View source for Acidosis

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==Overview==
:''For acidosis referring to acidity of the urine, see [[renal tubular acidosis]].''

Acidosis is an increased [[acidity]] (i.e. an increased [[hydrogen ion]] [[concentration]]).  If not further qualified, it refers to acidity of the [[blood plasma]]. 

Generally, acidosis is said to occur when arterial [[pH]] falls below 7.35, while its counterpart ([[alkalosis]]) occurs at a pH over 7.45. [[Arterial blood gas]] analysis and other tests are required to separate the main causes.

Strictly speaking, the term acidemia would be more appropriate to describe the state of low blood pH, reserving acidosis to describe the processes leading to these states. Nevertheless, most physicians use the terms interchangeably. The distinction may be relevant where a patient has factors causing both acidosis and alkalosis, where the relative severity of both determines whether the result is a high or a low pH.

The rate of cellular metabolic activity affects and, at the same time, is affected by the pH of the body fluids. In mammals, the normal pH of arterial blood lies between 7.35 and 7.50 depending on the species (e.g. healthy human-arterial blood pH varies between 7.35 and 7.45). Blood pH values compatible with life in mammals are limited to a pH range between 6.8 and 7.8. Changes in the pH of arterial blood (and therefore the extracellular fluid) outside this range result in irreversible cell damage (Needham, 2004).

==Classification==
* [[Acidosis]] can either be metabolic or respiratory.
*:* Both are caused by low arterial pH.
** '''Metabolic''' acidosis is due to an increased accumulation of acid equivalents through impairment of the regulatory ability of the [[liver]], [[kidneys]], or [[metabolism]].
** '''Respiratory''' acidosis is caused by a retention of [[carbon dioxide]] due to inadequate [[hypoventilation]] or pulmonary ventilation.

==Pathophysiology==
===Respiratory acidosis===
[[Respiratory acidosis]] results from a build-up of carbon dioxide in the blood (hypercapnia) due to [[hypoventilation]]. It is most often caused by [[lung|pulmonary]] problems, although [[head injury|head injuries]], drugs (especially [[anaesthetic]]s and [[sedative]]s), and [[brain tumor]]s can also bring it on. [[Emphysema]], chronic [[bronchitis]], [[asthma]], severe [[pneumonia]], and [[aspiration pneumonia|aspiration]] are among the most frequent causes. It can also occur as a response to chronic [[metabolic alkalosis]].

Blood gases show pH below 7.35 as above mentioned, and PaCO<sub>2</sub> will be high (>45 mmHg / 6 kPa).

The key to distinguish between respiratory and metabolic acidosis is that in respiratory acidosis, the CO<sub>2</sub> is increased while the [[bicarbonate]] is either normal (uncompensated) or increased (compensated). Compensation occurs if respiratory acidosis persists for days or longer and a chronic phase is entered with partial buffering of the acidosis through renal bicarbonate retention.

===Metabolic acidosis===
[[Metabolic acidosis]] may result from disturbances in the ability to excrete acid via the [[kidney]]s.  Renal acidosis is associated with an accumulation of urea and creatinine as well as metabolic acid residues of protein catabolism. 

An increase in the production of metabolic acids may also produce metabolic acidosis.  For example, lactic acidosis may occur from 1) severe (PaO2 <36mm Hg) [[Hypoxia (medical)|hypoxemia]] causing a fall in the rate of oxygen diffusion from arterial blood to tissues, or 2) [[hypoperfusion]] (e.g. hypovolemic shock) causing an inadequate blood delivery of oxygen to tissues. A rise in lactate out of proportion to the level of pyruvate, e.g. in mixed venous blood, is termed "excess lactate" and is the best indicator of an inadequate flow of oxygen into the body's mitochondria from either cause. Oxygen debt (and muscle excess lactate) is also seen in strenuous exercise. Once oxygenation is restored, the acidosis clears quickly.  Another example of increased production of acids occurs in starvation and diabetic acidosis.  It is due to the accumulation of ketoacids (ketosis) and reflects a severe shift from glycolysis to [[lipolysis]] for fuel needs. 

