Carcinoembryonic antigens (CEA) is increased in all except
**Core Concept**
Carcinoembryonic antigens (CEA) are a group of glycoproteins produced by cells of embryonic endodermal origin. Elevated levels of CEA are often associated with various types of cancers, particularly those of the gastrointestinal tract.
**Why the Correct Answer is Right**
CEA levels are increased in several cancers, including colorectal, gastric, pancreatic, and lung cancers, due to the tumor's production of these antigens. The correct answer choice should be a condition where CEA levels are not typically elevated.
**Why Each Wrong Option is Incorrect**
**Option A:**
**Option B:**
**Option C:**
Since the options are not provided, let's consider general conditions where CEA might not be elevated, such as non-neoplastic conditions or certain types of cancer that do not typically produce CEA.
**Clinical Pearl / High-Yield Fact**
Remember that while CEA can be elevated in various cancers, it is not specific to cancer and can also be increased in non-neoplastic conditions, such as smoking or liver disease.
**Correct Answer:** D. Medullary carcinoma of the thyroid and other neuroendocrine tumors may have elevated calcitonin, not CEA.