Vitamin D deficiency

Abstract

Vitamin D deficiency is common among elderly patients in temperate countries, especially in early spring due to reduced cutaneous synthesis during the winter months, (1,2) and in housebound individuals (3) and medical inpatients.The prevalence of vitamin D deficiency is even higher in elderly patients with fragility fractures, ranging from 55%-91.6%. A recent local study in Singapore showed a vitamin D deficiency prevalence of 57.5% and vitamin D insufficiency of 34.5% in elderly patients admitted to hospital with hip fractures. Consequences of vitamin D deficiencyVitamin D deficiency results in abnormalities in calcium, phosphorus and bone metabolism. Specifically, it causes a decrease in the efficiency of intestinal calcium and the phosphorus absorption of dietary calcium and phosphorus, resulting in an increase in parathyroid levels. (9,10) In secondary hyperparathyroidism, serum calcium is maintained at the normal range at the expense of mobilising calcium from the skeleton and increasing phosphorus wasting in the kidneys. This process causes a generalised decrease in bone mineral density, resulting in osteopenia and osteoporosis. The secondary hyperparathyroidism also causes phosphaturia, which results in a low or low-normal serum phosphorus level. This leads to inadequate calciumphosphorus levels and a mineralisation defect in the skeleton. In young children with little mineral in their skeleton, this defect results in rickets. In adults, the result is osteomalacia. Quantified by bone mineral density scores, osteomalacia presents symptomatically with isolated or generalised aches and pains in bones and muscles.(11) In the elderly, vitamin D deficiency causes increasing sway and frequent falls, (12,13) increasing the risk of fracture. In addition to improvements in bone density and the prevention of falls and fracture, vitamin D may have several other putative benefits, including beneficial effects on the immune and cardiovascular systems. (14) Some risk factors Table I shows some common risk factors for vitamin D deficiency in the general population. For the elderly in Singapore, being housebound and of Malay ethnicity is significantly associated with vitamin D deficiency. In a recent study, 90.5% of the Malay patients had a vitamin D level of less than 20 µg/mL compared to 55.0% of the Chinese patients.(8) Those at risk of vitamin D deficiency may be able to overcome it by increasing their exposure to sunlight or dietary intake of vitamin D. In children and adults, exposing the hands, face and arms to the sun for 10-15 minutes per day is usually sufficient. However, the amount of vitamin D that is produced from sunlight depends on the time of day, geographic location and the colour of one's skin. Vitamin D can also be obtained from food and dietary supplements. However, sources in food are limited and include oily fish such as salmon, sardines and mackerel, fortified foods such as margarine, dairy products and cereals, as well as eggs and liver. As vitamin D production in skin and from dietary intake var...

Higher-Order Field Theories: $$\phi ^6$$ , $$\phi ^8$$ and Beyond

“…, which has both full-and half-kink solutions [4], the full-kink has an internal mode (ω1 ≈ 1.645) [35] while the halfkink does not [36]. The possibility of power-law (as opposed to exponential) tails in higher-order field theories adds further complications.…”

“…The possibility of power-law (as opposed to exponential) tails in higher-order field theories adds further complications. The kink of the φ 8 model with two degenerate minima, specifically V (φ) = (φ 2 − a 2 ) 2 (φ 2 − b 2 ) with a = 4/5 and b = 1, is reported to possess three internal modes (ω1 ≈ 2.068, ω2 ≈ 3.192 and ω3 ≈ 3.689) [36], while kink solutions with power-law tails of other sextic and non-polynomial models possess only the zero mode [37].…”

“…Some initial forays into the excitation spectra of kinks with power-law tails (i.e., linearization about a kink, along the lines of Sec. 3.2) were presented in [35,36].…”

Comment on: Vitamin D deficiency

“…Dear Sir, Gani and How (1) presented an informative overview of vitamin D deficiency and valuable information on treatment and nutritional requirements. The article clearly supports the use of vitamin D supplementation to enhance skeletal health.…”

Independent factors associated with serum levels of 25- Hydroxyvitamin D in very elderly Chinese males

“…Vitamin D deficiency gains more and more attention because it not only leads to osteopenia, osteoporosis [5] and increased fall [6] and fracture risk [7], but also mounting evidence has implied its role as an emerging risk factor for a good variety of chronic diseases [8]. A series of observational studies reported that low circulating concentrations of 25(OH)D were associated with high risk for cardiovascular diseases [9], cerebrovascular disease [10], cancer [11], type 2 diabetes mellitus [12], cognitive impairment [13], depression [14], orthostatic hypotension [15], and even all-cause mortality [16].…”