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Biomedical subjects

S Adami

Publications and source records attributed to S Adami.

At least 37 records · Page 2Linked to original sources
PubMed2003

Intravenous neridronate in adults with osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a heritable disease of connective tissue, characterized by increased bone fragility. Bisphosphonates currently seems to be the most promising therapy, at least in children. We tested IV neridronate, an amino-bisphosphonate structurally similar to alendronate and pamidronate in adults with OI. Twenty-three men and 23 premenopausal women with OI were randomized to either iv neridronate (100 mg infused intravenously for 30 minutes every 3 months) or no treatment with a ratio of 2 to 1. Control patients were given the same bisphosphonate therapy at the end of the first year. Clinical evaluation included bone densitometry measurements using dual energy X-ray absorptiometry (DXA), fasting serum and urinary biochemistry every 6 months, and radiographs of the spine taken at baseline and after 12 and 24 months of follow-up. Spine and hip bone mineral density rose by 3.0 +/- 4.6% (SD) and by 4.3 +/- 3.9%, respectively, within the first 12 months of treatment, whereas small insignificant changes were observed in the control group. During the second year of follow-up, additional 3.91% and 1.49% increases were observed at the spine and hip, respectively. Markers of skeletal turnover significantly fell during neridronate treatment. Fracture incidence during neridronate treatment was significantly lower than before therapy and compared with controls. Neridronate iv infusions, administered quarterly, significantly increase bone mineral density and lowered the risk of clinical fracture in adults with OI. Bisphosphonate therapy seems to provide clinical benefits, not only to children with OI, but also to adult patients.

Adult↗
PubMed2003

The effect of teriparatide [human parathyroid hormone (1-34)] therapy on bone density in men with osteoporosis.

Teriparatide [rhPTH(1-34)] increases bone mineral density and reduces the risk of vertebral fracture in women. We randomized 437 men with spine or hip bone mineral density more than 2 SD below the young adult male mean to daily injections of placebo, teriparatide 20 microg, or teriparatide 40 microg. All subjects also received supplemental calcium and vitamin D. The study was stopped after a median duration of 11 months because of a finding of osteosarcomas in rats in routine toxicology studies. Biochemical markers of bone formation increased early in the course of therapy and were followed by increases in indices of osteoclastic activity. Spine bone mineral density was greater than in placebo subjects after 3 months of teriparatide therapy, and by the end of therapy it was increased by 5.9% (20 microg) and 9.0% (40 microg) above baseline (p < 0.001 vs. placebo for both comparisons). Femoral neck bone mineral density increased 1.5% (20 microg; p = 0.029) and 2.9% (40 microg; p < 0.001), and whole body bone mineral content increased 0.6% (20 microg; p = 0.021) and 0.9% (40 microg;p = 0.005) above baseline in the teriparatide subjects. There was no change in radial bone mineral density in the teriparatide groups. Bone mineral density responses to teriparatide were similar regardless of gonadal status, age, baseline bone mineral density, body mass index, smoking, or alcohol intake. Subjects experienced expected changes in mineral metabolism. Adverse events were similar in the placebo and 20-microg groups, but more frequent in the 40-microg group. This study shows that teriparatide treatment results in an increase in bone mineral density and is a potentially useful therapy for osteoporosis in men.

Adult↗
PubMed2003

Calcium-sensing receptor gene polymorphism is not associated with bone mineral density in Italian postmenopausal women.

OBJECTIVE: Calcium-sensing receptor (CaR) is a candidate gene for osteoporosis susceptibility. Several CaR polymorphisms have been identified and an association between the A986S genotype and serum calcium levels has been found in Canadian postmenopausal women. We investigated whether the presence of 986S allele was associated with bone mineral density (BMD) and osteoporotic fractures. DESIGN: The study group consisted of 164 Italian postmenopausal women without fragility fracture (Fx(-)) and 55 women with fracture (Fx(+)). METHODS: A fragment of exon 7 of CaR gene containing three polymorphisms (A986S, R990G and Q1011E) was amplified by PCR and sequenced. Anthropometric characteristics and BMD were evaluated. RESULTS: The A986S polymorphism was the most commonly observed (27.9%), whereas the other two CaR polymorphisms, R990G and Q1011E, occurred in a minority of cases (8.8 and 5.5% respectively). There was no significant difference in the frequency distribution of any CaR allele between Fx(-) and Fx(+) patients. Body mass index was found to predict BMD at the lumbar spine and femoral neck. The A986S polymorphism and Years since menopause were not independent predictors of BMD at any site. As far as fracture occurrence, there was no statistically significant difference in the prevalence of fractures between women carrying or not carrying the 986S allele. CONCLUSIONS: Our data do not support a role of A986S CaR polymorphism in BMD and in the prevalence of fragility fractures in Italian postmenopausal women.

