Metabolic alkalosis
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223938264
2008-07-06T16:35:37Z
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{{Infobox_Disease |
Name = {{PAGENAME}} |
Image = Davenport Fig 12.jpg |
Caption = [[Davenport diagram]] |
DiseasesDB = 402 |
ICD10 = {{ICD10|E|87|3|e|70}} |
ICD9 = {{ICD9|276.3}} |
ICDO = |
OMIM = |
MedlinePlus = |
eMedicineSubj = med |
eMedicineTopic = 1459 |
MeshID = |
}}
'''Metabolic alkalosis''' is a [[metabolic]] condition in which the [[pH]] of the blood is elevated beyond the normal range. This is usually the result of decreased [[hydrogen ion]] concentration, leading to increased [[bicarbonate]], or alternatively a direct result of increased [[bicarbonate]] concentrations.
==Causes==
There are five main causes of metabolic alkalosis<ref>[http://www.emedicine.com/MED/topic1459.htm eMedicine - Metabolic Alkalosis : Article by Sameer Yaseen<!-- Bot generated title -->]</ref>:
'''1. Loss of hydrogen ions''' - Most often occurs via two mechanisms, either vomiting or renally. Vomiting results in the loss of [[hydrochloric acid]] with the stomach content, which consumes hydrogen ions, raising the pH of the blood. Renal losses of hydrogen ions occurs when excess [[aldosterone]] induces the retention of sodium and hence the excretion of hydrogen.
'''2. Retention of bicarbonate''' - As a compensatory mechanism for respiratory [[acidosis]], the kidneys will increase their retention of [[bicarbonate]] in order to raise blood pH. Prolonged respiratory acidosis may cause the retention of bicarbonate. If respiratory acidosis is prolonged, due to impaired pulmonary function, the resulting excess of bicarbonate can then raise blood pH too high, which compensates respiratory acidosis.
'''3. Shift of hydrogen ions into intracellular space''' - Seen in [[hypokalemia]]. Due to a low extracellular potassium concentration, potassium shifts out of the cells. In order to maintain electrical neutrality, hydrogen shifts into the cells, raising blood pH.
'''4. Alkalotic agents''' - Alkalotic agents, such as bicarbonate or antacids, administered in excess can lead to an alkalosis.
'''5. Contraction alkalosis''' - This results from a loss of water in the extracellular space which is poor in bicarbonate, typically from diuretic use. Since water is lost while bicarbonate is retained, the concentration of bicarbonate increases blood pH.
(See also [[loop diuretics]] and [[hyperaldosteronism]].)
==Compensation==
Compensation for metabolic alkalosis occurs mainly in the lungs, which retain [[carbon dioxide]] (CO<sub>2</sub>) through slower breathing, or [[hypoventilation]] ([[respiratory compensation]]). CO<sub>2</sub> is then consumed toward the formation of the [[carbonic acid]] intermediate, thus decreasing pH.
[[Renal compensation]] for metabolic alkalosis, less effective than respiratory compensation, consists of increased excretion of HCO<sub>3</sub><sup>-</sup> (bicarbonate), as the filtered load of HCO<sub>3</sub><sup>-</sup> exceeds the ability of the renal tubule to reabsorb it.
==See also==
* [[hypokalemia]]
==References==
{{reflist}}
==External links==
* {{FPnotebook|REN7}}
{{Fluid, electrolyte, acid base metabolic pathology}}
[[Category:Electrolyte disturbances]]
{{disease-stub}}
[[de:Metabolische Alkalose]]
[[it:Alcalosi metabolica]]