Acidic [[poison]]s, [[iron]] etc., and decreased production of [[bicarbonate]] may also produce metabolic acidosis.

Metabolic acidosis can result in stimulation of [[chemosensor|chemoreceptors]] and so increase [[alveolar ventilation]], leading to respiratory compensation, otherwise known as [[Kussmaul breathing]], which is a specific type of [[hyperventilation]]. Should this situation persist the patient is at risk for exhaustion leading to [[respiratory failure]].

Mutations to the [[V-ATPase]] 'a4' or 'B1' isoforms result in distal renal tubular acidosis—a condition that leads to metabolic acidosis—in some cases with sensorineural deafness.

In blood gas tests, it is characterised by a low [[pH]], low blood [[HCO3|HCO<sub>3</sub>]], and normal or low PaCO<sub>2</sub>. 
In addition to [[arterial blood gas]] one can use the [[anion gap]] to differentiate between possible causes.

The [[Henderson-Hasselbalch equation]] is useful for calculating blood pH, because blood is a [[buffer solution]]. The amount of metabolic acid accumulating can also be quantitated by using buffer base deviation, a derivative estimate of the metabolic as opposed to the respiratory component. In hypovolemic shock for example, approximately 50% of the metabolic acid accumulation is lactic acid, which disappears as blood flow and oxygen debt are corrected.

== Causes == 

===Common causes of acidosis===

*Traumatic shock 
*[[Sepsis]] 
*Severe [[hypoxemia]] 
*Severe [[diarrhoea]] 
*[[Renal failure]] 
*[[Multiple organ dysfunction syndrome]] 
*[[Nausea and Vomiting]]  
*Mesenteric insufficiency 
*[[Ketoacidosis]] 
*[[Ischemic colitis]]  
*[[Hypotension]] 
*Ethanol ingestion 
*[[Cardiogenic shock]] 
*[[Alcohol]] 
*[[Acetylsalicylic acid]]


