Metabolic abnormalities related to cardiovascular risk in primary hyperparathyroidism: effects of surgical treatment

A predictive model for hyperuricemia among type 2 diabetes mellitus patients in Urumqi, China

BACKGROUND

Patients with type 2 diabetes Mellitus (T2DM) are more likely to suffer from a higher uric acid level in blood-hyperuricemia (HUA). There are no conclusive studies done to predict HUA among T2DM patients. Therefore, this study aims to explore the risk factors of HUA among T2DM patients and finally suggest a model to help with its prediction.

METHOD

In this retrospective research, all the date were collected between March 2017 and October 2019 in the Medical Laboratory Center of the First Affiliated Hospital of Xinjiang Medical University. The information included sociodemographic factors, blood routine index, thyroid function indicators and serum biochemical markers. The least absolute shrinkage and selection operator (LASSO) and multivariate binary logistic regression were performed to screen the risk factors of HUA among T2DM patients in blood tests, and the nomogram was used to perform and visualise the predictive model. The receiver operator characteristic (ROC) curve, internal validation, and clinical decision curve analysis (DCA) were applied to evaluate the prediction performance of the model.

RESULTS

We total collected the clinical date of 841 T2DM patients, whose age vary from 19-86. In this study, the overall prevalence of HUA in T2DM patients was 12.6%. According to the result of LASSO-logistic regression analysis, sex, ethnicity, serum albumin (ALB), serum cystatin C (CysC), serum inorganic phosphorus (IPHOS), alkaline phosphatase (ALP), serum bicarbonate (CO2) and high-density lipoprotein (HDLC) were included in the HUA risk prediction model. The nomogram confirmed that the prediction model fits well (χ2 = 5.4952, P = 0.704) and the calibration curve indicates the model had a good calibration. ROC analysis indicates that the predictive model shows the best discrimination ability (AUC = 0.827; 95% CI: 0.78-0.874) whose specificity is 0.885, and sensitivity is 0.602.

CONCLUSION

Our study reveals that there were 8 variables that can be considered as independent risk factors for HUA among T2DM patients. In light of our findings, a predictive model was developed and clinical advice was given on its use.

Association Between Primary Hyperparathyroidism and Secondary Diabetes Mellitus: Findings From a Scoping Review

An ill-defined association exists between diabetes mellitus (insulin resistance) and primary hyperparathyroidism. This article explores this phenomenon while providing an explanation for such a relationship and reviewing the evidence regarding the response to insulin sensitivity following a parathyroidectomy. Primary hyperparathyroidism may increase the risk of developing insulin resistance; peculiarly, this is not present in all patients. It is likely that both intracellular hypercalcemia and hypophosphatemia alter the insulin receptor expression and response; the contribution of parathyroid hormone is less clear. Following parathyroidectomy, patients may demonstrate improvement in their insulin sensitivity, while others have no response or a detrimental effect. A varied phenotype exists among patients, and furthermore, it is unclear why certain patients demonstrate improvement in insulin sensitivity following a parathyroidectomy, whereas others fail to do so. While this review provides a broad overview of the general endocrine community, it is imperative to note that clinical applicability is limited until further studies address these remaining uncertainties. Due to the lack of understanding regarding this endocrinological enigma, the presence of insulin resistance, at this present time, should not be a criterion for a parathyroidectomy.

Hyperuricemia is associated with secondary hyperparathyroidism in patients with chronic kidney disease

PURPOSE

Hyperuricemia is common among patients with chronic kidney disease (CKD). In the general population, hyperuricemia is associated with secondary hyperparathyroidism (SHPT), in a mechanism that involves vitamin D metabolism. Data for patients with CKD, however, are scarce. We aimed to evaluate the relationship between hyperuricemia and mineral and bone metabolism, particularly hyperparathyroidism.

METHODS

This is a retrospective study that included 922 adult patients with stages 3, 4, or 5 CKD, not on dialysis. Clinical, demographic, and biochemical data were collected from charts and included uric acid, parathyroid hormone (PTH), 25(OH)-vitamin D, calcium, phosphate, renal function (estimated glomerular filtration rate-eGFR), and medications such as allopurinol, furosemide, and cholecalciferol. SHPT was defined as PTH > 65 pg/ml.

RESULTS

Our patients were mostly Caucasian women, with a mean age of 64 ± 16 years. SHPT and hyperuricemia were observed in 70% and 62.4% of patients, respectively. Patients with SHPT presented higher levels of uric acid (7.2 ± 1.8 vs. 6.6 ± 1.7 mg/dL, p = 0.0001) and a higher frequency of hyperuricemia (66% vs. 33%, p = 0.0001). Patients with hyperuricemia were mostly female, with lower eGFR, higher phosphate, and higher PTH. The risk of hypovitaminosis D was higher among patients with SHPT (69.7% vs. 53.1%, p = 0.0001). Hyperuricemia remained independently associated with hyperparathyroidism, (p = 0.033) even after adjustments for eGFR, calcium, phosphate, hypovitaminosis D, and use of allopurinol, calcitriol, furosemide, and cholecalciferol.

CONCLUSION

Hyperuricemia seems to be a contributing factor for SHPT in patients with CKD. The mechanisms behind this finding have yet to be elucidated.

Comparison of Profile of Primary Hyperparathyroidism With and Without Type 2 Diabetes Mellitus: Retrospective Analysis From the Indian Primary Hyperparathyroidism Registry

OBJECTIVE

To describe the prevalence and compare the clinicobiochemical profile of patients with primary hyperparathyroidism (PHPT) with and without type 2 diabetes mellitus (T2DM).

METHODS

We conducted a retrospective observational study wherein the details of patients with PHPT with T2DM (PHPT-T2DM) and without T2DM were retrieved from the Indian PHPT Registry (www.indianphptregistry.com) between 2005 and 2019. We compared the clinical, biochemical, and postoperative findings of patients with PHPT-T2DM with age-, sex-, and body mass index-matched patients with PHPT without T2DM (in 1:2 ratio).

RESULTS

Of the 464 patients with PHPT, 54 (11.6%) had T2DM. We observed an increase in the prevalence of PHPT-T2DM cases over time; only 7 (7.1%) of the total patients with PHPT had T2DM between 2005 and 2009 that increased to 31 (12.8%) in the last half decade (2015-2019). Patients with PHPT-T2DM had a significantly lower prevalence of nephrolithiasis (18.5% vs 36.1%, respectively; P = .03) and a higher prevalence of pancreatitis (22.2% vs 5.6%, respectively; P = .007) than those without T2DM. Furthermore, intact parathyroid hormone (203 pg/mL [139.8-437.3 pg/mL] vs 285 pg/mL [166-692 pg/mL], respectively; P = .04) and serum creatinine (0.90 mg/dL [0.67-1.25 mg/dL] vs 1.10 mg/dL [0.73-1.68 mg/dL], respectively; P = .03) levels were significantly lower in patients with PHPT-T2DM than those without T2DM. Also, tumor weight tended to be lower in patients with PHPT-T2DM than in the non-T2DM counterparts (1.05 g [0.5-2.93 g] vs 2.16 g [0.81-7.0 g], respectively; P = .06).

