Bone metabolism in patients with primary hyperparathyroidism before and after surgery

Primary hyperparathyroidism (PHPT) is accompanied with a reduced bone mineral density (BMD) and an increased risk of fracture. Surgery is the only option for cure. It is hypothesized that in patients with PHPT bone metabolism normalizes after parathyroidectomy (PTX) and that BMD gradually increases. Fifty-two patients with PHPT who underwent surgery were prospectively followed for 1 year. Biochemical analyses were performed at baseline and 1, 4, 7 days; 6 weeks; and 3, 6, and 12 months, and BMD before and one year after surgery. Parathyroid hormone (PTH), calcium, and the bone resorption marker dropped immediately, but transiently after PTX, bone formation decreased more slowly. Osteoprotegerin (OPG) as well as cathepsin K did not show significant changes. BMD of the lumbar spine, but not of the femoral neck, increased significantly within one year after surgery. Moderate correlations existed between the changes of total calcium, ionized calcium, as well as bone-specific alkaline phosphatase and changes of the lumbar BMD. Patients who needed postoperative supplementation with calcium and vitamin D had significantly higher PTH levels. Some gender-specific differences in patients with PHPT were observed. In patients with PHPT, males appear to be more severely affected than females. Within the first year after PTX, bone metabolism normalized, and BMD of the lumbar spine increased. Patients who needed a supplementation with calcium and vitamin D after PTX preoperatively had higher serum levels of PTH.     

Switching to Denosumab or Bisphosphonates After Completion of Teriparatide Treatment in Women With Severe Postmenopausal Osteoporosis

ObjectiveTo compare bone mineral density (BMD) changes after 12 months of treatment with denosumab or bisphosphonates in postmenopausal women with severe osteoporosis after stopping teriparatide therapy.MethodsWe retrospectively analyzed 140 postmenopausal women (mean age, 74.2 years) with severe osteoporosis who had been treated with teriparatide for 18 to 24 months at our outpatient clinic in a tertiary endocrine center between 2006 and 2015. After stopping teriparatide therapy, they continued treatment with a bisphosphonate (alendronate, risedronate, ibandronate, or zoledronic acid) or denosumab while receiving daily vitamin D and calcium. BMD at the lumbar spine (LS), total hip (TH), and femoral neck (FN) was measured by dual energy x-ray absorptiometry when teriparatide therapy was discontinued (baseline) and after 12 months of further treatment. Multivariate linear regression models were used to identify the predictors of BMD gain.ResultsAfter stopping teriparatide therapy, 70 women continued treatment with bisphosphonates and 70 received denosumab. LS, but not TH or FN, BMD gain was significantly greater in the denosumab group than in the bisphosphonates group at 12 months. Multivariate analysis showed that BMD gain at the LS was negatively associated with bisphosphonate versus denosumab treatment and positively associated with baseline serum total procollagen type I N-terminal propeptide. BMD gains at the FN were predicted by higher baseline serum urate levels. BMD gains at the TH and FN were negatively associated with pretreatment BMD gains at the same site.ConclusionTwelve months after stopping teriparatide therapy, sequential denosumab treatment appeared to yield higher additional LS BMD gain on average compared with bisphosphonates treatment.     

Bone mineral density in hypoparathyroid women on LT4 suppressive therapy. Effect of calcium and 1,25(OH)2 vitamin D3 treatment

Our aim was to study the bone mineral density (BMD) of patients with chronic hypoparathyroidism (hypoPTH) after longterm calcium and vitamin D treatment. Twenty hypoPTH women (mean-/+SD, aged 50-/+15 years, IPTH 4-/+6 pg/ml) and 20 matched euparathyroid women (euPTH) after near total thyroidectomy for thyroid cancer, completed with I-131 ablation and on suppressive therapy with L-Thyroxine (LT(4)), were studied. In addition eight hypoPTH patients who were receiving LT(4) replacement therapy after surgery for compressive goiter were simultaneously studied. The hypoPTH patients were on calcium and 1,25(OH)(2) vitamin D(3) therapy to normalize serum calcium. Bone mineral density (BMD) (DXA, at the lumbar spine [L(2)- L(4), LS], femoral neck [FN] and Ward triangle [WT]), serum and urine calcium, serum phosphorus, TOTALALP and osteocalcin were measured. Patients with hypoPTH showed greater lumbar BMD than euPTH patients on suppressive therapy (Z-score; 1.01-/+1.34 vs. -0.52-/+0.70, p<0.05). Serum osteocalcin levels were higher in hypoPTH patients on suppressive therapy compared to hypoPTH patients on replacement therapy. The LS BMD from hypoPTH patients correlated with calcium supplements (r=0.439; p=0.02), 1,25(OH)(2)D(3) dose (r=0.382; p=0.04) and LT(4) dose (r=0.374; p=0.05). Our data suggest that long-term treatment with calcium and 1,25(OH)(2) vitamin D3 supplements in hypoPTH patients on suppressive LT4 therapy results in increased BMD when compared with patients with normal PTH levels.     

