Metabolic Acidosis
Produced by an underlying disorder, metabolic acidosis is a physiologic state of excess acid accumulation and deficient base bicarbonate. Symptoms result from the body’s attempts to correct the acidotic condition through compensatory mechanisms in the lungs, kidneys, and cells. Severe or untreated metabolic acidosis can be fatal.
Pediatric pointerMetabolic acidosis is more prevalent among children than adults because children have faster metabolic rates and lower ratios of water to total body weight and are therefore more vulnerable to acid-base imbalance.
Causes
Metabolic acidosis usually results from excessive burning of fats in the absence of usable carbohydrates. This can be caused by diabetic ketoacidosis, chronic alcoholism, malnutrition, or a low-carbohydrate, high-fat diet—all of which produce more keto acids than the metabolic process can handle. Other causes include:
anaerobic carbohydrate metabolism. A decrease in tissue oxygenation or perfusion (as occurs with pump failure after myocardial infarction or with pulmonary or hepatic disease, shock, or anemia) forces a shift from aerobic to anaerobic metabolism, causing a corresponding rise in the lactic acid level.
renal insufficiency and failure (renal acidosis). Underexcretion of metabolized acids or inability to conserve base bicarbonate results in excess acid accumulation or deficient base bicarbonate.
diarrhea and intestinal malabsorption. Loss of sodium bicarbonate from the intestines causes the bicarbonate buffer system to shift to the acidic side.
massive rhabdomyolysis. High quantities of organic acids added to the body with the breakdown of cells causes high anion gap acidosis.
poisoning and drug toxicity. Common causative agents such as salicylates, ethylene glycol, and methyl alcohol may produce acid-base imbalance.
hypoaldosteronism or use of potassium-sparing diuretics. These conditions inhibit distal tubular secretion of acid and potassium.
Complications
If untreated, metabolic acidosis may lead to hypotension, coma, arrhythmias, and cardiac arrest.
Assessment
The history of a patient with metabolic acidosis may point to the presence of risk factors, including associated disorders or the use of medications that contain alcohol or aspirin. Information about the patient’s urine output, fluid intake, and dietary habits (including any recent fasting) may help to establish the underlying cause and severity of metabolic acidosis.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
