Metabolic Alkalemia in Hypercalciuria Stone Formers: Does It Matter?

Area of Science:

• Nephrology
• Internal Medicine
• Clinical Chemistry

Background:

• Metabolic alkalemia occurrence in hypercalciuric nephrolithiasis outpatients is not well-documented.
• Patients with hypercalciuric nephrolithiasis are frequently treated with thiazides to lower urinary calcium, which can cause chloride loss.
• Potassium citrate supplementation, common in these patients, adds an alkali source.

Purpose of the Study:

• To investigate the incidence of metabolic alkalemia in outpatients with hypercalciuric nephrolithiasis.
• To identify potential risk factors and associated electrolyte disturbances in these patients.

Main Methods:

• Retrospective chart review of outpatients with calcium kidney stones (Jan 2013 - July 2021).
• Diagnosis of metabolic alkalemia based on venous blood gas: pH ≥7.46 and bicarbonate >26 mEq/L.
• Statistical analysis to compare patient groups with and without metabolic alkalemia.

Main Results:

• Metabolic alkalemia was diagnosed in 4.3% of patients.
• Thiazide use was noted in nearly all affected patients, with higher daily doses in those with alkalemia.
• Hypokalemia occurred in 37% of patients with metabolic alkalemia, alongside lower serum chloride, magnesium, and ionic calcium levels.

Conclusions:

• Metabolic alkalemia is uncommon but significant in hypercalciuric kidney stone formers.
• Close monitoring for hypokalemia and other electrolyte disorders is recommended for these patients, especially those on thiazide therapy.