How quickly can your levels drop?

I have had 2 sets of tests, 24hrs apart (dr ordered the second set accidentally with more bloods I needed) and all of my iron levels seem to have dropped quite a lot in those 24hrs.

Just wondering if this is a normal amount in the short time frame?

Ferritin      40 -> 32  (20-170)

Iron sat     20           (20-50)

Vit B12      292 -> 245 (140-650)

Folate       19.3 -> 12.7 (7-45)

I have been feeling very lightheaded, nauseas and tired in the last 2 weeks which is why these tests were ordered.

A few others were abnormal (low sodium, high Alk Phos, high monocytes) but nothing very obvious jumped out in the blood tests.