Medication Summary
Sodium bicarbonate (NaHCO3) is the agent most commonly used to correct metabolic acidosis. However, the role of alkali therapy is controversial in the treatment of lactic acidosis, with some evidence suggesting that HCO3- therapy produces only a transient increase in the serum HCO3- level and that this can lead to intracellular acidosis and worsening of lactic acidosis. Other agents may be indicated in patients with metabolic acidosis due to certain underlying disease processes (eg, carbonic anhydrase inhibitors in salicylate toxicity, insulin in diabetic ketoacidosis).
Alkalinizing Agents
Class Summary
Acute metabolic acidosis is usually treated with alkali therapy to raise plasma pH and to maintain it at greater than 7.20.
Sodium bicarbonate
Sodium bicarbonate is a systemic and urinary alkalinizer used to increase serum or urinary HCO3- concentration and raise pH. Dosing is based on the clinical setting, blood pH, serum HCO3- level, and PaCO2.
Tromethamine (THAM)
THAM combines with hydrogen ions to form a bicarbonate buffer. It is used to prevent and correct systemic acidosis. It is available as 0.3-mol/L IV solution containing 18 g (150 mEq) per 500 mL (0.3 mEq/mL).
Carbonic Anhydrase Inhibitors
Class Summary
Agents in this class may be used to induce alkaline diuresis.
Acetazolamide (Diamox)
This agent is used in the treatment of salicylate poisoning. It reduces the reduction of hydrogen ion secretion at the renal tubule and increases excretion of sodium, potassium, bicarbonate, and water. The goal is to maintain the urine pH at greater than 7.5 until the salicylate level falls below 30-50 mg/dL.
Antidiabetic Agents
Class Summary
These agents are used for the treatment of ketoacidosis.
Insulin
Insulin is administered, to facilitate cellular uptake of glucose, reduce gluconeogenesis, and halt lipolysis and production of ketone bodies. In addition, normal saline is administered to restore extracellular volume; potassium and phosphate replacement also may be necessary.
Detoxification Agents
Class Summary
These agents may be used in methanol or ethylene glycol poisoning.
Fomepizole (Antizol)
Begin fomepizole treatment immediately upon suspicion of ethylene glycol ingestion based on patient history or anion gap metabolic acidosis, increased osmolar gap, oxalate crystals in urine, or documented serum methanol level.
Activated charcoal (Actidose-Aqua, Requa Activated Charcoal)
This agent can be used to increase the excretion of salicylate. It is used in the emergency treatment of poisoning caused by drugs and chemicals. The network of pores present in activated charcoal absorbs 100-1000 mg of drug per gram of charcoal. It prevents absorption by adsorbing the drug in the intestine. Multidose charcoal may interrupt enterohepatic recirculation and enhance elimination by enterocapillary exsorption. Theoretically, by constantly bathing the GI tract with charcoal, the intestinal lumen serves as a dialysis membrane for reverse absorption of the drug from intestinal villous capillary blood into the intestine. It does not dissolve in water.
Tables
Characteristics |
Proximal (Type 2) |
Distal (Type 1) |
Type 4 |
Primary defect |
Proximal HCO3 - reabsorption |
Diminished distal H+ secretion |
Diminished ammoniagenesis |
Urine pH |
< 5.5 when serum HCO3 - is low |
>5.5 |
< 5.5 |
Serum HCO3 - |
>15 mEq/L |
Can be < 10 mEq/L |
>15 mEq/L |
Fractional excretion of HCO3 - (FEHCO3) |
>15-20% during HCO3 - load |
< 5% (can be as high as 10% in children) |
< 5% |
Serum K+ |
Normal or mild decrease |
Mild-to-severe decrease* |
High |
Associated features |
Fanconi syndrome |
... |
Diabetes mellitus, renal insufficiency |
Alkali therapy |
High doses |
Low doses |
Low doses |
Complications |
Osteomalacia or rickets |
Nephrocalcinosis, nephrolithiasis |
... |
*K+ may be high if RTA is due to volume depletion. |
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- Overview
- Presentation
- DDx
- Workup
- Approach Considerations
- Laboratory Evaluation
- Complete Blood Count
- Urinalysis
- Urine Anion Gap
- Ketone Level
- Serum Lactate level
- Salicylate levels and Iron levels
- Transtubular Potassium Gradient
- Plasma Renin Activity, Plasma Aldosterone levels, and FEHCO3-
- Ammonium Chloride Loading Test
- Urine-Blood PaCO2 Gradient Following HCO3- Loading
- Imaging Studies and Electrocardiography
- Show All
- Treatment
- Medication
- Questions & Answers
- Tables
- References
