From the Guidelines
Metabolic alkalosis should be managed by addressing the underlying cause, correcting electrolyte imbalances, and considering the use of normal saline infusion, potassium chloride supplementation, and acetazolamide as needed, as recommended by the most recent guidelines 1.
Causes and Symptoms
Metabolic alkalosis is a condition characterized by elevated blood pH due to increased bicarbonate levels in the body. It typically results from excessive loss of acid or accumulation of base. Common causes include vomiting, diuretic use, hypokalemia, and excessive alkali intake. Symptoms may include confusion, muscle twitching, and in severe cases, seizures or arrhythmias.
- Hypokalemic metabolic alkalosis is a key feature of Bartter syndrome, a rare genetic disorder affecting the kidneys 1.
- Other rare tubulopathies, such as congenital chloride diarrhea, can also cause metabolic alkalosis 1.
Treatment
Treatment focuses on addressing the underlying cause while correcting electrolyte imbalances.
- For volume-depleted patients, normal saline infusion helps correct the alkalosis by improving kidney function and bicarbonate excretion.
- Potassium chloride supplementation is often necessary, typically 40-80 mEq daily divided into multiple doses, as potassium deficiency frequently accompanies and perpetuates alkalosis.
- In severe cases (pH > 7.60), dilute hydrochloric acid may be administered in an ICU setting.
- Acetazolamide (250-500 mg orally or IV every 6 hours) can help increase bicarbonate excretion in volume-overloaded patients.
- Monitoring electrolytes, particularly potassium, is essential during treatment, as recommended by the European Rare Kidney Disease Reference Network Working Group for Tubular Disorders 1.
Diagnosis and Management
The diagnosis of metabolic alkalosis involves assessing urinary chloride excretion and distinguishing renal from extrarenal salt losses 1.
- Genetic analysis and clinical testing, such as diuretic tests, may be used to characterize the clinical diagnosis of rare tubulopathies, but their diagnostic value is limited 1.
- The Kidney Disease: Improving Global Outcomes consensus statement on GS advises against routine tubular function testing in patients with BS, except in individual challenging cases or for research purposes 1.
From the Research
Definition and Causes of Metabolic Alkalosis
- Metabolic alkalosis is a primary pathophysiologic event characterized by the gain of bicarbonate or the loss of nonvolatile acid from extracellular fluid 2.
- It is the result of an increase in bicarbonate production, a decrease in bicarbonate excretion, or a loss of hydrogen ions 3.
- Metabolic alkalosis results from alkali accumulation or acid loss, and it is associated with a secondary increase in carbon dioxide arterial pressure (PaCO2) 4.
Pathogenesis and Maintenance of Metabolic Alkalosis
- The pathogenesis of metabolic alkalosis involves either a loss of fixed acid or a net accumulation of bicarbonate within the extracellular fluid 5.
- The kidney is equipped with sophisticated mechanisms to avert the generation or the persistence (maintenance) of metabolic alkalosis by enhancing bicarbonate excretion 5.
- Factors that interfere with these mechanisms will impair the ability of the kidney to eliminate excess bicarbonate, therefore promoting the generation or impairing the correction of metabolic alkalosis 5.
Clinical States Associated with Metabolic Alkalosis
- Clinical states associated with metabolic alkalosis include vomiting, mineralocorticoid excess, the adrenogenital syndrome, licorice ingestion, diuretic administration, and Bartter's and Gitelman's syndromes 2.
- Other clinical states associated with metabolic alkalosis include aldosterone or cortisol excess, licorice ingestion, chloruretic diuretics, excess calcium alkali ingestion, and genetic diseases such as Bartter syndrome, Gitelman syndrome, and cystic fibrosis 5.
Treatment of Metabolic Alkalosis
- Treatment of metabolic alkalosis is simple, once the pathophysiology of the cause is delineated 2.
- Therapy consists of reversing the contributory factors that are promoting the alkalosis and, in severe cases, administration of carbonic anhydrase inhibitors, acid infusion, and low bicarbonate dialysis 2.
- Most cases of metabolic alkalosis can be managed with fluid and electrolyte therapy 6.
- When metabolic alkalosis needs to be resolved quickly or when conventional therapy cannot be tolerated, mineral acid administration should be instituted 6.