CONCLUSION

The prevalence of T2DM in Asian Indians with PHPT is 11.6%. Patients with PHPT-T2DM are characterized by a higher prevalence of pancreatitis, a lower prevalence of nephrolithiasis, and lower levels of intact parathyroid hormone/creatinine. Part of the clinical picture can possibly be explained by early detection of PHPT in patients with T2DM consequent to more frequent screening.

Cardiovascular Risk in Patients with Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is one of the most common endocrine disorders characterized by parathyroid hormone (PTH)-dependent hypercalcemia. Cardinal features include low trauma fractures, nephrolithiasis, and chronic kidney disease. Several experimental studies established that parathyroid hormone exerts actions on the cardiovascular (CV) system, including vasodilatation and positive inotropic and chronotropic effects. Observational studies, especially in severe cases, report a higher prevalence of hypertension, diabetes mellitus, lipid abnormalities, endothelial dysfunction, arrhythmias, and left ventricular hypertrophy in patients with PHPT, while the risk of CV events seems to be increased in severe cases. However, the effect of surgery is inconsistent on CV abnormalities and, more importantly, on CV disease (CVD) events, especially in mild cases. In the current review, we describe the available evidence linking PHPT and CVD, as well as the effect of surgical management and pharmacological treatment on CVD manifestations in patients with PHPT. Based on the current evidence, CVD is not considered an indication for surgery.

The influence of parathyroidectomy on cardiometabolic risk factors in patients with primary hyperparathyroidism: a systematic review and meta-analysis

PURPOSE

Primary hyperparathyroidism (PHPT) is associated with increased risk of cardiovascular morbidity and mortality. We aim to determine whether parathyroidectomy (PTX) can change cardiometabolic risk factors including serum lipids, glycemic parameters, systolic and diastolic blood pressure, C reactive protein (CRP), and body mass index (BMI).

METHODS

MEDLINE, Web of Science, Scopus, and Google Scholar were searched for relevant articles published till June 2020. Fixed-effect or random-effects models were used to estimate the weighted mean difference (WMD) and 95% CI for outcomes where applicable.

RESULTS

In total, 34 studies were eligible to be included in the current meta-analysis. Our results indicated no favorable change in serum triglyceride (n = 13, WMD = -0.06, 95% CI: -0.15, 0.03 mmol/L), total cholesterol (n = 15, WMD = 0.01, 95% CI: -0.14, 0.16 mmol/L), LDL-C (n = 10, WMD = -0.01, 95% CI: -0.17, 0.19 mmol/L), HDL-C (n = 10, WMD = 0.03, 95% CI: -0.001, 0.06 mmol/L), and CRP (n = 5, WMD = 0.82, 95% CI: -0.01, 1.64 mg/L) after PTX in PHPT patients. However, glucose (n = 24, WMD = -0.16, 95% CI: -0.26, -0.06 mmol/L), serum insulin (n = 12, WMD = -1.11, 95% CI: -1.73, -0.49 µIU/mL), systolic (n = 17, WMD = -10.14, 95% CI: -12.27, -8.01 mmHg), and diastolic (n = 16, WMD = -5.21, 95% CI: -7.0, -3.43 mmHg) blood pressures were decreased after PTX, whilst a significant increase was observed in BMI (n = 13, WMD = 0.35, 95% CI: 0.19, 0.51 kg/m²).

CONCLUSIONS

PTX could improve glycemic parameters and blood pressure, without any significant change in serum lipoproteins and CRP.

Primary hyperparathyroidism is associated with a higher level of serum uric acid: A systematic review and meta-analysis

OBJECTIVES

Studies have suggested that primary hyperparathyroidism could be a risk factor for hyperuricemia although the results were not consistent across the studies. This systematic review and meta-analysis was performed in order to identify all available studies and summarize their results together.

METHODS

A systematic review was performed using EMBASE and MEDLINE from inception to August 2018 to identify all cohort studies that consisted of 2 cohorts, a cohort of patients with primary hyperparathyroidism and a cohort of individuals without hyperparathyroidism. Eligible studies had to provide data on mean serum uric acid level and standard deviation of both cohorts, which would be extracted to calculate mean difference (MD). Pooled MD was then calculated by combining MDs of each study using a random-effects model. Funnel plot was used for evaluation for publication bias.

RESULTS

A total of 9 cohort studies met the inclusion criteria and were included into the meta-analysis. The pooled analysis found that patients with primary hyperparathyroidism had a significantly higher level of serum uric acid than individuals without hyperparathyroidism with the pooled MD of 65.00 μmol/L (95% CI 37.74-92.25). The statistical heterogeneity was high with I² of 90%. The funnel plot was relatively symmetric and did not provide evidence for publication bias.

CONCLUSION

Patients with primary hyperparathyroidism had a significantly higher level of serum uric acid compared to individuals without hyperparathyroidism.

Association between serum uric acid and bone health in adolescents

Previous studies are suggestive of the protective role of uric acid on bone in the middle-aged and elderly. Whether this association exists in younger individuals has not been examined. This investigation showed a significant positive association between serum uric acid and bone parameters among Iranian adolescents.

INTRODUCTION

Uric acid (UA) might be linked to bone health, but it is unclear whether its effects on bone are limited to certain population subgroups. This study is aimed at investigating the correlation between serum uric acid levels and bone mineral density (BMD) in Iranian adolescents.

METHODS

This cross-sectional study was conducted on 413 (221 girls and 192 boys) Iranian adolescents aged 9-19 years. An analysis of anthropometric, biochemical parameters and bone density was performed on the participants. Measurements included serum uric acid, calcium, phosphorus, alkaline phosphatase, albumin, and vitamin D. They were divided according to their serum UA into the low UA group who had UA ≤ 6 mg/dL and the high UA group with UA > 6 mg/dL. BMD and bone mineral content (BMC) were measured in the total body, lumbar spine, and left femoral neck, using dual energy X-ray absorptiometry (DXA), and bone mineral apparent density (BMAD) was calculated.

RESULTS

A Pearson correlation analysis revealed a significant correlation between UA and bone parameters. In multiple regression analyses adjusted for potential confounders, serum UA was proven to be associated with BMD and BMC at all sites. There was no association between UA, serum calcium, and vitamin D concentrations.

CONCLUSION

Our study, as the first research on adolescents, demonstrated a higher bone density in those who had higher UA levels.

The effect of vitamin D supplementation on plasma non-oxidised PTH in a randomised clinical trial

OBJECTIVE

PTH can be oxidised in vivo, rendering it biologically inactive. Non-oxidised PTH (n-oxPTH) may therefore give a better image of the hormonal status of the patient. While vitamin D supplementation decreases total PTH (tPTH) concentration, the effect on n-oxPTH concentration is unexplored. We investigated the effect of vitamin D on n-oxPTH concentration in comparison to tPTH and compared the correlations between parameters of calcium, bone and lipid metabolism with n-oxPTH and tPTH.

