A physician investigating unexplained hypercobalaminemia will typically order some combination of the following: Complete blood count (CBC) with differential to check for abnormal red blood cell, white blood cell, or platelet counts Liver function tests (ALT, AST, ALP, bilirubin, albumin) to assess liver health Kidney function tests (creatinine, BUN, estimated GFR) to evaluate renal clearance Peripheral blood smear if a myeloproliferative disorder is suspected Abdominal imaging (ultrasound or CT) if liver or abdominal pathology is a concern Cancer-specific markers or screenings if clinical suspicion warrants them The NIH Office of Dietary Supplements fact sheet notes that observational data from a Danish registry analysis of 757,185 people found the adjusted 1-year cancer risk was 1.74 to 4.72 times higher among those with B12 above 813 pg/mL compared to those in the normal range of 203 to 813 pg/mL

It tends to appear a few months in and resolves on its own once weight stabilizes, with hair regrowing fully
If you have a history of pancreatitis, gallbladder disease, or diabetic retinopathy, additional precautions apply
The faster you lose weight, and the more you lose, the more likely you are to notice facial changes
It's a known side effect following bariatric surgery, she said, and would be something she would keep an eye on