Alendronate Therapy in Men With Primary Hyperparathyroidism

ObjectiveTo determine the skeletal effects of alendronate therapy in men with primary hyperparathyroidism (PHPT) in comparison with those in postmenopausal women.MethodsThere essentially are no published data on the effects of bisphosphonate therapy in men with PHPT. We previously conducted a double-blind, randomized, single-crossover trial of alendronate, 10 mg daily, in PHPT and reported that alendronate significantly increases bone mineral density (BMD) at 12 months relative to baseline values. That study sample included both women (n = 28) and men (n = 9) and both premenopausal (n = 4) and postmenopausal (n = 24) women. Study subjects were randomly assigned to receive either alendronate or placebo during the first year, and all subjects received alendronate during the second year. Among the men, 3 received alendronate and 6 received placebo during the first year. The current analysis focuses on the skeletal effects of alendronate therapy in the 9 men during their first year of treatment versus the 6 men during their first year while receiving placebo as well as the 24 postmenopausal women during their first year of alendronate therapy. Paired t tests comparing baseline and 12-month data were performed for the 9 treated men and the 6 control subjects; unpaired t tests were used to compare the 9 treated men and the 24 treated women.ResultsAlendronate therapy for 1 year (n = 9) resulted in a 4.8% increase in BMD at the lumbar spine (P = .1) in comparison with the men who received 1 year of placebo (n = 6). Relative to baseline, men receiving alendronate showed a significant 4.4% gain in BMD at the lumbar spine (P = .009) and a 2.95% gain in total hip BMD (P = .027). A 47% decline in serum levels of bone-specific alkaline phosphatase activity was also noted with alendronate therapy (P = .003). Changes in BMD in the male population were similar to previously reported effects of alendronate therapy in postmenopausal women with PHPT.ConclusionAlendronate therapy in men with PHPT is associated with improvements in BMD and reductions in bone turnover. These data, similar to the findings in postmenopausal women with PHPT, suggest that aminobisphosphonates may be of value in providing skeletal protection for men with PHPT. Further study is needed to confirm skeletal protection and fracture efficacy in this population. (Endocr Pract. 2009;15:705-713)     

Parathyroid hormone versus bisphosphonate treatment on bone mineral density in osteoporosis therapy: a meta-analysis of randomized controlled trials

Background

Bisphosphonates and parathyroid hormone (PTH) represent the antiresorptive and anabolic classes of drugs for osteoporosis treatment. Bone mineral density (BMD) is an essential parameter for the evaluation of anti-osteoporotic drugs. The aim of this study was to evaluate the effects of PTH versus bisphosphonates on BMD for the treatment of osteoporosis.

Methods/Principal Findings

We performed a literature search to identify studies that investigated the effects of PTH versus bisphosphonates treatment on BMD. A total of 7 articles were included in this study, representing data on 944 subjects. The pooled data showed that the percent change of increased BMD in the spine is higher with PTH compared to bisphosphonates (WMD = 5.90, 95% CI: 3.69–8.10, p<0.01,). In the hip, high dose (40 µg) PTH (1–34) showed significantly higher increments of BMD compared to alendronate (femoral neck: WMD = 5.67, 95% CI: 3.47–7.87, p<0.01; total hip: WMD = 2.40, 95%CI: 0.49–4.31, p<0.05). PTH treatment has yielded significantly higher increments than bisphosphonates with a duration of over 12 months (femoral neck: WMD = 5.67, 95% CI: 3.47–7.86, p<0.01; total hip: WMD = 2.40, 95% CI: 0.49–4.31, P<0.05) and significantly lower increments at 12 months (femoral neck: WMD = −1.05, 95% CI: −2.26–0.16, p<0.01; total hip: WMD: −1.69, 95% CI: −3.05–0.34, p<0.05). In the distal radius, a reduction in BMD was significant between PTH and alendronate treatment. (WMD = −3.68, 95% CI: −5.57–1.79, p<0.01).