METHODS

N-oxPTH was measured in 108 vitamin D-insufficient (25(OH)D <75 nmol/L) hypertensive patients, treated with vitamin D (2800 IE daily) or placebo for 8 weeks in the Styrian Vitamin D Hypertension Trial (NCT02136771). We calculated the treatment effect and performed correlation analyses of n-oxPTH and tPTH with parameters of calcium, bone and lipid metabolism and oxidative stress.

RESULTS

After treatment, compared to placebo, 25(OH)D concentrations increased, tPTH decreased by 9% (P < 0.001), n-oxPTH by 7% (P = 0.025) and the ratio of n-oxPTH/tPTH increased (P = 0.027). Changes in phosphate and HDL concentration correlated with changes in n-oxPTH, but not tPTH.

CONCLUSIONS

tPTH and n-oxPTH decrease upon vitamin D supplementation. Our study suggests that vitamin D supplementation reduces the oxidation of PTH, as we observed a small but significant increase in the non-oxidised proportion of PTH upon treatment. In addition, we found that changes in phosphate and HDL concentration showed a relationship with changes in n-oxPTH, but not tPTH. This may be explained by the biological activity of n-oxPTH. Further research should be carried out to establish the clinical relevance of n-oxPTH.

The effect of surgery on fat mass, lipid and glucose metabolism in mild primary hyperparathyroidism

CONTEXT

Mild primary hyperparathyroidism has been associated with increased body fat mass and unfavorable cardiovascular risk factors.

OBJECTIVE

To assess the effect of parathyroidectomy on fat mass, glucose and lipid metabolism.

DESIGN, PATIENTS, INTERVENTIONS, MAIN OUTCOME MEASURES

119 patients previously randomized to observation (OBS; n = 58) or parathyroidectomy (PTX; n = 61) within the Scandinavian Investigation of Primary Hyperparathyroidism (SIPH) trial, an open randomized multicenter study, were included. Main outcome measures for this study were the differences in fat mass, markers for lipid and glucose metabolism between OBS and PTX 5 years after randomization.

RESULTS

In the OBS group, total cholesterol (Total-C) decreased from mean 5.9 (±1.1) to 5.6 (±1.0) mmol/L (P = 0.037) and LDL cholesterol (LDL-C) decreased from 3.7 (±1.0) to 3.3 (±0.9) mmol/L (P = 0.010). In the PTX group, the Total-C and LDL-C remained unchanged resulting in a significant between-group difference over time (P = 0.013 and P = 0.026, respectively). This difference was driven by patients who started with lipid-lowering medication during the study period (OBS: 5; PTX: 1). There was an increase in trunk fat mass in the OBS group, but no between-group differences over time. Mean 25(OH) vitamin D increased in the PTX group (P < 0.001), but did not change in the OBS group. No difference in parameters of glucose metabolism was detected.

CONCLUSION

In mild PHPT, the measured metabolic and cardiovascular risk factors were not modified by PTX. Observation seems safe and cardiovascular risk reduction should not be regarded as a separate indication for parathyroidectomy based on the results from this study.

Role of Parathyroid Hormone in Regulating Transporter and Metabolizing Enzyme Function

Recent studies demonstrate that parathyroid hormone (PTH) not only maintains mineral homeostasis through targeting the kidneys and bone, but also exerts its effects on other organs. For instance, PTH induces urate accumulation through inhibiting the expression of the ABCG2 in both the intestine and the kidney. In addition, PTH downregulates the expression of cytochrome P450 (CYP) 3A, a major enzyme for drug metabolism in both the intestine and liver, resulting in the increase of substrate drug exposure. These functions of PTH are mediated through the PTH receptor (PTHR) signaling. Since PTHR exists in various organs, PTH may regulate other, still unspecified transporters or enzymes in the organs that express PTHR.

The impact of parathyroidectomy on serum ADAMTS1, ADAMTS4 levels, insulin resistance, and subclinical cardiovascular disease in primary hyperparathyroidism

PURPOSE

Primary hyperparathyroidism has been associated with increased incidence of morbidity and mortality of the cardiovascular system. The etiopathogenetic mechanisms underlying this association are still not completely clear. Accumulating evidence suggested that a disintegrin and metalloproteinase with thrombospondin-like motifs (ADAMTS) has a role in the development of inflammation and atherosclerosis. In this study, we aimed to determine whether there is a change in serum levels of ADAMTS1, ADAMTS4, carotid intima-media thickness, and cardiovascular risk score after the surgery and also whether there is a relationship between ADAMTS levels and cardiovascular risk score in hypercalcemic primary hyperparathyroidism patients.

METHODS

The study included the 48 consecutive newly diagnosed patients with primary hyperparathyroidism. The patients were evaluated before and six months after parathyroidectomy. The Framingham score is used to calculate cardiovascular risk. Serum ADAMTS levels were determined by a human enzyme-linked immunoassay in all subjects.

RESULTS

The fasting glucose, fasting insulin levels and HOMA values were decreased significantly in all patients after surgery compared to the pretreatment values (p < 0.05). ADAMTS1, ADAMTS4, and carotid intima-media thickness levels were significantly lower after surgical correction of primary hyperparathyroidism compared to the preoperative values (p < 0.05). cardiovascular risk score was decreased after parathyroidectomy however, the difference were not statistical significant (p > 0.05). There were statistically significant relationship between cardiovascular risk score and waist/hip ratio, calcium, LDL-cholesterol, carotid intima-media thickness, ADAMTS4 values.

CONCLUSION

Based on the results of the present study, fasting glucose, fasting insulin levels, ADAMTS1, ADAMTS4, and carotid intima-media thickness might be an additional parameters during the management of patients with primary hyperparathyroidism, since these factors might improve after surgery.

Associations of fibroblast growth factor 23 with urate metabolism in patients with chronic kidney disease

OBJECTIVE

In patients with preserved kidney function, a positive association of fibroblast growth factor 23 (FGF23) with serum uric acid (SUA) has been reported; however, the relationship in overall chronic kidney disease (CKD) patients has not been investigated. No report has examined the relationship between FGF23 and uric acid clearance (CUA). The aim of the present study was to determine whether FGF23 is independently associated with urate metabolism in patients with CKD stages 1-5.

MATERIALS AND METHODS

In this cross-sectional study, 537 CKD patients were enrolled. SUA, CUA, FGF23, parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D (1,25(OH)2D) were measured. Multivariable linear regression analysis was applied to determine independent factors associated with SUA or CUA.

RESULTS

In all patients, both SUA and CUA were independently associated with male sex, use of diuretics, use of uric acid-lowering agents, estimated glomerular filtration rate, and log FGF23 (β=0.29, P<0.01 for SUA; β=-0.11, P<0.01 for CUA), but not with log PTH or log 1,25(OH)2D. Dyslipidemia and diabetes were also independent factors for SUA and CUA, respectively. In multivariable analyses by sex, log FGF23 was associated with SUA in both sexes (β=0.32, P<0.01 in males vs. β=0.20, P=0.02 in females). Conversely, log FGF23 was independently associated with CUA in males (β=-0.15, P<0.01), but not in females (β=-0.09, P=0.17).

