Cytokeratin Cells in Whole Blood

What Is Being Measured

Cytokeratins are structural proteins found in epithelial cells, the cells that line organs, skin, and glands. Normal blood cells do not produce cytokeratin, so finding cytokeratin-positive cells in whole blood suggests that epithelial cells, or cells derived from an epithelial tumor, are present in the circulation. The test identifies and may count these cells.

Why This Test Is Done

This testing is generally used in cancer care and research, such as evaluating whether tumor cells are circulating in the blood (sometimes called circulating tumor cells) in cancers of epithelial origin, including breast, lung, prostate, and colorectal cancers. It may help assess disease spread or response to treatment, though its role varies by cancer type and clinical setting.

How the Sample Is Collected

A standard blood draw is used to collect whole blood into an appropriate tube. Because these cells are rare, specialized processing and detection methods are often needed, and results depend on the specific laboratory technique and instrument used.

What Results May Mean

A result that reports cytokeratin-positive cells may indicate that epithelial or tumor-derived cells are present in the blood. The meaning depends heavily on the clinical context, the detection method, and the cancer type being evaluated. Results should always be interpreted by the ordering clinician alongside other findings.