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.
Tylenol's Makeup and Use. To understand how long Tylenol stays in your system, you must know what the drug is and how it is used and metabolized by your body. Tylenol is the brand name for acetaminophen, an over-the-counter analgesic (or pain reliever) and antipyretic (or fever reducer).