Body fluids are most often analyzed to determine the number and types of cells present. The most commonly analyzed fluids include urine, cerebrospinal, pleural, peritoneal, pericardial, and joint aspirate.
A body fluid cell count enumerates the RBCs and WBCs. The WBCs are further classified into neutrophils and mononuclears (lymphocytes, monocytes-macrophages). Abnormal cells, such as malignant cells or mesothelial cells can be detected, but may require cytopathologic analysis for further description.
It is possible to perform flow cytometry to detect cell types present in a body fluid.
The chemical constituent of body fluids most often measured is protein. This can be further classified as albumin or globulin. Enzymes such as lipase and LDH can also be measured.
Cells counts and chemical analyses help to determine if a traumatic (red blood cells), inflammatory (white blood cells), or neoplastic process (malignant cells) may be present.
To perform a cell count, microscopic examination is necessary. At the same time, the fluid can be analyzed for the presence of abnormal constituents, such as crystals and malignant cells.
Joint synovial fluid may contain crystals:
- Sodium urate: gout
- Pyrophosphate: pseudogout
- Cholesterol: prior hemorrhage