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CA 15-3 Unit Converter
Cancer Antigen 15-3 (CA 15-3) is a mucin-like glycoprotein encoded by the MUC1 gene. It is shed from the surface of epithelial cells and is the most widely used serum marker for Breast Cancer. While not sensitive enough for early screening, CA 15-3 is valuable for monitoring the response to therapy in patients with metastatic breast cancer and detecting recurrence.
Elevated levels are seen in about 70-80% of patients with metastatic breast disease but only in 10% of patients with Stage I disease. Benign conditions like liver cirrhosis, sarcoidosis, and benign breast disease can also cause mild elevations. Results are reported in Units per milliliter (U/mL) or kU/L. This converter allows seamless switching between these reporting standards.
SI Units
RecommendedUnits per milliliter (Standard Clinical Unit).
Conventional Units
Clinical Context
Reference Range: In healthy individuals, CA 15-3 is typically < 30 U/mL.
In metastatic breast cancer, levels often correlate with tumor burden. A significant rise (>25%) suggests disease progression, while a decrease suggests response to therapy. Another related marker, CA 27.29, measures the same MUC1 antigen but with a different antibody; they are not interchangeable but provide similar clinical information. The conversion factor is 1:1 for most standard units: 1 U/mL = 1 kU/L = 1 IU/mL.
Clinical References
How to Use This Calculator
Follow these steps to get accurate clinical conversions instantly.
Enter Values
Input your laboratory results into the corresponding unit field (e.g., U/mL). You can use either dot or comma decimals.
Automatic Conversion
The calculator works in real-time. As you type in one field, all other units (like kU/L) are instantly updated.
Verify Units
Check the SI Units section. Note that U/mL and kU/L are numerically identical.
Reset
Use the Clear button to reset all fields before starting a new calculation.
Frequently Asked Questions & Tips
CA 15-3 is defined by its antibody binding reactivity, not by weight. There is no standard conversion to mass.
Yes, for CA 15-3, “Units” and “International Units” are used interchangeably.