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PAPP-A Unit Converter
Pregnancy-Associated Plasma Protein A (PAPP-A) is a key glycoprotein produced by the placenta. It is a critical biomarker used in first-trimester screening for chromosomal abnormalities, specifically **Down Syndrome (Trisomy 21)**.
In pregnancies affected by Trisomy 21, maternal serum PAPP-A levels are typically reduced (approx. 0.4 MoM). Low PAPP-A is also associated with adverse obstetric outcomes such as preeclampsia and intrauterine growth restriction. This converter allows for quick conversion between standard activity units (mIU/L, IU/L).
Common Activity Units
StandardMilli-International Units per Liter (Most common lab reporting unit).
Equivalent Variations
Clinical Context
Interpretation: PAPP-A levels increase exponentially during the first trimester. To be clinically useful, the raw unit value must be converted to **Multiples of the Median (MoM)**, adjusted for gestational age (CRL), maternal weight, ethnicity, and smoking status.
Typical Patterns:
• Normal Pregnancy: 1.0 MoM.
• Trisomy 21 (Down Syndrome): Low (~0.4 MoM).
• Trisomy 18/13: Very Low (<0.2 MoM).
Conversion Logic:
1 IU/L = 1,000 mIU/L.
1 mIU/mL = 1 IU/L (Volume conversion cancels out prefix).
Clinical References
How to Use This Converter
Follow these steps to normalize PAPP-A values.
Enter Values
Input your laboratory results into the corresponding unit field (e.g., mIU/L).
Automatic Conversion
The calculator converts between milli-International Units (mIU) and standard International Units (IU).
Verify MoM
Remember that this tool converts units only. Risk assessment requires conversion to MoM based on gestational age.
Reset
Use the Clear button to reset all fields.
Frequently Asked Questions
No. 1 U/L (or IU/L) = 1,000 mIU/L.
PAPP-A assays are standardized against WHO reference preparations defined in International Units (IU), not mass. Using mass units can cause errors between different assay platforms.