WILTIMS #109: T4: Judgement Day

Medical euphemisms are interesting. Today we were discussing hypothyroidism, which when left untreated causes physical and mental symptoms that were once referred to as cretinism. This is where we get the word cretin. Well, that's actually tricky because the term vastly predates our understanding of the illness, so in a way the disease was named for the people described by the word. Like spastic, crippled, moron, and many other terms, cretinism was once perfectly acceptable but has become politically incorrect.

The word retarded is particularly interesting because it has a very literal meaning that is still used extensively in medicine, among other places. Retard simply means to slow, e.g. fire retardant slows the spread of a fire. So to say that a child is mentally retarded literally means that their mental faculties are developing slowly. This has become taboo to say outside of a strict medical setting, so we've had to come up with new euphemisms like developmentally delayed. It still means the same thing but hasn't been used as a derogatory slur... yet.

TIL: Competency is a legal distinction determined by a court. Capacity is a medical distinction determined by medical professionals. The latter can be used as evidence of the former. In every other way these two words are synonymous in regards to medical ethics.

T4 - Note the 4 iodine atoms

Thyroid hormone comes in two active flavors, T3 and T4, which differ only by the number of iodine atoms bound to the molecule. T3 is the more active of the two but T4 is both more prominent in the circulating blood and the preferred hormone given orally for thyroid replacement therapy. This is the case because T4 has a half-life of about a week, compared to T3's paltry 1 day. This increased retention allows thyroid hormone levels to remain more constant.

This related tidbit was something I learned while volunteering at a cancer screening clinic last year. The iodine used in the synthesis of thyroid hormone is actually the reason we make and consume iodized salt. The thyroid is the only organ that uses this trace but essential nutrient. This provides a surprisingly easy target for treating thyroid cancers. By injecting radioactive iodine, you can use the body's own natural pathways to target the radiation directly to the thyroid.