CONCLUSIONS

FGF23 was independently associated with urate metabolism in this population of CKD patients. FGF23 might also have a stronger association with urate metabolism in males compared with females.

Uric Acid-Induced Inflammation Is Mediated by the Parathyroid Hormone:25-Hydroxyvitamin D Ratio in Obese Adolescents

BACKGROUND

Elevated serum uric acid (SUA) level is strongly associated with prevalence of metabolic syndrome (MS), elevated parathyroid hormone (PTH) levels, and 25-hydroxyvitamin D [25(OH)D] insufficiency in adults. We examined the relationship among SUA, [25(OH)D], PTH, and inflammation in obese adolescents, in obese adolescents with and without MS.

METHODS

Body mass index, body composition, 25(OH)D, PTH, fasting lipids, glucose, high-sensitivity C-reactive protein (hs-CRP), SUA, hemoglobin A1c (HbA1c), insulin, and the homeostatic model assessment of insulin resistance (HOMA-IR) were evaluated in 152 obese adolescents.

RESULTS

Hyperuricemia [SUA ≥ 6.0 mg/dL (357 μM)] was present in 54.6% of entire cohort without significant ethnic/racial differences. While SUA was negatively correlated with high-density lipoprotein cholesterol (HDL-C) and 25(OH)D (P < 0.01), it was positively correlated with fat mass (FM), PTH, PTH:25(OH)D, and hs-CRP (P < 0.01). Vitamin D deficiency [25(OH)D <50 nM] was present in 47.4% of subjects, and PTH and 25(OH)D were inversely correlated (P < 0.0001). FM was negatively correlated with 25(OH)D (r = -0.29; P < 0.001), but was positively correlated with PTH (P < 0.0001). MS was identified in 53.3% of cohort with higher FM, SUA, hs-CRP, HOMA-IR, PTH, and PTH:25(OH)D ratio than the non-MS subgroup (P < 0.001) with similar 25(OH)D status. Multiple regression analysis showed that the PTH:25(OH)D ratio mediated the relationship between SUA and hs-CRP (β = 0.19, P < 0.05 to β = 0.15, P = 0.19).

CONCLUSIONS

Hyperuricemia is strongly associated with PTH and hs-CRP levels independent of vitamin D status. The relationship between SUA and low-grade inflammation is mediated by the PTH:25(OH)D ratio in obese adolescents.

Parathyroidectomy in asymptomatic primary hyperparathyroidism reduces carotid intima-media thickness and arterial stiffness

OBJECTIVE

Although an International Workshop has suggested that cardiovascular assessment in asymptomatic primary hyperparathyroidism (PHPT) patients is not necessary, improvements in risk factors of subclinical atherosclerosis have been shown following parathyroidectomy. The objectives of this study were to determine whether parathyroidectomy in asymptomatic PHPT patients causes any change in carotid intima-media thickness (CIMT), arterial stiffness [pulse wave velocity (PWV)] and soluble CD40 ligand (sCD40L) levels.

DESIGN

Prospective study evaluating female patients diagnosed with asymptomatic PHPT in a single centre over a 6-month period.

PATIENTS

A total of 48 subjects were included: 17 hypercalcaemic (HC, mean age: 51 ± 8 years, Ca: 2·73 ± 0·17 mmol/l) and 16 normocalcaemic (NC, mean age: 58 ± 7 years, Ca: 2·30 ± 0·10 mmol/l) PHPT patients, and 15 healthy controls (mean age: 52 ± 4 years, Ca: 2·27 ± 0·07 mmol/l).

MEASUREMENTS

Biochemical tests, CIMT, PWV and sCD40L levels were compared at baseline and 6 months after parathyroidectomy (PTx).

RESULTS

At baseline, CIMT and PWV values in the HC and NC patients were higher than in the control group. While there was a significant reduction in CIMT (601 ± 91 μm vs 541 ± 65 μm, P = 0·006) and PWV (9·6 ± 1·8 vs 8·4 ± 1·5 m/s, P = 0·000) in the hypercalcaemic group at the end of the 6th month after PTx, no change was observed in normocalcaemic group (P = 0·686 and P = 0·196 respectively). No differences were observed in sCD40L levels between patient and control groups or between baseline and 6 months in patients undergoing parathyroidectomy.

CONCLUSION

Parathyroidectomy leads to an improvement in the structural and functional impairment associated with atherosclerosis in the vascular wall in asymptomatic hypercalcaemic PHPT patients.

Serum uric acid is associated with quantitative ultrasound parameters in men: data from the Camargo cohort

This study analyzes the association between serum uric acid levels and heel quantitative ultrasound (QUS) parameters in men aged 50 or more from the Camargo cohort. We found that higher serum uric acid levels are positively associated with all QUS measurements, suggesting a better bone quality in men with elevated serum uric acid values.

INTRODUCTION

Higher serum uric acid concentrations have been associated with higher bone mineral density and lower prevalence of fractures. However, there are no studies that have assessed the bone quality properties in Caucasians. Therefore, we have analyzed the association between quantitative ultrasound (QUS) and serum uric acid levels in adult men from a population-based cohort.

METHODS

A total of 868 men older than 50 were recruited from a larger cohort (Camargo Cohort) after excluding those with any known condition or drug treatment with a possible influence on bone metabolism, or those with a previous diagnosis of gout or taking hipouricemic agents. Bone turnover markers (PINP and CTX), 25OH-vitamin D and PTH levels were measured by electrochemiluminiscence. BMD was determined by DXA, and heel QUS with a gel-coupled device.

RESULTS

Lumbar, femoral neck and total hip BMD was significantly higher in men with higher serum uric acid levels. QUS parameters were also significantly higher in men with high uric acid levels than those with lower values, and increased continuously across quartiles after adjustment for confounding variables. In multiple regression analysis, serum uric acid was significantly associated with all QUS parameters. Finally, men with serum acid levels above median showed higher values in all the QUS parameters than men with lower values.

CONCLUSIONS

Higher serum uric acid levels in men older than 50 years are positively associated with QUS parameters. These data might suggest a better bone quality in men with elevated serum uric acid values.

Cardiovascular risk factors in patients with asymptomatic primary hyperparathyroidism

OBJECTIVES

Patients with primary hyperparathyroidism (PHP), even asymptomatic, have an increased cardiovascular risk. However, data on reversibility or improvement of cardiovascular disorders with surgery are controversial. Our aims were to assess the prevalence of classic cardiovascular risk factors in patients with asymptomatic PHP, to explore their relationship with calcium and PTH levels, and analyze the effect of parathyroidectomy on those cardiovascular risk factors.

PATIENTS AND METHODS

A retrospective, observational study of two groups of patients with asymptomatic PHP: 40 patients on observation and 33 patients who underwent surgery. Clinical and biochemical data related to PHP and various cardiovascular risk factors were collected from all patients at baseline and one year after surgery in the operated patients.

RESULTS

A high prevalence of obesity (59.9%), type 2 diabetes mellitus (25%), high blood pressure (47.2%), and dyslipidemia (44.4%) was found in the total sample, with no difference between the study groups. Serum calcium and PTH levels positively correlated with BMI (r=.568, P=.011, and r=.509, P=.026 respectively) in non-operated patients. One year after parathyroidectomy, no improvement occurred in the cardiovascular risk factors considered.

