The laboratory investigation of pleural fluids: An update based on the available evidence

Selecting appropriate laboratory tests based on available evidence is central to improve clinical effectiveness and impacting on patient outcome. Although long studied, there is no mutual agreement upon pleural fluid (PF) management in the laboratory context. Given the experienced confusion about the real contribution of laboratory investigations to guide clinical interpretation, in this update, we tried to identify useful tests for the PF analysis, aiming to unravel critical points and to define a common line in requesting modalities and practical management. We performed a careful literature review and a deepened study on available guidelines to finalize an evidence-based test selection, intended for clinicians' use to streamline PF management. The following tests depicted the basic PF profile routinely needed: (1) abbreviated Light's criteria (PF/serum total protein ratio and PF/serum lactate dehydrogenase ratio) and (2) cell count with differential analysis of haematological cells. This profile fulfils the primary goal to determine the PF nature and discriminate between exudative and transudative effusions. In specific circumstances, clinicians may consider additional tests as follows: the albumin serum to PF gradient, which reduces exudate misclassification rate by Light's criteria in patients with cardiac failure assuming diuretics; PF triglycerides, in differentiating chylothorax from pseudochylothorax; PF glucose, for identification of parapneumonic effusions and other causes of effusion, such as rheumatoid arthritis and malignancy; PF pH, in suspected infectious pleuritis and to give indications for pleural drainage; and PF adenosine deaminase, for a rapid detection of tuberculous effusion.

Urgent Thyroid-Stimulating Hormone Testing in Emergency Medicine: A Useful Tool?

BACKGROUND

Thyroid-stimulating hormone (TSH) has recently been introduced among the tests available to the Emergency Department (ED) of our hospital.

OBJECTIVE

To evaluate the prevalence of TSH-level-dependent thyroid dysfunction and to assess the usefulness of urgent TSH testing in a series of emergency patients.

METHODS

We planned a single-center observational cross-sectional clinical study. We divided patients in groups according to their thyroid status using defined TSH decision levels. Previously diagnosed history of thyroid dysfunction and newly diagnosed thyroid dysfunctions were differentiated. Further, we analyzed the subset of emergency patients affected by atrial fibrillation (AF) due to the role of hyperthyroidism in AF pathogenesis. For each TSH request, we made a retrospective chart review to assess the usefulness of the test based on clinical efficacy and management efficiency indicators.

RESULTS

The present study showed that, although the overall thyroid dysfunction rate was higher than in the general population, only a few newly diagnosed thyroid dysfunctions were found with limited clinical utility. We categorized urgent TSH requests as useful and not useful, by retrospective evaluation, and we identified and compared the main TSH testing clinical indications in the two groups.

CONCLUSION

We found a positive impact of urgent TSH determination in emergency decision-making. Nevertheless, a stronger clinical impact could be achieved by improving request appropriateness and by targeting TSH testing to some clinical indications identified by the study. The work was considered a quality-improvement project by the Hospital Committee for Quality Management.