Pleural fluid lactate as a point-of-care adjunct diagnostic aid to distinguish tuberculous and complicated parapneumonic pleural effusions during initial thoracentesis: Potential use in a tuberculosis endemic setting.

BACKGROUND: Tuberculous pleural effusions (TBEs) and parapneumonic pleural effusion (PPEs) have similar clinical presentations and fluid biochemistry. A pleural biopsy is usually required to diagnose TBE but complete fluid evacuation may not be necessary, contrasting with complicated PPE (CPPE). A point-of-care test that distinguishes between TBE and CPPE enables the appropriate procedures to be performed during the initial diagnostic thoracentesis. Lactate is a metabolic product measurable by a blood-gas analyzer. This study measured pleural fluid (Pf) lactate levels in TBE and compared them with those in PPE/CPPE. We hypothesized that Pf lactate would be significantly higher in PPE because of active metabolic activities than in TBE which is driven by delayed hypersensitivity. METHODS: All patients undergoing an initial diagnostic thoracentesis over 18 months with Pf lactate measured using a calibrated point-of-care blood gas analyzer were assessed. RESULTS: The diagnoses of the enrolled patients (n = 170) included TBE (n = 49), PPE (n = 47), malignancy (n = 63), and transudate (n = 11). Pf lactate level in TBE, median 3.70 (inter-quartile range 2.65-4.90) mmol/l, was significantly lower than in PPE and CPPE. In the subgroup of TBE and CPPE patients whose initial Pf pH and glucose could suggest either condition, Pf lactate was significantly higher in those with CPPE. Pf lactate (cutoff ≥7.25 mmol/l) had a sensitivity of 79.3%, specificity 100%, positive predictive value 100%, and negative predictive value 89.1% for discriminating CPPE from TBE (area under the curve 0.947, p < 0.001, 95% confidence interval 0.89-0.99). CONCLUSIONS: Point-of-care Pf lactate measurements may have practical value in early separation of TBE or CPPE during initial thoracentesis, and warrants further investigation.

Feasibility of objectively measured physical activity and sedentary behavior in patients with malignant pleural effusion.

PURPOSE: Malignant pleural effusion (MPE) affects 1 million people worldwide annually and can significantly impair physical activity. Accelerometry is a validated method of objectively assessing physical activity. The purpose of this study was to determine the compliance in patients with MPE to accelerometry and describe their activity. METHODS: Patients with MPE wore an Actigraph GT3X accelerometer over a 7-day continuous wear protocol. Compliance was measured as the percent of patients who had ≥4 valid days (i.e., 8-h/day of waking wear-time). Eastern Cooperative Oncology Group performance status was documented the day of actigraphy initialization. RESULTS: Forty-six patients with MPE received accelerometers; 44 (95.7%) returned their device. No complications were reported on their use. Forty subjects (90.9%) had ≥4 valid days of wear-time. Patients spent most of their waking hours sedentary [mean 11.0 h (SD 1.95)], with limited participation in moderate and vigorous physical activity [mean 9.5 min (SD 14.16)]. Compared to patients with better performance status (n = 32), patients with poorer performance status (n = 11) spent significantly more hours/day sedentary [mean difference 2.1 (CI 0.86-3.32); p = 0.001], as did those who survived <3 months (n = 5) compared to >12 months (n = 27) [mean difference 2.6 (CI 0.49-4.77); p = 0.013). CONCLUSION: Accelerometry was applied successfully in patients with MPE with high compliance and no adverse events. This is the first reported objectively measured physical activity in patients with MPE and revealed high sedentary behavior and low physical activity. The data reflected patient performance status and discriminated between survival groups. Accelerometry can provide a useful measure for future interventional studies in patients with MPE.

A distinctive colour associated with high iodine content in malignant pleural effusion from metastatic papillary thyroid cancer: a case report.

INTRODUCTION: Pleural effusions are a common clinical problem and affect about one million people in the United States and United Kingdom each year. Over 60 causes of pleural effusion have been identified; establishing the definitive aetiology can be difficult, and often requires invasive procedures. Guidelines state that macroscopic examination of the fluid should be the first step in determining the aetiology of a pleural effusion. Papillary thyroid carcinoma is an uncommon cause of malignant pleural effusion, with only 10 cases reported in the literature, their physical characteristics and composition having been rarely described. We describe for the first time a distinctive brown colour of the malignant effusion (despite centrifugation) from a rare case of metastatic papillary thyroid cancer to the pleura, associated with a high pleural fluid iodine content. Such a characteristic may be useful in expediting diagnosis of a malignant pleural effusion in the appropriate clinical context. CASE PRESENTATION: We present the case of a 71-year-old Caucasian man with metastatic papillary thyroid cancer; a large, long-standing, right-sided pleural effusion and a 83-fold higher pleural thyroglobulin level compared to corresponding serum, supporting this malignancy as the cause of the patient's effusion. The pleural fluid had a distinctive pigmentation similar to iodine-containing antiseptic preparations. Biopsy during medical thoracoscopy confirmed metastatic papillary thyroid carcinoma. Analysis of pleural fluid showed a pleural thyroglobulin level over 80 times that of serum levels (29,000µg/L versus 350ug/L). Pleural fluid iodine content was 23,000ug/L and may account for the fluid's distinctive pigment, as iodine is an essential component in thyroglobulin and thyroid hormone synthesis. CONCLUSIONS: Pleural fluid pigmentation may aid diagnosis in the appropriate clinical setting. A distinctive iodine-like brown colour of pleural fluid may represent elevated iodine content and should raise consideration of metastatic thyroid cancer as a cause for a pleural effusion.