Abstract
Total serum magnesium is a common clinical measurement for assessing magnesium status; however, magnesium in blood represents less than 1% of the body’s total magnesium content. We measured intramuscular ionized magnesium by phosphorus magnetic resonance spectroscopy (31P-MRS) and tested the hypothesis that this measure better correlates with skeletal muscle function and captures more closely the effect of aging than the traditional measure of total serum magnesium. Data were collected from 441 participants (age 24–98 years) in the Baltimore Longitudinal Study of Aging (BLSA), a study of normative aging that encompasses a broad age range. Results showed that intramuscular ionized magnesium was negatively associated with age (β = −0.29, p < 0.001, R2 = 0.08) and positively associated with knee-extension strength (β = 0.31, p < 0.001, and R2 = 0.1 in women; and β = 0.2, p = 0.003, and R2 = 0.04 in men), while total serum magnesium showed no association with age or strength (p = 0.27 and 0.1, respectively). Intramuscular ionized magnesium was significantly lower in women that in men (p < 0.001), perhaps due to chronic latent Mg deficiency in women that is not otherwise detected by serum magnesium levels. Based on these findings, we suggest that intramuscular ionized magnesium from 31P-MRS is a better clinical measure of magnesium status than total serum magnesium, and could be measured when muscle weakness of unidentified etiology is detected. It may also be used to monitor the effectiveness of oral magnesium interventions, including supplementation.
Highlights
Readily accessible as a clinical measurement, serum magnesium (Mg) represents only 0.3% of total body Mg, the majority of which is located in tissue and is active in a variety of enzymatic processes
We investigate the relationships between these measures, age, sex, and muscle function in a cohort of normatively aging men and women from the Baltimore Longitudinal Study of Aging (BLSA), ranging from 24 to 98 years old
This association remained significant after adjusting for serum calcium, serum albumin, and 25-hydroxyvitamin D, with β = −0.11, 95% CI = [−0.2, −0.02], p = 0.02, adjusted R2 = 0.08
Summary
Readily accessible as a clinical measurement, serum magnesium (Mg) represents only 0.3% of total body Mg, the majority of which is located in tissue and is active in a variety of enzymatic processes. Recent work by Welch et al has shown associations between dietary Mg and indices of skeletal muscle mass, grip strength, and leg explosive power in men and women of all ages (Welch et al, 2016, 2017; Hayhoe et al, 2018). For this reason, measures of intramuscular Mg may serve as better markers than serum Mg for understanding the relationship between Mg levels and skeletal muscle function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
