Renal compensation is a mechanism by which the

kidneys In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and right in the retro ...

can regulate the plasma pH. It is slower than respiratory compensation, but has a greater ability to restore normal values. Kidneys maintain the acid-base balance through two mechanisms: (1) the secretion of H⁺ ions into the urine (from the blood) and (2) the reabsorption of bicarbonate HCO (i.e., bicarbonate moves from urine back into the blood). The regulation of H⁺ ions and bicarbonate HCO is determined by the concentration of the two released within the urine. These mechanisms of secretion and reabsorption balance the pH of the bloodstream. A restored acid-base balanced bloodstream thus leads to a restored acid-base balance throughout the entire body. __TOC__

Human pH

An ideal pH within the human body ranges from 7.35 to 7.45. When the pH of the body falls below 7.35, an acidemia occurs. Similarly, when the pH of the body rises above 7.45, an alkalemia occurs. Renal compensation is one of the many compensatory mechanisms within the body which assist the pH level in ranging between 7.35 and 7.45 as the body cannot function properly when the pH falls out of this range. Respiratory and renal changes in acid-base elimination typically contrast each other, and respiratory pH disturbances often commence renal compensation. The renal compensation process usually takes a few days to complete as it is dependent upon changes in the reabsorption of bicarbonate. End-staged renal diseases as well as chronic kidney diseases increase the overall risk of individuals developing pneumonia due to the interactions between the kidneys and the lungs. Both organs are targets of similar systematic diseases and loss of normal function of one organ can induce the disregulation of and abnormalities within the other.

Production in the kidneys

respiratory acidosis The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gr ...

, the kidney produces and excretes

ammonium Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) polyatomic ion, molecular ion with the chemical formula or . It is formed by the protonation, addition of a proton (a hydrogen nucleu ...

(NH₄⁺) and monophosphate, generating

bicarbonate In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula . Bicarbonate serves a crucial bioche ...

in the process while clearing acid. There is also an excretion of Cl- and a reabsorption of sodium, resulting in a negative urinary anion gap. In

respiratory alkalosis Respiratory alkalosis is a medical condition in which Tachypnea, increased respiration elevates the blood pH beyond the normal range (7.35–7.45) with a concurrent reduction in arterial levels of carbon dioxide. This condition is one of the four ...

, less

(HCO₃⁻) is reabsorbed, thus lowering the pH.

References

{{Renal physiology Acid–base disturbances