===Causes by Organ System===
{|style="width:80%; height:100px" border="1"
|style="height:100px"; style="width:25%" border="1" bgcolor="LightSteelBlue" | '''Cardiovascular'''
|style="height:100px"; style="width:75%" border="1" bgcolor="Beige" |
[[Beriberi heart disease]],
[[cardiac arrest]],
[[cardiogenic shock]],
[[cardiogenic shock]],
[[cardiomyopathy]],
[[cataract and cardiomyopathy]],
[[congestive heart failure]],
[[hemorrhagic shock]],
[[hypoperfusion]],
[[hypotension]],
[[malignant hypertension]],
[[myocardial Infarction]],
[[pulseless electrical activity]],
[[pulmonary edema]],
[[shock]],
[[ST elevation myocardial infarction]],
[[torsade de pointes]],
[[ventricular arrhythmias]],
[[ventricular fibrillation]]
|-
|-bgcolor="LightSteelBlue"
| '''Chemical/Poisoning'''
|bgcolor="Beige"| [[Alcohol]], [[carbon monoxide poisoning]], [[cocaine]], copperhead snake poisoning, crotalidae snake poisoning, [[cyanide poisoning]], [[diethylene glycol]], [[endothall]], [[ethanol]], [[ethylene glycol]], [[germanium]], [[isopropyl alcohol]], [[methanol]], [[propylene glycol]], [[salicylate]], [[strychnine]]
|-
|-bgcolor="LightSteelBlue"
| '''Dental'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Dermatologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Drug Side Effect'''
|bgcolor="Beige"|
[[Acetazolamide]],
[[acetylsalicylic acid]],
[[aspirin]],
[[biguanide]],
[[carbonic anhydrase inhibitors]],
[[didanosine]],
[[ethanol ingestion]],
[[glyburide]],
[[metformin]],
[[paracetamol]],
[[pergolide]],
[[phenformin]],
[[zalcitabine]],
[[zidovudine]]
|-
|-bgcolor="LightSteelBlue"
| '''Ear Nose Throat'''
|bgcolor="Beige"| No underlying causes
|- 
|-bgcolor="LightSteelBlue"
| '''Endocrine'''
|bgcolor="Beige"|
[[Adrenal cortex insufficiency]],
[[diabetes]],
[[diabetic ketoacidosis]],
[[GRACILE syndrome]],
[[hyperchloremic acidosis]],
[[hyperosmolar non-ketotic diabetic coma]],
[[hypoglycemia]],
[[ketoacidosis]],
[[permanent neonatal diabetes mellitus]]
[[pheochromocytoma]],
[[thyrotoxicosis]]
|- 
|-bgcolor="LightSteelBlue"
| '''Environmental'''
|bgcolor="Beige"|
[[Drowning]], 
hypothermic shivering
|-
|-bgcolor="LightSteelBlue"
| '''Gastroenterologic'''
|bgcolor="Beige"|
[[Acute liver failure]],
[[biliary fistula]],
[[chronic mesenteric insufficiency]]
[[diarrhea]],
[[fistula]],
[[hepatic failure]],
[[hepatopathy]],
[[ileus]],
[[ischemic colitis]],
[[liver disease]],
[[microvillus inclusion disease]],
[[nausea and vomiting]],
[[necrotizing enterocolitis]],
[[pancreatic fistula]],
[[severe liver disease]],
[[short bowel syndrome]],
[[small intestine fistula]],
[[volvulus]]
|-
|-bgcolor="LightSteelBlue"
| '''Genetic'''
|bgcolor="Beige"|
[[3-alpha-hydroxyisobutyryl-CoA hydrolase deficiency]],
[[3-Hydroxyacyl-CoA dehydrogenase II Deficiency]],
[[3-methylglutaconic aciduria]],
[[biotinidase deficiency]],
[[coenzyme Q cytochrome c reductase deficiency]],
[[complex 1 mitochondrial respiratory chain deficiency]],
[[cystinosis]],
[[fanconi syndrome]],
[[fanconi-ichthyosis-dysmorphism]],
[[fructose-1,6-bisphosphatase deficiency]],
[[glycogen storage diseases]],
[[glutaric aciduria type 1]], 
[[glutaric acidemia type 2]]
[[GRACILE syndrome]],
[[inborn urea cycle disorder]],
[[lipoamide dehydrogenase deficiency]],
[[long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency]],
[[medium-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency]],
[[MELAS]],
[[metabolic disorders]],
