Biomedical subjects

L A Martini

Publications and source records attributed to L A Martini.

12 recordsLinked to original sources

PubMed2006

Dietary phylloquinone depletion and repletion in postmenopausal women: effects on bone and mineral metabolism.

INTRODUCTION: Vitamin K has been implicated in increased bone fracture risk. Despite a potential role of vitamin K in bone, little is known about the effects of altered dietary phylloquinone intake on the underlying components of bone and mineral metabolism. METHODS: A 84-day in-house dietary phylloquinone (vitamin K) depletion-repletion study was undertaken in 21 postmenopausal women (mean age: 70 years) to assess the effects of altered vitamin K status on intestinal calcium (Ca) absorption, urinary and serum Ca and phosphorus (P), serum calcemic hormones, and serum biomarkers of bone turnover [osteocalcin and N-telopeptide type 1 collagen cross-links (NTx)] and the response to 1,25-dihydroxyvitamin D treatment (1 microg/dayx7 d). RESULTS: The group receiving calcitriol treatment (n=11) had higher Ca absorption, urinary Ca, urinary and serum P and serum osteocalcin and lower serum parathyroid hormone (PTH). There were no significant effects of acute (4-week) phylloquinone depletion on response to 1,25-dihydroxyvitamin D treatment or on measures of bone formation or mineral metabolism. However, phylloquinone treatment had a significant effect (p<0.04) on serum NTx. Phylloquinone repletion, up to five times (450 microg phylloquinone per day) the currently recommended adequate intake level of dietary phylloquinone for women, significantly reduced serum NTx (16.8+/-0.9 nmol bone collagen equivalents (BCE) per liter following repletion vs 18.4+/-1.1 nmol BCE per liter following depletion; p<0.01). CONCLUSIONS: These findings suggest that altering vitamin K status in postmenopausal women by manipulating phylloquinone intake does not have an acute affect on intestinal Ca absorption, renal mineral excretion, or bone formation, but high phylloquinone intake may modestly reduce bone resorption. The impact of high phylloquinone intake on bone mineral density and fracture risk needs to be ascertained in randomized clinical trials.

Aged↗

PubMed2006

Body composition changes in haemodialysis patients with secondary hyperparathyroidism after parathyroidectomy measured by conventional and vector bioimpedance analysis.

Considering the negative effects of secondary hyperparathyroidism (SHPT) in patients with chronic renal failure (CRF), the objective of the present study was to evaluate body composition changes using conventional and vector bioimpedance analysis in patients before and after parathyroidectomy (PTX). Twelve adult patients, mean age 43.4 (sd 12.7) years, were evaluated prior to and 6 months after PTX. Diets were assessed with 3 d dietary records, and mean energy, protein, calcium and phosphorus intake were estimated from these inventories. Weight, height, BMI and bioelectrical impedance were measured; and biochemical markers of nutritional status (albumin and total protein) and bone metabolism (calcium, phosphorus and intact parathyroid hormone) were determined. No significant differences were observed in mean energy, protein and phosphorus after surgery. There was a significant increase in calcium intake after PTX (382.3 (sd 209.6) mg to 656.6 (sd 313.8) mg; P<0.05). Mean weight, BMI, conventional bioelectrical impedance measurements, total body fat, lean body mass and total body water were unaffected by surgery. However, the phase angle and reactance significantly increased after PTX (5.0 degrees (sd 1.4) to 5.6 degrees (sd 1.3); 44.1 (sd 15.6) Omega to 57.1 (sd 14.4) Omega, respectively). The high levels of intact parathyroid hormone before surgery had a negative effect on total body fat (r -0.69, P<0.05). After PTX, the mean albumin significantly increased (3.9 (sd 0.4) g/dl to 4.2 (sd 0.6) g/dl; P<0.05). PTX for SHPT is associated with certain changes in laboratory values, dietary intake and body composition. The latter is best seen with bioimpedance vector analysis.

Adipose Tissue↗

PubMed2002

Effect of calcium intake on urinary oxalate excretion in calcium stone-forming patients.

