Background: Several studies have consistently shown that soluble CD40 ligand (sCD40L) concentrations are increased in patients with acute coronary syndromes and can serve as a biomarker for risk stratification. However, few data are available on preanalytic conditions that impact sCD40L values. Thus, the aim of our prospective study was to evaluate the impact of sampling techniques and storage conditions on sCD40L concentrations. Methods: We included a total of 30 patients with no, stable, or unstable coronary heart disease. Blood samples were collected in gel-filled tubes without additives, in EDTA-filled tubes, and in citrate-filled tubes and were kept at various storage conditions. Results: Median (interquartile range) sCD40L values at baseline were higher in serum samples [5.29 (3.89–6.33) μg/L] than in either EDTA plasma [0.78 (0.39–1.12) μg/L; P <0.001] or citrate plasma [0.37 (0.22–0.51) μg/L; P <0.001]. Serum values increased with delayed processing [7.94 (5.97–9.62) μg/L after 1.5 h (P <0.001) vs baseline; 10.55 (7.58–11.55) μg/L after 3 h (P <0.001) vs baseline]. However, after centrifugation, sCD40L values remained stable for all 3 sample types. Conclusion: Plasma, but not serum, samples are appropriate for sCD40L measurements. In general, preanalytic conditions are critical in the assessment of sCD40L concentrations and thus should be carefully considered for future studies.

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The aim of this study was to evaluate thyroid peroxidase (TPO) mRNA expression in peripheral blood of patients with benign and malignant thyroid disease. Included were 120 thyroid cancer patients, 85 patients with goitre or Graves' disease (GD) and 54 healthy volunteers. TPO mRNA expression was analysed in peripheral blood by nested RT-PCR. In cancer patients, RT-PCR results were compared with staging, grading and serum thyroglobulin (TG) measurement. TPO transcripts were detected in 7/10 (70%) patients with known metastases of thyroid cancer and in 39 of 110 (36%) patients without metastases (P<0·05), in 15/44 (34%) patients with goitre, in 17/41 (41%) cases with GD and in 4/54 (7·4%) subjects in the control group (P<0·05, controls vs all patients with thyroid disease). Among cancer patients without metastatic disease, RT-PCR results correlated positively with lymph node status (P=0·05), grading (P=0·01) and elevated serum thyroglobulin levels (P=0·03). This is the largest study investigating the use of the TPO-RT-PCR assay. Positivity in TPO-RT-PCR correlates significantly with metastatic disease in cancer patients and with the presence of thyroid disease in general. To date, TPO-RT-PCR cannot substitute for standard techniques in the diagnosis of local recurrence or metastatic spread in thyroid cancer patients. However, as results of TPO-RT-PCR correlate significantly with lymph node status, grading and serum TG measurements in patients with non-metastatic disease, TPO seems to be an interesting molecular marker to look at in follow-up studies.

SummaryThe sensitive detection of circulating tumour cells in patients with differentiated thyroid cancer may precede the detection of relapse by other diagnostic studies -such as serum thyroglobulin -and thus may have important therapeutic and prognostic implications. We performed reverse transcription-polymerase chain reaction (RT-PCR) on blood samples from patients diagnosed with thyroid disease using two different RT-PCR sensitivities. Additionally, tissue specificity of TG mRNA-expression was determined using RNA extracts from 27 different human tissues. The lower limit of detection was 50-100 TG mRNA producing cells/ml blood using a 'normal' RT-PCR sensitivity and 10-20 cells/ml blood using a 'high' sensitivity. With the normal sensitivity TG mRNA was detected in 9/13 patients with thyroid cancer and metastasis, 63/137 patients with a history of thyroid cancer and no metastasis, 21/85 with non-malignant thyroid disease and 9/50 controls. With the high sensitivity TG mRNA was detected in 11/13 patients with thyroid cancer and metastasis, 111/137 patients with a history of thyroid cancer and no metastasis, 61/85 with non-malignant thyroid disease and 41/50 controls. Interestingly, using the normal RT-PCR sensitivity TG mRNA transcripts are specific for thyroid tissue and detectable in the peripheral blood of controls and patients with thyroid disease, which correlates with a diagnosis of metastasized thyroid cancer. However, with a high RT-PCR sensitivity, TG mRNA expression was found not to be specific for thyroid tissue and was not correlated with a diagnosis of thyroid cancer in patients. As a consequence, to date TG mRNA detected by RT-PCR in the peripheral blood cannot be recommended as a tumour marker superior to TG serum-level.