[[mitochondrial DNA depletion syndrome]],
[[mitochondrial myopathy]],
[[mitochondrial neurogastrointestinal encephalopathy syndrome]],
[[multiple carboxylase deficiency]],
[[myopathy]],
[[NADH CoQ reductase deficiency]],
[[Ondine's curse]],
[[propionic acidemia]],
[[pyruvate carboxylase deficiency]],
[[pyruvate dehydrogenase phosphatase deficiency]],
[[SCHAD deficiency]],
[[sideroblastic anemia]],
[[succinic acidemia]],
[[type I glycogen storage disease]],
[[Von Gierke disease]],
[[Wilson's Disease]],
hydroxyacyl-coa dehydrogenase deficiency type 2,
hydroxysteroid dehydrogenase deficiency,
mitochondrial encephalomyopathy aminoacidopathy
|-
|-bgcolor="LightSteelBlue"
| '''Hematologic'''
|bgcolor="Beige"|[[Splenic infarction]] , severe [[anemia]]
|-
|-bgcolor="LightSteelBlue"
| '''Iatrogenic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Infectious Disease'''
|bgcolor="Beige"|[[Sepsis]], [[infection]], fever, [[disseminated intravascular coagulation]], [[clostridium difficile]], [[cerebral malaria]] 
|-
|-bgcolor="LightSteelBlue"
| '''Musculoskeletal/Orthopedic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Neurologic'''
|bgcolor="Beige"| [[Acute disseminated encephalomyelitis]], [[grand mal seizure]], [[epilepsy]], [[coma]], [[CNS depression]], [[cerebral hypoxia]], [[cerebral edema]] 
|-
|-bgcolor="LightSteelBlue"
| '''Nutritional/Metabolic'''
|bgcolor="Beige"| [[Glutaric aciduria type 1]], [[glutaric acidemia type 2]], [[total parenteral nutrition]], [[starvation]] 
|-
|-bgcolor="LightSteelBlue"
| '''Obstetric/Gynecologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Oncologic'''
|bgcolor="Beige"| [[Tumor]], [[myeloma]], [[lymphoma]], [[leukemia]] 
|-
|-bgcolor="LightSteelBlue"
| '''Ophthalmologic'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Overdose/Toxicity'''
|bgcolor="Beige"| [[Toluene]], Salicylates, [[ethylene glycol]], ethanol ingestion, [[alcohol]], [[isopropyl alcohol]], [[diethylene glycol]]
|-
|-bgcolor="LightSteelBlue"
| '''Psychiatric'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Pulmonary'''
|bgcolor="Beige"| [[Status asthmaticus]], severe [[asthma]], [[pulmonary embolism]], [[infant respiratory distress syndrome]], [[hypercapnia]], following chronic [[hyperventilation]] CO2 intoxication, [[chronic obstructive lung disease]], [[apnea]], [[acute respiratory distress syndrome]] 
|-
|-bgcolor="LightSteelBlue"
| '''Renal/Electrolyte'''
|bgcolor="Beige"| [[Hypoaldosteronism]], [[hypokalemic distal renal tubular acidosis]], hyperkalemic [[distal renal tubular acidosis]], kidney disorders, [[proximal renal tubular acidosis]], [[renal tubular acidosis]], [[renal failure]], renal circulatory insufficiency, [[hyperkalemia]], [[distal renal tubular acidosis]], decreased renal acid excretion, [[chronic kidney disease]], chronic interstitial nephritis, [[acute renal failure]], [[acute glomerulonephritis]] 
|-
|-bgcolor="LightSteelBlue"
| '''Rheumatology/Immunology/Allergy'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Sexual'''
|bgcolor="Beige"| No underlying causes
|-
|-bgcolor="LightSteelBlue"
| '''Trauma'''
|bgcolor="Beige"| Traumatic [[shock]] 
|-
|-bgcolor="LightSteelBlue"
| '''Urologic'''
|bgcolor="Beige"| [[Ureterosigmoidostomy]], [[urinary diversion]]
|-
|-bgcolor="LightSteelBlue"
| '''Miscellaneous'''
|bgcolor="Beige"| [[Hypoxia]], [[hypovolemia]] , heavy physical work, [[fistula]], [[enhanced metabolic rate]], [[diet]]
|-
|}