CONCLUSIONS

Our results confirm the high prevalence of obesity, type 2 diabetes mellitus, high blood pressure, and dyslipidemia in patients with asymptomatic PHP. However, parathyroidectomy did not improve these cardiovascular risk factors.

Association of serum uric acid and incident nonspine fractures in elderly men: the Osteoporotic Fractures in Men (MrOS) study

Uric acid (UA) is produced from purines by the enzyme xanthine oxidase, and elevated levels may cause arthritis and kidney stones. Conversely, UA also appears to function as an antioxidant and may protect against the oxidative stress associated with aging and disease. We performed a prospective fracture case-cohort study to understand the relation of UA and fracture risk in older men enrolled in the Osteoporotic Fractures in Men (MrOS) study. In the cohort of 5994 men aged 65 years and older attending the baseline MrOS examination, we evaluated a subgroup 1680 men in a case-cohort study design. The analytic group included 387 men with incident nonspine fractures (73 hip) and a random sample of 1383. Serum UA was measured in baseline serum samples. Modified proportional hazards models that account for case-cohort study design were used to estimate the relative hazards (RH) of hip and nonspine fracture in men for serum UA. Models were adjusted for age, race, clinic site, body mass index, vitamin D, parathyroid hormone, walking speed, Physical Activity Scale for the Elderly (PASE) score, frailty, and total. Subjects with incident nonspine fractures were older, had lower total hip bone mineral density (BMD), and higher serum phosphorus. There was an 18% decreased risk of nonspine fractures (95% confidence interval [CI] 0.71-0.93; p = 0.003) per 1 SD increase of baseline serum and 34% decreased risk of nonspine fractures in quartile 4 of UA versus quartiles 1, 2, and 3 (95% CI 0.49-0.89; p = 0.028) compared with nonfracture cases after multivariate adjustment. Hip fractures were not significantly associated with UA. Total hip BMD was significantly higher in the group of men with high UA levels compared with lower UA levels and increased linearly across quartiles of UA after multivariate adjustment (p for trend = 0.002). In summary, higher serum UA levels were associated with a reduction in risk of incident nonspine fractures but not hip fractures and higher hip BMD.

Serum uric acid is associated with left ventricular hypertrophy independent of serum parathyroid hormone in male cardiac patients

Background

Several studies have shown that serum uric acid (UA) is associated with left ventricular (LV) hypertrophy. Serum levels of parathyroid hormone (PTH), which has bbe shown to be correlated with UA, is also known to be associated with cardiac hypertrophy; however, whether the association between UA and cardiac hypertrophy is independent of PTH remains unknown.

Purpose

We investigated whether the relationship between serum uric acid (UA) and LV hypertrophy is independent of intact PTH and other calcium-phosphate metabolism-related factors in cardiac patients.

Methods and Results

In a retrospective study, the association between UA and left ventricular mass index was assessed among 116 male cardiac patients (mean age 65±12 years) who were not taking UA lowering drugs. The median UA value was 5.9 mg/dL. Neither age nor body mass index differed significantly among the UA quartile groups. Patients with higher UA levels were more likely to be taking loop diuretics. UA showed a significant correlation with intact PTH (R = 0.34, P<0.001) but not with other calcium-phosphate metabolism-related factors. Linear regression analysis showed that log-transformed UA showed a significant association with left ventricular mass index, and this relationship was found to be significant exclusively in patients who were not taking loop and/or thiazide diuretics. Multivariate logistic regression analysis showed that log-transformed UA was independently associated with LV hypertrophy with an odds ratio of 2.79 (95% confidence interval 1.48–5.28, P = 0.002 per one standard deviation increase).

Conclusions

Among cardiac patients, serum UA was associated with LV hypertrophy, and this relationship was, at least in part, independent of intact PTH levels, which showed a significant correlation with UA in the same population.

Investigation of insulin resistance in patients with normocalcemic primary hyperparathyroidism

While derangements in glucose metabolism in patients with primary hyperparathyroidism are well-defined, this issue is not investigated in patients with normocalcemic primary hyperparathyroidism (NPHPT). The aim of this study was to investigate the presence of insulin resistance in patients with NPHPT. Eighteen patients with NPHPT (two males and 16 females) and 18 healthy volunteers were enrolled into the study. Secondary causes of parathyroid hormone elevations were excluded in all patients. Blood samples were obtained for the measurement of serum calcium, phosphate, alkaline phosphatase (ALP), albumin, creatinine, glucose, and serum lipid levels. Glucose and insulin responses to oral glucose tolerance test (OGTT) were obtained. Homeostasis model assessment (HOMA-IR) was also used as an indice of insulin resistance. Patients and control subjects had similar age, body mass index, and sex distribution. Although within normal limits, serum calcium and ALP levels were higher in patients than in the control subjects. None of the patients and the control subjects had diabetes mellitus, while eight patients and six control subjects had impaired glucose tolerance. Insulin responses to OGTT and HOMA-IR were not significantly different among the patient and control subjects. In addition, both groups have similar serum lipid levels. Patients with NPHPT do not exhibit insulin resistance and glucose intolerance. Since so little is known about this form of disease, subjects should be monitored regularly for the metabolic aspects of the disease as well as the progression of their disease.

Glucose intolerance and primary hyperparathyroidism: an unresolved relationship

Primary hyperparathyroidism (PHPT) can be characterized as either symptomatic or asymptomatic, or, most recently, as normocalcemic. In the current issue of the journal, Cakir et al. report that insulin resistance and glucose intolerance is not an aspect of normocalcemic PHPT. However, both the current study as well as the literature are compromised by the lack of appropriate classification of normocalcemic PHPT subjects. Rigorously characterized cohorts are necessary to determine whether glucose intolerance is in fact present in normocalcemic PHPT.

Serum uric acid is associated with bone health in older men: a cross-sectional population-based study

Serum uric acid (UA) is a strong endogenous antioxidant. Since oxidative stress has been linked to osteoporosis, we examined the association between serum UA levels and bone mineral density (BMD), prevalent vertebral and nonvertebral fractures, and laboratory measures such as calcitropic hormones and bone turnover marker levels. This cross-sectional analysis consisted of 1705 community-dwelling men aged 70 years or over who participated in the baseline part of the Concord Health and Ageing in Men Project (CHAMP), a population-based study of older men in Sydney, Australia. BMD at all sites was significantly higher among men with serum UA levels above the group median than among men with UA levels below the median. In multiple regression analyses adjusted for potential confounders, serum UA remained associated with BMD at all sites (β = 0.12 to 0.14, p < .001), serum calcium (β = 0.11, p = .001), parathyroid hormone (β = 0.09, p = .002), 25-hydroxyvitamin D (β = 0.09, p = .005), and was negatively associated with urinary excretion amino-terminal cross-linked telopeptide of type 1 collagen (β = -0.09, p = .006). Overall, serum UA accounted for 1.0% to 1.44% of the variances in BMD (R(2)  = 0.10 to 0.22). In multiple logistic regression analyses, above-median serum UA levels were associated with a lower prevalence of osteoporosis at the femoral neck [odds ratio (OR) = 0.42, 95% confidence interval (CI) 0.22-0.81, p = .010) and lumbar spine (OR = 0.44, 95% CI 0.23-0.86, p = .016) and a lower prevalence of vertebral (OR = 0.62, 95% CI 0.43-0.91, p = .015) and nonvertebral (OR = 0.51, 95% CI 0.29-0.89, p = .018) fractures. In conclusion, higher serum UA levels are associated with higher BMD at all skeletal sites and with a lower prevalence of vertebral and nonvertebral fractures in older men.