Aged↗
PubMed2002

Relationship among VDR (BsmI and FokI), COLIA1, and CTR polymorphisms with bone mass, bone turnover markers, and sex hormones in men.

Osteoporosis is a disease characterized by low bone mineral density (BMD) and up to 80% of its variance is under genetic control. Although osteoporosis is more frequent in women, one-third of hip fractures also occur in men. Much information on genetic factors and bone density has been obtained in women, but only a few studies have been performed in osteoporotic men. We have evaluated the relationship between polymorphisms for several candidate genes such as vitamin D receptor (VDR), collagen type Ia1 (COLIA1), and calcitonin receptor (CTR) in a sample of unrelated Italian men (n = 253, mean age 58.41 +/- 15.64 SD). We found no significant differences in BMD when subjects were stratified for their VDR (BsmI and FokI) and COLIA1 genotypes. BMD both at the lumbar spine and at the femoral neck were associated with polymorphism of CTR gene. The CC genotype of CTR gene had the lowest BMD value (P <0.05 and P <0.01 at the spine and hip, respectively) and its prevalence was significantly over-represented in the subgroup of men with prior hip or vertebral fracture as compared with controls (P = 0.004% c2 = 11.10). The men with the CC genotype also showed significantly lower body mass index (BMI), serum sex hormone binding globulin (SHBG), estradiol, total alkaline phosphatase-(total AP) and bone alkaline phosphatase (bone AP) levels and significantly higher free androgen index (FAI). In conclusion, the polymorphism of CTR gene but not VDR and COLIA1 is associated with osteoporosis incidence and the levels of alkaline phosphatase and estradiol. The lower BMD in CC genotype is apparently associated in males with depressed bone formation and lower estradiol levels.

Adult↗
PubMed2002

Two-year results of once-weekly administration of alendronate 70 mg for the treatment of postmenopausal osteoporosis.

The aim of this study was to provide confirmation that once-weekly dosing with 70 mg of alendronate (seven times the daily oral dose) and twice-weekly dosing with 35 mg is equivalent to the 10-mg once-daily regimen and to gain more extensive safety experience with this new dosing regimen. Twelve hundred fifty-eight postmenopausal women (aged 42-95 years) with osteoporosis (bone mineral density [BMD] of either lumbar spine or femoral neck at least 2.5 SDs below peak young adult mean or prior vertebral or hip fracture) were assigned to receive oral once-weekly alendronate, 70 mg (n = 519); twice-weekly alendronate, 35 mg (n = 369); or daily alendronate 10 mg (n = 370) for a total of 2 years of double-blind experience. Mean BMD increases from baseline (95% CI) at 24 months in the once-weekly, twice-weekly, and daily treatment groups, respectively, were 6.8% (6.4, 7.3), 7.0% (6.6,7.5), and 7.4% (6.9,7.8) at the lumbar spine and 4.1% (3.8,4.5), 4.3% (3.9,4.7), and 4.3% (3.9,4.7) at the total hip. These increases in BMD as well as the BMD increases at the femoral neck, trochanter, and total body and the reductions of biochemical markers of bone resorption (urinary cross-linked N-telopeptides of type I collagen [NTx]) and bone formation (serum bone-specific alkaline phosphatase [BSAP]) were similar for the three dosing regimens. All treatment regimens were well tolerated with a similar incidence of upper gastrointestinal (GI) adverse experiences. The incidence rates of clinical fractures, captured as adverse experiences, were similar among the groups. The 2-year results confirm the conclusion reached after 1 year that once-weekly alendronate is therapeutically equivalent to daily dosing, providing patients with a more convenient dosing option that may potentially enhance adherence to therapy.

Adult↗
PubMed2001

Effect of risedronate on the risk of hip fracture in elderly women. Hip Intervention Program Study Group.

