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PubMed2006

Association of prevalent hypertension with 24-hour urinary excretion of calcium, citrate, and other factors.

BACKGROUND: The relation between hypertension and the urinary excretion of calcium, citrate, and other factors is unclear. It has been proposed that increased urinary calcium excretion is a central feature of essential hypertension. Metabolic acidosis also may be associated with hypertension and decreases urinary citrate levels. METHODS: To compare the urine composition of individuals with and without hypertension, we studied 24-hour urinary excretion of calcium, citrate, oxalate, uric acid, sodium, magnesium, potassium, phosphorus, and creatinine and pH in a subset of participants with and without nephrolithiasis in the Nurses' Health Study I (older women; N = 1,284), Nurses' Health Study II (younger women; N = 952), and the Health Professionals Follow-up Study (men; N = 788). Logistic regression models adjusted for age, weight, dietary intake, and urinary factors. RESULTS: In participants with and without nephrolithiasis, citrate was the only urinary factor consistently related to hypertension. Compared with those in the lowest quartile of urinary citrate excretion, multivariate odds ratios of prevalent hypertension in the highest quartile were 0.37 (95% confidence interval [CI], 0.24 to 0.55; P trend < 0.001) for older women, 0.54 (95% CI, 0.32 to 0.92; P trend = 0.03) for younger women, and 0.27 (95% CI, 0.16 to 0.45; P trend < 0.001) for men. Urinary calcium levels were not related consistently to hypertension. Excluding participants with single 24-hour urine collections and those administered thiazide diuretics or angiotensin-converting enzyme inhibitors did not change the results. CONCLUSION: Lower urinary citrate excretion is associated independently with prevalent hypertension. Factors that regulate urinary citrate excretion may play a role in hypertension.

Adult↗
PubMed1993

Measurement of intrinsic bone quality in vivo by reflection ultrasound: correction of impaired quality with slow-release sodium fluoride and calcium citrate.

The intrinsic (material) quality of cancellous and cortical bone was evaluated in vivo from the measurement of reflection ultrasound velocities in the ulna. In cancellous bone, the reflection ultrasound velocity was inversely correlated with age in normal women (r = -0.48, p = 0.001), with a significantly lower mean value in 32 normal postmenopausal women than in 14 premenopausal women (3124 versus 3341 m/s, p < 0.0001). In 32 untreated osteoporotic women the cancellous bone velocity was lower than in normal postmenopausal subjects (2906 versus 3124 m/s, p = 0.0001). Following treatment with slow-release sodium fluoride plus calcium citrate (mean 2.4 years in 33 osteoporotic patients with no fracture during treatment), the cancellous bone velocity was significantly higher than in untreated osteoporotic women (3082 versus 2906 m/s, p = 0.0002) and was not significantly different from that in normal postmenopausal women. The cortical bone velocity displayed similar trends, but the changes did not attain statistical significance. The measurements were repeated approximately 9 months later in 9 untreated and in 20 treated patients; in 5 additional patients, the measurements were made both before and after 9 months of treatment with slow-release sodium fluoride and calcium citrate. The cancellous bone velocity increased significantly (p = 0.046) in these patients, from 3008 m/s before treatment to 3112 m/s after the first 9 months of treatment. The velocity rose significantly from 3037 to 3167 m/s (p = 0.017) in patients treated for a short time (12-30 months at first measurement), but it did not change in untreated patients or those treated for more than 30 months. Thus, the material quality of cancellous bone decreases with normal aging and is reduced further with the osteoporotic process. This impaired quality may be corrected by treatment with slow-release sodium fluoride plus calcium citrate.

Analysis of Variance↗
PubMed1998

In vitro characterization of poly(ethylene) glycol calcium citrate microspheres as a delivery system for the study of reparative dentinogenesis.

The characterization of poly(ethylene) glycol calcium citrate microspheres is described. The calcium content and content uniformity of microspheres, prepared at five concentrations ranging from 46.56 micrograms/g to 81.49 mg/g, were determined by spectroscopy. Under sink conditions first-order in vitro dissolution kinetics were observed. Granules containing approximately 80 mg Ca++/g PEG gave an in vitro calcium release over a 3-day period similar to that of a calcium hydroxide product, Pulpdent.

