It is also sometimes called erythrocytosis, which means too many red blood cells. And it used to be called polycythaemia rubra vera or PCRV. PV is a type of rare blood disorder called a myeloproliferative neoplasm.These are conditions that cause an increase in the number of blood cells.t is also sometimes called erythrocytosis, which means too many red blood cells. And it used to be called polycythaemia rubra vera or PCRV. PV is a type of rare blood disorder called a myeloproliferative neoplasm.
Acetaminophen -- best known as Tylenol in the United States -- does not appear to help ease lower back pain and offers little relief for the most common form of arthritis, according to a new report.
How Tylenol works How Tylenol works Acetaminophen, the active ingredient in Tylenol, is one of the most widely used pain relievers in the world. However, scientists don't know exactly how it works to relieve pain. It is thought that this drug increases the body's pain threshold so that pain is actually felt less.