Reference intervals for serum concentrations of three bone turnover markers for men and women

OBJECTIVE

Bone turnover markers (BTMs) reflect the metabolic activity of bone tissue and can be used to monitor osteoporosis therapy. To adequately interpret BTMs, method-specific reference intervals are needed. We aimed to determine reference intervals for serum concentrations of intact amino-terminal propeptide of type I procollagen (PINP), bone-specific alkaline phosphatase (BAP) and carboxy-terminal telopeptide of type I collagen (CTX).

MATERIAL AND METHODS

We established a healthy reference population of 1107 men as well as 382 pre- and 450 postmenopausal women, who participated in the first follow-up of the Study of Health in Pomerania. Serum PINP, BAP and CTX concentrations were measured on the IDS-iSYS Automated System (Immunodiagnostic Systems, Frankfurt am Main, Germany). The reference interval was defined as the central 95% range. We determined age-specific reference intervals for PINP, BAP, and CTX for men by quantile regression. Reference intervals for women were age-independent.

RESULTS

Reference intervals for men for PINP and CTX decreased with age (25-29year-old men: PINP 31.1-95.9ng/mL, CTX 0.12-0.83ng/mL; 75-79year-old men: PINP 15.7-68.1ng/mL, CTX 0.05-0.58ng/mL). The reference interval for men for BAP did not significantly change with age (25-29year-old men: 7.4-27.7ng/mL; 75-79year-old men: 7.6-24.4ng/mL). The reference intervals for 30-54year-old premenopausal women were: PINP 19.3-76.3ng/mL, BAP 6.0-22.7ng/mL, and CTX 0.05-0.67ng/mL. The reference intervals for 50-79year-old postmenopausal women were: PINP 18.2-102.3ng/mL, BAP 8.1-31.6ng/mL, and CTX 0.09-1.05ng/mL.

CONCLUSION

An intensively characterized, large reference population free of bone-related diseases allowed us to determine robust reference intervals for serum concentrations of PINP, BAP and CTX. Our normative data may aid to interpret bone turnover in adult men and pre- and postmenopausal women.

Do current incretin mimetics exploit the full therapeutic potential inherent in GLP-1 receptor stimulation?

Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are incretin-derived glucose-lowering agents that have been used for the treatment of type 2 diabetes since 2007. Agents such as exenatide (short-acting and once weekly preparations), liraglutide, taspoglutide, albiglutide and lixisenatide lower fasting glucose and HbA1c upon subcutaneous injection, leading to glycaemic control that is equivalent to, or better than, that observed with other oral glucose-lowering agents or bedtime insulin. However, varying proportions of patients report nausea and vomiting, adverse events that typically narrow the therapeutic dose range. Furthermore, GLP-1 RAs reduce fasting glucose to a clinically meaningful extent, but not into the normal range. In contrast, where GLP-1 is administered as a short-term intravenous infusion, a full normalisation of glucose concentrations (approximately 5 mmol/l) has been observed without any risk of gastrointestinal side effects. Subcutaneous infusions or injections of GLP-1 are much less effective. The present analysis relates the proportion of patients who report nausea following treatment with GLP-1 and GLP-1 RAs to the clinical effectiveness of the treatment (represented by the fasting glucose concentration achieved with treatment). The results suggest that GLP-1 RAs injected into the subcutaneous compartment do not exploit the full potential inherent in GLP-1 receptor activation. Reasons for this may include modifications of the peptide molecules in the subcutaneous environment or high local concentrations triggering side effects through GLP-1 receptors on autonomic nerves in subcutaneous adipose tissue. Elucidation of the mechanisms underlying differential responses to GLP-1/GLP-1 RAs administered intravenously vs subcutaneously may help to develop improved agents or modes of administration that are more effective and have fewer side effects.

[Dapagliflozin versus glipizide as add-on therapy in patients with type 2 diabetes who have inadequate glycemic control with metformin]

OBJECTIVE

Although initially effective, sulfonylureas are associated with poor glycemic durability, weight gain, and hypoglycemia. Dapagliflozin, a selective inhibitor of sodium-glucose cotransporter 2 (SGLT2), reduces hyperglycemia by increasing urinary glucose excretion independent of insulin and may cause fewer of these adverse effects. We compared the efficacy, safety, and tolerability of dapagliflozin with the sulfonylurea glipizide in patients with type 2 diabetes inadequately controlled with metformin monotherapy.

