After removal, the fluid may then be evaluated for:

Chemical composition including protein, lactate dehydrogenase (LDH), albumin, amylase, pH, and glucose
Gram stain and culture to identify possible bacterial infections
White and red blood cell counts and differential white blood cell counts
Cytopathology to identify cancer cells, but may also identify some infective organisms
Other tests as suggested by the clinical situation – lipids, fungal culture, viral culture, tuberculosis cultures, lupus cell prep, specific immunoglobulins

Lights criteria
Definitions of the terms "transudate" and "exudate" are the source of much confusion. Briefly, transudate is produced through pressure filtration without capillary injury while exudate is "inflammatory fluid" leaking between cells.Transudative pleural effusions are defined as effusions that are caused by systemic factors that alter the pleural equilibrium, or Starling forces. The components of the Starling forces – hydrostatic pressure, permeability, and oncotic pressure (effective pressure due to the composition of the pleural fluid and blood) – are altered in many diseases, e.g., left ventricular failure, kidney failure, liver failure, and cirrhosis. Exudative pleural effusions, by contrast, are caused by alterations in local factors that influence the formation and absorption of pleural fluid (e.g., bacterial pneumonia, cancer, pulmonary embolism, and viral infection).An accurate diagnosis of the cause of the effusion, transudate versus exudate, relies on a comparison of the chemistries in the pleural fluid to those in the blood, using Lights criteria. According to Lights criteria (Light, et al.
Causes
Hormonal disorders or fluctuations can lead to the formation of a lot of visceral fat and a protruding abdomen. Medications such as protease inhibitors that are used to treat HIV and AIDS also form visceral fat. Android fat can be controlled with proper diet and exercise. A poor diet with lack of exercise is likely to increase android fat level. Health consequences
Differences in body fat distribution are found to be associated with high blood pressure, high triglyceride, lower high-density lipoprotein (HDL) cholesterol levels and high fasting and post-oral glucose insulin levels The android, or male pattern, fat distribution has been associated with a higher incidence of coronary artery disease, in addition to an increase in resistance to insulin in both obese children and adolescents. Studies have also related central abdominal obesity (indicated via increased waist–hip ratio) with increases in peripheral fasting insulin levels.Android fat is also associated with a change in pressor response in circulation. Specifically, in response to stress in a subject with central obesity the cardiac output dependent pressor response is shifted toward a generalised rise in peripheral resistance with an associated decrease in cardiac output.There are differences in android and gynoid fat distribution among individuals, which relates to various health issues among individuals. Android body fat distribution is related to high cardiovascular disease and mortality rate. People with android obesity have higher hematocrit and red blood cell count and higher blood viscosity than people with gynoid obesity.