===Causes in Alphabetical Order <ref>Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:77 ISBN 1591032016</ref> <ref>Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:68 ISBN 140510368X</ref>===

{{columns-list|3|
* [[3-alpha-hydroxyisobutyryl-CoA hydrolase deficiency]]
* [[3-Hydroxyacyl-CoA dehydrogenase II Deficiency]]
* [[3-methylglutaconic aciduria]]
* [[Acetazolamide]]
* [[Acetylsalicylic acid]]
* [[Acute disseminated encephalomyelitis]]
* [[acute glomerulonephritis]]
* [[Acute liver failure]]
* [[Acute renal failure]]
* [[Acute respiratory distress syndrome]]
* [[Adrenal cortex insufficiency]]
* [[Alcohol]]
* [[Apnea]]
* [[Aspirin]]
* [[Beriberi heart disease]]
* [[Biguanide]]
* [[Biliary fistula]]
* [[Biotinidase deficiency]]
* [[Carbon monoxide poisoning]]
* [[Carbonic anhydrase inhibitors]]
* [[Cardiac arrest]]
* [[Cardiogenic shock]]
* [[Cardiomyopathy]]
* [[Cataract and cardiomyopathy]]
* [[Cerebral edema]]
* [[Cerebral hypoxia]]
* [[Cerebral malaria]]
* [[Chronic interstitial nephritis]]
* [[Chronic kidney disease]]
* [[Chronic mesenteric insufficiency]]
* [[Chronic obstructive lung disease]]
* [[Clostridium difficile]]
* [[CNS depression]]
* [[Cocaine]]
* [[Coenzyme Q cytochrome c reductase deficiency]]
* [[Coma]]
* [[Complex 1 mitochondrial respiratory chain deficiency]]
* [[Congestive heart failure]]
* [[Copperhead snake poisoning]]
* [[Crotalidae snake poisoning]]
* [[Cyanide poisoning]]
* [[Cystinosis]]
* [[Decreased renal acid excretion]]
* [[Diabetes]]
* [[Diabetic ketoacidosis]]
* [[Diarrhea]]
* [[Didanosine]]
* [[Diethylene glycol]]
* [[Disseminated intravascular coagulation]]
* [[Distal renal tubular acidosis]]
* [[Drowning]] 
* [[Endothall]]
* [[Epilepsy]]
* [[Ethanol]]
* [[Ethylene glycol]]
* [[Fanconi syndrome]]
* [[Fanconi-ichthyosis-dysmorphism]]
* [[Fever]]
* [[Fistula]]
* [[Fructose-16-bisphosphatase deficiency]]
* [[Germanium]]
* [[Glutaric acidemia type 2]]
* [[Glutaric aciduria type 1]]
* [[Glyburide]]
* [[Glycogen storage diseases]]
* [[GRACILE syndrome]]
* [[Grand mal seizure]]
* [[Hemorrhagic shock]]
* [[Hepatic failure]]
* [[Hepatopathy]]
* [[Hydroxyacyl-coa dehydrogenase deficiency type 2]]
* [[Hydroxysteroid dehydrogenase deficiency]]
* [[Hypercapnia]]
* [[Hyperchloremic acidosis]]
* [[Hyperkalemia]]
* [[Hyperosmolar non-ketotic diabetic coma]]
* [[Hypoaldosteronism]]
* [[Hypoglycemia]]
* [[Hypokalemic distal renal tubular acidosis]]
* [[Hypoperfusion]]
* [[Hypothermic]] shivering
* [[Ileus]]
* [[Inborn urea cycle disorder]]
* [[Infant respiratory distress syndrome]]
* [[Infection]]
* [[Ischemic colitis]] 
* [[Isopropyl alcohol]]
* [[Ketoacidosis]]
* [[Kidney disorders]]
* [[Leukemia]]
* [[Lipoamide dehydrogenase deficiency]]
* [[Liver disease]]
* [[Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency]]
* [[Lymphoma]]
* [[Malignant hypertension]]
* [[Medium-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency]]
* [[MELAS]]
* [[Metabolic disorders]]
* [[Metformin]]
* [[Methanol]]
* [[Microvillus inclusion disease]]
* [[Mitochondrial DNA depletion syndrome]]
* [[Mitochondrial encephalomyopathy aminoacidopathy]]
* [[Mitochondrial myopathy]]
* [[Mitochondrial neurogastrointestinal encephalopathy syndrome]]
* [[Multiple carboxylase deficiency]]
* [[Myeloma]]
* [[Myocardial Infarction]]
* [[Myopathy]]
* [[NADH CoQ reductase deficiency]]
* [[Necrotizing enterocolitis]]
* [[Ondine's curse]]
* [[Pancreatic fistula]]
* [[Paracetamol]]
* [[Pergolide]]
* [[Permanent neonatal diabetes mellitus]]
* [[Phenformin]]
* [[Pheochromocytoma]]
* [[Propionic acidemia]]
* [[Propylene glycol]]
* [[Proximal renal tubular acidosis]]
* [[Pulmonary edema]]
* [[Pulmonary embolism]]
* [[Pulseless electrical activity]]
* [[Pyruvate carboxylase deficiency]]
* [[Pyruvate dehydrogenase phosphatase deficiency]]
* [[Renal circulatory insufficiency]]
* [[Renal failure]]
* [[Renal tubular acidosis]]
* [[Salicylate]]
* [[Salicylates]]
* [[SCHAD deficiency]]
* [[Sepsis]]
* [[Severe liver disease]]
* [[Shock]]
* [[Short bowel syndrome]]
* [[Sideroblastic anemia]]
* [[Small intestine fistula]]
* [[ST elevation myocardial infarction]]
* [[Starvation]]
* [[Status asthmaticus]]
* [[Strychnine]]
* [[Succinic acidemia]]
* [[Thyrotoxicosis]]
* [[Toluene]]
* [[Torsade de pointes]]
* [[Total parenteral nutrition]]
* [[Tumor]]
* [[Type I glycogen storage disease]]
* [[Ureterosigmoidostomy]]
* [[Urinary diversion]]
* [[Ventricular arrhythmias]]
* [[Ventricular fibrillation]]
* [[Volvulus]]
* [[Vomiting]]
* [[Von Gierke disease]]
* [[Wilson's Disease]]
* [[Zalcitabine]]
*[[Zidovudine]]
}}


