AB0682 Lupus nephritis is a significant predictor of vitamin D deficiency in SLE patients
Authors: K. Sumethkul, S. Boonyaratavej, T. Kitumnuaypong, S. Angthararuk, P. Cheewasat, N. Manadee, V. Sumethkul
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Serum 25 Hydroxy vitaminD(25OHD) is a steroid hormone that has effect not only on calcium and bone homeostasis but also to more effects on many systems such as cardiovascular system, kidney function and immunologic system. 25OHD was reported to be low in patients with SLE. However, the association of vitamin D[Kittiwan1] level and SLE disease activity and lupus nephritis(LN) are not clearly known. <h3>Objectives</h3> The primary objective of this study is to compare mean serum 25OHD in SLE patients with inactive disease, SLE patients with active disease but no LN and SLE patients with active disease and LN. The secondary objective is to determine clinical predictors of vitamin D deficiency in SLE patients. <h3>Methods</h3> This prospective study included 108 SLE patients. Patients were classified as Group(Gr) 1,2 and 3 if the patients had SLE disease activity index(SLEDAI) &lt;3, ≥3 but no LN and ≥3 with LN. Important baseline characteristics were collected including age, disease duration, body mass index(BMI), current and cumulative dose of corticosteroid, serum cholesterol, serum albumin, estimated GFR(MDRD formula), and urine protein creatinine index(UPCI). Serum 25OHD was measured by HPLC method. <h3>Results</h3> Mean(SD) age and disease duration of patients was 35.2(11.1) and 7.9(8.3) years respectively. Mean SLEDAI in Gr1, Gr2, Gr3 was 0.7(0.9), 5.6(2.3) and 9.2(5.2) respectively. 29/108(26.9%) patients had vitaminD adequacy. 47/108(43.5%) had vitamin D insufficiency(25OHD&lt;30μg/L) and 32/108(29.6%) had vitamin D deficiency(25OHD&lt;20μg/L). Mean 25OHD in each groups were 28.3(7.1), 26.7(9.5) and 19.9(7.6)μg/L respectively. Patients with LN had significantly lower 25OHD than other groups(p=0.001). Mean difference of 25OHD level between Gr 1 and Gr 3 was 8.3(2.0); 95%CI(3.5,13.1): p&lt;0.001. Mean difference of 25OHD between Gr 2 and Gr 3 was 6.8(2.0); 95%CI(2.1, 11.5): p=0.003. Percentage of VitaminD deficiency in Gr1, 2 and 3 was 11.1%, 22.2% and 69.4% respectively. Serum 25OHD was significantly correlated with serum albumin(r=0.28, p=0.004), inversely correlated with SLEDAI(r=-0.22, p=0.03) and inversely correlated with UPCI(r=-0.28, p=0.005), but not correlated with sun exposure score(r=0.008, p=0.93), BMI(r=0.001, p=0.10) and eGFR(r=0.04, p=0.70). Multiple linear regression showed that only UPCI was significantly inversely correlated with serum 25OHD with a standardized coefficient beta -0.31(p=0.02). Multivariate logistic regression revealed that only LN was a significant predictor of vitamin D deficiency HR5.97; 95%CI(1.68, 21.26): p=0.006. Vitamin D deficiency and insufficiency was found in 93% of LN patients with proteinuria≥500mg/day. Vitamin D deficiency and insufficiency was also found in 86% of LN patients with proteinuria&lt;500 mg/day. <h3>Conclusions</h3> SLE patients with LN have significantly lower vitamin D level than inactive SLE and active SLE without LN. Nephritis is shown to be a significant predictor of vitamin D deficiency in SLE patients. High proportion of Vitamin D deficiency can be found in both LN patients with and without proteinuria more than 500 mg/day. <h3>References</h3> Toloza SMA, Cole DEC, Gladman DD, Ibañez D, Urowitz MB. Vitamin D insufficiency in a large female SLE cohort. Lupus. 2010;19(1):13-9. <h3>Disclosure of Interest</h3> K. Sumethkul Shareholder of: no, Grant/Research support from: no, Consultant for: no, Employee of: no, Paid Instructor for: no, Speakers Bureau: no, S. Boonyaratavej Shareholder of: no, Grant/Research support from: no, Consultant for: no, Employee of: no, Paid Instructor for: no, Speakers Bureau: no, T. Kitumnuaypong Shareholder of: no, Grant/Research support from: no, Consultant for: no, Employee of: no, Paid Instructor for: no, Speakers Bureau: no, S. Angthararuk Shareholder of: no, Grant/Research support from: no, Consultant for: no, Employee of: no, Paid Instructor for: no, Speakers Bureau: no, P. Cheewasat Shareholder of: no, Grant/Research support from: no, Consultant for: no, Employee of: no, Paid Instructor for: no, Speakers Bureau: no, N. Manadee Shareholder of: no, Grant/Research support from: no, Consultant for: no, Employee of: no, Paid Instructor for: no, Speakers Bureau: no, V. Sumethkul Shareholder of: no, Grant/Research support from: no, Consultant for: no, Employee of: no, Paid Instructor for: no, Speakers Bureau: no