RESEARCH DESIGN AND METHODS

This 52-week, double-blind, multicenter, active-controlled, noninferiority trial randomized patients with type 2 diabetes (baseline mean HbA1c, 7.7 %), who were receiving metformin monotherapy, to add-on dapagliflozin (n = 406) or glipizide (n = 408) up-titrated over 18 weeks, based on glycemic response and tolerability, to ≤ 10 or ≤ 20 mg/day, respectively.

RESULTS

The primary end point, adjusted mean HbA1c reduction with dapagliflozin (-0.52 %) compared with glipizide (-0.52 %), was statistically noninferior at 52 weeks. Key secondary end points: dapagliflozin produced significant adjusted mean weight loss (-3.2 kg) versus weight gain (1.2 kg; P < 0.0001) with glipizide, significantly increased the proportion of patients achieving ≥ 5 % body weight reduction (33.3 %) versus glipizide (2.5 %; p < 0.0001), and significantly decreased the proportion experiencing hypoglycemia (3.5 %) versus glipizide (40.8 %; p < 0.0001). Events suggestive of genital infections and lower urinary tract infections were reported more frequently with dapagliflozin compared with glipizide but responded to standard treatment and rarely led to study discontinuation.

CONCLUSIONS

Despite similar 52-week glycemic efficacy, dapagliflozin reduced weight and produced less hypoglycemia than glipizide in type 2 diabetes inadequately controlled with metformin. Long-term studies are required to further evaluate genital and urinary tract infections with SGLT2 inhibitors.

Long-term efficacy and safety comparison of liraglutide, glimepiride and placebo, all in combination with metformin in type 2 diabetes: 2-year results from the LEAD-2 study

AIMS

To investigate efficacy and safety of dual therapy with liraglutide and metformin in comparison to glimepiride and metformin, and metformin monotherapy over 2 years in patients with type 2 diabetes.

METHODS

In the 26-week the Liraglutide Effect and Action in Diabetes (LEAD)-2 core trial, patients (n = 1091) were randomized (2 : 2 : 2 : 1: 2) to liraglutide (0.6, 1.2 or 1.8 mg once-daily), placebo or glimepiride; all with metformin. Patients were enrolled if they were 18-80 years old with HbA1c 7.0-11.0% (previous monotherapy ≥3 months), or 7.0-10.0% (previous combination therapy ≥3 months), and body mass index ≤40 kg/m(2) . Patients completing the 26-week double-blinded phase could enter an 18-month open-label extension.

RESULTS

HbA1c decreased significantly with liraglutide (0.4% with 0.6 mg, 0.6% with 1.2 and 1.8 mg) versus 0.3% increase with metformin monotherapy (p < 0.0001). HbA1c decrease with liraglutide was non-inferior versus 0.5% decrease with glimepiride. Liraglutide groups experienced significant weight loss (2.1, 3.0 and 2.9 kg with 0.6, 1.2 and 1.8 mg, respectively) compared to weight gain (0.7 kg) with glimepiride (p < 0.0001). Weight loss with liraglutide 1.2 and 1.8 mg was significantly greater than with metformin monotherapy (1.8 kg; p = 0.0185 and p = 0.0378 for 1.2 and 1.8 mg, respectively). The occurrence of minor hypoglycaemia was <5.0% in all liraglutide groups, significantly less than with glimepiride (24.0%; p < 0.0001). Liraglutide was well tolerated overall: gastrointestinal events were more common than with glimepiride or metformin monotherapy, but occurrence decreased with time.

CONCLUSIONS

Liraglutide provided sustained glycaemic control over 2 years comparable to that provided by glimepiride. Liraglutide was well tolerated, and was associated with weight loss and a low rate of hypoglycaemia.

