5%). Hypercalciuric (HC) patients used deferasirox (DFX) more often than normocalciuric (NC) patients (47.5% vs 29.6%; p < 0.05). In HC subjects plasma parathyroid hormone (PTH) (24.1 ± 10.4 vs 30.1 ± 13.2 pg/ml) and phosphate levels (3.6 ± 0.5 vs 3.8 ± 0.7 mg/dl) were lower, whereas serum calcium (9.6 ± 0.4 vs 9.4 ± 0.4 mg/dl) and urinary 24-h phosphaturia (0.9 ± 0.4 vs 0.6 ± 0.3 g/day) were higher as compared to NC patients (p < 0.05 for all comparisons). Supplementation with oral calcium and cholecalciferol was similar between the groups. A higher rate of kidney stones was present in HC (14.8%) versus NC patients (3.7%) (p < 0.05). Hypercalciuria is a frequent complication in adequately treated adult TM patients. Hypercalciuria prevalence is increased in DFX users whereas haemoglobin level or calcium supplements play no role. A significant proportion of HC patients developed kidney stones.

Vitamin D, Hypercalciuria and Kidney Stones.

The estimated lifetime risk of nephrolithiasis is growing nowadays, and the formation of kidney stones is frequently promoted by hypercalciuria. Vitamin D, and especially its active metabolite calcitriol, increase digestive calcium absorption-as urinary calcium excretion is directly correlated with digestive calcium absorption, vitamin D metabolites could theoretically increase calciuria and promote urinary stone formation. Nevertheless, there was, until recently, low evidence that 25-hydroxyvitamin D serum levels would be correlated with kidney stone formation, even if high calcitriol concentrations are frequently observed in hypercalciuric stone formers. Low 25-hydroxyvitamin D serum levels have been associated with a broad spectrum of diseases, leading to a huge increase in vitamin D prescription in the general population. In parallel, an increased frequency of kidney stone episodes has been observed in prospective studies evaluating vitamin D alone or in association with calcium supplements, and epidemiological studies have identified an association between high 25-hydroxyvitamin D serum levels and kidney stone formation in some groups of patients. Moreover, urinary calcium excretion has been shown to increase in response to vitamin D supplements, at least in some groups of kidney stone formers. It seems likely that predisposed individuals may develop hypercalciuria and kidney stones in response to vitamin D supplements.

Etiologic risk factors and vitamin D receptor gene polymorphisms in under one-year-old infants with urolithiasis.

The incidence of urinary tract stones in infancy has been increasing in Turkey. Risk factors and vitamin D receptor (VDR) gene polymorphisms were investigated in infants aged < 1 year who had stones. Forty infants with urinary tract stones and 80 infants without stones, aged < 1 year were enrolled in this study. Detailed surveys were taken of all infants, metabolic parameters and ApaI and FokI VDR gene polymorphisms were investigated. Infants with stones tended to be more commonly fed formula and multivitamins (vitamins A, C, D) (p < 0.05). Positive family history came into prominence in the stony group (p < 0.05). There were no significant differences in ApaI and FokI VDR gene polymorphisms between the groups with stones and the control groups. However, CA genotype of ApaI polymorphism was associated with family history and C allele of ApaI was related with family history and hypercalciuria (p < 0.05). Hypercalciuria emerged as an underlying metabolic abnormality in the etiology of stones, and was observed at a rate of 38%. Infants who are given formula and multivitamins for vitamin D supplementation are at increased risk for the formation of urinary tract stones. VDR gene polymorphisms cause the formation of urinary tract stones and affect calcium (Ca) metabolism.

Efficacy and safety of high dose intramuscular or oral cholecalciferol in vitamin D deficient/insufficient elderly.

