Post op blood test
The obvious first place to start is your former doctor(s). While we all have different requirements, a generic list would include CBC with dif, CMP, lipid profile, HbA1C, Vit B1, Vit B12, Folate, 25 OH Vit D Level, Total Fe, TIBC, Fe saturation, Ferritin, PTH intact with ionized calcium. Other things may be required for your specific health care but this is close to what my surgeon and PCP both require for most patients, as a base line. Your specific case will doubtless be somewhat different according to your health, surgery type, etc.
Do keep records of your bloodwork, and how to read the results so that you can track how you are doing when you have it done annually. I no longer order it thru my doctor's office as I can order my own tests online, have blood drawn in a clinic in town, and the results are sent to me and my doctors...and it costs considerably less. You may find something similar in your area.
There is much information on the ASMBS site, whi*****ludes a pdf of bloodwork that may be of more help to you.
https://asmbs.org/patients/life-after-bariatric-surgery