Knowing i will consult with my dr, please offer your opinion: what can cause a drop in wbc count? also is a drop from 7.1 to 5.1 for wbc in 2 weeks concerning? again, i will talk to my dr but would appreciate any strong opinion. thank you?

Several things can cause: a change like that over 2 weeks could still be a laboratory variation & just needs to be checked again in 1-2 weeks if you feel fine, but can be due to a viral infection, medication effect, or exposure to a toxin that affects your bone marrow’s ability to make the cells. Definitely discuss with your Dr

It depends, partly on why you had labs drawn again. Numbers taken out of context are not usually very helpful. These particular numbers out of context sound fine.

Agree, but your white count is still within normal limits, so it's not time to get overly concerned yet. It should be monitored though. Various medications including antibiotics and chemotherapy as well as infections, or recovery from infections can cause a decrease in one's white count, as can certain other medical conditions . Blood work results must always be interpreted in context.