Serum 25-hydroxy vitamin D and the risk of low muscle mass in young and middle-aged Korean adults

U-Shaped Association of Standardized Serum 25-Hydroxyvitamin D with Risk of Low Muscle Mass: A Population-Based Cross-Sectional Study

Background

In the United States (U.S.) general population, the association between standardized serum 25-hydroxyvitamin D (25(OH)D) concentration and risk of low muscle mass (LMM) remains unclear. Our research aimed to determine whether or not there was a relationship between serum 25(OH)D concentration and risk of LMM.

Methods

We analyzed the cross-sectional data of the US population that participated in the National Health and Nutrition Examination Survey between 2011 and 2014. The relationship between serum 25(OH)D concentration and LMM risk was evaluated using restricted cubic spline (RCS) with multivariate logistic regression model and subgroup analysis.

Results

In all, we included 10,256 people in our analysis. The RCS plot demonstrated a U-shaped relationship between serum 25(OH)D concentration and risk of LMM (P for nonlinearity <0.05). At a Vitamin D concentration of 38.5 nmol/L, LMM risk was at its lowest. Based on analyses stratified by age, sex, hypertension, and diabetes mellitus (DM), serum 25(OH)D concentration and risk of LMM were U-curve correlated for those age 40 or older, male, with hypertension, or without DM. However, LMM risk was positively related to serum 25(OH)D concentration in those younger than age 40 or in women.

Conclusion

There is a U-shaped relationship between serum 25(OH)D concentration and the risk of LMM in the general U.S. population. Careful monitoring and appropriate Vitamin D supplementation might lessen the risk of LMM.

Sarcopenia in youth

Recent research has revealed causes other than aging that may induce sarcopenia in young people, contrary to the long-studied age-dependent reduction in muscular mass and function. The risk of sarcopenia begins in early adulthood, resulting in exaggerated muscle dysfunction in later life. Despite its clinical significance, research on youth-onset sarcopenia is still in its infancy. Due to a paucity of epidemiologic data and standardized criteria for sarcopenia in youth, determining the prevalence of sarcopenia in the young population remains challenging. Based on the evidence, >1 in every 10 young adults of most ethnicities is estimated to have sarcopenia. This review summarizes the possible etiologies of sarcopenia in young populations, including metabolic syndrome, physical inactivity, inadequate nutrition, inherent and perinatal factors, vitamin D deficiency, endocrinopathy, an imbalance of gut microbiota, neuromuscular diseases, organ failure, malignancy, and other inflammatory disorders. This is the first review of the current knowledge on the importance, prevalence, diagnosis, and causes of sarcopenia in youth.

The Effect of Vitamin D Level on Parathyroid Hormone and Alkaline Phosphatase

Over the years, we have noticed in our clinical practice that patients with 25-hydroxyvitamin D (25OHD) levels below 15 ng/mL are more symptomatic than those with higher levels. The aim of this research is to investigate changes in both parathyroid hormone (PTH) and alkaline phosphatase (ALP) at different vitamin D levels to determine if lower vitamin D levels are associated with more severe changes in PTH and ALP, which may explain the presence and severity of symptoms at those lower 25OHD levels. We looked for correlations between 25OHD level, PTH, and ALP in 1311 samples between 2015 and 2019 at our endocrine clinic to determine if vitamin D level correlates with changes in PTH and ALP. We further categorized vitamin D deficiency levels into three categories based on the severity of the reported symptoms. As expected, there were inverse but significant correlations between 25OHD, PTH, and ALP. The lower the 25OHD, the higher the PTH and ALP levels. When 25OHD was below 10 ng/mL, PTH was increased in 65% of the samples and ALP was elevated in 21% of the samples; however, PTH and ALP were normal in 70% and 87%, respectively, of patients with 25OHD levels between 15 < 20 ng/mL. The results support our clinical observations since most of the patients with 25OHD greater than 15 ng/mL had normal PTH and ALP, which may explain the lack of symptoms in these patients.

Recent Information on Vitamin D Deficiency in an Adult Korean Population Visiting Local Clinics and Hospitals

We retrospectively reviewed serum 25-hydroxy vitamin D (25(OH)D) test results from an adult Korean population visiting local clinics and hospitals between July 2017 and December 2021 to gather recent information on the prevalence of vitamin D deficiency. The prevalence of vitamin D deficiency status was investigated according to criteria offered by various clinical guidelines. During the study period, 180,289 subjects (29,658 men and 150,631 women) were tested for 25(OH)D. The overall prevalence rates of vitamin D deficiency status based on 25(OH)D level were as follows: 0.4% for <5 ng/mL, 12.5% for <10 ng/mL, 20.6% for <12 ng/mL, 49.4% for <20 ng/mL, and <75.3% for <30 ng/mL. Women tested their 25(OH)D level more frequently than men, and the overall prevalence of 25(OH)D < 10 ng/mL was higher among women than men, while that of 25(OH)D <30 ng/mL was lower among women than men. Among age groups, the prevalence of 25(OH)D <30 ng/mL was higher in younger patients (20s−40s, 79.6−85.5%) than older ones (≥50 years, 62.6−69.2%). The overall prevalence of vitamin D deficiency decreased over time from 2018 to 2021. Future studies are needed to clarify the clinical impact of this change.