A. Urine sodium >30 mEq/L.
Explanation:
Acute tubular necrosis (ATN) is a medical condition that involves the necrosis -death- of the tubular cells that form the renal tubule, which carries urine to the ureters while reabsorbing 99% of water and concentrates the salts and by-products of metabolism for disposal. So it is a kidney disorder that involves damage to cells in the tubules of the kidneys, which can lead to acute kidney failure. Tubules are small tubes in the kidneys that help filter blood as it passes through them. ATN is often caused by a lack of blood flow and oxygen to the kidney tissues (kidney ischemia). It can also occur if kidney cells are damaged by a poison or harmful substance.
ATN occurs with acute renal failure (ARF) and is one of the most common causes of ARF. The presence of "dark brown bodies" of epithelial cells found in the urine during urinalysis is pathognomonic for ATN.
Risks for ATN include:
Low blood pressure (hypotension) lasting more than 30 minutesInjury or trauma resulting in muscle damageRecent major surgeryReaction to blood transfusionSeptic shock (a serious condition that occurs when a whole-body infection leads to dangerously low blood pressure)
Since acute tubular necrosis is classified as a kidney cause of acute kidney failure, the diagnosis is made by a sodium excretion fraction greater than 3% and the presence of granular casts formed by Tamm-Horsfall protein with epithelial cell fragments on general urine examination. So, as it eas explained before, it concentrates the salts and by-products of metabolism thereby it is characterizad by urine sodium levels greater than 30 mEq/L.
The meq is a unit used in biology to represent the ionic concentration of a solution. The expression in milliequivalents of a known ionic concentration by weight is obtained by dividing the number of milligrams per liter by the atomic weight of the ion and multiplying the result by the valency of that ion.
