In renal physiology

Renal physiology

Renal physiology is the study of the physiology of the kidney. This encompasses all functions of the kidney, including reabsorption of glucose, amino acids, and other small molecules; regulation of sodium, potassium, and other electrolytes; regulation of fluid balance and blood pressure;...

, net acid excretion (NAE) is the net amount of acid excreted in the urine

Urine

Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...

 per unit time. Its value depends on urine flow rate, urine acid concentration, and the concentration of bicarbonate

Bicarbonate

In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...

 in the urine (the loss of bicarbonate, a buffering agent

Buffering agent

A buffering agent is a weak acid or base used to maintain the acidity of a solution at a chosen value. The function of a buffering agent is to prevent a rapid change in pH when acids or bases are added to the solution. Buffering agents have variable properties—some are more soluble than others;...

, is physiologically equivalent to a gain in acid). NAE is commonly expressed in units of milliliters per minute

Minute

A minute is a unit of measurement of time or of angle. The minute is a unit of time equal to 1/60th of an hour or 60 seconds. In the UTC time scale, a minute on rare occasions has 59 or 61 seconds; see leap second. The minute is not an SI unit; however, it is accepted for use with SI units...

 (ml/min) and is given by the following equation:


where

Variable

Meaning >- | NAE

>- | V

>- | UNH4

ammonium Ammonium The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia... >- | UTA

titratable acid Titratable acid Titratable acid is a term to describe acids such as phosphoric acid, sulfuric acid which are involved in renal physiology.It is used to explicitly exclude ammonium as a source of acid, and is part of the calculation for net acid excretion....  (e.g., phosphoric acid Phosphoric acid Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way... , sulfuric acid Sulfuric acid Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates... ) >- | UHCO3

urine concentration of bicarbonate Bicarbonate In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...

Pathology

Increased net acid excretion is a compensation for respiratory acidosis

Respiratory acidosis

Respiratory acidosis is a medical condition in which decreased ventilation causes increased blood carbon dioxide concentration and decreased pH ....

, while decreased net acid excretion is a compenstation for respiratory alkalosis

Respiratory alkalosis

Respiratory alkalosis is a medical condition in which increased respiration elevates the blood pH...

.