Discussion

Our results demonstrated that PTH significantly increased lumbar spine BMD as compared to treatment with bisphosphonates and PTH treatment induced duration- and dose-dependent increases in hip BMD as compared to bisphosphonates treatment. This study has also disclosed that for the distal radius, BMD was significantly lower from PTH treatment than alendronate treatment.     

Normal responsiveness of serum parathyroid hormone to beta-adrenergic blockade in patients with secondary hyperparathyroidism

Infusion of calcium gluconate (15 mg Ca++/kg body weight in 4 h) to 6 patients with secondary hyperparathyroidism (due to mild renal insufficiency) decreased serum parathyroid hormone (PTH) levels to the same degree (on a percent basis) as in normal subjects. Serum PTH values at 4 h were 60 +/- 4.5 (SEM)% of baseline in the patients and 59 +/- 2.9% of baseline in the normal subjects. Infusion of propranolol (1 mg i.v. bolus followed by an infusion of 60 micrograms/min for 2 h) to 7 additional patients with secondary hyperparathyroidism also decreased serum PTH to the same degree as in normal subjects. Serum PTH values at 2 h were 68 +/- 10.4% of baseline in the patients and 68 +/- 3.3% of baseline in the normal subjects. The studies indicate normal responsiveness of serum PTH to calcium or beta-adrenergic blockade in secondary hyperparathyroidism due to mild renal insufficiency.     

Does Baseline PTH Influence Recovery of Bone Mineral Density,Trabecular Bone Score and Bone Turnover Markers? A Prospective Study Following Curative PArathyroidectomy in Primary Hyperparathyroidism

Objective: This prospective study was carried out to assess trabecular bone score, bone mineral density (BMD), and bone biochemistry in Indian subjects with symptomatic primary hyperparathyroidism (PHPT), and to study the influence of baseline parathyroid hormone (PTH) on recovery of these parameters following curative surgery.Methods: This was a 2-year prospective study conducted at a tertiary care centre in southern India. Baseline assessment included demographic details, mode of presentation, bone mineral biochemistry, BMD, trabecular bone score (TBS), and bone turnover markers (BTMs). These parameters were reassessed at the end of the first and second years following curative parathyroid surgery.Results: Fifty-one subjects (32 men and 19 women) with PHPT who had undergone curative parathyroidectomy were included in this study. The mean (SD) age was 44.6 (13.7) years. The TBS, BTMs, and BMD at lumbar spine and forearm were significantly worse at baseline in subjects with higher baseline PTH (≥250 pg/mL) when compared to the group with lower baseline PTH (<250 pg/mL). At the end of 2 years, the difference between high versus low PTH groups (mean ± SD) persisted only for forearm BMD (0.638 ± 0.093 versus 0.698 ± 0.041 g/cm²; P =.01). However, on follow-up visits in the first and second year after curative parathyroidectomy, there was no significant difference in BTMs, BMD at the femoral neck, lumbar spine, and TBS between the 2 groups stratified by baseline PTH.Conclusion: The BMD at the forearm remained significantly worse in individuals with high baseline PTH even at 2 years after surgery, while other parameters including TBS improved significantly from baseline.Abbreviations: 25(OH)D = 25-hydroxyvitamin D; BMD = bone mineral density; BMI = body mass index; BTMs = Bone turnover markers; CTX = C-terminal telopeptide of type 1 collagen; DXA = dual energy X-ray absorptiometry; P1NP = N-terminal propeptide of type 1 procollagen; PHPT = primary hyperparathyroidism; PTH = parathyroid hormone; TBS = trabecular bone score     

Factors regulating circulating vascular endothelial growth factor (VEGF): Association with bone mineral density (BMD) in post-menopausal osteoporosis