[Clinical manifestations and asymptomatic forms of primary hyperparathyroidism]

The clinical profile of primary hyperparathyroidism (PHPT) has changed considerably, especially since the introduction of autoanalyzers in the laboratory, allowing calcium to be determined more frequently and a large number of cases of hypercalcemia to be detected. The most frequent causes are PHPT and cancer-related hypercalcemia. All of these factors have modified the prevalence of the clinical manifestations and currently the presence of recurrent kidney stones is observed in 20% of patients, while bone lesions, even the most subtle, are infrequent. Differentiating and establishing the limits between symptomatic and asymptomatic PHPT is difficult and many asymptomatic cases will never show disease progression, such as severe hypercalcemia, bone disease, hypercalciuria and/or kidney stones. An important question is whether patients not showing the classical manifestations of PHPT will benefit from surgery. This question is all the more important since, among patients not surgically treated, many are lost to follow-up after 5 to 10 years and the cost of follow-up exceeds that of surgery. Those against intervention base their arguments on the lack of progression in many patients and the possibility of alternative treatments.

Molecular diagnosis and clinical characterization of pseudohypoparathyroidism type-Ib in a patient with mild Albright's hereditary osteodystrophy-like features, epileptic seizures, and defective renal handling of uric acid

We describe a patient who presented with epileptic seizures unresponsive to anticonvulsive treatment. Laboratory investigations demonstrated epileptiform seizure activity in the brain but also revealed severe hypocalcemia, hyperphosphatemia, and elevated serum parathyroid hormone. In addition, the patient showed a reduced serum level of 25-[OH]-vitamin D. The diagnosis of pseudohypoparathyroidism type-Ib (PHP-Ib) was made based on these clinical findings and upon identification of a 3-kb deletion within the STX16 locus, a genetic defect frequently associated with autosomal dominant PHP-Ib. This mutation was also present in the patient's unaffected mother and her affected sister. Despite the molecular diagnosis of PHP-Ib, which is characterized by parathyroid hormone resistance in the absence of Albright's hereditary osteodystrophy (AHO), the patient had a round face, slightly short stature, and short fourth metacarpals, which were consistent with mild AHO. The patient and her affected sister, who lacked AHO-like features, showed reduced serum levels of uric acid and increased fractional excretion of uric acid, a finding that was reported only once previously for PHP-Ib. Unlike the previous report, the fractional uric acid excretion and serum uric acid levels returned to normal in our patient and her sister after 3 months of treatment period. These findings underscore several important points with respect to the pathogenesis and clinical presentation of PHP-Ib. Furthermore, the findings in the index case present interesting novel aspects, including a previously undescribed coexistence of the 3-kb STX16 deletion and AHO-like features and a clinical course complicated by concomitant 25-[OH]-vitamin D deficiency, which may have resulted, at least partly, from long-term use of antiepileptic drugs.

Prevalence of glucose intolerance in primary hyperparathyroidism and the benefit of parathyroidectomy

BACKGROUND

Increased prevalence of diabetes mellitus (DM) in primary hyperparathyroidism (PHPT) is established, but not glucose intolerance (GI), nor benefit from parathyroidectomy on GI. We determined these during management of a continuous series of patients with PHPT routinely followed after surgery.

PATIENTS AND METHODS

WHO criteria classified 75 g oral glucose tolerance tests (OGTT) in 51/54 consecutively proven PHPT patients, into normal glucose tolerance (NGT), DM, impaired glucose tolerance (IGT) or impaired fasting glucose (IFG); GI was derived by adding those with DM and IGT/IFG. OGTT were repeated after parathyroidectomy (mean follow up 2.4 +/- SD 1.6 years). Paired student t tests were used to compare fasting and 2-h plasma glucose (PG).

RESULTS

At presentation 32/54 patients (59%) had NGT, 10 IGT/IFG (19%) and 12 type 2 DM (22%), nine newly diagnosed. Before parathyroidectomy 17/35 patients had NGT (49%), 18 GI (51%), 12 DM (34%) and 6 IGT/IFG (17%). Five out of six patients with IGT/IFG had NGT, one with NGT developed IGT. At completion 23 patients (66%) had NGT, 12 GI (34%), 4 IGT/IFG (11%) and 8 DM (23%). After parathyroidectomy fasting and 2-h. PG fell in 30/34 normocalcaemic patients not on hypoglycaemic agents, 5.6 +/- 1.0 to 5.4 +/- 0.8 mmol/l, 7.2 +/- 3.0 to 6.3 +/- 3.1 mmol/l (p < 0.05, p < 0.01).

CONCLUSIONS

1. At presentation with PHPT, OGTT commonly identifies Type 2 DM and GI.2. After successful parathyroidectomy fasting and 2-h. PG fall significantly (p < 0.05, p < 0.01). DM and IGT/IFG often ameliorates to IGT or NGT, persistently.

Serum ionised calcium and cardiovascular disease in 45-years old men and women followed for 18 years

High level of total serum calcium within the normal range has been associated with increased cardiovascular risk. We wanted to evaluate whether the physiological active ionised form of calcium also was a risk factor for cardiovascular disease (CVD).

METHODS

A total of 974 participants from a health survey in 1981 in Copenhagen had ionised serum calcium and different cardiovascular risk factors measured. The participants were followed until 1999 in The National Hospital Patients Registry and The National Death Registry in Denmark regarding the diagnosis ischemic heart disease (IHD) and a broader definition of CVD. Persons with ionised serum calcium in the highest quintile were compared with persons in the lower four quintiles.

RESULTS

In a univariate analysis persons with ionised serum calcium in the highest quintile had increased risk of IHD (p=0.001) and CVD (p=0.02) compared to persons in the lower quintiles. The increased risk disappeared when gender and cardiovascular confounders were included in a Cox proportional hazards analysis (p=0.20 for IHD and p=0.50 for CVD, respectively). In a separate analysis of men and IHD the result remained insignificant (p=0.07).

CONCLUSIONS

Serum ionised calcium in the upper quintile in women and men together did not seem to be a risk factor in development of IHD and CVD, but a non-significant tendency towards increased risk of IHD was observed in men with ionised calcium in the upper quintile compared to men in the lower four quintiles.

Growth hormone and insulin-like growth factor binding protein-1 responses to oral glucose in patients with primary hyperparathyroidism

BACKGROUND

GH and IGFBP-1 both play a role in glucose homeostasis.

