Andrea N. Jones

Vitamin D and musculoskeletal health

Vitamin D is critical for calcium homeostasis. Following cutaneous synthesis or ingestion, vitamin D is metabolized to 25(OH)D and then to the active form 1,25(OH)2D. Low serum vitamin D levels are common in the general population and cause a decline in calcium absorption, leading to low serum levels of ionized calcium, which in turn trigger the release of parathyroid hormone, promoting skeletal resorption and, eventually, bone loss or osteomalacia. Vitamin D deficiency is generally defined as a serum 25(OH)D concentration <25–37 nmol/l (<10–15 ng/ml), but the definition of the milder state of vitamin D insufficiency is controversial. Three recent meta-analyses concluded that vitamin D must be administered in combination with calcium in order to substantially reduce the risk of nonvertebral fracture in adults over the age of 50 years. Fracture protection is optimal when patient adherence to medication exceeds 80% and vitamin D doses exceed 700 IU/day. In addition to disordered calcium homeostasis, low vitamin D levels might have effects on cell proliferation and differentiation and immune function. Randomized, double-blind, placebo-controlled trials are needed to clarify whether vitamin D supplementation is beneficial in cancer, autoimmune disease and infection. This Review focuses on the pathophysiology, clinical correlates, evaluation and treatment of hypovitaminosis D.

Vitamin D repletion does not alter urinary calcium excretion in healthy postmenopausal women

To evaluate, in a posthoc analysis of a previous study, whether vitamin D repletion in postmenopausal women with insufficient vitamin D increases urinary calcium excretion, as vitamin D therapy might contribute to hypercalciuria and calcium stones in susceptible individuals, and the effect of vitamin D on the risk of urolithiasis warrants attention.

Vitamin D and calcium levels in Ugandan adults with human immunodeficiency virus and tuberculosis

BACKGROUND Vitamin D increases cathelicidin production, and might alter mortality due to tuberculosis (TB) in human immunodeficiency virus (HIV) coinfection. However, due to abundant sun exposure, vita min D levels might be excellent among Ugandans with HIV and TB. METHODS We measured 25(OH)D and calcium levels in 50 HIV-negative, 50 HIV-infected and 50 TB-HIV coinfected Ugandan adults. RESULTS Mean ± standard deviation 25(OH)D levels were 26 ± 7 ng/ml in HIV-negative, 28 ± 11 ng/ml in HIV-infected and 24 ± 11 ng/ml in TB-HIV co-infected adults (P > 0.05 all comparisons). Vitamin D deficiency (< 12 ng/ml) was present in 10% of the HIV-infected subjects, 12% of the TB-HIV co-infected and none of the healthy controls (P = 0.03 for healthy vs. TB, P > 0.05 for other comparisons); 20% of the healthy controls, 22% of the HIV-positive and 38% of the TB-HIV co-infected subjects (P = 0.047 for healthy vs. TB, P > 0.05 for other comparisons) had suboptimal vitamin D levels (< 20 ng/ml). No participant had hypercalcemia. Serum 25(OH)D levels correlated positively with body mass index (r = 0.22, P = 0.03) and serum calcium levels (r = 0.18, P = 0.03). CONCLUSIONS Ugandan HIV-infected adults with and without TB commonly had suboptimal vitamin D levels. Clinical trials are needed to evaluate the effect of vitamin D on health outcomes in HIV-infected patients with low vitamin D levels.

An evaluation of high-dose vitamin D for rheumatoid arthritis.

Vitamin D receptors (VDR) are present in T-lymphocytes, macrophages, chondrocytes, and synovial cells of patients with rheumatoid arthritis (RA) but not healthy individuals [1]. As recently reviewed [1], 1,25(OH)2D inhibits T-cell proliferation and cytokine secretion in vitro, and ameliorates murine RA [2, 3]. We hypothesized that correction of hypovitaminosis D in subjects with RA would decrease parathyroid hormone (PTH), increase bone mineral density (BMD), improve functional capacity (Health Assessment Questionnaire, HAQ) and down-regulate inflammatory cytokines, thereby diminishing RA disease activity (RA-DAS) scores and improving quality of life.

Vitamin d supplement intake in elderly fallers

To the Editor: Approximately 30% of ambulatory older adults fall yearly; 5% to 10% are seriously injured. Vitamin D deficiency increases body sway and decreases muscle mass and strength, increasing falls risk. Vitamin D supplementation reduces falls by 11% to 22%. To our knowledge, no studies have been conducted that report characteristics of ambulatory fallers associated with meeting the recommended adequate intake (RAI) of vitamin D. Patient characteristics associated with vitamin D intake in a falls study are reported.