Bone Mineral Density, 25-OH Vitamin D and Inflammation in Patients with Psoriasis

Low levels of vitamin D may play a role in the pathogenesis of psoriasis and is related to increased risk of osteoporosis. There are a few studies showing increased rate of osteoporosis in patients with psoriasis; however, none of them investigated impact of vitamin D levels and gender status together. We aimed to evaluate relationship between vitamin D and osteoporosis in psoriasis patients with an emphasis on gender difference.

Forty-three psoriasis patients without arthritis and 41 healthy controls were enrolled. All patients were <50 years, and women were premenopausal. Participants were questioned about demographic features, sun exposure, regular physical exercise, and smoking status. The serum levels of 25-OH vitamin D, calcium, phosphorus, C-reactive protein, parathyroid hormone, total alkaline phosphatase, and sedimentation rate were measured. Body mass index was calculated. We determined the bone mineral density of the lumbar spine and femur using dual-energy X-ray absorptiometry.

Femur neck Z score and lumbar spine total Z score were lower in psoriasis group than those of the control group. Additionally, total femoral Z score, lumbar spine total T, and Z scores were lower in female patients with psoriasis than female controls, whereas for male subjects there was not a remarkable difference between the groups. There was no significant difference between the two groups regarding vitamin D levels. The latter was significantly lower in psoriasis group than in controls for females; however, there was no significant difference between the two groups of males. Patients with psoriasis had higher CRP level and sedimentation rate, than control subjects. Female patients had also higher CRP level and sedimentation rate, than female controls, but there were no significant differences between male patients and controls.

As osteoporosis has multifactorial etiology, psoriasis may be among the triggering or facilitating factors for osteoporosis particularly in psoriatic women via several mechanisms such as low blood level of vitamin D and increased inflammation.