Conclusion
Although bloodletting may sound like an ancient medical practice, the principle behind it is still used in rare clinical situations. Historically, the practice was used due to limited understanding of medical conditions. However, physicians have more understanding of medical conditions and blood removal is commonly done for diagnostic purposes or as an evidence-based method to remove certain amounts of blood to treat specific conditions.
References;
[1] https://www.cdc.gov/bloodpressure/about.htm
[2] https://www.healthline.com/health/hemorrhagic-shock
[3] https://www.osmosis.org/answers/hypovolemia
[4] https://www.msdmanuals.com/home/blood-disorders/blood-clotting-process/how-blood-clots
[5] https://my.clevelandclinic.org/health/diagnostics/17820-ferritin-test
[6] https://medlineplus.gov/iron.html