25-hydroxyvitamin-d-2 and Muscle-Weakness

The aim of this review is to summarize current knowledge on the relation between vitamin D and muscle function. Molecular mechanisms of vitamin D action on muscle tissue have been known for many years and include genomic and non-genomic effects. Genomic effects are initiated by binding of 1,25-dihydroxyvitamin D3 (1,25(OH)2D) to its nuclear receptor, which results in changes in gene transcription of messenger RNA and subsequent protein synthesis. Non-genomic effects of vitamin D are rapid and mediated through a membrane-bound vitamin D receptor (VDR). Genetic variations in the VDR and the importance of VDR polymorphisms in the development of osteoporosis are still a matter of controversy and debate. Most recently, VDR polymorphisms have been described to affect muscle function. The skin has an enormous capacity for vitamin D production and supplies the body with 80-100% of its requirements of vitamin D. Age, latitude, time of day, season of the year and pigmentation can dramatically affect the production of vitamin D in the skin. Hypovitaminosis D is a common feature in elderly people living in northern latitudes and skin coverage has been established as an important factor leading to vitamin D deficiency. A serum 25-hydroxyvitamin D level below 50 nmol/l has been associated with increased body sway and a level below 30 nmol/l with decreased muscle strength. Changes in gait, difficulties in rising from a chair, inability to ascend stairs and diffuse muscle pain are the main clinical symptoms in osteomalacic myopathy. Calcium and vitamin D supplements together might improve neuromuscular function in elderly persons who are deficient in calcium and vitamin D. Thus 800 IU of cholecalciferol in combination with mg of elemental calcium reduces hip fractures and other non-vertebral fractures and should generally be recommended in individuals who are deficient in calcium and vitamin D. Given the strong interdependency of vitamin D deficiency, low serum calcium and high levels of parathyroid hormone, however, it is difficult to identify exact mechanisms of action.

Topics: 25-Hydroxyvitamin D 2; Aged; Blood Pressure; Calcium; Female; Hip Fractures; Humans; Male; Muscle Weakness; Muscle, Skeletal; Muscle, Smooth, Vascular; Parathyroid Hormone; Receptors, Calcitriol; Vitamin D; Vitamin D Deficiency

Four cases of hypovitaminosis D were seen in a general practitioner's population in the Netherlands: a Somalian veiled woman aged 53 and her 11-year-old daughter, a dark-skinned Surinam woman aged 31, and a veiled Moroccan woman aged 56 years. This cause of myopathy has only been recently recognised and is more prevalent than often thought, especially in high-risk groups such as veiled and dark-skinned immigrants who lack sunlight in the Netherlands. Symptoms are muscle pain and mainly proximal muscle weakness resulting in difficulties in ascending a staircase or getting up out of a chair. The diagnosis is made on the basis of a detailed history and measurement of serum 25-hydroxyvitamin D. Calcium and serum alkaline phosphatase activity may be normal. Treatment with ergocalciferol is effective and cheap. As diagnosis and treatment are relatively simple, finding and treating hypovitaminosis D is a rewarding challenge to primary health care practitioners in the Netherlands.

Topics: 25-Hydroxyvitamin D 2; Adult; Child; Cultural Characteristics; Ergocalciferols; Female; Humans; Life Style; Middle Aged; Morocco; Muscle Weakness; Muscular Diseases; Netherlands; Pain; Risk Factors; Skin Pigmentation; Somalia; Suriname; Vitamin D Deficiency

To quantify muscle strength and size in subjects with impaired glucose tolerance (IGT) in relation to intramuscular non-contractile tissue, the severity of neuropathy and vitamin D level.. A total of 20 subjects with impaired glucose tolerance and 20 control subjects underwent assessment of strength and size of knee extensor, flexor and ankle plantar and dorsi-flexor muscles, as well as quantification of intramuscular non-contractile tissue and detailed assessment of neuropathy and serum 25-hydroxy vitamin D levels.. In subjects with impaired glucose tolerance, proximal knee extensor strength (P = 0.17) and volume (P = 0.77), and knee flexor volume (P = 0.97) did not differ from those in control subjects. Ankle plantar flexor strength was significantly lower (P = 0.04) in the subjects with impaired glucose tolerance, with no difference in ankle plantar flexor (P = 0.62) or dorsiflexor volume (P = 0.06) between groups. Intramuscular non-contractile tissue level was significantly higher in the ankle plantar flexors and dorsiflexors (P = 0.03) of subjects with impaired glucose tolerance compared with control subjects, and it correlated with the severity of neuropathy. Ankle plantar flexor muscle strength correlated significantly with corneal nerve fibre density (r = 0.53; P = 0.01), a sensitive measure of small fibre neuropathy, and was significantly lower in subjects with vitamin D deficiency (P = 0.02).. People with impaired glucose tolerance have a significant reduction in distal but not proximal leg muscle strength, which is not associated with muscle atrophy, but with increased distal intramuscular non-contractile tissue, small fibre neuropathy and vitamin D deficiency.

