An apparatus for analyzing the composition of bodily fluid. The apparatus comprises a fluid handling network including a patient end configured to maintain fluid communication with a bodily fluid in a patient; and a pump unit in operative engagement with the fluid handling network. The pump unit has an infusion mode in which the pump unit is operable to deliver infusion fluid to the patient through the patient end, and a sample draw mode in which the pump unit is operable to draw a sample of the bodily fluid from the patient through the patient end. The apparatus further comprises a spectroscopic analyzer positioned to analyze at least a portion of the sample; a processor in communication with or incorporated into the spectroscopic analyzer; and stored program instructions executable by the processor to obtain measurements of two or more properties of the sample. In one implementation, the pump unit comprises a first pump operable in the infusion mode but not in the sample draw mode, and a second pump operable in the sample draw mode but not in the infusion mode.