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Magnesium deficiency in two hypertensive patient groups
1University of Nebraska Medical Center, Omaha.
Insights
Magnesium deficiency, linked to heart issues, may occur with hydrochlorothiazide (HCTZ) use. Measuring magnesium retention, not just serum levels, is crucial for accurate assessment in hypertensive patients.
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.
Abstract:
Magnesium (Mg) deficiency can contribute to cardiac dysrhythmias and may predispose to ischemic heart disease. Most diuretic agents cause loss of Mg, but serum levels may be normal despite cellular depletion. We studied the clinical characteristics of hypertensive patients treated for at least 6 months with either hydrochlorothiazide (HCTZ) or a single nondiuretic drug. To evaluate Mg status in our patients, we measured the percentage retention of a parenterally administered Mg load as an accurate indicator of functionally available total body Mg. Serum lipid, blood chemistry, and serum Mg values were obtained, and cardiac exercise testing and Holter monitoring were done. Levels of potassium were lower, but those of serum Mg were higher with HCTZ treatment despite double the Mg load retention. The Mg load retention data indicate relative Mg depletion in the HCTZ-treated group. Eighty percent of all patients studied had abnormal retention of Mg, even though their serum levels were normal. A percentage Mg load retention determination is needed to assess accurately Mg status.