Hans-Gerhard Schneider

Procalcitonin for the clinical laboratory: a review

&NA; Procalcitonin measurement has been claimed as a helpful marker in bacterial infection and sepsis. It has obtained FDA approval and is now widely marketed in the United States and Europe. This review summarises the current assays available, the evidence for its use and possible future applications of the assay.

Age-related reference intervals for bone turnover markers from an Australian reference population

BACKGROUND This study was performed to establish age-related serum reference intervals for procollagen type I N-propeptide (P1NP) and type I collagen C-telopeptide (CTx) in the Australian population. METHODS Fasting sera from 1143 males (mean age 60 years; range 20-97 years) and 1246 females (mean age 53 years; range 20-93 years) who participated in the Geelong Osteoporosis Study were analysed for CTx and P1NP using the automated Roche Modular Analytics E170 analyser. RESULTS Optimal age-related reference intervals were based on the central 90% of the distribution. The male CTx reference interval was divided into three age groups. For men aged 25 to 40 years, the interval was 170-600 ng/L; 40 to 60 years, the interval was 130-600 ng/L; and for men aged greater 60 years the interval was 100-600 ng/L. For P1NP the male reference interval was 15-80 μg/L for men aged between 25 to 70 years. In men greater than 70 years of age values were higher possibly due to increased bone turnover. High values are frequently seen for both CTx and P1NP in males aged younger than 25 years. This is probably due to bone growth that is not completely finalised. The female CTx reference interval was divided into four age groups. For women aged less than 30 years, the interval was 150-800 ng/L; 30-39 years, the interval was 100-700 ng/L; 40-49 years, the interval was 100-600 ng/L; and for women aged 50 years or more the interval was 100-700 ng/L. The female P1NP reference interval was divided into four age groups. For women aged less than 30 years, the interval was 25-90 μg/L; 30-39 years, the interval was 15-80 μg/L; 40-49 years, the interval was 15-60 μg/L; and for women aged 50-69 years the interval was 15-75 μg/L. In women greater than 70 years of age values were higher possibly due to increased bone turnover. CONCLUSION Values obtained from this large study provide sound age-related reference intervals for serum P1NP and CTx values in the Australian population.

Serum selenium status in Graves’ disease with and without orbitopathy: a case–control study

Selenium is effective in improving quality of life and reducing the progression of active Graves’ orbitopathy. The effect of correcting relative selenium deficiency on improving Graves’ orbitopathy is unknown, as baseline selenium levels have not previously been measured. The study aims to determine whether serum selenium levels are reduced in patients with Graves’ disease with orbitopathy (GO) compared with without orbitopathy (GD).

Overreporting of vitamin D deficiency with the Roche Elecsys Vitamin D3 (25-OH) method

Background: Vitamin D deficiency is common. Recently Roche Diagnostics removed their Elecsys Vitamin D3 (25OH) electrochemiluminescence immunoassay (ECLIA) from use, citing deteriorating traceability to the reference method (liquid chromatography tandem mass spectrometry; LCMSMS). We investigated the performance of the Roche assay (2 assay formulations) against an LCMSMS method and the widely used DiaSorin radioimmunoassay (RIA) method. Methods: Two sets of samples from separate populations were assayed for vitamin D. The first set was assayed using three different methods: RIA (DiaSorin) in 2004, polyclonal ECLIA (Roche) in early 2009 and LCMSMS in early 2010. The second set was assayed using polyclonal and monoclonal ECLIA (Roche) and LCMSMS in mid-2010. Results: The correlation of the polyclonal ECLIA with the RIA was poor (ECLIA = 0.45 × RIA + 19, r2 = 0.59, n = 773). LCMSMS results correlated with RIA (RIA = 0.86 × LCMSMS + 4, r2 = 0.69, n = 49) better than with polyclonal ECLIA (polyclonal ECLIA = 0.55 × LCMSMS + 6, r2 = 0.62, n = 55) despite a storage interval of 6 years. In recently collected samples monoclonal and polyclonal immunoassays gave similar results (monoclonal ECLIA = 0.93 polyclonal ECLIA −3, r2 = 0.60, n = 153). The correlation between monoclonal Roche ECLIA and LCMSMS in these samples was very poor (monoclonal ECLIA = 0.31 × LCMSMS + 23, r2 = 0.27). Conclusions: At the time of its removal from the market, the Roche Elecsys Vitamin D3 (25OH) assay showed unacceptable performance, underestimating vitamin D levels. It seems that this bias preceded the introduction of the monoclonal assay. The worldwide distribution of the assay and the duration of this bias likely led to a significant number of patients starting supplementation unnecessarily.

Towards optimising the provision of laboratory services for bone turnover markers

Summary Bone turnover markers (BTMs) are either secreted by osteoblasts during bone formation or released by degradation of the collagen matrix of bone during bone resorption, and may be measured in blood or urine to provide an estimate of the rate of bone remodelling. Increased bone remodelling rate is often associated with bone loss which can result in osteoporosis; however, lack of data preclude the inclusion of BTMs in fracture risk algorithms. The changes in BTMs following therapy for osteoporosis may be useful for monitoring. Serum procollagen type I amino-terminal propeptide (s-PINP) and serum carboxy-terminal cross-linking telopeptide of type I collagen (s-&bgr;CTX) have been designated as reference standard markers of bone formation and resorption respectively in osteoporosis; further research is needed for their routine use in osteoporosis. BTMs are useful in diagnosing and monitoring Pagets disease of bone and other bone diseases associated with abnormal bone formation and/or resorption. Standardised patient preparation is required to mitigate the effect of biological variation, and appropriate sample handling and storage are important to minimise sample degradation. Significant inter-method differences exist for BTMs, and harmonisation of methods for the reference BTMs is being pursued. This will help develop universally accepted decision limits and treatment goals. Australian consensus reference intervals have been developed for some methods for s-PINP and s-&bgr;CTX.