BACKGROUND: Risedronate increases bone mineral density in elderly women, but whether it prevents hip fracture is not known. METHODS: We studied 5445 women 70 to 79 years old who had osteoporosis (indicated by a T score for bone mineral density at the femoral neck that was more than 4 SD below the mean peak value in young adults [-4] or lower than -3 plus a nonskeletal risk factor for hip fracture, such as poor gait or a propensity to fall) and 3886 women at least 80 years old who had at least one nonskeletal risk factor for hip fracture or low bone mineral density at the femoral neck (T score, lower than -4 or lower than -3 plus a hip-axis length of 11.1 cm or greater). The women were randomly assigned to receive treatment with oral risedronate (2.5 or 5.0 mg daily) or placebo for three years. The primary end point was the occurrence of hip fracture. RESULTS: Overall, the incidence of hip fracture among all the women assigned to risedronate was 2.8 percent, as compared with 3.9 percent among those assigned to placebo (relative risk, 0.7; 95 percent confidence interval, 0.6 to 0.9; P=0.02). In the group of women with osteoporosis (those 70 to 79 years old), the incidence of hip fracture among those assigned to risedronate was 1.9 percent, as compared with 3.2 percent among those assigned to placebo (relative risk, 0.6; 95 percent confidence interval, 0.4 to 0.9; P=0.009). In the group of women selected primarily on the basis of nonskeletal risk factors (those at least 80 years of age), the incidence of hip fracture was 4.2 percent among those assigned to risedronate and 5.1 percent among those assigned to placebo (P=0.35). CONCLUSIONS: Risedronate significantly reduces the risk of hip fracture among elderly women with confirmed osteoporosis but not among elderly women selected primarily on the basis of risk factors other than low bone mineral density.

Aged↗
PubMed2001

Tolerability of risedronate in postmenopausal women intolerant of alendronate.

Bisphosphonates are effective treatments for osteoporosis, but some have been associated with upper gastrointestinal intolerance. This randomized, double-blind study assessed the upper gastrointestinal tolerability of risedronate in postmenopausal women who had discontinued alendronate treatment because of upper gastrointestinal adverse events. Sixty-six women who had previously discontinued treatment with alendronate 10 mg/day because of upper gastrointestinal symptoms received placebo (N=31) or risedronate 5 mg (N=35) daily for 3 months. The primary outcome was the rate of discontinuation due to upper gastrointestinal adverse events: 5/31 (16.1%) in the placebo group, and 4/35 (11.4%) in the risedronate group. Discontinuation rates were also similar in the two treatment groups among subgroups of patients with a history of gastrointestinal disorder, prior use of acid suppression drugs, and concomitant use of NSAIDs. The overall incidence of upper gastrointestinal events was comparable between the placebo (19.4%) and risedronate (20.0%) groups. Overall, risedronate 5 mg/day for 3 months was as well tolerated as placebo in patients who could not tolerate alendronate 10 mg. These results are consistent with, and complement those from previous studies showing that risedronate 5 mg has a gastrointestinal tolerability similar to that of placebo.

Alendronate↗
PubMed2001

Radial bending breaking resistance derived by densitometric evaluation predicts femoral neck fracture.

Bone mineral density (BMD) measurement by hip dual-energy X-ray absorptiometry (DXA) is considered the best predictor of osteoporotic fracture risk. BMD takes into account only in part the bone cross-sectional area that is an important determinant of both bone compression strength and of bending breaking resistance. From DXA measurements of proximal radius (Osteoplan, NIM, Verona, Italy) we obtained the projected outer diameter (D) and the mean diameter of the medulla (d), by an algorithm based on the assumption of a constant cortical volumetric density of 1050 g/cm3. The algorithm was validated by the good correlation found (r = 0.8) between calculated d and that actually measured by peripheral quantitative tomography (pQCT; XCT 960, Stratec, Unitrem, Italy) at the same radial site. The D and d values were used to calculate a bending breaking resistance index (BBRI) that is a component of the cross-sectional moment of inertia. The BBRI measured in 5460 women aged 35-89 years, was stable up to the age of 65-70 years and rapidly declined thereafter by 0.7% per year. This profile appears to be due to the fact that the increase in medullary area is compensated in terms of mechanical resistance by enlargement of cross-sectional area. In 68 women with either previous femoral neck (n = 41) or pertrochanteric fracture (n = 27) DXA measurements at proximal and ultradistal radius, lumbar spine and femoral neck were obtained together with the evaluation of proximal radius BBRI. The diagnostic accuracy of BBRI was somewhat comparable to that of spine and femoral neck BMD and significantly superior to that of ultradistal and proximal radius BMD, from which it was derived. Despite the obvious limitation of the cross-sectional nature of this study, our results indicate that a simple re-elaboration of the data obtained by peripheral radial densitometry may achieve diagnostic accuracy for hip fracture risk assessment only marginally lower than that of the direct measure of the BMD of the femoral neck. They also give additional support to the view that bone geometry, particularly for compact skeletal segments, is a determinant of its strength at least as important as bone density.