Dietary calcium lowers the risk of nephrolithiasis due to a decreased absorption of dietary oxalate that is bound by intestinal calcium. The aim of the present study was to evaluate oxaluria in normocalciuric and hypercalciuric lithiasic patients under different calcium intake. Fifty patients (26 females and 24 males, 41 +/- 10 years old), whose 4-day dietary records revealed a regular low calcium intake (<or=500 mg/day), received an oral calcium load (1 g/day) for 7 days. A 24-h urine was obtained before and after load and according to the calciuria under both diets, patients were considered as normocalciuric (NC, N = 15), diet-dependent hypercalciuric (DDHC, N = 9) or diet-independent hypercalciuric (DIHC, N = 26). On regular diet, mean oxaluria was 30 +/- 14 mg/24 h for all patients. The 7-day calcium load induced a significant decrease in mean oxaluria compared to the regular diet in NC and DIHC (20 +/- 12 vs 26 +/- 7 and 27 +/- 18 vs 32 +/- 15 mg/24 h, respectively, P<0.05) but not in DDHC patients (22 +/- 10 vs 23 +/- 5 mg/24 h). The lack of an oxalate decrease among DDHC patients after the calcium load might have been due to higher calcium absorption under higher calcium supply, with a consequent lower amount of calcium left in the intestine to bind with oxalate. These data suggest that a long-lasting regular calcium consumption <500 mg was not associated with high oxaluria and that a subpopulation of hypercalciuric patients who presented a higher intestinal calcium absorption (DDHC) tended to hyperabsorb oxalate as well, so that oxaluria did not change under different calcium intake.

Adult↗

PubMed2001

Parathyroid hormone changes during phosphorus load in patients with chronic renal insufficiency with low serum parathyroid hormone or adynamic bone disease.

UNLABELLED: Adynamic bone disease (ABD) is frequently associated with low serum parathyroid hormone (PTH) concentrations. Many clinical and therapeutic conditions have been associated with ABD, and recently, a low phosphorus intake accompanied by low serum concentration of phosphorus and PTH has been described. AIM: To evaluate the parathyroid gland response of chronic renal insufficiency patients (CRI) with low serum PTH or ABD to a phosphorus load. METHODS: We examined the effects of 0.5 and 1.0 g/d of phosphorus load over a period of 60 days in 18 patients with mild CRI with a bone biopsy showing ABD (n = 7) or with low serum PTH (serum intact PTH < or = 40 ng/l) and serum phosphorus < 4.5 mg/dl (n = 11). RESULTS: Serum intact PTH increased significantly only after 1 g of phosphorus (58.5 to 83 ng/l) with a median percent increase of 72%. PTH secretion increased more in patients with lower basal PTH levels (81%). Serum phosphorus did not change significantly and urinary phosphorus increased from 487 to 1,062 mg/dl (p < 0.05). Significant decreases in serum ionized calcium (from 1.26 to 1.19 mmol/l) and calcitriol (from 34.5 to 24.9 pg/ml) were observed. Changes in PTH were inversely correlated with changes in serum ionized calcium (r = -0.54, p < 0.05) and the final PTH concentrations were positively correlated with changes in serum phosphorus (r= 0.52, p < 0.05). CONCLUSIONS: The parathyroid glands of chronic renal insufficiency patients with "relative hypoparathyroidism" or ABD responded to a phosphorus load with an increase in serum PTH levels. The decrease in serum ionized calcium and calcitriol as well as minimal changes in serum phosphorus appeared to be involved in this response.

Adult↗

PubMed2000

Should dietary calcium and protein be restricted in patients with nephrolithiasis?

Renal stone disease is a painful condition that affects 1-20% of the general population. Therapy aimed at decreasing the incidence of recurrent stones includes dietary advice. Dietary considerations include intake of both calcium and protein. Calcium restriction in stone formers is not recommended because it can have adverse effects on bone and the incidence of stones. Although a high-protein diet can elevate urinary calcium, uric acid, and sulfate and decrease urinary citrate, which may alter the propensity to form stones, restriction of protein to less than the current RDA for the management of stone disease can not be recommended at this time.

Calcium↗

PubMed2000

High sodium chloride intake is associated with low bone density in calcium stone-forming patients.