The Incidence and Significance of Raised Troponin Levels in Acute Burns

The place and significance of troponin testing in acute burn injuries has not yet been established. The aims of this study were to determine the incidence and pattern of troponin testing within a large population of acute burn injuries and subsequently to determine the resultant clinical significance of the troponin test results. A retrospective analysis of all patients with acute burn admissions (n = 1,621 patients) to a busy tertiary adult burns center between July 2009 and July 2015. More than a third of our patients had at least one troponin test performed. Men, the elderly, and those with larger burns were more likely to be tested. The majority tested had the laboratory test done within 24 hours of admission. A positive troponin test strongly correlated with increased risk of acute cardiac complication and death, as did burns greater than 15% total body surface area (%TBSA) and age. Acute burns of ≥15% TBSA are associated with elevated troponin levels. Troponins should be tested in those ≥50 years old, with significant burns, and/or premorbid cardiac disease; positive results investigated as they affect cardiac and survival outcomes.

High-sensitivity C-reactive protein test results predict fracture risk in elderly women

A group of mice were treated with either 33 mg/kg or 100 mg/kg imatinib (which produced blood levels similar to a mid-range dose in humans), administered 1 day before CIA induction. A further group of mice were treated with either 33 mg/kg or 100 mg/kg imatinib after established CIA had developed. Imatinib was an effective treatment for both established and new-onset CIA: in both experiments, imatinib-treated mice experienced lesssevere CIA symptoms and also showed fewer histologically visible signs of inflammation and tissue destruction than control mice (which did not receive imatinib). In vitro studies in human and murine cell lines demonstrated that imatinib selectively inhibited multiple signal-transduction pathways that are known to be important in the pathogenesis of RA. In particular, imatinib inhibited plateletderived growth factor signaling in fibroblast-like synoviocytes from RA patients, and inhibited production of proinflammatory cytokines by several cell types. Imatinib also reduced B-cell proliferative responses to lipopolysacchide. The authors conclude that imatinib might be a useful treatment for the autoimmune or inflammatory diseases characterized by fibroproliferation, and suggest prospective clinical trials to determine whether the results found in the CIA model are applicable to human RA.

The association of high sensitivity C-reactive protein levels with fracture risk in postmenopausal women: Geelong osteoporosis study

We have previously demonstrated that maternal body build and lifestyle factors predict neonatal bone mineral accrual. However, the paternal determinants of neonatal bone mass remain little known. In this study we explored the relationship between a father’s bone mass and that of his offspring. 280 pregnancies were recruited from the Southampton Women’s Survey, a unique, well established cohort of women, aged 20-34 years, who had been assessed before and during early and late pregnancy. The neonates underwent whole body DXA within 20 days of birth; at this time the fathers were invited to undergo a whole body DXA scan using an Hologic Discovery instrument. Multivariate regression methods were used to explore the parental determinants of neonatal bone mass. Full ethical approval was given for this study. After adjustment for the father’s age, and the baby’s gestational age, sex and age at DXA scan, there were highly significant positive associations between baby’s whole body bone area (BA), bone mineral content (BMC), and bone mineral density (BMD), and the corresponding indices in the father (p=0.009, 0.001, 0.03 respectivelytable 1). When mother’s height, body composition (fat mass estimated from skin folds), smoking, and calcium intake were included in multivariate regression models of father’s DXA indices, the associations for paternal variables remained statistically significant (BA: p=0.02, BMC: p=0.002, BMD: p=0.04). Thus father’s skeletal size predicts skeletal size in the offspring, independently of the mother’s body build and lifestyle. These data point to the importance of considering paternal genotype in studies exploring the developmental origins of adult osteoporotic fracture. Table 1Reduced bone mass and increased risk of fracture are common among patients with inflammatory diseases. Furthermore, mediators of inflammation like IL-6 or TNFa have been shown to stimulate bone resorption. Systemic inflammation may be implicated in the pathophysiology of osteoporosis. We therefore tested the association between serum high sensitivity C-reactive protein (hsCRP) levels and risk of fracture in 744 postmenopausal women randomly-selected from the community and enrolled in the Geelong Osteoporosis Study, 1994-7. Baseline hsCRP levels were measured using a high-sensitivity immunoturbimetrical assay; BMD was also measured at baseline. Fractures were identified from radiological reports. Subjects were followed longitudinally until the end of 2002, or until sustaining a fracture, death, or migration from the study region. Multivariable Cox proportional hazards regression was used to determine the association between hsCRP and fracture. 126 fractures were sustained during 4013 person-years of follow-up. Median hsCRP concentration was 2.5 mg/L (IQR 1.3-4.9). After adjusting for potential confounders, women with hsCRP in the highest quartile (>4.9 mg/L) had a 1.6-fold (95%CI 1.1-2.4) greater risk of fracture than the lower quartiles pooled, independent of BMD. Both increased hsCRP and increased bone deficits contributed to increased fracture risk. Using hsCRP quartiles 1-3 and normal hip BMD (T-score>-1.0) as the referent group, women in the highest hsCRP quartile and with low BMD (T-score<-2.5) had the highest adjusted fracture risk (RR=9.1; 95%CI 3.6-23). Elevating hsCRP from quartiles 1-3 into the highest quartile was equivalent to increasing the fracture risk normally associated with osteopenia to that of osteoporosis. A similar pattern was observed for BMD measured at the spine. Circulating hsCRP is an independent predictor of fracture risk in postmenopausal women. These results may implicate systemic inflammation as a factor in the pathophysiology of osteoporosis. hsCRP may be a useful assay to predict fracture risk in conjunction with BMD.