**5. Bone status in patients with psoriasis treated with UVB phototherapy**

Multiple risk factors that contribute to low serum 25(OH)D and osteoporosis have been identified. They include inadequate sun exposure(99), insufficient intake of fortified foods or vitamin D supplements(100), low body mass index, white ethnicity, lack of exercise, use of medications that accelerate vitamin D metabolism, diseases that alter vitamin D metabolism such as malabsorption syndromes, and chronic liver disease(9, 13, 101).

Information regarding the prevalence of osteoporosis in addition to the epidemiological study of risk factors for developing osteoporosis among psoriasis patients has been sparse and controversial. Psoriasis patients with or without arthritis may suffer from osteoporosis(102). However, a previous study showed that patients with chronic plaque psoriasis had a low BMD despite risk factors, although the subgroup with joint involvement appeared to be at a higher risk of developing osteoporosis and therefore required prevention therapy(103). Reduced BMD has been linked to palmoplantar pustular psoriasis(104). The existence of less severe periarticular osteoporosis has also been reported(105). Psoriasis patients with peripheral arthritis with longer duration of joint disease(106) and patients with a greater number of affected joints are at a higher risk of developing osteoporosis(102).In a study by Pedreira, patients with psoriasis and psoriatic arthritis did not present with a lower BMD, but they had a higher prevalence of osteoporotic fractures and were at a higher risk of developing metabolic syndrome(107).

Postmenopausal women with psoriasis treated with phototherapy had higher BMD of both the hip and lumbar spine compared with age-matched controls (57, 108). In the same study(108), patients with 25(OH)D levels below 30 ng/ml and secondary hyperparathyroidism had lower BMD in terms of both T and Z scores of the hip and the lumbar spine compared with those with higher vitamin D levels, consistent with another study(109). No relationship between psoriasis onset and bone status was found. Higher body weight and BMI are factors, which may have contributed to the higher BMD in patients(108) compared with controls

In general, bone loss increases with age. BMD has been shown to be a predictive indicator for bone fractures in healthy subjects and in patients with osteoporosis(111).

A family history of fractures, physical activity, smoking and estrogen substitution are important factors influencing bone mass(112-114). Low body weight is related to low skeletal muscle mass and an increased risk of fractures(114, 115). Muscle tissue and strength are important for body balance and the prevention of falls(116). Previous studies confirm the protective effect of weight gain against fractures(17).

Physical activity correlated positively with BMD in psoriasis patients(108). Physical activity has been claimed to be beneficial for bone mass and protective against fractures(117). Regular walking in middle-aged and elderly women is associated with a reduced risk of vertebral deformity(118). Subjects who took a daily walk of at least 30 min had a significantly better climbing capacity, higher BMD and lower concentration of serum triglycerides than subjects who walked less(119). Lifetime exercise was also positively associated with BMD of the hip(120).

older ages and with part of the skin covered by psoriatic lesions. Serum concentrations of

Multiple risk factors that contribute to low serum 25(OH)D and osteoporosis have been identified. They include inadequate sun exposure(99), insufficient intake of fortified foods or vitamin D supplements(100), low body mass index, white ethnicity, lack of exercise, use of medications that accelerate vitamin D metabolism, diseases that alter vitamin D metabolism

Information regarding the prevalence of osteoporosis in addition to the epidemiological study of risk factors for developing osteoporosis among psoriasis patients has been sparse and controversial. Psoriasis patients with or without arthritis may suffer from osteoporosis(102). However, a previous study showed that patients with chronic plaque psoriasis had a low BMD despite risk factors, although the subgroup with joint involvement appeared to be at a higher risk of developing osteoporosis and therefore required prevention therapy(103). Reduced BMD has been linked to palmoplantar pustular psoriasis(104). The existence of less severe periarticular osteoporosis has also been reported(105). Psoriasis patients with peripheral arthritis with longer duration of joint disease(106) and patients with a greater number of affected joints are at a higher risk of developing osteoporosis(102).In a study by Pedreira, patients with psoriasis and psoriatic arthritis did not present with a lower BMD, but they had a higher prevalence of osteoporotic

Postmenopausal women with psoriasis treated with phototherapy had higher BMD of both the hip and lumbar spine compared with age-matched controls (57, 108). In the same study(108), patients with 25(OH)D levels below 30 ng/ml and secondary hyperparathyroidism had lower BMD in terms of both T and Z scores of the hip and the lumbar spine compared with those with higher vitamin D levels, consistent with another study(109). No relationship between psoriasis onset and bone status was found. Higher body weight and BMI are factors, which may have contributed to the higher BMD in

In general, bone loss increases with age. BMD has been shown to be a predictive indicator

A family history of fractures, physical activity, smoking and estrogen substitution are important factors influencing bone mass(112-114). Low body weight is related to low skeletal muscle mass and an increased risk of fractures(114, 115). Muscle tissue and strength are important for body balance and the prevention of falls(116). Previous studies confirm the

Physical activity correlated positively with BMD in psoriasis patients(108). Physical activity has been claimed to be beneficial for bone mass and protective against fractures(117). Regular walking in middle-aged and elderly women is associated with a reduced risk of vertebral deformity(118). Subjects who took a daily walk of at least 30 min had a significantly better climbing capacity, higher BMD and lower concentration of serum triglycerides than subjects who walked less(119). Lifetime exercise was also positively

**5. Bone status in patients with psoriasis treated with UVB phototherapy** 

calcium and creatinine were unaltered after phototherapy(58).

such as malabsorption syndromes, and chronic liver disease(9, 13, 101).

fractures and were at a higher risk of developing metabolic syndrome(107).

for bone fractures in healthy subjects and in patients with osteoporosis(111).

patients(108) compared with controls

associated with BMD of the hip(120).

protective effect of weight gain against fractures(17).

Vitamin D is important for bone metabolism(121). Vitamin D deficiency thus contributes to the pathogenesis of osteoporosis and hip fractures(122). Supplementation strategies involving calcium and vitamin D supplements are cost-effective for preventing osteoporotic fractures(123).

The same range of UVB (290–315 nm) that induces vitamin D synthesis also improves psoriasis. Treatment with UVB in patients with psoriasis is most common during winter months when UVB is lacking, and levels of vitamin D are low in Northern countries(123). Furthermore, UVB therapy heals psoriasis and supplies these patients with vitamin D at levels similar to those of the general population(123), which might have positive effects on bone status as well.
