When should hemodialysis (HD) be considered in patients with metabolic alkalosis?

Hemodialysis for Metabolic Alkalosis

Hemodialysis is rarely indicated for metabolic alkalosis alone, but should be initiated when severe metabolic alkalosis occurs in dialysis-dependent patients who cannot be managed with conservative measures, specifically using a low-bicarbonate or bicarbonate-free dialysate to correct the alkalemia. 1, 2

Clinical Context and Pathophysiology

Metabolic alkalosis is uncommon in hemodialysis patients compared to metabolic acidosis, and typically only develops when precipitating factors are present such as vomiting, nasogastric suction, or excessive alkali ingestion (including baking soda). 2 When severe metabolic alkalosis does occur in dialysis patients, it can cause serious clinical consequences including:

• Sleep apnea 2
• Resistant hypertension 2
• Cardiac dysrhythmias 2
• Seizures 2
• Volume overload 2

When to Initiate Hemodialysis

Hemodialysis for metabolic alkalosis should be considered when:

• Severe symptomatic metabolic alkalosis develops in a dialysis-dependent patient with complications such as respiratory depression, altered mental status, or refractory hypertension that cannot be managed conservatively 1, 2

• The patient is already on hemodialysis and develops severe alkalosis from precipitating factors (vomiting, alkali ingestion, citrate infusion during dialysis) 1, 2, 3

• Conservative measures have failed to correct the alkalosis in a patient requiring dialysis for other indications 1

Dialysis Prescription for Metabolic Alkalosis

The key intervention is using a modified dialysate with reduced or zero bicarbonate concentration (negative-bicarbonate hemodialysis or low-bicarbonate dialysate) to allow correction of the alkalemia. 2 This approach has been successfully used to correct severe metabolic alkalosis and relieve associated clinical symptoms. 2

Important Caveats

Metabolic alkalosis is NOT a standard indication for initiating dialysis in non-dialysis-dependent patients. The primary indications for emergent hemodialysis remain persistent hyperkalemia, severe metabolic acidosis (not alkalosis), volume overload unresponsive to diuretics, and overt uremic symptoms including pericarditis and severe encephalopathy. 4, 5, 6

In mechanically ventilated patients receiving regional citrate anticoagulation during hemodialysis, severe metabolic alkalosis can develop with high citrate infusion rates, requiring careful monitoring of acid-base status and potential reduction of citrate dosing. 3

The evidence base for hemodialysis in metabolic alkalosis consists primarily of case reports rather than controlled trials, reflecting the rarity of this indication. 1, 2, 3, 7