How you prepare

If your blood sample is being tested only for hemoglobin, you can eat and drink normally before the test. If your blood sample will be used for other tests, you may need to fast for a certain amount of time before the sample is taken. Your doctor will give you specific instructions.

March 16, 2017
References
  1. Hemoglobin. Lab Tests Online. http://labtestsonline.org/understanding/analytes/hemoglobin/tab/sample/. Accessed Nov. 27, 2016.
  2. Longo DL, et al., eds. Disorders of hemoglobin. In: Harrison's Principles of Internal Medicine. 19th ed. New York, N.Y.: McGraw-Hill Education; 2015. http://accessmedicine.com. Accessed Nov. 27, 2016.
  3. CBC with differential, blood. Mayo Medical Laboratories. Rochester, Minn.: Mayo Foundation for Medical Education and Research. http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9109. Accessed Nov. 27, 2016.
  4. Nicoll D, et al. Pocket Guide to Diagnostic Tests. 6th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com. Accessed Nov. 27, 2016.