Metabolic Acidosis Summarized

Metabolic Acidosis is excessive blood acidity caused by an overabundance of acid in the blood or a loss of bicarbonate from the blood.

• Blood acidity increases when people ingest substances that contain or produce acid.
• People with metabolic acidosis experience nausea, vomiting, and fatigue and may breathe faster and deeper than normal. 
• Tests on blood samples show there is too much acid.

If an increase in acid overwhelms the body’s pH buffering systems, the blood will become acidic.  The kidneys try to compensate by excreting more acid in the urine.  However, they can be overwhelmed if the body continues to produce too much acid, leading to severe acidosis and eventually, coma. 

Causes

Metabolic acidosis develops when the amount of acid in the body is increased through ingestion of a substance that is, or can be broken down (metabolized) to, an acid – such as wool alcohol (methanol), antifreeze (ethylene glycol), or large doses of aspirin (acetylsalicylic acid).  Metabolic acidosis can also occur as a consequence of abnormal metabolism.  The body produces excess acid in the advanced stages of shock and in poorly controlled type 1 diabetes mellitus.  Even the production of normal amounts of acid may lead to acidosis when the kidneys are not functioning normally, and are not, therefore, able to excrete sufficient quantities of acid in the urine.   

Major causes of Metabolic Acidosis

• Diabetic ketoacidosis (buildup of ketones)
• Drugs and substances such as acetazolamide, alcohol, aspirin and iron
• Lactic acidosis (buildup of lactic acid, as occurs in shock)
• Loss of bases such as bicarbonate, through the digestive tract from diarrhea, an ileostomy, or colostomy.
• Kidney failure
• Poisons such as carbon monoxide, cyanide, ethylene glycol, and methanol
• Renal tubular acidosis (a form of kidney malfunction)

Symptoms

People with mild metabolic acidosis may have not symptoms, but usually experience nausea, vomiting, and fatigue.  As the acidosis worsens, people begin to feel extremely week and drowsy and may feel confused and increasingly nauseated.  Eventually blood pressure can fall leading to shock, coma and death. 

Treatment

The treatment of metabolic acidosis depends primarily on the cause.  For instance, treatment may be needed to control diabetes with insulin or to remove the toxic substance from the blood in cases of poisoning.  Acidosis may also be treated directly.  If the acidosis is mild, the administration of intravenous fluids may be all that is needed.  Rarely, when acidosis is very severe, bicarbonate may be given intravenously.  However, bicarbonate provides only temporary relief and may cause harm – for example, by overloading the body with sodium and water.

Referrence: Merickmanuals.com  Merick Manual Home Edition: Section Disorders of Nutrition and Metabolism: Subject: Acid-Base Balance.