What on earth is pyelonephritis? Let’s understand what it actually is by taking a look at its etymological breakdown.

Origin: Greek, pyelos (basin, taken to mean pelvis) + nephros (kidney) + –itis (inflammation of)
Inflammation of the basin and the kidney

At first, this seems cryptic. What does basin refer to, and what exactly does kidney refer to? Starting with the root pyelo-, it denotes “pelvis,” but its base etymology comes from the Greek pyelos (basin). There is in fact such a thing as pyelitis, which would be inflammation localized to the renal pelvis. As for the nephr- root, it of course means kidney, but to be more precise, it refers to the kidney parenchyma. Nephritis on its own denotes the inflammation of the kidney’s functional tissue.

kidney anatomy rev

At the end of the day, pyelonephritis is the joint inflammation of the renal pelvis and the renal parenchyma. A vast majority of the cases are caused by a bacterial agent such as E. coli., and as such, they proliferate in a large portion of the kidney instead of being localized to only the pelvis or the parenchyma.

There are three types of pyelonephritis: acute, chronic, and xanthogranulomatous. Let’s look at the last one:

Origin [1]: Greek, xanthos (yellow)
Origin [2]: Latin, granum (grain) + –ula (diminutive) + –oma (mass/proliferation/tumor)
Forming yellow granulomas

Indeed, under the microscope, one would find granulomas—collections of macrophages that try to wall off infections they cannot eradicate. On gross appearance, these granulomas appear yellow because they are macrophages that have been filled to the brim with lipids.

xantho rev

Diabetes is a household name in this day and age. More often than not, people are concerned about their sugar intake in order to prevent diabetes. A quick Google Scholar search will reveal that a high sugar intake does not increase the risk of developing diabetes. But, of course, a chronically-high concentration of glucose in the blood will lead to a variety of problems down the line. An age-old clinical observation of diabetes is the tendency to urinate often, termed polyuria [Greek: poly (many) + ourein (to urinate)]. This is in fact where the word diabetes comes from:

Origin: Greek, dia- (through) + banein (to pass)
To pass through, siphon

What about the two words appended to the end of “diabetes”? They are the following:

Origin: Latin, mel (sweet thing)
Something sweet, honey

Origin: Latin, in- (without) + sapere (to have taste)
Lacking taste, in this case sweetness

Diabetes mellitus (DM) has two types, Type 1 and Type 2. The former is usually ascribed to insulin insufficiency, whereas the latter is usually ascribed to insulin resistance. It is given the name “mellitus” because of glucose in the urine, or glucosuria. The large amounts of glucose in the blood finds its way to the urine, and as a result, makes the urine—the entity being passed through—sweet. The polyuria is caused by the osmotic effect of water “following” the glucose. The quick and easy way that physicians would diagnose diabetes mellitus was to simply taste the urine of a patient suspected to have this condition.

vasopressin rev

On the contrary, diabetes insipidus (DI) is caused by a lack of water control and is not related to diabetes mellitus. This “lack of water control” involves problems with anti-diuretic hormone (ADH) production or ADH insensitivity. The former is termed central DI, since it originates in the central nervous system, and the latter is termed nephrogenic [Greek: nephros (kidney) + -genes (born from)] DI. This lack of mechanistic control stimulates profound thirst to replace the massive amounts of water lost in the urine since the water is not being reclaimed by the distal convoluted tubule and collecting duct of the nephron. However, blood glucose is not affected by this condition, there is no glucosuria, and in turn there is no sweetness in the urinehence the urine is without taste, or “insipid.”

In colloquial language, we often append the suffix ­-itis to a word to denote a disease or condition of said word. It is in effect an indication of an unhealthy amount of something either abstract or tangible. If someone is being lazy, we can say that he or she has come down with a case of lazyitis. Too much time in front of a computer can afflict you with a nasty case of computeritis. At its roots, –itis means “pertaining to” in Greek, so in some sense, this colloquial use of the suffix is the most faithful to its base etymology.

In more technical language, –itis is used as a medical suffix, and it simply denotes “inflammation of.” I can’t tell you how many times I have heard people use ­–itis to immediately denote “infection of.” Let’s list some examples.

Origin: Neo-Latin, appendix (something appended, in this case to the colon) + -itis (inflammation of)
Inflammation of the appendix

Origin: Greek, byrsa (hide/skin) + ­-itis
Inflammation of the bursa (a pouch or sack that facilitates motion, e.g., suprapatellar bursa)

Origin: Greek, chole (bile) + kystis (bag) + -itis
Inflammation of the gall bladder (which stores bile)

Yes, many times, these conditions come about from infection by a bug that isn’t supposed to be there. But there are many other causes of inflammation, such as:

  1. Trauma
  2. Autoimmune reaction
  3. Drugs
  4. Burns
  5. Radiation

So the next time someone mentions an ­–itis, always remember that the inflammation of the target organ can be caused by something other than infection. If you wish to convey the fact that an inflammation of the appendix is caused by an infection, you can prepend the word with “infectious,” to make it an infectious appendicitis. Or if you are more certain of the cause of this infection, you can use a bacterial/viral/fungal modifier, for a bacterial appendicitis. For a non-infectious cause, you could say the cause for an inflammation of the liver is a drug-induced hepatitis.

Finally, if someone mentions a type of ­­itis that you are not familiar with, use the word itself to help you out. I remember hearing the term bronchiolitis last year when learning about COPD (chronic obstructive pulmonary disease). I didn’t know what bronchiolitis was until I stopped for a second to think about it: the inflammation of the bronchiole(s). Contrast this with bronchitis, which is the inflammation of a main stem bronchus.

lung anatomy rev

So, given this, let me know in the comments what these terms are and what their most common causes are:

  1. Cholangitis
  2. Colitis
  3. Pneumonitis
  4. Endocarditis
  5. Vasculitis
  6. Phlebitis
  7. Gastroenteritis