Hi how much can hemoglobin fluctuate in a day ? thank you?

If there is no acute bleeding, the fluctuation due to lab variation or fluid status change should be within (+/-) 0.2 gm/dL. Give example: the first Hb is 14 gm/dL and another check in the same day could be in the range of 13.8 to 14.2 gm/dL.

Hemoglobin can fluctuate with the state of hydration and posture without any blood loss. A variation of 1-2 g/dL could be due to these factors.