OBJECTIVE

To assess the GH and IGFBP-1 responses to an oral glucose load and their relationship with glucose homeostasis in patients with primary hyperparathyroidism.

DESIGN

A cross-sectional study with a control group followed by a longitudinal study after parathyroidectomy.

PATIENTS AND METHODS

We studied 15 patients with primary hyperparathyroidism (eight women, aged 59.6 +/- 2.2 years) and nine healthy normocalcaemic controls. All subjects were ambulatory and were studied as outpatients. Glucose, insulin, GH and IGFBP-1 were measured during an oral glucose (75 g) tolerance test (OGTT).

RESULTS

Patients with hyperparathyroidism showed similar glucose responses to OGTT to those found in controls. Insulin responses were higher in patients (peak insulin 96.33 +/- 9.71 mU/l) in relation to values found in controls (58.11 +/- 9.03 mU/l; P < 0.01). Suppression of GH levels after OGTT was more marked in patients [nadir 0.03 (0.02-0.05) microg/l] than in normocalcaemic subjects [nadir GH 0.12 (0.08-0.42) microg/l; P = 0.002]. However, baseline IGFBP-1 concentration and its decrease after glucose load were similar in patients and controls. Normalization of calcium levels after parathyroidectomy was not followed by any significant changes in glucose, insulin and GH responses to OGTT. The minimum concentration of IGFBP-1 and the area under the curve (AUC) of IGFBP-1 after OGTT were higher after parathyroidectomy (3.34 +/- 0.69 microg/l and 8.94 +/- 1.72 microg x h/l, respectively) than at diagnosis (2.19 +/- 0.42 microg/l and 6.74 +/- 1.28 microg x h/l, respectively; P < 0.05). No correlation was found between PTH, calcium and phosphorus concentrations and GH and IGFBP-1 values in patients before or after normalization of calcium metabolism.

CONCLUSION

GH and IGFBP-1 do not seem to be directly involved in the hyperparathyroidism-associated changes in carbohydrate metabolism. The postoperative changes in the depression of IGFBP-1 after OGTT remain to be elucidated.

Mortality in sporadic primary hyperparathyroidism: nationwide cohort study of multiple parathyroid gland disease

BACKGROUND

The risk of dying from primary hyperparathyroidism (pHPT) is controversial and has been explored mainly in single parathyroid gland disease. The present study investigates mortality in pHPT due to multiple parathyroid gland disease.

METHODS

We used the nationwide Swedish In-patient Register and Cause-of-Death Registry to compare the mortality in 3485 Swedish patients subjected to parathyroidectomy during 1964 to 1999 with that of the Swedish population (standardized for age, gender, and calendar year). The patient cohort includes 36,596 person years.

RESULTS

Increased risk of death beyond the first postoperative year (standardized mortality ratio, 1.4; 95% CI, 1.37-1.52) was found in both sexes and for all age intervals below 80 years. The increased risk persisted more than 15 years postoperatively and related to cardiovascular diseases, diabetes mellitus, urogenital diseases, and malignant disorders. The increased risk of dying in cardiovascular diseases normalized during 1990 to 1999.

CONCLUSIONS

pHPT caused by multiple parathyroid gland enlargement is associated with an excessive mortality similar to pHPT of single parathyroid adenoma. The findings substantiate that modern modes of surgical treatment for pHPT normalize the risk of dying from cardiovascular complications and that the hyperpararthyroid state per se is the possible cause of the premature death.

Association between primary hyperparathyroidism and increased body weight: a meta-analysis

Although primary hyperparathyroidism is frequently asymptomatic, it has been associated with an increased prevalence of hypertension, insulin resistance, dyslipidemia, cardiovascular mortality, and cancer. Previously we reported that patients with primary hyperparathyroidism are heavier than age-matched controls. Increased body weight could contribute to the association between primary hyperparathyroidism and these extraskeletal complications. We searched MEDLINE for English language studies published between 1975 and 2003 that reported body weight or body mass index in subjects with primary hyperparathyroidism and a healthy age- and sex-comparable eucalcemic control group. Seventeen eligible studies were identified. Subjects with primary hyperparathyroidism were 3.34 kg (95% confidence interval, 1.97-4.71; P < 0.00001) heavier than controls in 13 studies reporting body weight. In four studies reporting body mass index, subjects with primary hyperparathyroidism had an increased body mass index of 1.13 kg/m(2) (-0.29 to 2.55; P = 0.12) compared with controls. Standard mean difference analysis showed that subjects with primary hyperparathyroidism had an increased weight or body mass index of 0.3 sd (0.19-0.40; P < 0.00001) compared with controls. We conclude that patients with primary hyperparathyroidism are heavier than their eucalcemic peers, and that increased body weight may contribute to the reported associations between primary hyperparathyroidism and some extraskeletal complications.

Increased mortality in patients hospitalized with primary hyperparathyroidism during the period 1977-1993 in Denmark

The aim of the present study was to determine whether patients with the incident hospital diagnosis of primary hyperparathyroidism (PHPT) in Denmark during the period 1977-1993 had an increased mortality from cardiovascular disease and cancer compared to the rest of the Danish population. In a random sample of half of the Danish population, all patients with an incident hospital diagnosis of PHPT were identified in the National Hospital Patients Register. The mortality in the cohort was analyzed and compared with the background population. A cohort of 1578 patients was identified. Follow-up of 1179 women and 376 men, who did not die in the same month as the incident PHPT diagnosis, was made through 1993. Of these, 312 (20%) died within the follow-up period. The standard mortality ratio (SMR) for women was 1.7 (95% confidence interval [95% CI]: 1.5-1.9). SMR for men was 1.6 (95% CI: 1.3-2.0). In women an increased mortality from ischemic heart disease, cerebrovascular disease, and cancer was found. In men an increased mortality from cerebrovascular disease and cancer was found.

Derangement of glucose metabolism in hyperparathyroidism

The derangement of glucose metabolism is found frequently in all forms of hyperparathyroidism. Both in primary (PHPT) and secondary hyperparathyroidism (SHPT) PTH excess is thought to be involved in deteriorating insulin sensitivity and secretion though their different clinical and pathophysiological conditions. In PHPT these abnormalities are related to a high frequency of Type 2 diabetes mellitus and also impaired glucose tolerance according to recent clinical studies, without differences between symptomatic and asymptomatic clinical presentation. In chronic renal failure (CRF), the disorders of glucose metabolism due to SHPT do not bear an increased risk for diabetes whereas they seem to be involved in the progression of atherosclerotic vascular damage which connotes CRF. Moreover, clinical and experimental studies have shown that vitamin D deficiency associated with glucose metabolism abnormalities favors the development of the metabolic syndrome. The potential for metabolic and cardiovascular harm related to hyperparathyroidism, especially PHPT, is the most interesting issue for clinical endocrinologists. This short review of the clinical and pathophysiological data of literature on glucose homeostasis disorders in hyperparathyroidism focuses on its potential clinical and therapeutic impact, particularly in the management of PHPT.

