Medical Etymology: Tales Behind the Terms is a series of articles discussing the stories, origins and meanings of the words we use every day in medicine. The goal is to explore the history of complex jargon used with patients and learners. In doing so, I hope that we, as physicians in training, will be able to deliver better health care that can be understood and remembered by all.
Rickets is a childhood condition that is characterized by dysfunctional mineralization, or poor bone development, in the epiphyseal plates – more commonly known as growth plates. The true origin of the term “rickets” is unclear, but several theories exist. One postulates that it comes from the Old English wrickken, meaning “to twist,” describing the bent deformation of bones. Another comes from an early Dorset word, rucket, meaning “to breathe with difficulty,” referring to the respiratory distress demonstrated by patients with rickets. A third possibility is the Greek rhakhis, meaning “spine,”which is the root for the modern Latin name of the disease, rachitis.
While the exact origin of rickets remains uncertain, each of the possible meanings provides insight into how early observers interpreted the disease. From these origins, we get familiar terms like rickety, used to describe something liable to collapse due to an unstable structure. One term sometimes mistakenly linked to rickets is rickettsia, the name of a parasitic organism. However, it is unrelated and instead derives its origin from its discoverer, Howard Taylor Ricketts. This type of naming is known as an eponym, from epi- (“upon”) and -onoma, (“name”).
Before describing the symptoms of rickets, it is worthwhile to understand the pathophysiology and how one might explain it to patients. Rickets is a childhood presentation of osteomalacia, where osteo- refers to “bone” and –malacia means “softening.” While osteomalacia typically refers to softening of the bone matrix (the substance providing most of the bone’s structure), rickets specifically affects the epiphyseal, or growth, plates, which exist only in developing children.
The prefix epi- means “upon,” and -physis means “growth,” so the epiphyseal plate is where new bone growth occurs. The most common cause of rickets is acquired nutritional deficiency. Vitamin D, calcium, and phosphorus are critical in bone development. The word vitamin comes from vita- (“life”) and -amine (“a nitrogen-containing compound”). Originally spelled vitamine, the final ”e” was dropped once it was discovered that not all vitamins were amines. The letters assigned to vitamins reflect their order of discovery: Vitamin A in 1913, for example. Vitamin K is an exception, with “K” derived from Koagulation, due to its role in proper blood clotting. Vitamin D was discovered in 1922, specifically in the study of rickets.
Low levels of vitamin D cause low calcium, and when the body senses this, it mobilizes calcium stores from the bone, weakening their structure. Calcium comes from kalk, meaning “lime,” a material found in limestone or chalk. Phosphorus comes from phos- (“light”) and -phoros (“bringing”), as the element glows in the dark. These vivid origins, “life substance D,” “chalk,” and “light-bringing mineral”– can help patients and families remember the condition more easily. Knowing that these deficiencies cause “softening of bones” at the site where “bone grows upon” reinforce the signs and symptoms.
Rickets is most frequently noted between 6 months to 2 years of life. There are numerous indicators of the disease, most of which are directly related to improper bone development. Patients will develop craniotabes, a soft skull, from cranio- (“skull”) and -tabes (“wasting”). Additionally, there will be frontal bossing, a protuberance of the skull at the forehead. This can be remembered as frontal refers to the forehead above the eyebrows, and “boss”, which in this context, refers to a protruding feature, from the Middle French, “embocer”. Finally, there will be wide fontanelles in the skull. The fontanelle is the “soft spot” on a baby’s head, and it comes from a term meaning “fountain”, the dent in earth where a spring might arise. In the chest, rachitic rosary occurs, a widening of the joints in the rib cage. These appear as prominent bony knobs, resembling the beads of a Catholic Christian rosary, a type of garland originally made from roses. Weight-bearing limbs may present with deformities, such as genu varus, or bow legs, from genu- (“knee”) and varus (“bent outwards”). The spinal column may also twist, echoing the possible Old English root wrickken.
Once the origins and signs of this bone-softening disease are understood, treatment becomes more intuitive. Nutritional rickets is treated by restoring vitamin D levels and ensuring adequate calcium and phosphorus. There are two types of Vitamin D that can be administered, Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol). D2 is found in plants and mushrooms; D3 derives from animal sources and is synthesized by the skin when exposed to sun. They differ by a single carbon, yet D3 is the form which is more often prescribed to patients. Cholecalciferol comes from chole-, (“bile”), referencing its original connection to cholesterol metabolism;, -calc-, from the “lime” we described earlier in calcium and -ferol, similar to –phoros, meaning “to bear.” Therefore, vitamin D3 is a bile-related, calcium-carrying substance, linking it to its function in calcium metabolism. Ergocalciferol has a similar meaning, though here the term ergo-, refers to ergot, a fungus from which vitamin D2 was first isolated. While patients may not benefit from learning the fungal origins and calcium-bearing properties of the Vitamin D subtypes, it may aid students and providers in remembering the difference between the two, and critically, which one is typically used for treatment. It should help to remember that the mighty animal- and sun- derived Vitamin D3 is the more potent and efficacious option, rather than that which comes from the humble ergot fungus.
Rickets can have multiple causes and this article does not explore all of them. Nonetheless, this article gives an overview of the most common terminology associated with rickets and the fascinating origins behind those terms. Ideally, learning the medical etymology through vivid images and stories allows the learner to better retain the critical information pertaining to rickets. Consequently, patients and their families, regardless of their baseline health literacy, will benefit from a clear, interesting and meaningful explanation of the diseases, its clinical manifestations and its treatment options.
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