Table 2.

Comparison of physical-chemical and microscopic findings of thoracentesis fluid, expressed breast milk and serum

Test		Thoracentesis fluid	Expressed breast milk	Serum
Appearance		Opalescent white	Opalescent white	Clear
Centrifugation		Remains uniform	Forms a creamy layer	–
pH		7.5 (7.4–7.8)	7.2	–
Benedict’s test		Trace	Strongly positive	–
Glucose		2.0 mmol/L (2.7–11)	0.8 mmol/L	5.4 mmol/L
Protein		20 g/L (20–30)	14 g/L	33 g/L
Triglyceride		0.64 mmol/L (>1.24)	0.33 mmol/L	0.34 mmol/L
Total cholesterol		Undetectable (<5.17)	Undetectable	2.72 mmol/L
Fluid triglyceride-to-cholesterol ratio		>1 (>1.0)	–	–
Fluid-to-serum triglyceride ratio		1.9 (>1.0)	–	–
Fluid-to-serum cholesterol ratio		<1 (<1.0)	–	–
Microscopy	Cytology	A field full of lymphocytes (>1000 cells/µL)	–	–
	Cholesterol crystals	Absent	–	–

Reference limits for chyle are given within parentheses with the respective parameters.^6–8