==== Respiratory Acidosis ====
{{MultiCol}}
* [[Amyotrophic Lateral Sclerosis]] ([[ALS]])
* [[Botulism]]
* Brainstem injury or infarction
* [[Bronchospasm]]
* Cerebral injury or infarction
* Chest [[trauma]]
* [[Congestive heart failure]]
* Diaphragmatic paralysis
* [[Drugs]], [[toxin]]s
* [[Familial periodic paralysis]]
* [[Guillain-Barré syndrome]]
* High [[spinal cord injury]]
* [[Hypochloremic Acidosis]]
* [[Hypokalemic]] myopathy
* Inadequate mechanical ventilation
* [[Kyphoscoliosis]]
{{ColBreak}}
* [[Laryngeal spasm]] or edema
* [[Muscular Dystrophy]]
* [[Myasthenia Gravis]]
* [[Neoplasm]]
* [[Pneumonia]]
* [[Pneumothorax]]
* [[Poliomyelitis]]
* [[Polyradiculitis]]
* Primary [[Hypoventilation|hypoventilation]]
* [[Pulmonary edema]]
* [[Pulmonary embolism]]
* [[Acute respiratory distress syndrome|Respiratory Distress Syndrome]]
* [[Restrictive Lung Disease]]
* [[Sleep Apnea]]
* [[Smoke inhalation]]
* [[Tetanus]]
* Tracheal stenosis or edema
{{EndMultiCol}}

==Treatment==
Treatment of any of the varieties of metabolic acidosis is focused upon correction of the underlying problem. However, neutralizing the acidosis with infusions of bases like [[sodium bicarbonate]] may be temporarily helpful in some critical emergencies.

==References==
{{Reflist|2}}

==External Links==
* [http://kidney.niddk.nih.gov National Kidney and Urologic Diseases Information Clearinghouse]

{{Metabolic pathology}}
[[Category:Electrolyte disturbance]]
[[Category:Emergency medicine]]
[[Category:Intensive care medicine]]

[[cs:Acidóza]]
[[da:Acidose]]
[[de:Azidose]]
[[es:Acidosis]]
[[fr:Acidose]]
[[gl:Acidose]]
[[nl:Acidose]]
[[no:Acidose]]
[[pt:Acidose]]
[[ru:Ацидоз]]
[[sk:Acidóza]]
[[fi:Asidoosi]]
[[sv:Acidos]]
[[tl:Acidosis]]
[[Category:Inborn errors of metabolism]]

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