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In 2003, The National Academy of Clinical Biochemistry published a consensus monograph on thyroid tests (available via Internet from 2002). The document, a result of international collaboration, describes the pathophysiological background and clinical application of the measurements as well as principles for their technical performance. Of value, and of definite clinical relevance, is the detailed description of factors affecting the results in health and disease. However, we lack a description of the sometimes large differences in values obtained with different generally available methods, as well as a presentation of the occurrence and evaluation of analytical interference and related technical factors affecting results. Readers with little experience from quantitative measurement in the clinical laboratory, therefore, are not stimulated to obtain a better understanding of causes and evaluation of unexpected results.

Patients with unstable coronary artery disease have a serious but variable prognosis. An early and specific prediction of risk is essential for stratification of treatment. Serum was obtained at a median of 9.5 hours from symptom onset in 7800 patients with unstable coronary artery disease included in the GUSTO-IV trial for analyses of creatinine, troponin-T, C-reactive protein (CRP) and N-terminal pro brain natriuretic peptide (NT-proBNP). Quartiles of troponin-T were related to an increased mortality and to an increased incidence of myocardial infarction. Increasing quartiles of C-reactive protein were also related to an increased mortality but there was no relation to the incidence of myocardial infarction. On multivariate analysis, troponin-T was the strongest marker for prediction of myocardial infarction, but reduced creatinine clearance and ST-depression at admission were also significant predictors. Prediction of subsequent mortality was possible with several risk indicators. Elevation of NT-proBNP was the strongest predictor of short and long-term mortality with a continuous increase in one-year mortality in relation to the levels. Also reduced creatinine clearance, elevation of CRP, troponin-T, ST-depression and clinical factors indicating a history of cardiovascular disease provided independent prognostic information on long-term mortality. A multimarker strategy with creatinine clearance, troponin, CRP and NT-proBNP together with ischemic ECG changes and clinical background characteristics provides the best prognostic information for choice of treatment in patients with unstable coronary artery disease.

The heart is increasingly being recognised as a major endocrine organ involved in haemodynamic homeostasis. Natriuretic peptides, i.e. atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), affect renal, adrenal and central nervous system functions as well as vessel tonus and permeability thus causing decreased preload and afterload. Natriuretic peptides, BNP in particular, are independent risk factors for morbidity and mortality. They also have high negative predictive values for cardiac insufficiency indicating high diagnostic sensitivity for heart failure in outpatient practice. Monitoring of therapy for heart failure may be improved if BNP measurement is used in conjunction with clinical assessment. However, several problems remain to be solved, such as optimal decision limits in relation to sex and age for the assessment of heart failure.