Normalized dyslipidaemia after parathyroidectomy in mild primary hyperparathyroidism: population-based study over five years

OBJECTIVE

Postmenopausal women are at increased risk of primary hyperparathyroidism (pHPT). Secondary dyslipidaemia in pHPT has attracted little attention, although morbidity and mortality associated with cardiovascular diseases have been reported to be increased in these patients.

DESIGN

A population-based screening programme was used to recruit postmenopausal women with mild, asymptomatic pHPT (mean serum calcium 2.57 +/- 0.12 mmol/l) and matched controls. MEASUREMENTS AND PATIENTS: Serum lipids, lipoprotein fractions and influences of treatment for the parathyroid disease were studied in 87 case-control pairs (mean age 67 years), 69 of whom completed a 5-year follow-up period.

RESULTS

pHPT was characterized by decreased serum high-density lipoprotein (HDL)-cholesterol, increased total triglycerides, very-low-density lipoprotein (VLDL)-triglycerides and VLDL-cholesterol levels and an elevated atherogenic index. The differences were more pronounced in the cases with serum parathyroid hormone levels in the normal range and were inversely correlated to the serum parathyroid hormone level. Parathyroidectomy, with or without additive hormone replacement therapy, normalized the dyslipidaemia. Five-year surveillance of pHPT without treatment was associated with a maintained increase in total triglycerides and the atherogenic index and a decrease in HDL-cholesterol levels.

CONCLUSION

Proatherosclerotic dyslipidaemia characterizes mild pHPT and is effectively reversed by parathyroidectomy. As dyslipidaemia might contribute to the increased risk of cardiovascular diseases and death observed in pHPT, the findings favour operative intervention rather than conservative surveillance in mild, asymptomatic pHPT in postmenopausal females.

Urate and arteriosclerosis in primary hyperparathyroidism

OBJECTIVE

An increased mortality due to cardiovascular disease has been reported in patients with primary hyperparathyroidism (pHPT). An association between urate and cardiovascular disease has been suggested. Metabolic abnormalities in pHPT may include urate. We therefore evaluated the metabolic arteriosclerotic risk profile in pHPT with special focus on the role of urate.

DESIGN

Retrospective analysis of data before and 1 year after surgery for pHPT.

PATIENTS

130 consecutive patients, over the age of 44 years, who underwent surgery for pHPT.

MEASUREMENTS

Biochemical variables known to reflect risk of arteriosclerotic disease (AD) and renal function tests including measurement of glomerular filtration rate (GFR) were investigated before and 1 year after surgery.

RESULTS

pHPT patients with AD (n = 40) were older and had higher serum levels of urate and triglyceride, and more impaired renal function in comparison with patients without AD. PTH and calcium values did not differ. Multiple logistic regression analysis indicated that urate was an independent risk factor for AD in pHPT (P < 0.01). Three variables were shown to be positively associated with urate; male gender (P < 0.01), fasting blood glucose (P < 0.05) and serum level of triglyceride (P < 0.05).

CONCLUSIONS

Urate was found to be an independent risk factor for arteriosclerotic disease in primary hyperparathyroidism. Serum level of urate could (in addition to gender) be associated with a metabolic disorder comprising increased glucose and triglyceride levels.

Role of surgery in mild primary hyperparathyroidism in the elderly

BACKGROUND

The appropriate management of elderly patients with mild hyperparathyroidism is the subject of much debate.

METHODS

A Medline literature search was conducted using the keywords 'hyperparathyroidism', 'asymptomatic' and 'elderly'. The references of the primary sources were examined for further citations. Personally collected cullings from journals and abstracts from journals were used as an additional source of data.

RESULTS AND CONCLUSION

No prospective randomized controlled trial comparing parathyroidectomy with conservative management for patients with mild or asymptomatic hyperparathyroidism has been published. There are a number of longitudinal studies that attempt to characterize the natural history of hyperparathyroidism, but most do not stratify patients according to age when assessing outcome. None the less, it is clear that elderly patients present with a different spectrum of problems, particularly indistinct neuropsychiatric and musculoskeletal symptoms, and these are likely to be improved by surgery. The evidence allows the conclusion that the truly asymptomatic elderly patient can be successfully managed conservatively; there is a good prospect of benefit from surgery for those with symptomatic disease, and such patients should not be denied an operative option.

Hyperparathyroidism: the limits of surgery in cases of bone or cardiovascular involvement

In primary hyperparathyroidism (PHPT), asymptomatic bone disease can be detected by bone densitometry. The bone mineral density is about 10% lower than normal control values, especially in the cortical radius. Without parathyroidectomy, bone mineral density is frequently stable, but a few patients, mostly postmenopausal women, have a significant decrease. Histology shows maintenance of trabecular connectivity but with an increase in cortical porosity. After parathyroidectomy, bone mineral density increases, particularly at the lumbar spine and femoral neck, and the benefit persists after 10 years. The fracture risk is controversial but risk of trabecular bone fracture may be higher than that for controls. The impact of PHPT on survival is also controversial, but highest quartile of serum calcium, osteoporosis, old age, and low lean mass are each associated with a death risk. There is also a debate about the criteria for distinguishing between asymptomatic and symptomatic PHPT and about the bone mineral density threshold that should be used as a basis to recommend surgery. The rate of progression of PHPT is slow but in some cases bone loss progresses, justifying bone mineral density follow-up. The frequency of inadequate follow-up and the cost of nonoperative follow-up are in favor of recommending surgery. With broader indications for surgery, it is mandatory to improve the biochemical diagnosis of PHPT.

Diabetes mellitus with hyperparathyroidism: another indication for parathyroidectomy?

BACKGROUND

Patients with hyperparathyroidism have alterations in carbohydrate metabolism characterized by insulin resistance, hyperinsulinemia, and glucose intolerance. The clinical significance of these findings in the management of patients with diabetes mellitus (DM) after parathyroidectomy for hyperparathyroidism has been controversial.

METHODS

A retrospective review identified 87 patients with DM and hyperparathyroidism who underwent parathyroidectomy. The follow-up documentation of 70 patients who underwent diabetic management was then evaluated to assess the benefit of parathyroidectomy on glucose management.

RESULTS

Thirteen patients had type 1 DM, and 74 patients had type 2 DM. Primary hyperparathyroidism was present in 93% of patients with type 2 DM; 64% of patients with type 1 DM had secondary hyperparathyroidism. At follow-up, glucose control was stable in 40% of patients, had improved in 37% of patients, and had deteriorated in 23% of patients (P = .003). Improved glucose control was not dependent on age, duration of DM, duration of hyperparathyroidism, length of follow-up, or calcium levels. The patients with decreased requirements had a significantly lower parathyroid hormone level (P = .05). Improved glucose control was most significant in patients whose condition was managed with oral hypoglycemics (P = .05) or insulin (P = .03).

CONCLUSIONS

The clinical and laboratory investigations on the influence of hyperparathyroidism on DM support the benefit of parathyroidectomy in patients with DM. Patients with type 1 and type 2 DM show improvement in glucose control after parathyroidectomy. The presence of DM and hyperparathyroidism is an indication for parathyroidectomy because it results in either stabilization or improved glucose control in 77% of patients.