Metabolic acidosis is a pH imbalance that occurs when the body has accumulated too much acid and does not have enough bicarbonate (an acid neutralizer) toeffectively neutralize the acid's effects. This disruption of the body's acid/base balance can be a mild symptom brought on by a lack of insulin (an antidiabetic drug), a starvation diet, or a gastrointestinal disorder like vomiting and diarrhea. Metabolic acidosis can indicate a more serious problem witha major organ like the liver, heart, or kidneys. It can also be one of the first signs of drug overdose or poisoning.
Metabolic acidosis occurs when the body has more acid than base in it. Chemists use the term "pH" to describe how acidic or basic a substance is. Based ona scale of 14, a pH of 7.0 is neutral. A pH below 7.0 is an acid; the lowerthe number, the stronger the acid. A pH above 7.0 is a base; the higher the number, the stronger the base. Blood pH is slightly basic (alkaline), with a normal range of 7.36-7.44. Although metabolic acidosis is suspected based on symptoms, it is usually confirmed by laboratory tests on blood and urine samples. Blood pH below 7.35 confirms the condition. Levels of other blood components, including potassium, glucose, ketones, or lactic acid, may also be abovenormal ranges. The level of bicarbonate in the blood will be low, usually less than 22 mEq/L. Urine pH may fall below 4.5 in metabolic acidosis.
Acid is a natural by-product of the breakdown of fats and other processes inthe body; however, in some conditions, the body does not have enough bicarbonate to balance the acids produced. This can occur when the body uses fats forenergy instead of carbohydrates. Conditions where metabolic acidosis can occur include chronic alcoholism, malnutrition, and diabetic ketoacidosis. Consuming a diet low in carbohydrates and high in fats can also produce metabolicacidosis. The disorder may also be a symptom of another condition like kidneyfailure, liver failure, or severe diarrhea. The build up of lactic acid in the blood, due to such conditions as heart failure, shock, or cancer, inducesmetabolic acidosis. Some poisonings and overdoses (aspirin, methanol, or ethylene glycol) also produce symptoms of metabolic acidosis.
In mild cases of metabolic acidosis, symptoms include headache, lack of energy, and sleepiness. Breathing may become fast and shallow. Nausea, vomiting, diarrhea, dehydration, and loss of appetite are also associated with metabolicacidosis. Diabetic patients with symptoms of metabolic acidosis may also have breath that smells fruity. The patient may lose consciousness or become disoriented. Severe cases can produce coma and death.
Treatment focuses first on correcting the acid imbalance. Usually, sodium bicarbonate and fluids are injected into the blood through a vein. An intravenous line may be started to administer fluids and allow for the quick injectionof other drugs that may be needed. If the patient is diabetic, insulin may beadministered. Drugs to regulate blood pressure or heart rate, to prevent seizures, or to control nausea and vomiting might be given. Vital signs like pulse, respiration, blood pressure, and body temperature will be monitored. Theunderlying cause of the metabolic acidosis must also be diagnosed and corrected.
If metabolic acidosis is recognized and treated promptly, the patient may have no long-term complications; however, the underlying condition that caused the acidosis needs to be corrected or managed. Severe metabolic acidosis thatis left untreated will lead to coma and death.
Diabetic patients especially need to routinely test their urine for sugar andacetone, strictly follow their appropriate diet, and take any medications orinsulin to prevent metabolic acidosis. Patients receiving tube feedings or intravenous feedings must be monitored to prevent dehydration or the accumulation of ketones or lactic acid.