BACKGROUND: Although renal stone disease has been associated with reduced bone mass, the impact of nutrient intake on bone loss is unknown. SUBJECTS AND METHODS: The present study was undertaken to investigate the influence of nutrient intake on bone density of 85 calcium stone-forming (CSF) patients (47 male and 38 premenopausal females) aged 41+/-11 years (X+/-SD). Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry at the lumbar spine (L2-L4) and femoral neck sites, and low BMD was defined as a T score < -1 (WHO criteria). A 4-day dietary record and a 24-hour urine sample were obtained from each patient for the assessment of nutrient intake and urinary calcium (U(Ca)), sodium (U(Na)), phosphate and creatinine excretion. RESULTS: Forty-eight patients (56%) presented normal BMD and 37 (44%) low BMD. There were no statistical differences regarding age, weight, height, body mass index, protein, calcium and phosphorus intakes between both groups. The mean U(Ca), phosphorus and nitrogen appearance also did not differ between groups. However, there was a higher percentage of hypercalciuria among low vs normal BMD patients (62 vs 33%, p < 0.05). Low BMD patients presented a higher mean sodium chloride (NaCl) intake and excretion (UNa) than normal BMD (14+/-5 vs 12+/-4 g/day and 246+/-85 vs 204+/-68 mEq/day, respectively p < 0.05). The percentage of patients presenting NaCl intake > or = 16 g/day was also higher among low vs normal BMD patients (35 vs 12%, p < 0.05). After adjustment for calcium and protein intakes, age, weight, body mass index, urinary calcium, citrate and uric acid excretion, and duration of stone disease, multiple-regression analysis showed that a high NaCl intake (> or = 16 g/day) was the single variable that was predictive of risk of low bone density in CSF patients (odds ratio = 3.8). CONCLUSION: These data suggest that reducing salt intake should be recommended for CSF patients presenting hypercalciuria and osteopenia.

Absorptiometry, Photon↗

PubMed1999

Magnesium supplementation and bone turnover.

Two-thirds of total body magnesium content is located in the skeleton. Recently, there have been reports that high dietary magnesium intakes are associated with higher bone mineral density. The effect of magnesium supplementation on bone turnover has recently been investigated in young adults. However, the findings from these studies are conflicting. More studies are necessary to better elucidate the role of magnesium in bone health.

Adult↗

PubMed1998

Potassium and sodium intake and excretion in calcium stone forming patients.

OBJECTIVE: To determine mean potassium (K) intake and its correlation with urinary calcium (uCa) and citrate excretion, as well as uCa, sodium (Na), and K levels of calcium stone forming patients. We determined the K-rich foods most commonly consumed by these patients. DESIGN: Case-control. SETTING: University-affiliated outpatient renal Lithiasis Unit. PATIENTS AND CONTROLS: One hundred hypercalciuric calcium stone forming patients (CSF, 54 men/46 women), 37 with associated hypocitraturia, were sequentially enrolled in the study that was performed before the initiation of any care for their renal stones. The control group consisted of 100 age-matched healthy subjects (HS, 47 men/53 women) who were laboratory employees with no history of renal stones. INTERVENTION: The analyses consisted of a 3-day dietary record to determine the mean K and calcium (Ca) intakes, and a 24-hour urine sample with measurements of K, Ca, Na, and citrate. MAIN OUTCOME MEASURE: K and Na intake determined by dietary record. RESULTS: uCa and Na levels and the Na/K ratio were significantly higher for CSF versus HS (238 +/- 118 v 148 +/- 74 mg/24 hours, 238 +/- 100 v 181 +/- 68 mEq/24 hours, 6.6 +/- 3.5 v 5.1 +/- 2.3, respectively, P < .05). The mean citrate excretion was lower in CSF than in HS patients (410 +/- 265 v 530 +/- 240 mg/24 hours). Mean uCa did not differ between groups. CSF patients showed a higher sodium chloride intake compared with HS (14 +/- 4 vs 8 +/- 3 g/day). The mean Ca intake of CSF and HS were 559 +/- 327 and 457 +/- 363 mg/day, respectively. The mean K intake of CSF and HS were 58 +/- 17 and 51 +/- 27 mEq/day. A positive correlation was observed between uCa and urinary sodium (r = .40 and r = .65, P < .05), urinary potassium and urinary citrate (r = .25 and r = .53, P < .05), uCa and Na/K (r = .33 and r = .56, P < .05) respectively for CSF and HS. The following were the K-rich foods consumed at least once a day by these groups: beans (by 70% of CSF and 75% of HS), tomatoes (by 42% of CSF and 50% of HS), oranges (by 30% of CSF and 55% of HS), and bananas (by 42% of CSF and 23% of HS). CONCLUSION: Despite the consumption of K-rich foods at least once a day, the mean K intake by CSF patients was 58 mEq/day. This intake can still be considered to be low, although it meets recommended daily dietary allowance requirements. Therefore, we describe herein a population of CSF with high-Na intake and normal- to low-K intake, which may contribute to stone formation.