Vascular endothelial growth factor (VEGF) plays an important role in bone health. We investigated the factors which influence circulating VEGF and their association with bone mineral density (BMD). Two hundred and fifty two post-menopausal women aged 64.5 [9.2] years were studied. BMD was determined at the lumbar spine (LS), femoral neck (FN) and total hip (TH). Serum oestradiol and VEGF were measured. Subjects were genotyped for two polymorphic variants in the 5′ untranslated region of the VEGF gene; G(634)C and C(936)T. Positive correlations were seen between circulating VEGF and BMI (r = 0.2, p < 0.02) and oestradiol (r = 0.25, p < 0.001). Following multi-linear regression analysis, serum VEGF was associated with the G(634) polymorphism (p = 0.08) and dietary calcium intake (p = 0.02). The association with calcium intake may be mediated by PTH as suggested by the in vitro studies. Following correction for confounders, there was no association between circulating VEGF and BMD at any site. Both VEGF polymorphisms were significant predictors of LS BMD G(634)C: p = 0.017 and C(936)T: p = 0.05. Circulating VEGF may be influenced by genetic, environmental and endocrine factors. Polymorphic variants in the VEGF gene are associated with spine BMD. Further larger studies are needed.     

Physical Activity and Bone Mineral Accrual in Boys with Different Body Mass Parameters during Puberty: A Longitudinal Study

The aim of our longitudinal study was to investigate the relationships between physical activity and bone mass in boys with different body mass status during the years surrounding pubertal growth spurt. Two hundred and six boys entering puberty took part in this study. The subjects were divided into underweight (), normal weight (), overweight () and obese () groups at baseline according to age related categories. Whole-body DXA scans were performed at baseline, after 12 and 24 months to assess body composition (lean body mass, fat mass), and total body (TB), lumbar spine (LS) and femoral neck (FN) bone mineral density (BMD) parameters. Physical activity was measured by 7- day accelerometry. For longitudinal analysis, multilevel fixed effects regression models were constructed. Biological age, height and lean body mass had an effect for explanation of TB BMD, FN BMD and LS BMD. Moderate to vigorous physical activity (MVPA), vigorous physical activity (VPA) and sedentary time (SED) had the significant effect only on FN BMD. Being an underweight boy at the baseline indicated greater chance (p<0.01) to have lower TB BMD in the future (2 years at follow up) development, compared to normal weight (estimates = −0.038), overweight (estimates = −0.061) and obese boys (estimates = −0.106).     

Effect of parathyroid extract on renal cyclic AMP excretion in patients with normocalciuric nephrolithiasis.

It is uncertain whether normocalcemic, normocalciuric patients with calcium nephrolithiasis have a disorder of calcium metabolism. We studied the effect of a parathyroid extract (PTE) INFUSION (1.4 U/kg body weight) on the urinary cyclic AMP excretion in 16 such patients. For comparison, we investigated groups of normal individuals and patients with primary hyperparathyroidism, renal insufficiency and different gastrointestinal diseases. The increase of cyclic AMP above basal excretion in patients with nephrolithiasis was only 1.2 +/- 0.3 mumol/h (mean +/- SEM), versus 2.5 +/- 0.5 mumol/h in normal subjects (p less than 0.05) although the basal excretion was similar. Patients with renal insufficiency had low basal excretion of cyclic AMP and little stimulation of excretion by PTH (increase, 0.3 +/- 0.06 mumol). Patients with primary hyperparathyroidism had high baseline cyclic AMP excretion but sub-normal stimulation by PTE (increase, 0.46 +/- 0.13); in contrast, patients with different gastrointestinal disease had high baseline excretion and supranormal stimulation of cyclic AMP excretion (increase, 5.2 +/- 0.6). We speculate that an impaired response to PTH might be involved in the slightly increased urinary calcium excretion in normocalcemic stone formers suggested by others.     

