Magnesium deficiency in two hypertensive patient groups.

Area of Science:

• Cardiology
• Clinical Chemistry
• Pharmacology

Background:

• Magnesium deficiency is associated with cardiac dysrhythmias and ischemic heart disease.
• Diuretic agents, like hydrochlorothiazide (HCTZ), can lead to magnesium loss.
• Serum magnesium levels may not reflect true cellular depletion.

Purpose of the Study:

• To evaluate the magnesium status in hypertensive patients treated with hydrochlorothiazide (HCTZ) versus nondiuretic drugs.
• To assess the accuracy of magnesium load retention as an indicator of total body magnesium.
• To investigate the clinical characteristics and magnesium levels in these patient groups.

Main Methods:

• Studied hypertensive patients on HCTZ or a nondiuretic drug for at least 6 months.
• Measured percentage retention of a parenterally administered magnesium load to assess functional body magnesium.
• Obtained serum lipid, blood chemistry, serum magnesium, performed cardiac exercise testing, and Holter monitoring.

Main Results:

• HCTZ-treated patients had lower potassium and higher serum magnesium levels, but retained less magnesium.
• Magnesium load retention data indicated relative magnesium depletion in the HCTZ group.
• Eighty percent of all patients exhibited abnormal magnesium retention despite normal serum levels.

Conclusions:

• Percentage magnesium load retention is a necessary determinant for accurately assessing magnesium status.
• Hydrochlorothiazide treatment may lead to functional magnesium depletion not evident in serum levels.
• Standard serum magnesium tests may underestimate magnesium deficiency in patients on diuretics.