Italian to English Medical Medical (general) laboratory test codes

This is an entry in a list of laboratory tests to be administered to subjects in a clinical trial, which also states how much the sponsor will pay for each test. It's the added letter 'B' at the end of these acronyms that I can't figure out; the first part just seems to be the English acronym.

There is one column titled "Codice" followed by another column titled "Descrizione." This is what it looks like:

PTTB P-Tempo di Tromboplastina Parziale
ALBB S-Albumina
CALB S-Calcio Totale
CREB S-Creatinina
GLUB S-Glucosio
QUIB P-Tempo di Protrombina [QUI here probably stands for Quick test]
HCGB S-Gonadotropina Corionica [HCG = Human Chorionic Gonadotropin]

etc.

Does this added letter 'B' have any medical/clinical meaning? I'm inclined to think it may just be the way the research site writes the codes they use for billing, and that there is nothing to translate ... they should just be left as-is.

Any thoughts or suggestions?

Grazie mille.