When empyema is suspected: Send the sample for centrifuge to differentiate from chylothorax. When chylothorax is suspected: Send the sample for investigation of presence of chylomicrons and cholesterol crystals and level of triglycerides and cholesterol. When haemothorax is suspected: The sample is grossly bloody. Send the sample to check hematocrit level. When rheumatoid disease is suspected: Send sample to check complement levels and glucose. When pancreatitis is suspected: Send sample to check amylase level.