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| Urine urea nitrogen | |
|---|---|
| Purpose | assess nitrogen balance. |
Urine urea nitrogen (UUN) refers to a test that measures the urine urea to assess nitrogen balance.
Urea nitrogen is the end product of breakdown of proteins in the body. In individuals with normal kidney and liver functions, urea is excreted via urine.
By testing for UUN, clinicians can assess one's nitrogen balance. Calculating nitrogen balance is a useful tool in assessing adequacy of protein provision in clinical setting in:
UUN is determined from 24-hour urine collection. Along with UUN, values for BUN, protein content of diet, enteral or parenteral nutrition, and notable outputs other than urine (gastric residual, fistula output, drainages) are needed to calculate nitrogen balance. Nitrogen Balance = Protein intake/6.25- UN + 4 * For average loss via sweat.
As UUN test is based on 24-hour urine, in individuals with kidney disease with less than 1000 ml urine out/day or on dialysis, this test cannot be applied.
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about 12 centimetres in length. They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder.
Clinical chemistry is the area of chemistry that is generally concerned with analysis of bodily fluids for diagnostic and therapeutic purposes. It is an applied form of biochemistry.
Parenteral nutrition (PN) is the feeding of nutritional products to a person intravenously, bypassing the usual process of eating and digestion. The products are made by pharmaceutical compounding companies. The person receives a nutritional formulae that contain nutrients including glucose, salts, amino acids, lipids and added vitamins and dietary minerals. It is called total parenteral nutrition (TPN) or total nutrient admixture (TNA) when no significant nutrition is obtained by other routes, and partial parenteral nutrition (PPN) when nutrition is also partially enteric. It is be called peripheral parenteral nutrition (PPN) when administered through vein access in a limb rather than through a central vein as central venous nutrition (CVN).
Uremia is the condition of having high levels of urea in the blood. Urea is one of the primary components of urine. It can be defined as an excess of amino acid and protein metabolism end products, such as urea and creatinine, in the blood that would be normally excreted in the urine. Uremic syndrome can be defined as the terminal clinical manifestation of kidney failure. It is the signs, symptoms and results from laboratory tests which result from inadequate excretory, regulatory and endocrine function of the kidneys. Both uremia and uremic syndrome have been used interchangeably to denote a very high plasma urea concentration that is the result of renal failure. The former denotation will be used for the rest of the article.
Renal functions include maintaining an acid-base balance; regulating fluid balance; regulating sodium, potassium, and other electrolytes; clearing toxins; absorption of glucose, amino acids, and other small molecules; regulation of blood pressure; production of various hormones, such as erythropoietin; and activation of vitamin D.
Clinical urine tests is an examination of urine for certain physical properties, solutes, cells, casts, crystals, organisms, or particulate matter, and mainly serves for medical diagnosis. The word is a blend of the words urine and analysis. Urine culture and urine electrolyte levels are part of urinalysis.
Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging.
Acute kidney injury (AKI), previously called acute renal failure (ARF), is an abrupt loss of kidney function that develops within 7 days.
Protein toxicity is the effect of the buildup of protein metabolic waste compounds due to insufficient kidney function. It can occur in people with pre-existing chronic kidney disease, or those who have lost kidney function due to age.
Nitrogen balance is a measure of nitrogen input minus nitrogen output.
Argininosuccinic aciduria, is an inherited disorder that causes the accumulation of argininosuccinic acid in the blood and urine. Some patients may also have an elevation of ammonia, a toxic chemical, which can affect the nervous system. Argininosuccinic aciduria may become evident in the first few days of life because of high blood ammonia, or later in life presenting with "sparse" or "brittle" hair, developmental delay, and tremors.
Interstitial nephritis, also known as tubulointerstitial nephritis, is inflammation of the area of the kidney known as the renal interstitium, which consists of a collection of cells, extracellular matrix, and fluid surrounding the renal tubules. In addition to providing a scaffolding support for the tubular architecture, the interstitium has been shown to participate in the fluid and electrolyte exchange as well as endocrine functions of the kidney.
Hypouricemia is a level of uric acid in blood serum that is below normal. In humans, the normal range of this blood component has a lower threshold set variously in the range of 2 mg/dL to 4 mg/dL, while the upper threshold is 530 micromol/L (6 mg/dL) for women and 619 micromol/L (7 mg/dL) for men. Hypouricemia usually is benign and sometimes is a sign of a medical condition.
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra.
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 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.
Biological value (BV) is a measure of the proportion of absorbed protein from a food which becomes incorporated into the proteins of the organism's body. It captures how readily the digested protein can be used in protein synthesis in the cells of the organism. Proteins are the major source of nitrogen in food. BV assumes protein is the only source of nitrogen and measures the amount of nitrogen ingested in relation to the amount which is subsequently excreted. The remainder must have been incorporated into the proteins of the organisms body. A ratio of nitrogen incorporated into the body over nitrogen absorbed gives a measure of protein "usability" – the BV.
Proteins are essential nutrients for the human body. They are one of the building blocks of body tissue and can also serve as a fuel source. As a fuel, proteins provide as much energy density as carbohydrates: 4 kcal per gram; in contrast, lipids provide 9 kcal per gram. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition.
Ornithine translocase deficiency, also called hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome, is a rare autosomal recessive urea cycle disorder affecting the enzyme ornithine translocase, which causes ammonia to accumulate in the blood, a condition called hyperammonemia.
T. Alp Ikizler is a nephrologist, currently holding the Catherine McLaughlin Hakim chair in Medicine at Vanderbilt University School of Medicine, where he does clinical work and heads a research lab. Born in Istanbul, Turkey, he received his M.D. from the Istanbul University Faculty of Medicine.
Indirect calorimetry calculates heat that living organisms produce by measuring either their production of carbon dioxide and nitrogen waste, or from their consumption of oxygen. Indirect calorimetry is the method by which the type and rate of substrate utilization, and energy metabolism are estimated in vivo starting from gas exchange measurements. This technique provides unique information, is noninvasive, and can be advantageously combined with other experimental methods to investigate numerous aspects of nutrient assimilation, thermogenesis, the energetics of physical exercise, and the pathogenesis of metabolic diseases.