Topics: 25-Hydroxyvitamin D 2; Adiposity; Aged; Ankle; Calcifediol; Early Diagnosis; Female; Glucose Intolerance; Humans; Knee; Leg; Lipid Metabolism; Magnetic Resonance Imaging; Male; Middle Aged; Muscle Strength; Muscle Weakness; Muscle, Skeletal; Polyneuropathies; Severity of Illness Index; Small Fiber Neuropathy; Vitamin D Deficiency

Vitamin D is thought to regulate skeletal muscle function and boost physical performance. The aim of this study was to assess the relationship between vitamin D and physical performance in physically active children. This cross-sectional study included 125 children who practice football as a leisure activity. Plasma 25-hydroxyvitamin D (25-OHD) was assessed using a chemiluminescence immunoassay method. Vitamin D inadequacy was defined as 25-OHD < 20 ng/mL. Physical performance testing included measurements of muscle strength (maximal isometric contraction), jumping ability (vertical jump, standing broad jump, triple hop test), linear sprint (10 m and 20 m), and agility (9 × 4-m shuttle run). Plasma 25-OHD concentrations were positively correlated with muscle strength (r = 0.539; p < 0.001), vertical jump (r = 0.528; p < 0.001), and standing broad jump (r = 0.492; p < 0.001) but inversely correlated with sprint performance (r = -0.539; p < 0.001). In multivariate analysis models, plasma 25-OHD concentrations were associated with each physical performance parameter independently of age, maturity status, body mass index, fat mass, and protein and calcium intakes. In conclusion, a low plasma 25-OHD level was associated with decreased muscle strength, agility, and jumping and sprinting abilities in physically active children. Vitamin D inadequacy may limit exercise performance. Further research should verify whether correction of vitamin D deficiency enhances physical performance.

Topics: 25-Hydroxyvitamin D 2; Adolescent; Adolescent Behavior; Athletic Performance; Calcifediol; Child; Child Behavior; Confounding Factors, Epidemiologic; Cross-Sectional Studies; Healthy Lifestyle; Humans; Male; Motor Activity; Muscle Strength; Muscle Weakness; Physical Fitness; Prevalence; Soccer; Sports and Recreational Facilities; Track and Field; Tunisia; Vitamin D Deficiency

Low serum concentrations of 25-hydroxyvitamin D (25(OH)D) have been associated with poor physical function in older adults, but few, if any, studies have examined this relationship in the very old. Therefore, the purpose of this study is to examine this relationship in the very old. Serum 25(OH)D concentrations were obtained from 194 centenarians and near centenarians (98 years and older). The associations between 25(OH)D concentrations and measures of physical function were evaluated with unadjusted and adjusted regression models. We found that 35% of centenarians had 25(OH)D concentrations less than 50 nmol/L. Adjusted mean grip strength was lower for centenarians with 25(OH)D concentrations less than 75 nmol/L than for centenarians with higher concentrations (P<0.05). However, there were no differences in the Georgia Centenarian Study (GCS) Composite Scale, a global measure of physical function, between those with higher and lower 25(OH)D concentrations. We conclude that low 25(OH)D concentrations are associated with poor grip strength, but not GCS Composite Scale, in the very old. Considering the high burden of poor physical function in older adults, understanding the relationship between vitamin D and different measures of physical function, including strength, becomes increasingly important.

Topics: 25-Hydroxyvitamin D 2; Aged, 80 and over; Aging; Calcifediol; Cross-Sectional Studies; Female; Frail Elderly; Georgia; Geriatric Assessment; Hand Strength; Humans; Male; Muscle Weakness; Nutritional Status; Seasons; Vitamin D Deficiency