Absorptiometry, Photon↗
PubMed2001

Risedronate increases bone density and reduces vertebral fracture risk within one year in men on corticosteroid therapy.

Limited information is available on the effect of bisphosphonates in men receiving corticosteroid therapy. We studied 184 men among the patients enrolled in two, double-blind, placebo-controlled, 1-year studies with similar protocols. The studies evaluated the effects of risedronate in patients beginning corticosteroid treatment at a dose of at least 7.5 mg per day of prednisone or equivalent (prevention study) or continuing long-term treatment of corticosteroid at that dose (treatment study). The men received either placebo or risedronate (2.5 mg or 5 mg) daily, along with calcium supplementation (500-1000 mg). Endpoints included differences in bone mineral density (BMD) at the lumbar spine, femoral neck, and femoral trochanter, assessment of vertebral fractures, changes in biochemical markers of bone turnover, and overall safety. In the treatment study, risedronate 5 mg significantly (P < 0.01) increased lumbar spine BMD by 4.8% at the lumbar spine, 2.1% at the femoral neck, and 2.6% at the femoral trochanter compared with baseline values. In the prevention study, bone loss was prevented with risedronate 5 mg; in the placebo group, BMD decreased significantly (P < 0.01) by 3.4%, 3.3%, and 3.4% in the lumbar spine, femoral neck, and trochanter, respectively, at 1 year. The differences between risedronate 5 mg and placebo groups were significant at all skeletal sites in the prevention study (P < 0.01) and at the lumbar spine in the treatment study (P < 0.001). The 2.5 mg dose also had a positive effect on BMD, although of a lesser magnitude than the 5 mg dose. When the data from the two studies were combined, the incidence of vertebral fractures decreased 82.4% (95% confidence interval, 36.6%-95.1%) in the pooled risedronate groups compared with placebo (P = 0.008). Risedronate was well tolerated in men, with a similar incidence of upper gastrointestinal adverse events in the placebo and treatment groups. Daily treatment with risedronate increases bone density and decreases vertebral fracture risk within 1 year in men receiving corticosteroid therapy.

Adolescent↗
PubMed2001

Alendronate for the treatment of osteoporosis in men.

The incidence of osteoporotic fracture in males is approximately one-third of that observed in women, but information on specific therapies is almost exclusively limited to bisphosphonate alendronate. The most important study with this compound included 241 men, randomized to receive either alendronate 10 mg/day or placebo. In another study 134 men were given either 10 mg alendronate or alfacalcidiol 1 microg/day. After 24 months, the treatment with alendronate bone mineral density (BMD) significantly increased in both studies by 7-10% at the lumbar spine and by 2.5-5.2% at the femoral neck. These changes were associated with decreases in vertebral fracture rate and in stature loss, both statistically significant when the data of the two trials were meta-analysed. The BMD changes after alendronate therapy were comparable to those observed in postmenopausal osteoporosis. This was confirmed in a trial specifically designed to compare alendronate efficacy in men and postmenopausal women with either primary or secondary osteoporosis. Gender-comparative efficacy data can also be inferred from clinical trials in glucocorticoid-induced osteoporosis of alendronate, risedronate, and etidronate, carried out in both women and men. By combining the results of all these trials, bisphosphonate efficacy in terms of both BMD changes and fracture incidence appears to be moderate in premenopausal women but quite obvious and comparable in males and postmenopausal women.

Alendronate↗
PubMed2001

Effects of oral alendronate in elderly patients with osteoporosis and mild primary hyperparathyroidism.

