Anyway, the typical CEA range is < 3.0 ng/mL (that is < 30mg/DL). Some folks are naturally higher. Others are in that range. Sometimes certain cancers will elevate a patients CEA levels, othertimes or with other cancers, CEA will be normal. Sometimes other things elevate CEA. Typically, from what I've read, heard, and studied, most doctors would say CEA < 10ng/mL (< 100ug/DL) could be normal or caused by things like smoking, not really a cause for alarm, but screening might be in order to determine the cause.
Operating System. An operating system or OS is a software program that enables the computer hardware to communicate and operate with the computer software. Without a computer operating system, a computer and software programs would be useless. The picture is an example of Microsoft Windows XP, a popular operating system and what the box may look like if you were to visit a local retail store to purchase it.
Often abbreviated as OS, an operating system is a powerful, and usually large, program that controls and manages the hardware and other software on a computer. All computers and computer-like devices have operating systems, including your laptop, tablet, desktop, smartphone, smartwatch, router... you name it. Examples of Operating Systems Laptops, tablets, and desktop computers all run operating systems that you've probably heard of. Some examples include versions of Microsoft Windows (like Windows 10, Windows 8, Windows 7, Windows Vista, and Windows XP), Apple's macOS (formerly OS X), iOS, Chrome OS, BlackBerry Tablet OS, and flavors of the open source operating system Linux. Your smartphone runs an operating system too, probably either Apple's iOS or Google's Android.