Adult↗

PubMed1998

Effect of etidronate treatment on bone mass of male nephrolithiasis patients with idiopathic hypercalciuria and osteopenia.

Osteopenia is frequently found among calcium stone forming (CSF) patients with hypercalciuria. We investigated the effect of a 2-year therapeutic course of etidronate, a bone-sparing agent, in 7 young male CSF patients. The treatment consisted of a cyclic intermittent administration of phosphate followed by sodium etidronate and calcium supplementation every 74 days. Bone mineral density (BMD) measured at 12-month intervals and bone biopsies performed at baseline and after 2 years were the primary efficacy parameters. Mean lumbar spine BMD increased significantly after the 1st year by 2.6 +/- 1.0% (mean +/- SE, p < 0.05) and nonsignificantly after the 2nd year by 5.6 +/- 2.6%. Nonsignificant changes were observed for femoral neck mean BMD after either the 1st or the 2nd year (decrease of 2.0 +/- 1.0% and 2.0 +/- 3.0%, respectively). Mean histomorphometric parameters showed that bone volume, osteoid volume, and eroded surfaces did not differ from baseline (13.9 +/- 2.2 vs. 12.2 +/- 1.1%, 1.2 +/- 0.7 vs. 2.6 +/- 0.7%, and 20.7 +/- 6.2 vs. 13. 7 +/- 1.3%, respectively). Osteoid surface was significantly lower than baseline values (9.5 +/- 5.2 vs. 18.8 +/- 5.3%, p < 0.05). These data suggest that etidronate given to young male CSF patients presenting with hypercalciuria and osteopenia led to a significant amelioration of BMD, evident only in the lumbar spine after 1 year of treatment. There was no histological evidence of long-term improvement in bone remodeling.

Adult↗

PubMed1996

Sensitivity to calcium intake in calcium stone forming patients.

The absorptive or renal origin of hypercalciuria can be discriminated using an acute oral calcium load test (ACLT). Of 86 patients with calcium oxalate kidney stones, 28 (23%) were found to be hypercalciuric (HCa) and 58 (67%) normocalciuric (NCa) on their customary free diet, containing 542 +/- 29 mg/day (mean +/- SE) of calcium. Since the apparently normal 24-hour calcium excretion of many calcium stone formers (CSF) may be due to a combination of high calcium absorption with moderately low calcium intake, all patients were investigated by ACLT. Of 28 HCa patients, 13 (46%) were classified as absorptive (AH) and 15 (54%) as renal hypercalciuria (RH). Of the 58 NCa patients, 38 (65%) presented features of intestinal hyperabsorption and were therefore designated as AH-like, and 20 (35%) as RH-like. To further elucidate the role of dietary calcium in these CSF, a chronic calcium load test (CCLT), consisting of 1 g/day of oral Ca for 7 days, was designed. A positive response to the CCLT was considered to occur when urinary calcium (uCa) was > or = 4 mg/ kg/24 h on the 7th day. Among NCa patients, 29% of AH-like subjects responded to the CCLT and 71% did not; 50% of RH-like subjects also responded and 50% did not. In HCa patients, 85% of AH and 67% of RH subjects maintained uCa > or = 4 mg/kg/24 h after the CCLT and 15% of AH and 23% of RH subjects did not. However, a significant additional increase in mean uCa was not observed among HCa patients. All patients were submitted to a second evaluation of fasting calciuria (Ca/Cr). A modification of this parameter was noticed in 89% of RH-like and 78% of RH patients. In conclusion, these data suggest the presence of subpopulations of patients sensitive or not to calcium intake, regardless of whether the acute response to a calcium overload test suggested AH or RH. The CCLT disclosed dietary hypercalciuria in 21/58 (36%) of previously NCa patients. In these NCa patients, the ACLT may be replaced by the CCLT. The distinction between AH and RH initially evidenced by the ACLT was not further confirmed. These data suggest that either fasting Ca/Cr is not adequate for subclassification of HCa or that AH and RH represent a different spectrum of the same disease, and that a primary resorptive component should also be considered.