In a large proportion of the patients with primary hyperparathyroidism (PHPT), a variable degree of osteopenia is the only relevant manifestation of the disease. Low bone mineral density (BMD) in patients with PHPT is an indication for surgical intervention because successful parathyroidectomy results in a dramatic increase in BMD. However, low BMD values are almost an invariable finding in elderly women with PHPT, who are often either unwilling or considered unfit for surgery. Bisphosphonates are capable of suppressing parathyroid hormone (PTH)-mediated bone resorption and are useful for the prevention and treatment of postmenopausal osteoporosis. In this pilot-controlled study, we investigated the effects of oral treatment with alendronate on BMD and biochemical markers of calcium and bone metabolism in elderly women presenting osteoporosis and mild PHPT. Twenty-six elderly patients aged 67-81 years were randomized for treatment with either oral 10 mg alendronate on alternate-day treatment or no treatment for 2 years. In the control untreated patients a slight significant decrease was observed for total body and femoral neck BMD, without significant changes in biochemical markers of calcium and bone metabolism during the 2 years of observation. Urine deoxypyridinoline (Dpyr) excretion significantly fell within the first month of treatment with alendronate, while serum markers of bone formation alkaline phosphatase and osteocalcin fell more gradually and the decrease became significant only after 3 months of treatment; thereafter all bone turnover markers remained consistently suppressed during alendronate treatment. After 2 years in this group we observed statistically significant increases in BMD at lumbar spine, total hip, and total body (+8.6 +/- 3.0%, +4.8 +/- 3.9%, and +1.2 +/- 1.4% changes vs. baseline mean +/- SD) versus both baseline and control patients. Serum calcium, serum phosphate, and urinary calcium excretion significantly decreased during the first 3-6 months but rose back to the baseline values afterward. Increase in serum PTH level was statistically significant during the first year of treatment. These preliminary results may make alendronate a candidate as a supportive therapy in patients with mild PHPT who are unwilling or are unsuitable for surgery, and for whom osteoporosis is a reason of concern.

Absorptiometry, Photon↗
PubMed2000

Alendronate for the treatment of osteoporosis in men.

BACKGROUND: Despite its association with disability, death, and increased medical costs, osteoporosis in men has been relatively neglected as a subject of study. There have been no large, controlled trials of treatment in men. METHODS: In a two-year double-blind trial, we studied the effect of 10 mg of alendronate or placebo, given daily, on bone mineral density in 241 men (age, 31 to 87 years; mean, 63) with osteoporosis. Approximately one third had low serum free testosterone concentrations at base line; the rest had normal concentrations. Men with other secondary causes of osteoporosis were excluded. All the men received calcium and vitamin D supplements. The main outcome measures were the percent changes in lumbar-spine, hip, and total-body bone mineral density. RESULTS: The men who received alendronate had a mean (+/-SE) increase in bone mineral density of 7.1+/-0.3 percent at the lumbar spine, 2.5+/-0.4 percent at the femoral neck, and 2.0+/-0.2 percent for the total body (P<0.001 for all comparisons with base line). In contrast, men who received placebo had an increase in lumbar-spine bone mineral density of 1.8+/-0.5 percent (P<0.001 for the comparison with base line) and no significant changes in femoral-neck or total-body bone mineral density. The increase in bone mineral density in the alendronate group was greater than that in the placebo group at all measurement sites (P<0.001). The incidence of vertebral fractures was lower in the alendronate group than in the placebo group (0.8 percent vs. 7.1 percent, P=0.02). Men in the placebo group had a 2.4-mm decrease in height, as compared with a decrease of 0.6 mm in the alendronate group (P=0.02). Alendronate was generally well tolerated. CONCLUSIONS: In men with osteoporosis, alendronate significantly increases spine, hip, and total-body bone mineral density and helps prevent vertebral fractures and decreases in height.

Adult↗
PubMed2000

Prevention of early postmenopausal bone loss with cyclical etidronate.