Efectos del tratamiento con ácido zoledrónico en pacientes adultos con osteogénesis imperfecta

Background and objectiveOsteogenesis imperfecta (OI) is a genetic disorder that results in bone fragility. Several studies have demonstrated the effectiveness of bisphosphonate therapy. The aim of this study was to evaluate the effects of intravenous zoledronic acid on bone mineral density (BMD) and biochemical markers of bone turnover in adults with OI.Material and methodsWe carried out a prospective non-randomized study in patients with osteoporosis or severe osteopenia (T score <?2) related to OI and intolerance or contraindication to oral bisphosphonates. The patients were treated with a zoledronic acid infusion every 6 months. Densitometry was carried out annually. Calcium (Ca), phosphate (P), intact parathormone (PTH), 25 hydroxyvitamin D and biochemical markers of bone turnover [bone alkaline phosphatase (BAP), beta-cross-laps (CTX) and urinary deoxypyridoxine (DOP)] were measured every year. Adverse events and new fractures were registered.ResultsTen patients (2 men and 8 women) were treated. Treatment increased BMD measured in the lumbar spine after 24 (0.738±0.141 vs 0.788±0.144 g/cm²; p=0.048) and 36 months (0.720±0.139 vs 0.820±0.128; p=0.01). Significant increases in BMD were also observed after 24 months in the femoral neck (0.677±0.121 vs 0.703±0.122 g/cm²; p<0.016). Serum Ca, P, BAP and CTX concentrations remained unchanged. PTH concentrations increased and vitamin D concentrations decreased after 36 months of treatment. DOP excretion decreased significantly after 24 months. Seven patients had mild influenza-like symptoms occurring within the first 24 h after the first infusion. No severe adverse events were observed. None of the patients had new fractures.ConclusionZoledronic acid seems to be a safe and effective treatment option in adults with osteoporosis related to OI.     

Increased PTH and 1.25(OH)(2)D levels associated with increased markers of bone turnover following bariatric surgery

The objective of this study was to characterize changes in metabolic bone parameters following bariatric surgery. Seventy-three obese adult patients who underwent either gastric banding (GB), Roux-en-Y gastric bypass (RYGB), or biliopancreatic diversion with duodenal switch (BPD/DS) were followed prospectively for 18 months postoperatively. Changes in the calcium-vitamin D axis (25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D (1,25(OH)(2)D), calcium, parathyroid hormone (PTH)), markers of bone formation (osteocalcin, bone-specific alkaline phosphatase) and resorption (urinary N-telopeptide (NTx)), as well as bone mineral density (BMD) were assessed at 3-month intervals during this time period. Bariatric surgery resulted in significant and progressive weight loss over 18 months. With supplementation, 25OHD levels increased 65.3% (P < 0.0001) by 3 months, but leveled off and decreased <30 ng/ml by 18 months. PTH initially decreased 21.4% (P = 0.01) at 3 months, but later approached presurgery levels. 1,25(OH)(2)D increased significantly starting at month 12 (50.3% increase from baseline, P = 0.008), and was positively associated with PTH (r = 0.82, P = 0.0001). When stratified by surgery type, median PTH and 1,25(OH)(2)D levels were higher following combined restrictive and malabsorptive operations (RYGB and BPD/DS) compared to GB. Bone formation/resorption markers were increased by 3 months (P < 0.05) and remained elevated through 18 months. Radial BMD decreased 3.5% by month 18, but this change was not significant (P = 0.23). Our findings show that after transient improvement, preoperative vitamin D insufficiency and secondary hyperparathyroidism persisted following surgery despite supplementation. Postoperative secondary hyperparathyroidism was associated with increased 1,25(OH)(2)D levels and increased bone turnover markers.     

Peripheral effects of PTH are not altered after thyroid surgery in euthyroid patients

BACKGROUND: We have previously found decreased serum levels of both ionized calcium and 1,25(OH)2D and an increase in serum phosphate levels at 1 year after hemithyroidectomy. However, basal and stimulated parathyroid hormone (PTH) secretions were not altered. To investigate whether the observed biochemical changes after unilateral thyroid surgery may be due to a relative end-organ resistance to PTH, we studied the peripheral effects of infused hPTH-(1-34) in 6 patients preoperatively and 3 months after hemithyroidectomy. METHODS: Serum levels of TSH, FT4 and FT3 were measured pre- and postoperatively. hPTH-(1-34) was infused at 0.9 IU/kg/h during 6 h. Blood samples for analysis of ionized calcium, intact PTH, phosphate, 25(OH)D, 1,25(OH)2D and urinary samples for calcium, phosphate and nephrogenous(n)-cAMP analysis were taken at baseline, when the infusion was discontinued after 6 h and at 24 h. RESULTS: Three months after hemithyroidectomy, serum levels of FT3 were decreased and TSH levels increased. Pre- and postoperative hPTH-(1-34) infusions induced increased serum levels of ionized calcium, 1,25(OH)2D, increased urinary excretion of phosphate and elevated n-cAMP levels. The changes in the studied biochemical variables during the hPTH-(1-34) infusions did not differ between the two study occasions. CONCLUSION: By using a 6-hour hPTH-(1-34) infusion protocol, we have shown that the peripheral PTH effect is not altered by a slight reduction in thyroid hormone levels at 3 months after hemithyroidectomy.     