Osteocalcin is associated with testosterone in the general population and selected patients with bone disorders

Research in the last decade has revealed that bone is not only a target tissue for numerous circulating hormones but functions as an endocrine organ itself. As a recent study demonstrated a stimulatory effect of the osteoblast-derived hormone osteocalcin (OCN) on testosterone production in mice, we investigated whether such an association can be replicated in humans. We used data from 1338 men (25-86 years) in the population-based epidemiological Study of Health in Pomerania and from 110 male outpatients with bone disorders (18-85 years) for the study. We analysed cross-sectional associations between OCN and total testosterone serum concentrations (TT), as well as associations between further markers of bone turnover [bone-specific alkaline phosphatase (BAP), serum C-terminal telopeptides of Type I collagen (CTX), urinary deoxypyridinoline] and TT using ordinary least square (OLS) regression models. Multivariable OLS models revealed a positive association between OCN and TT in the population-based (β coefficients for a one standard deviation increase, 0.590; standard error (SE), 0.175; p-value, <0.01) and patient-based (β coefficient, 0.575; SE, 0.132; p-value, <0.01) samples even after adjustment for age and body mass index (both samples), and time of blood sampling (population-based sample only). Furthermore, we observed positive associations between BAP and TT (β coefficient, 0.403; SE, 0.170; p-value, 0.02) as well as between CTX and TT (β coefficient, 0.733; SE, 0.172; p-value, <0.01) in men from the general population. The present investigation shows that OCN is associated with TT in the general population and in patients with bone disorders, and may thus indicate general male health status. Additional longitudinal observational studies are warranted to confirm our findings and future experimental research is necessary to elucidate potential mechanisms underlying the observed associations.

Direct effect of GLP-1 infusion on endogenous glucose production in humans

AIMS/HYPOTHESIS

Glucagon-like peptide-1 (GLP-1) lowers glucose levels by potentiating glucose-induced insulin secretion and inhibiting glucagon release. The question of whether GLP-1 exerts direct effects on the liver, independently of the hormonal changes, is controversial. We tested whether an exogenous GLP-1 infusion, designed to achieve physiological postprandial levels, directly affects endogenous glucose production (EGP) under conditions mimicking the fasting state in diabetes.

METHODS

In 14 healthy volunteers, we applied the pancreatic clamp technique, whereby plasma insulin and glucagon levels are clamped using somatostatin and hormone replacement. The clamp was applied in paired, 4 h experiments, during which saline (control) or GLP-1(7-37)amide (0.4 pmol min⁻¹ kg⁻¹) was infused.

RESULTS

During the control study, plasma insulin and glucagon were maintained at basal levels and plasma C-peptide was suppressed, such that plasma glucose rose to a plateau of ~10.5 mmol/l and tracer-determined EGP increased by ~60%. During GLP-1 infusion at matched plasma glucose levels, the rise of EGP from baseline was fully prevented. Lipolysis (as indexed by NEFA concentrations and tracer-determined glycerol rate of appearance) and substrate utilisation (by indirect calorimetry) were similar between control and GLP-1 infusion.

CONCLUSIONS/INTERPRETATION

GLP-1 inhibits EGP under conditions where plasma insulin and glucagon are not allowed to change and glucose concentrations are matched, indicating either a direct effect on hepatocytes or neurally mediated inhibition.

Using BD Laboratory Consulting Services™ to understand the impact of the preanalytical phase on sample quality and safety, a multi country perspective

Background

The complexity of the preanalytical (PA) phase has precluded standardisation of PA processes, despite its impact on sample quality, laboratory efficiency, or patient & healthcare worker safety. The BD Laboratory Consulting Services™ Preanalytical Review audits PA procedures and practices in hospitals in different countries. Processes were assessed from storage of blood collection materials through specimen collection, transportation, processing of the samples and the resulting sample quality. By following the samples through the complete process, it was possible to link specific PA attributes to sample quality deficiencies.

Materials and methods:

A consistent method and data collection form were used for audits (N = 48) of all blood collection systems. Data were collected by observation of the PA phase. Sample quality was assessed for laboratory samples of the same type.

Results:

The PA phase was observed for 3597 blood collection tubes over 1350 collections. Sample quality was assessed for 8016 chemistry and 3532 coagulation tubes. For collections that resulted in hemolysed samples, 48% had prolonged use of tourniquet, 31% used catheters and for 38% the disinfectant was not allowed to dry. For serum samples with fibrin where the PA process had been observed, 26% had less than 30 minutes between collection and centrifugation and 81% had not been mixed. The following list gives the percentage of collections where a particular behaviour was observed, incorrect patient identification procedure, 56%; tubes labelled prior to collection 61%; coagulation tubes filled to less than 90% of tube volume 7%; gloves not worn 37%; incorrect activation of needle safety device 19%.