Animals↗
PubMed1992

Modification by food of the calcium absorbability and physicochemical effects of calcium citrate.

The food-calcium (Ca) interaction was examined in 12 healthy women (mean age 38 years) maintained on a constant metabolic diet. They underwent three phases of study, comprised of control (no Ca), Ca citrate (1 g Ca/day) during meals, and Ca citrate separately from meals. Each phase was 7 days in length and two 24-hour urine samples were collected on days 6 and 7. The rise from the control phase in urinary Ca was slightly more prominent when Ca citrate was given with meals than without (68 and 62%, respectively). The fall in urinary phosphorus was equivalent at about 25% between Ca citrate phases. The rise in urinary citrate and pH and the decline in urinary ammonium were more prominent when Ca citrate was given with meals; however, the changes were small or nonsignificant. The urinary saturation of Ca oxalate, brushite or monosodium urate did not differ between the two Ca citrate phases. There was a nonsignificant rise in serum iron during Ca citrate phases. The results suggest that: 1) dissolution and absorption of Ca citrate might be slightly greater when given with food than without; 2) that the ability of Ca citrate to attenuate crystallization of stone-forming Ca salts in urine is not modified by food; and 3) that Ca citrate may not impair iron absorption from food.

Adult↗
PubMed1991

Fluoride bioavailability from immediate-release sodium fluoride with calcium carbonate compared with slow-release sodium fluoride with calcium citrate.

The circadian variation in serum fluoride was compared between treatment with immediate-release sodium fluoride (IR-NaF) (30 mg) and calcium carbonate (500 mg calcium) and slow-release sodium fluoride (SR-NaF) (25 mg) and calcium citrate (400 mg calcium) in seven patients with postmenopausal osteoporosis maintained on long-term fluoride treatment. During 12 h following a dose of SR-NaF, serum fluoride levels could be largely kept within the therapeutic window (believed to be 95-190 ng/ml or 5-10 mumol/l). In contrast, IR-NaF produced a wide circadian fluctuation with peak-to-trough change of about 200 ng/ml. Compared to SR-NaF, IR-NaF caused a significantly higher peak fluoride concentration in serum (322 vs. 158 ng/ml), and greater area under the curve (2269 vs. 1321 ng.h/ml) and urinary fluoride (6.72 vs. 3.80 mg/12 h). Thus, fluoride absorption from IR-NaF was twice as high as that from SR-NaF.

Aged↗
PubMed1991

Calcium citrate for vulvar vestibulitis. A case report.

A woman had suffered from vulvar vestibulitis (vulvodynia) for four years. Pain from the disorder had disrupted her ability to function at work and home as well as sexually. An initial full range of treatments, including multiple operations, had produced no relief. Examination of the urine for evidence of excess oxalate, which has been shown to cause epithelial reactions similar to those found in vulvodynia, showed periodic hyperoxaluria and pH elevations related to the symptoms. Calcium citrate was given to modify the oxalate crystalluria. The symptoms were significantly reduced in three months, and the patient was pain free after one year. She was able to resume normal work, family, sexual and recreational activities. Withdrawal of the calcium citrate resulted in a return of the symptoms; reinstitution alleviated them. These findings suggest that further study of individualized metabolic factors that may underlie vulvodynia is warranted.

Administration, Oral↗
PubMed1994

Supplementation trials with calcium citrate malate: evidence in favor of increasing the calcium RDA during childhood and adolescence.

The vast majority of peak adult bone mass is accumulated by the time longitudinal growth is complete. As peak bone mass is an important determinant of future fracture risk, the goal of the current calcium recommended dietary allowance during youth is to provide a calcium intake that allows individuals to reach their full genetic potential for acquiring skeletal mass. The advent of controlled trials of calcium supplementation and total body bone mass measurements in children and adolescents provide the first direct way of determining the amount of calcium necessary to achieve optimal skeletal accretion. These studies indicate that the current RDAs are insufficient to support optimal bone mass gain during growth and development. Based on the recent intervention trials, recommendations are made for an RDA of 1250 mg during childhood and 1450 mg during adolescence. These values are consistent with established calcium balance intake thresholds for growth during pre-adolescence and adolescence.