OBJECTIVES: To evaluate and compare the effects and safety of high dose intramuscular (IM) or oral cholecalciferol on 25-hydroxyvitamin D [25(OH)D] levels, muscle strength and physical performance in vitamin D deficient/insufficient elderly. STUDY DESIGN: Randomized prospective study. MAIN OUTCOME MEASURES: 116 ambulatory individuals aged 65 years or older living in a nursing home were evaluated. Eligible patients with 25(OH)D levels <30 ng/ml (n=66) were randomized to IM or Oral groups according to the administration route of 600,000 IU cholecalciferol. Demographic and descriptive data were collected. Biochemical response was measured at baseline, 6th and 12th weeks. Muscle strength was measured from quadriceps by using a hand-held dynamometer and physical performance was evaluated by short physical performance battery (SPPB) at the beginning and 12th week. RESULTS: Among the screened ambulatory elderly only 5.2% (n=6) had adequate vitamin D levels. 37.1% (n=43) were vitamin D deficient and 57.7% (n=67) were insufficient. After administration of one megadose of vitamin D, mean serum 25(OH)D levels increased significantly at 6th week (32.72±9.0 ng/ml) and at 12th week (52.34±14.2 ng/ml) compared with baseline (11.76±7.6 ng/ml) in IM group (p<0.0001). In Oral group levels were 47.57±12.7 ng/ml, 42.94±13.4 ng/ml and 14.87±6.9 ng/ml, respectively (p<0.0001). At 12th week the increase in IM group was significantly higher than Oral group (p=0.003). At the end of the study period, serum 25(OH)D levels were ≥30 ng/ml in all patients in IM group and in 83.3% of the patients in the Oral group. Quadriceps muscle strength and SPPB total score increased significantly in both groups and SPPB balance subscale score increased only in IM group. Six patients (9.6%) developed hypercalciuria, no significant adverse events were observed. CONCLUSION: In vitamin D deficient/insufficient elderly, a single megadose of cholecalciferol increased vitamin D levels significantly and the majority of the patients reached optimal levels. Although both administration routes are effective and appear to be safe, IM application is more effective in increasing 25(OH)D levels and balance performance.

Demographic, dietary, and urinary factors and 24-h urinary calcium excretion.

BACKGROUND AND OBJECTIVES: Higher urinary calcium is a risk factor for nephrolithiasis. This study delineated associations between demographic, dietary, and urinary factors and 24-h urinary calcium. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Cross-sectional studies were conducted of 2201 stone formers (SF) and 1167 nonstone formers (NSF) in the Health Professionals Follow-up Study (men) and Nurses' Health Studies I and II (older and younger women). RESULTS: Median urinary calcium was 182 mg/d in men, 182 mg/d in older women, and 192 mg/d in younger women. Compared with NSF, urinary calcium as a fraction of calcium intake was 33 to 38% higher in SF (P values < or =0.01). In regression analyses, participants were combined because associations with urinary calcium were similar in each cohort and in SF and NSF. After multivariate adjustment, participants in the highest quartile of calcium intake excreted 18 mg/d more urinary calcium than those in the lowest (P trend =0.01). Caffeine and family history of nephrolithiasis were positively associated, whereas urinary potassium, thiazides, gout, and age were inversely associated, with urinary calcium. After multivariate adjustment, participants in the highest quartiles of urinary magnesium, sodium, sulfate, citrate, phosphorus, and volume excreted 71 mg/d, 37 mg/d, 44 mg/d, 61 mg/d, 37 mg/d, and 24 mg/d more urinary calcium, respectively, than participants in the lowest (P values trend < or =0.01). CONCLUSIONS: Intestinal calcium absorption and/or negative calcium balance is greater in SF than NSF. Higher calcium intakes at levels typically observed in free-living individuals are associated with only small increases in urinary calcium.

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

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

Occurrence of hypercalciuria in patients with osteoporosis treated with teriparatide.

CONTEXT: Teriparatide (TPTD) [recombinant human PTH(1-34)] given sc once daily transiently increases serum calcium concentrations at 4-6 h after dosing, but its effects on urinary calcium excretion are less well studied. OBJECTIVE: Our objective was to evaluate urinary calcium excretion, a prespecified safety endpoint, for up to 12 months of TPTD treatment. DESIGN: This study included two prospective, randomized, double-blind placebo-controlled clinical trials. PARTICIPANTS: A total of 2074 participants with osteoporosis or low bone mass (study 1, 1637 postmenopausal women; study 2, 437 men) were included. INTERVENTIONS: Participants were given calcium (1000 mg/d) and vitamin D (400-1200 IU/d) supplements, and were randomized to placebo, TPTD 20 mug/d, or TPTD 40 mug/d. MAIN OUTCOME MEASURES: Urinary calcium excretion was measured in 24-h collections at baseline, 1, 6, and 12 months. RESULTS: In each study, baseline urinary calcium excretion was similar among groups. All groups had significantly increased urinary calcium excretion, compared with baseline, at most post-baseline time points. Post-baseline urinary calcium excretion was increased in the TPTD 20 microg/d group by up to 32 mg/d compared with placebo at the same time point (P < 0.05) in study 1. A total of seven participants (0.3%), of which three and four were in the placebo and TPTD groups, respectively, discontinued study drug due to repeated hypercalciuria (>300 mg/d). CONCLUSION: Urinary calcium excretion was increased with TPTD treatment for up to 12 months, compared with placebo and baseline values, but the magnitude of these changes is unlikely to be clinically relevant or warrant urinary calcium monitoring for most patients.