Growth differentiation factor-15 (GDF-15), a stress responsive cytokine, is a promising biomarker of renal functional decline in diabetic kidney disease (DKD). This study aimed primarily to establish ...normative data and secondarily to evaluate the potential utility of GDF-15 in DKD using Roche Diagnostics electrochemiluminescence immunoassay (ECLIA) in an Irish Caucasian population.
Following informed consent, 188 healthy volunteers and 128 participants with diabetes (72 with and 56 without DKD) were recruited to a cross-sectional study. Baseline demographics, anthropometric measurements and laboratory measurements were recorded. Blood for GDF-15 measurement was collected into plain specimen tubes kept at room temperature and processed (centrifugation, separation of serum, freezing at -80 °C) within 1 h of phlebotomy pending batch analyses. Reference intervals were determined using the 2.5th and 97.5th percentiles for serum GDF-15 concentration.
Of 188 healthy participants, 63 failed to meet study inclusion criteria. The reference interval for serum GDF-15 was 399 ng/L (90% confidence interval CI: 399-399) - 1335 ng/L (90% CI: 1152-1445). Receiver operator characteristics (ROC) curve analysis for DKD determined the area under the ROC curve to be 0.931 (95% CI: 0.893-0.959; p<0.001). The optimum GDF-15 cutoff for predicting DKD was >1136 ng/L providing a diagnostic sensitivity and specificity of 94.4% and 79%, respectively, and positive likelihood ratio of 4.5:1 (95% CI: 3.4-6.0).
The reference interval for serum GDF-15 in a healthy Irish Caucasian population using Roche Diagnostics ECLIA was established and a preliminary determination of the potential of GDF-15 as a screening test for DKD was made. Further prospective validation with a larger DKD cohort will be required before the cutoff presented here is recommended for clinical use.
Adopting the WHO protocol for glucose analysis is arguably impractical in the routine clinical setting. Deviations may develop due to a lack of understanding regarding the impact of glycolysis on the ...accuracy of results.
We sought to assess the stability of glucose in two different blood collection tubes (BCT), BD Vacutainer® FX 'Fl-Ox' and Greiner Vacuette® FC-Mix 'FC-Mix' stored at room temperature (RT:18-22°C) and 4°C over 8.5 days.
Each participant provided venous whole blood collected into 51 BCTs; 'Fl-Ox' (n = 26) and 'FC-Mix' (n = 25). One Fl-Ox sample from each participant was handled according to the WHO recommended method. The remaining BCTs were stored at 4°C/RT prior to analyses at designated study timepoints. Glucose was measured using the hexokinase assay on the Cobas® 8000 platform.
Participants (n = 8, Male = 2) were aged 24-56 years. Plasma glucose measured in FI-Ox BCTs according to the WHO sample-handling method had a median concentration of 5.73 mmol/L (Range: 5.39-10.37 mmol/L). Glucose decreased by greater than minimal difference (>0.26 mmol/L) in blood collected into Fl-Ox and stored @4°C/RT within 24 h of phlebotomy. FC-Mix BCT maintained glucose <0.26 mmol/L @4°C over a period of 8.5 days and up to 4 days @RT when compared to the WHO recommended method.
Glucose in FC-Mix BCT stored @4°C demonstrated the best agreement with results determined using the WHO specifications. When FC-Mix tubes were stored @RT, glucose was stable for 4 days. These findings suggest that the FC-Mix BCT effectively inhibits glycolysis and should be introduced into routine clinical practice.
Introduction
In laboratory medicine, reference intervals (RIs) are key decision support tools used to guide the clinical interpretation of numerical test results. Best practice suggests each ...laboratory establishes RIs in the local population prior to introducing an assay into routine clinical practice.
Aim
The aim of this study was to define RIs for frequently requested biochemical/haematological parameters in a healthy adult Irish Caucasian population.
Methods
A cross-sectional study of non-pregnant apparently healthy volunteers was conducted. Baseline demographics, anthropometric and laboratory measurements were recorded. In total, 37 commonly requested biochemical (serum,
n
= 26) and haematological (venous blood,
n
= 11) ISO15189:2012 accredited tests were analysed, using the Roche Cobas® Sebia Capillarys 3 Tera and Siemens Advia® 2120i platforms following standard operating procedures. RIs were defined according to the International Federation of Clinical Chemistry (IFCC) recommended method.
Results
Of 208 apparently healthy volunteers, 76 failed to meet the study inclusion criteria. The reference population comprised of 132 participants (males:
n
= 65, 49.2%) with a median age of 29.7 (18.1–62.2) years. RIs for the majority of biochemical/haematological parameters were broadly in accord with those provided by Pathology Harmony (UK)/Irish RI Harmonisation Project and the manufacturer Roche Diagnostics. However, the established RI defined for HbA
1c
: 27–37 mmol/mol was markedly different from that quoted nationally, HbA
1c
: 20–42 mmol/mol.
Conclusion
Normative biological intervals established in a healthy adult Irish population for 37 commonly requested biochemical/haematological parameters will be a valuable aid to result interpretation in clinical laboratories after appropriate verification in accordance with ISO 15189: 2012.