Adolescent↗
PubMed1990

Influence of calcium acetate or calcium citrate on intestinal aluminum absorption.

The risk of aluminum (Al) accumulation in patients with chronic renal failure has led to use of non-Al phosphate binders. Frequently, Al and non-Al phosphate binders are co-administered. Unfortunately, calcium citrate (Ca citr), when given with Al-gel, markedly enhances Al absorption. To determine whether calcium acetate (Ca acetate) also augments Al absorption, 10 normal volunteers were each given orally, three-day courses of the following drug combinations dosed four times daily: 1) aluminum hydroxide gel (Al[OH]3) (5 ml) alone; 2) Al[OH]3 (5 ml) plus Ca acetate (1330 mg); 3) Al[OH]3 (5 ml) plus Ca citr (950 mg). A nine day wash-out occurred between each course. Al levels were measured using flameless atomic absorption spectrophotometry. Daily urine Al excretion was measured during a two-day baseline before each course and during each three-day drug course. Plasma Al was obtained during each baseline and drug course. Mean 24-hour Al excretion (micrograms/g creatinine/day) at baseline versus treatment for each combination was: 1) 5.9 +/- 3.2 versus 42.0 +/- 40.7 (mean +/- SD); 2) 5.7 +/- 3.0 versus 40.3 +/- 28.6: 3) 6.3 +/- 3.4 versus 175.8 +/- 103.3. Al excretion was significantly greater with combination 3 than with either 1 or 2 (P less than 0.05). The difference between 1 and 2 was not significant. Plasma Al (micrograms/liter) at baseline versus treatment for each combination was: 1) 5.3 +/- 4.2 versus 8.1 +/- 2.5 (mean +/- SD); 2) 3.1 +/- 2.2 versus 7.3 +/- 2.9; 3) 3.0 +/- 2.3 versus 12.0 +/- 6.1.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1986

A urinary calcium-citrate index for the evaluation of nephrolithiasis.

We have performed a multivariate analysis of urine abnormalities in patients with calcium oxalate nephrolithiasis, in which effects of gender were also considered. The characteristic of patients that most clearly sets them apart from normal people is a high level of urine calcium for any given level of urine citrate. Other urine measurements cannot improve upon the separation between patients and normals provided by urine calcium and citrate, and their abnormal relationship to each other. Normal women have higher urine citrate and lower urine calcium than normal men or patients of either sex; normal men differ from stone forming men only moderately. Direct measurements of supersaturation are not helpful in distinguishing between patients and normals, once calcium and citrate have been considered. From our analysis, we have derived a new index for evaluating the significance of urine calcium and citrate levels that seems to offer a better basis for clinical diagnosis than criteria presently in use.

Calcium↗
PubMed1991

Assessment by reflection ultrasound method of the effect of intermittent slow-release sodium fluoride-calcium citrate therapy on material strength of bone.

It has been suggested that fluoride therapy, while increasing bone mass, produces bone with inferior mechanical properties. In the present report this hypothesis was tested using a novel reflection ultrasound technique. Transiliac crest bone biopsies were obtained from 16 patients with osteoporosis and vertebral compression fractures (12 women and 4 men, mean age 56 years) before and after approximately 2 years of intermittent slow-release sodium fluoride therapy (25 mg twice a day) combined with continuous calcium citrate supplementation. Samples were analyzed by a reflection ultrasound method, which analyzes ultrasound velocity with a sample site resolution of 200 microns and thus provides a measure of the mechanical property of single trabeculae (material). For the group, mean fractional change in velocity increased 6.1 +/- 2.3% (SEM) from a mean value of 3303 +/- 80 to 3484 +/- 55 m/s (p = 0.028). A total of 13 patients (81%) demonstrated higher velocities after treatment. Thus reflection ultrasound analysis of bone appears to provide a sensitive means of assessing changes in the material property of bone. Furthermore, these results suggest that the treatment regimen utilized in these patients improves strength of bone at the material or trabecular level largely independently of change in bone mass. The combination therapy also increased spinal (L2-L4) bone density for the group as assessed by dual-photon absorptiometry (5.3 +/- 2.0%). There was no significant correlation between the change in ultrasound velocity and bone density (r = 0.0026, p = 0.996).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