Biochemical Dynamics of Untreated Primary Hyperparathyroidism: an Observational Study

Objective: The natural biochemical history of untreated primary hyperparathyroidism (PHPT) is poorly understood. The purpose of this study was to determine the extent of biochemical fluctuations in patients with PHPT.Methods: Retrospective cohort study from January 1, 1995, to December 31, 2014. Serum calcium and parathyroid hormone (PTH) levels in patients with classic (Ca >10.5 mg/dL, PTH >65 pg/mL) and nonclassic (Ca >10.5 mg/dL, PTH 40 to 65 pg/mL) PHPT were followed longitudinally at 1, 2, and 5 years. Biochemical profiles in follow-up were ranked in descending biochemical severity as classic PHPT, nonclassic PHPT, normal calcium with elevated PTH (Ca <10.5 mg/dL, PTH >65 pg/mL), possible PHPT (Ca >10.5 mg/dL, PTH 21 to 40 pg/mL), or absent PHPT (Ca >10.5 mg/dL, PTH <21 pg/mL or Ca <10.5 mg/dL, PTH <65 pg/mL).Results: Of 10,598 patients, 1,570 were treated with parathyroidectomy (n = 1,433) or medications (n = 137), and 4,367 were censored due to study closure, disenrollment, or death. In the remaining 4,661 untreated patients with 5 years of follow-up, 235 (5.0%) progressed to a state of increased biochemical severity, whereas 972 (20.8%) remained the same, and 3,454 (74.1%) regressed to milder biochemical states. In 2,522 untreated patients with classic PHPT, patients most frequently transitioned to the normal calcium with elevated PTH group (n = 1,257, 49.8%). In 2,139 untreated patients with nonclassic PHPT, patients most frequently transitioned to the absent PHPT group (n = 1,354, 63.3%).Conclusion: PHPT is a biochemically dynamic disease with significant numbers of patients exhibiting both increases and decreases in biochemical severity.Abbreviations: IQR = interquartile range; KPSC = Kaiser Permanente Southern California; PHPT = primary hyperparathyroidism; PTH = parathyroid hormone; PTx = parathyroidectomy     

Low Urine Calcium Excretion in African American Patients with Primary Hyperparathyroidism

ObjectiveTo evaluate the prevalence of low urine calcium excretion in African American patients with primary hyperparathyroidism (PHPT), a common disorder associated with bone and renal complications, and to assess the distinction between PHPT and familial hypocalciuric hypercalcemia (FHH), a rare benign genetic disease.MethodsWe conducted a retrospective study on a cohort of 1,297 patients in whom a 24-hour urine study was performed for measurement of urine calcium and creatinine. PHPT was diagnosed if the serum calcium concentration was ≥ 10.5 mg/dL and intact parathyroid hormone (PTH) was ≥ 40 pg/mL. Patients receiving medications that affect urine calcium or with glomerular filtration rate ≤ 30 mL/min were excluded.ResultsNinety-six patients satisfied the diagnostic criteria for PHPT. The African American (n = 70) and non-African American (n = 26) patients did not differ in their mean age, body mass index, glomerular filtration rate, serum PTH, 25-hydroxyvitamin D levels, and 24-hour urine creatinine values. Median values of urine calcium/creatinine (mg/g) were 122 for African American versus 214 for non-African American patients (P = .006). Thirty-one of 70 African American patients (44%) had a urine calcium/creatinine ratio ≤ 100 mg/g, whereas only 2 of 26 non-African American patients (8%) had this value (P = .001).ConclusionThe prevalence of low urine calcium excretion among African American patients with PHPT is unexpectedly high. A threshold of 100 mg/g urine calcium/ creatinine identified 44% of such patients with PHPT as having FHH in this cohort. Therefore, other clinical criteria and laboratory variables should be used to distinguish PHPT from FHH in African American patients with PTH-dependent hypercalcemia. (Endocr Pract. 2011;17: 867-872)     