Conclusions:

The BD Preanalytical Review standardised audit methodology allows comparison of results between departments and institutions. The prospective nature of the reviews permits identification of issues based on more data than from rejected samples alone and therefore affords a more complete understanding for those involved in the PA phase.

Taspoglutide, a once-weekly glucagon-like peptide 1 analogue, vs. insulin glargine titrated to target in patients with Type 2 diabetes: an open-label randomized trial

AIMS

To compare the efficacy and safety of once-weekly taspoglutide with insulin glargine in patients with advanced Type 2 diabetes failing metformin and sulphonylurea combination therapy.

METHODS

This open-label, parallel-group, multi-centre trial randomized 1049 patients continuing metformin 1:1:1 to taspoglutide 10 mg once weekly, taspoglutide 20 mg once weekly or insulin glargine once daily with forced titration to fasting plasma glucose ≤ 6.1 mmol/l. Sulphonylureas were discontinued before randomization. The primary endpoint was change in HbA(1c) after 24 weeks.

RESULTS

After 24 weeks, least-square mean changes from baseline in HbA(1c) in patients receiving taspoglutide 10 mg [-8 mmol/mol (se 1)] [-0.77% (se 0.05)] or taspoglutide 20 mg [-11 mmol/mol (se 1)] [-0.98% (se 0.05)] were non-inferior to insulin glargine [-9 mmol/mol (se 1)] [-0.84% (se 0.05)]; treatment difference of 0.07% (95% CI -0.06 to 0.21) and -0.14% (95% CI -0.28 to -0.01), for taspoglutide 10 and 20 mg, respectively, vs. insulin glargine. Taspoglutide was associated with more adverse events (mainly gastrointestinal) and significantly less hypoglycaemia than insulin glargine.

CONCLUSIONS

Compared with insulin glargine, taspoglutide provided non-inferior HbA(1c) reductions associated with less hypoglycaemia, but more gastrointestinal adverse events.

Initial white blood cell count is an independent risk factor for survival in patients with dilated cardiomyopathy

BACKGROUND

The impact of white blood cell count (WBCc) on the outcome of patients with non-ischemic left ventricular (LV) dysfunction is unknown. In the present study we investigated the influence of WBCc on mortality and cardiac inflammation in patients with reduced LV systolic function in the absence of ischemic or valvular etiology.

METHODS AND RESULTS

We included 381 patients with reduced left ventricular (LV) ejection fraction (LVEF ≤ 45%) quantified by two-dimensional echocardiography. Coronary artery disease and valvular diseases were excluded by angiography and echo, respectively, in all patients. WBCc was quantified routinely upon first hospital admission. In 291 patients, endomyocardial biopsies from the right ventricle were performed upon first hospital admission for assessment of cardiac inflammation. Follow-up was up to 5.5 years (median 2.93 [1.7;4.0]). Information on vital status of patients was obtained from official resident data files. WBCc >11 Gpt/l was associated with significantly increased mortality in patients with severe LV dilation (end-diastolic diameter (LVEDD) >70 mm quantified by echocardiography) in comparison to patients showing WBCc ≤ 11 Gpt/l (41.7% vs 13.6%, p=0.02). Multivariable Cox regression analysis showed that WBCc predicts mortality independently of other cardiovascular risk factors and LVEF (hazard ratio 1.14; p=0.04). Doses of heart failure medication did not differ significantly in patients with LVEDD >70 mm and WBCc >11 Gpt/l when compared to LVEDD >70 mm and WBCc ≤ 11 Gpt/l (percent of maximum doses: ß-blockers p=0.51, ACE inhibitors p=0.56, AT1 antagonists p=0.77, aldosterone antagonists p=0.35). WBCc including its subpopulations (monocytes, lymphocytes and granulocytes) did not show a significant correlation with cardiac amounts of CD3(+)-lymphocytes (r=0.02, p=0.78) or CD68(+)-macrophages (r=1.0, p=0.09) (n=291).

CONCLUSION

WBCc at first hospital admission predicts long term-mortality in patients with dilated cardiomyopathy independently of cardiovascular risk factors.