Cyclical etidronate has been shown to be effective in the treatment of established postmenopausal osteoporosis but less is known about its effects on early menopausal bone loss. The aim of the study was to establish the effects of cyclic etidronate therapy on spinal and proximal femoral bone mineral loss in early postmenopausal women. One hundred and seven women who were within 6 months to 3 years of the menopause were recruited into a 2-year, randomised, placebo-controlled, double-blind trial. Spinal bone mineral density was within 2 SD of the age-matched mean reference value at baseline. Bone mineral density in the lumbar spine and proximal femur was assessed by dual energy X-ray absorptiometry at baseline and thereafter at 6 monthly intervals for 2 years. Urinary collagen cross-links (deoxypyridinoline and pyridinoline) were measured at the same time points. Seventy-seven women completed the study. At the end of the treatment period, the mean bone mineral density change from baseline in the treated group was +0.14% and -0.06% in the lumbar spine and femoral neck, respectively, compared to -1.49 and -2.22 in the control group. Overall, there was a significant difference between the two groups at both these sites (p=0.01 and 0.001, respectively). No significant differences between the groups were demonstrated at the greater trochanter or Ward's triangle. The conclusion was that cyclical etidronate therapy prevents bone loss in the spine and femoral neck in early postmenopausal women. It provides a safe and effective therapeutic option for the prevention of postmenopausal osteoporosis in women who are unwilling or unable to tolerate hormone replacement therapy.

Absorptiometry, Photon↗
PubMed2000

Association of CTR and COLIA1 alleles with BMD values in peri- and postmenopausal women.

The variability of bone mass and bone strength is in part genetically determined. The pathophysiology of the disease is complex and its heritability is almost certainly polygenic. In a large group of women from north eastern Italy, homogeneous for calcium intake and other risk factors for osteoporosis, we investigated three different genetic polymorphic markers that have been associated with bone mineral density (BMD). The study includes 663 postmenopausal (aged 48-85 years) and 52 perimenopausal (aged 47-53 years) women. Lumbar spine and hip BMD were measured by dual energy X-ray absorptiometry (DXA). After DNA extraction, the restriction enzymes utilized were MscI for the SP1 site of the collagen type I regulatory region (COLIA1), AluI for the calcitonin receptor (CTR) gene, and BsmI for the Vitamin D receptor (VDR) gene. COLIA1 genotype was significantly associated with age-adjusted hip BMD, with the highest values in the SS group and the lowest in the ss group (p < 0.05). The COLIA1 effect was not visible until the sixth decade of life, but it increased thereafter with aging, becoming statistically significant also at the lumbar spine in subjects aged >70 years. CTR genotype was also significantly related to bone mass in the CC group, with the lowest age and weight-adjusted BMD values at the spine (p < 0.05). The CTR genotype effect was greater in the younger subset of women. This suggests that the CTR genotype might influence the process of acquiring peak bone mass rather than the process of bone loss along aging. No trend association was found between BMD values and VDR genotype. These findings suggest an association between the COLIA1 gene polymorphism more with the age-related rate of bone loss than with peak bone mass, which apparently is somewhat affected by CTR gene polymorphism.

Aged↗
PubMed2000

Calcium-induced natriuresis: physiologic and clinical implications.

Assessment of the tubular reabsorption of calcium (Ca) by infusion is complicated by suppression of parathyroid hormone (PTH) secretion, and by activation of the serpentine Ca sensing receptor in the renal tubule, which inhibits Ca and sodium reabsorption, but little is known about the magnitude of the natriuretic effect of Ca in human subjects. Accordingly, we reanalyzed the relationship between serum Ca and urine Ca and sodium excretion expressed per unit of creatinine clearance (CaE and NaE), and per unit of time (UCa and UNa), during a standard Ca infusion, in 14 healthy volunteers and in 8 primary hyperparathyroid patients. In healthy subjects we observed a large effect of Ca infusion on NaE, which rose as high as 8 mmol/liter GFR. In patients with primary hyperparathyroidism both CaE and NaE during Ca infusion were significantly lower overall than in healthy subjects for comparable values of serum Ca (P < 0.05 by covariance analysis), due mainly to a decline or reversal of the slopes at the highest serum Ca levels. In both controls and primary hyperparathyroid subjects the variance of CaE as dependent variable was explained by both serum Ca and by NaE as independent variables (P < 0.001). We conclude that (1) The natriuretic effect of hypercalcemia was unexpected large and if maintained would lead to substantial depletion of extracellular fluid. (2) Patients with chronic hypercalcemia, including primary hyperparathyroidism, probably have mild sodium depletion, and are more susceptible to volume depletion. (3) Calcium reabsorption during Ca infusion is reduced by suppression of PTH secretion and increased by volume contraction due to sodium depletion. Discrimination between different basal levels of parathyroid function is successful because these effects usually cancel out. (4) The increase in tubular reabsorption of Ca due to volume contraction can initiate a vicious circle, of importance to the pathogenesis and treatment of severe hypercalcemia.

Adult↗