Background: In last years it was emphasized the role of 25-OH Vitamin D (25-VitD) in P/Ca homeostasis as a principal factor to develop osteoporosis (OP). On the basis of these results we proposed to investigate deficit of 25-VitD in patients with systemic lupus erythematosus (SLE), and the response on parathyroid hormone (PTH) synthesis, as predisponent factors for development of OP in SLE(1,2,3).
Objectives: To determine the prevalence of 25-OH insufficiency vitamin D and secondary hyperparathyroidism in patients with SLE.
Methods: We determined the following variables from a 77 patients cohort who fulfilled SLE American College of Rheumatology’90 diagnosis criteria: serum levels of 25VitD (if <30 ng/ml = 25VitD insufficiency) and PTH (if >53 pg/ml = secondary hyperparathyroidism to 25VitD insufficiency), age, gender, use of hydroxychloroquine (HCQ).
Results: Different results ara exposed in following TABLE:
Table:

Vitamin D metabolism. Frequencies.
25OH VITAMIN D INSUFFICIENCY	51 / 81.9%
SECONDARY HYPERPARATHYROIDISM	19 / 38%
AGE	43.1 (17.06)
GENDER (females)	74 / 96.1%
HYDROXICHLOROQUINE USE	50 / 64.9%

Conclusion: we observed a very high prevalence of 25-VitD insufficiency in patients with SLE (greater to 67% found in other works(4)), with a marked presence of secondary hyperparathyroidism to 25VitD insufficiency (against observed in another work where was not an increase of PTH in 25-VitD insufficient patients(2)). The use of systemic corticoids can aggravate this situation and, morover, continuous use of HCQ could produce a diminution on 1,25-OH Vitamin D synthesis from 25-VitD(3).
References: 1-Bultnik IE et al. Prevalence of and risk factors for low bone mineral density and vertebral fractures in patients with systemic lupus erythematosus. Arthritis Rheum 2005;52(7):2044-50.
2-Becker A et al. Bone density and 25-OH vitamin D level in patients with systemic lupus erythematosus. Z Rheumatol 2001;60(5):352-8.
3-Huisman AM. Vitamin D levels in women with systemic lupus erythematosus and fibromyalgia. J Rheumatol 2001;28(11):2535-9.
4-Kamen DL et al. Vitamin D deficiency in systemic lupus erythematosus. Autoimmun Rev 2006;5(2):114-7.
5-Boyanov M. Bone mineral density changes in women with systemic lupus erythematosus. Clin Rheumatol 2003;22(4-5):318-23.