Calcium↗

PubMed1994

Bone disease in calcium stone forming patients.

The association between idiopathic hypercalciuria and osteopenia (OP) has been recently recognized. It is not established whether or not calcium intake plays a critical role in the loss of bone mass. Fifty-five calcium stone forming patients with either absorptive hypercalciuria (AH) or fasting hypercalciuria (FH), 29 males and 26 premenopausal females, were submitted to dual photon absorptiometry at lumbar spine. Calcium intake was assessed by a 72 hr dietary record. OP was detected in 20% (11/55) of patients, being more common among men, 9/26 (35%) than in women, 2/29 (7%), p < 0.05. Male FH patients presented lower mean bone mineral density (BMD) than sex, weight and age-matched control (1.058 +/- 0.18 vs 1.209 +/- 0.13 g/cm2, X +/- SD, p < 0.05). OP was more frequent in FH patients, 7/20 (35%) than in AH patients 4/35 (11%), albeit the difference was not statistically significant. There was no correlation between calcium intake and BMD measurement. Six osteopenic male FH patients were further submitted to histomorphometric evaluation with tetracycline double labeling. Bone volume was lower than the controls (13.2 +/- 3.0 vs 27.2 +/- 3.7%, p < 0.05). Osteoid surfaces were reduced, although not significantly (10.1 +/- 8.2% vs 15.9 +/- 6.7%). Eroded surfaces were markedly increased (23.9 +/- 13.4 vs 4.2 +/- 1.4%, p < 0.05). The bone formation rate was very low with a complete lack of tetracycline double labeling in 4 patients. These data suggest low bone volume, tendency to low bone formation, increased bone resorption and a severe mineralization defect, consistent with normal or low bone turnover osteoporosis.

Absorptiometry, Photon↗

PubMed1993

Dietary habits of calcium stone formers.

1. Since dietary factors are known to be related to nephrolithiasis, calcium stone-forming (CSF) patients were evaluated in terms of calcium, total protein of both animal and plant origin, carbohydrate and energy intakes, on the basis of 72-h dietary records during the week plus 24-h dietary records during the week-end. 2. The data for 77 calcium stone formers (57 with absorptive hypercalciuria and 20 with renal hypercalciuria) were compared to those for 29 age-matched healthy subjects. The body mass index of the CSF group was higher than that of healthy subjects (P < 0.05). Consumption of all nutrients was similar for both groups during the week but week-end dietary records for CSF showed higher calcium intake (586 +/- 38 vs 438 +/- 82 mg/day, P < 0.05), protein to body weight ratio (1.2 +/- 0.1 vs 1.0 +/- 0.5 g kg-1 day-1, P < 0.05) and animal protein (56 +/- 3 vs 40 +/- 3 g/day, P < 0.05) when compared with healthy subjects. 3. Comparison of hypercalciuria subtypes (renal hypercalciuria and absorptive hypercalciuria) did not indicate any difference in calcium or energy intake between groups, either during the week or during the week-end. However, the absorptive hypercalciuric group presented higher protein and animal protein consumption during the week-end. 4. These data suggest a low calcium intake in this population, even by stone formers. The higher animal protein consumption by our calcium stone formers observed during week-ends seems to be more important than calcium intake for stone formation.

Adult↗