How do laboratory specialists advise clinicians concerning the use and interpretation of renal tests?

BACKGROUND: The aim of this study was to elucidate how laboratory specialists advise clinicians concerning renal parameters and to compare their advice with guideline recommendations. METHODS: A questionnaire was distributed to laboratory specialists in Norway and The Netherlands together with two case histories from a primary health-care setting and one from a hospital setting, simulating questions from clinicians. The investigations that laboratory specialists suggested were compared to a test panel that was predefined based on clinical practice guideline recommendations (the 'recommended test panel'). The critical differences between two test results (creatinine, estimated glomerular filtration rate [eGFR] and albumin/creatinine ratio [ACR]) and the anticipated precision of the MDRD equation were evaluated. RESULTS: Fifty-two of the 100 laboratory specialists responded, and most of these were regularly contacted by clinicians to discuss laboratory results. Less than 30% would suggest using the recommended test panel to evaluate renal function in the two primary-care patients. For creatinine and eGFR, median changes stated to signal improvement or deterioration in renal function (creatinine: -14% and +14%, respectively; eGFR: +18% and -13%, respectively) were similar to what could be calculated using information on analytical and within-subject variation from the literature. There were variable critical differences for the ACR results (median values of -50% for improvement and +67% for deterioration). Only 23% of the participants would recommend a gold standard clearance examination for a patient who was to undergo nephrotoxic chemotherapy. CONCLUSION: Questions from GPs about renal parameters are answered differently by laboratory specialists, and adherences to guideline recommendations are low on some issues.