Arterial structure and function in mild primary hyperparathyroidism is not directly related to parathyroid hormone, calcium, or vitamin D

Objective

Elevated levels of calcium and parathyroid hormone (PTH), characteristics of primary hyperparathyroidism (PHPT), may be associated with cardiovascular morbidity and mortality in the general population. We evaluated the possible vascular effects of these risk factors in patients with mild PHPT by using standard methods and new imaging techniques.

Design

A prospective case-control study.

Subjects and Methods

Forty-eight patients with mild PHPT without any known cardiovascular risk factors were studied at baseline and at one year after parathyroidectomy (PTX) in comparison with 48 healthy age- and gender-matched controls. We measured biochemical variables, augmentation index (AIx), aortic pulse wave velocity (PWV_ao), radial (IMT_rad) and common carotid artery (IMT_cca) intima media thicknesses, and the grayscale median (IM-GSM) of the latter.

Results

No significant differences were observed between PHPT patients and controls at baseline for AIx (28.6±12.2 vs. 27.7±12.8%), IMT_rad (0.271±0.060 vs. 0.255±0.053 mm), IMT_cca (0.688±0.113 vs. 0.680±0.135 mm), or IM-GSM (82.3±17.2 vs. 86.5±15.3), while PWV_ao was slightly higher in patients (8.68±1.50 vs. 8.13±1.55, p<0.05). Systolic blood pressure (SBP), calcium, and PTH were higher in patients compared with controls, and decreased after PTX, while vitamin D was lower in patients and increased after PTX. While AIx, PWV_ao, IMT_rad, and IMT_cca were related to SBP, neither correlated to vitamin D levels. Only PWV_ao correlated weakly to plasma PTH (r = 0.29, p<0.01) and ionized calcium (r = 0.22, p<0.05) but showed no relation when age and SBP were adjusted for.

Conclusion

We found normal arterial function despite high calcium, PTH, and low vitamin D levels, in patients with mild PHPT without cardiovascular risk factors. The cardiovascular risk associated with low vitamin D and/or high PTH and calcium levels may be explained by their coupling to blood pressure and other risk factors rather than direct effects on arterial structure.     

Somatostatin analogues do not affect calcium metabolism in patients with acromegaly and primary hyperparathyroidism [corrected] due to MEN 1-like syndrome

Patients with clinical features of MEN 1 without mutations in the menin gene fulfill the criteria of MEN1-like syndrome. Primary hyperparathyroidism (PHP) is the most frequent clinical finding in both syndromes and is usually treated by surgery. However, PHP has been reported to respond to somatostatin analogues (SSA) in MEN 1 patients. 7 patients with PHP in the context of MEN 1-like syndrome (and absence of mutations in the menin gene) were enrolled in the study and treated with SSA for 6 months for the non-PHP disease before parathyroidectomy. Serum ionized calcium, phosphorus, and PTH concentrations, and 24-h urinary calcium and phosphorus excretion were measured before and after SSA therapy. Mean serum ionized calcium, phosphorus, and PTH concentrations did not significantly change after a 6-month course with SSA. SSA scintigraphy did not reveal uptake in the neck region corresponding to the parathyroid adenoma identified at surgery and confirmed at histology. However, immunohistochemistry revealed SS-type 2A receptor in parathyroid tissue samples of 6 out of 7 patients. SSA therapy does not affect calcium-phosphorus metabolism in patients with MEN 1-like syndrome, suggesting that the drug has no role in controlling PHP in these subset of patients.     

