AssessmentsMultiple endocrine neoplasia
Multiple endocrine neoplasia
USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A 28-year-old man comes for consultation before his parathyroid surgery. Three of his four parathyroid glands are enlarged. He has a family history of multiple endocrine neoplasia type 2, including a history of thyroid cancer on his mother’s side. The patient also has a past medical history of pheochromocytoma. Which of the following is the most appropriate treatment strategy?
The multiple endocrine neoplasias, or MEN for short, are a group of inherited diseases which cause tumors to grow in the endocrine glands of the body.
The endocrine glands affected in multiple endocrine neoplasia are the pituitary gland, the thyroid gland, the parathyroid glands, the adrenal glands and the pancreas.
So in multiple endocrine neoplasias there are tumors that form in these glands that lead to overproduction of hormones.
Let’s start by going through the glands that are affected and what they do.
The pituitary gland is a pea-sized gland found at the base of the brain that makes hormones to control many of the other endocrine glands in the body.
These hormones include thyroid stimulating hormone which acts on the thyroid to make thyroid hormone, adrenal corticotropic hormone that acts on the adrenal glands to make cortisol, follicle stimulating hormone and luteinizing hormone which acts on the ovaries and testes to make estrogen in women and testosterone in men.
So it’s like the king of the endocrine glands telling them how much hormone to produce.
The pituitary also makes growth hormone which makes you grow, prolactin which stimulates milk production in women, oxytocin which triggers milk release, antidiuretic hormone which help the kidneys reabsorb water, and melanocyte stimulating hormone helps the melanocytes create more melanin or pigment.
Within the thyroid gland, are buried four parathyroid glands which make parathyroid hormone which increases calcium levels.
Lower down, there are the adrenal glands which sit just above each kidney and produce epinephrine and norepinephrine which are fight or flight hormones that increase cardiac output, dilate the pupils, and increase blood flow to the muscles.
The pancreas also makes gastrin which increases hydrochloric acid production in the stomach, and vasoactive intestinal peptide which relaxes the intestinal wall allowing food to pass.
Multiple endocrine neoplasias are caused by genetic mutations to one of two genes, either MEN1 or RET.
Both of these genes have a dominant inheritance pattern, so you only need one copy of the mutated gene to get the disease.
The MEN1 gene is found on chromosome 11 and is a tumor suppressor gene, meaning it normally stops a cell from dividing uncontrollably.
An MEN1 mutation causes MEN type 1.
Mutated RET causes multiple endocrine neoplasia type 2A and 2B.
In multiple endocrine neoplasia type 1, there are three types of tumors: parathyroid, pancreatic, and pituitary.
The most common tumor is a parathyroid tumor.
Pancreatic tumors cause problems based on the type of hormone they produce.