Bun (hairstyle) Bun (hairstyle) A bun is a type of hairstyle wherein the hair is pulled back from the face, twisted or plaited, and wrapped in a circular coil around itself, typically on top or back of the head or just above the neck. A bun can be secured with a hair tie, barrette, bobby pins, one or more hair sticks, a hairnet, or a pen or pencil. Hair may also be wrapped around a piece called a "rat". Alternatively, hair bun inserts, or sometimes rolled up socks, may also be used to create donut-shaped buns. Buns may be tightly gathered, or
BUN-to-creatinine ratio BUN-to-creatinine ratio In medicine, the BUN-to-creatinine ratio is the ratio of two serum laboratory values, the blood urea nitrogen (BUN) (mg/dL) and serum creatinine (Cr) (mg/dL). Outside the United States, particularly in Canada and Europe, the truncated term urea is used (though it is still the same blood chemical) and the units are different (mmol/L). The units of creatinine are also different (μmol/L), and this value is termed the urea-to-creatinine ratio. The ratio may be used to determine the cause of acute kidney injury or dehydration. The principle behind this ratio is the fact that both urea (BUN) and creatinine