Humoral hypercalcemia caused by a rat Leydig-cell tumor is associated with suppressed parathyroid hormone secretion and increased urinary cAMP excretion

We studied the effect of a transplantable Leydig-cell tumor (Rice H-500) on serum calcium, parathyroid hormone (PTH), and urinary cAMP in intact Fischer-344 rats. The tumor caused rapid and severe hypercalcemia (control = 10.5 +/- 0.1 mg/dl [mean +/- S.E.] vs. 14.6 +/- 0.9 at day 12 post tumor inoculation) without evidence of metastasis. Progressive renal impairment and death generally occurred within 15 days of tumor inoculation. Serum PTH declined from control values before hypercalcemia occurred and was significantly reduced in tumor-bearing hypercalcemic rats (mean = 60 +/- 8% of control values). Urinary cAMP excretion was increased in tumor-bearing rats (mean at day 12 post inoculation = 12.2 +/- 1.4 nmol/dl creatinine clearance vs. control = 6.2 +/- 0.2) and correlated positively with serum calcium. The Rice H-500 Leydig-cell tumor appears to secrete a humoral factor capable of causing hypercalcemia. This factor may also increase urinary cAMP excretion in a manner analogous to PTH, but it is not detected by PTH radioimmunoassay.     

Determinants of parathormone secretion in primary hyperparathyroidism

We studied the effects of acute modifications in plasma calcium on parathormone (PTH) secretion in 23 patients with primary hyperparathyroidism (PHPT). In 12 patients, PTH hypersecretion was autonomous, and basal plasma calcium concentration was positively correlated with maximal serum PTH(1-84) reached during Na2EDTA infusions. In 11 patients, PTH hypersecretion remained suppressible, but with elevated set point value, and basal plasma calcium concentration was positively correlated with set point. Thus, the degree of hypercalcemia seems mainly determined by the magnitude of maximal PTH secretion and set point error in autonomous and suppressible PHPT, respectively. We have previously suggested that high serum calcitriol levels might chronically inhibit PTH hypersecretion in PHPT. We showed that hyperparathyroid patients with renal stone presentation exhibited an abnormally high value of circulating calcitriol and a moderately elevated PTH activity, while patients with severe bone disease presentation displayed a low to normal calcitriol value and a dramatically increased PTH activity. The hypothesis was supported by a recent study from our Unit in one hyperparathyroid patient with severe bone disease and normal serum calcitriol level. Increment of serum calcitriol after daily intravenous Rocaltrol for 5 days directly suppressed PTH hypersecretion without change in plasma ionized calcium.     

Metabolic effects of single-dose pamidronate administration in prostate cancer patients with bone metastases

BACKGROUND: Increased osteolysis usually accompanies sclerotic bone metastases from prostate cancer. This provides a rationale for the use of bisphosphonates to treat bone pain and prevent skeletal complications. METHODS: The fasting urinary levels of calcium, hydroxyproline (OHPRO), pyridinolines (PYD), deoxypyridinolines (DPYD), collagen cross-linked N-telopeptide (NTX) and the serum values of calcium, total alkaline phosphatase and relevant bone isoenzyme, bone gla protein (BGP), carboxy-telopeptide of type I collagen (ICTP) and parathyroid hormone (PTH) were determined at baseline and on the 15th, 30th, 60th and 90th days after single-dose (90 mg) pamidronate administration in 35 consecutive prostate cancer patients with bone metastases. These biochemical indices and serum interleukin 6 (IL-6) were also measured after four days in the last consecutive 17 cases. RESULTS: PYD, DPYD and NTX showed a significant decrease lasting four weeks (p<0.01, <0.01 and <0.001, respectively). OHPRO and ICTP did not change significantly. The NTX decline was greater than that of PYD and DPYD (maximum percent decrease: -71.3, -23.1 and -28.2, respectively). Bone formation markers and serum calcium did not change significantly. Serum PTH showed a rapid initial increase followed by a slow decrease (p<0.001). DPYD and NTX patterns did not correlate with changes in bone pain. As observed in the last 17 cases, the maximum osteolysis inhibition after pamidronate occurred on the fourth day after drug infusion. Serum IL-6 levels showed a short-lived decrease preceded by a transient rise on the fourth day. CONCLUSIONS: Pamidronate is able to induce a decrease in bone resorption without significantly influencing bone formation. The maximum decrease in bone resorption occurs very early. NTX is the most sensitive bone resorption marker in bisphosphonate therapy monitoring. Changes in IL-6 but not bone resorption markers may be useful in the prediction of symptomatic response.