The Prevalence Of Vitamin D Deficiency And Sub-clinical Osteomalacia In Spondyloarthritis

Objective: The aim of the study is to prove that vitamin D deficiency and sub-clinical osteomalacia are prevalent in the spondyloarthritis patients.Methods: 72 Sp A patients were recruited in rheumatology department in the First Affliated Hospital of Xiamen university, 74 healthy controls were of age- and sex-matched in the same time. People who were pregnant or took drugs which could affect the metabolism of vitamin D or suffered from bone structure diseases were excluded. All the patients were consistent with the assessment of Spondylo Arthritis international Society(ASAS) classification standard of Sp A, MRI or CT scan on sacroiliac joints were measured. Human leukocyte antigen B27(HLA-B27), c-reactive protein(CRP) were tested. The clinical datas were recorded and ASAS-endorsed disease activity score(ASDAS) were calculated as the same time. All Sp A patients and control individuals are requested for(1)Biochemical tests: Serum 25-hydroxyvitamin D(25OHD),serum calcium,phosphate, parathyroid hormone(PTH) and creatinine.(2) Bone turnover biomarkers: N-amino terminal propeptide of type I collagen(TPINP), N – terminal midfragment of osteocalcin(N-MID), β-Cross Laps of type I collagen cross-linked C-telopeptide(β-CTX).(3)Dual-energy X-ray absorptiometry(DEXA) was used to measure the BMD of the left femoral and lumbar spine.(4)Sun exposure time daily, milk dietary daily, living conditions(countryside ro city), work enviroment(indoor or outdoor), smoking and International Osteoporosis Foundation(IOF) one minute risk test were ascertained using a self-administered.Results:1 The clinical data Out of 72 Sp A were included in the study, of which 53(74%) were male and 19(26%) female. The mean age was 32.13±11.26(18 ~ 77) years old; The average duration of diseases was 4.54±5.04(0.3 ~ 30) years. Out of 67 patients’ HLA-B27 were measured, of which the positive rate was 82.7%. The mean ASDAS score was 2.41±1.22. Out of 74 healthy controls 50(68%) were males and 24(32%) females. The mean age was 34.23±11.52(19-70) years old. There were no significant difference in gender and age(P>0.05).2 Comparison of the 25 OHD levels and BMD between the two groups There was significant difference in 25 OHD levels and between Sp A and controls(27.57±9.96 vs 34.90±12.57ng/ml, P=0.001). The overall prevalence of normal vitamin D, vitamin D insuficiency, deficiency and severe deficiency was 27(37.5%),27(37.5%), 15(21%), 3(4%) respectively. The healthy controls were 45(61%), 20(27%),18(11%),1(1%) respectively. In patients group femoral normal BMD, osteopenia, osteoporosis were 37(51.4%), 29(40.3%), 6(8.3%) and lumbar BMD were 24(41.4%),21(36.2%),13(22.4%)respectively, and the healthy controls were 24(57.1%), 13(31.0%), 5(11.9%)respectively(P=0.725).3 Comparison of bone turnover biomakers between the two groups Both of the bone formation N-MID and resorption biomarkers β-CTX in Sp A group were higher than the healthy controls(P = 0.007 vs P= 0.001, respectively). The i PTH of Sp A were higher than healthy control group, however there was no significant difference between the two groups(P = 0.116).4 The correlation between 25 OHD levels、disease activity with other parameters The 25 OHD levels were negatively correlated with disease duration(r =- 0.350, P = 0.003), positively correlated with calcium(r=0.245,P = 0.038), and negatively correlated with PTH(P = 0.005). ASDAS was negatively correlated with both of femoral and lumbar bone mineral density(P = 0.001 vs P=0.003, respectively), also negatively correlated with body mass index(BMI)(P = 0.031),however positively correlated with alkaline phosphate(ALP)(P=0.023).5 The relationship of 25 OHD levels with disease activity, BMD and risk assessment questionnaire of osteoporosis in Sp A patients The sunshine time of two groups had no significant difference(P = 0.852). In Sp A, 25 OHD levels had significantly close relationship with sunshine time(P = 0.035). The male patients were with higher disease activity than the females(P = 0.009). The ASDAS score in smokers was higher than non-smokers(P = 0.097), however the lumber BMD scores in smokers was lower than non-smokers(P = 0.013).Conclutions:There were low vitamin D levels as well as high conversation rate of osteoporosis and osteopenia in Sp A patients. The effects of low 25 OHD levels on Sp A patient’s symptoms, biochemistry and bone structure were suggestive of subclinical osteomalacia.