Vol 11, Issue 11, 2018 Online - 2455-3891 Print - 0974-2441 PREDICTIVE VALUE OF SERUM INTERLEUKIN 31 IN DIAGNOSIS OF OSTEOPOROSIS IN POSTMENOPAUSAL WOMAN: A NOVEL CASE–CONTROL STUDY FROM IRAQ ASMA GHALIB ABID 1 , HAYFAA SALMAN AL-HADITHI 2 , FAIQ I GORIAL 3 1 Department of Infertility Treatment and IVF, Kamal Al-Samarai Hospital, Fertility Center, Baghdad, Iraq. 2 Department of Microbiology, College of Medicine, University of Baghdad, Baghdad, Iraq. 3 Department of Medicine, College of Medicine, University of Baghdad, Baghdad, Iraq. Email: faiqig@gmail.com Received: 10 September 2018, Revised and Accepted: 16 October 2018 ABSTRACT Objective: The objective of this study was to assess the predictive value of serum level of interleukin 31 (IL31) in diagnosis of osteoporosis (OP) in postmenopausal women. Methods: This case–control study was conducted on 80 individuals, 50 of them with postmenopausal OP diagnosed using dual X-ray absorptiometry study, and the other 30 were healthy postmenopausal female controls. Serum level of IL31 was measured using enzyme-linked immunosorbent assay technique in both groups. Results: The mean age of patients was 65.3±4.8 years and controls was 61.1±3.9 years. Mean serum IL31 level was significantly higher among postmenopausal patients with OP compared to healthy controls (83.5±34.2 vs. 34.9±7.3ng/ml, p<0.05). The optimum cutoff value of serum IL31 that can differentiate between patients with OP in postmenopausal women from controls was >44.51 ng/ml with perfect positive predictive value (PPV) (100%), very high accuracy of 92.5%, 88% sensitivity, 100% specificity, and negative predictive value (NPV) 83.3%. Conclusions: Serum IL31 level was significantly higher in postmenopausal osteoporotic women compared to healthy controls. It was a valid measure with high accuracy and perfect PPV and specificity, high sensitivity, and NPV. It can be used to confirm the diagnosis of OP in postmenopausal women. Keywords: Serum interleukin 31, Postmenopausal women, Osteoporosis, Aging, Inflammation. INTRODUCTION Osteoporosis (OP) is a disease characterized by low bone mass and microarchitectures destruction of bone tissue, leading to bone fragility and increased risk of fracture [1]. Postmenopausal OP is a common bone disorder in postmenopausal women and is caused primarily by estrogen deficiency resulting from menopause [2]. Due to its prevalence worldwide, OP is considered a serious public health concern [3]. In Iraq, the prevalence of OP in Iraqi postmenopausal women is 22.8% [4]. The underlying mechanism of OP is an imbalance between bone resorption and bone formation [5]. Interestingly, immune cells, mainly activated T-lymphocytes and antigen-presenting cells, can also express RANKL, therefore, influencing bone remodeling, both directly and through cytokine production [6]. For example, interleukin (IL)-6, IL-17, tumor necrosis factor-α, and interferon-γ promote bone loss by favoring osteoclast production and inhibiting osteoblast differentiation [7,8]. Other cytokines, such as IL-4, IL-12, and IL-33, are strong suppressors of osteoclast differentiation and inhibit bone loss [9,10]. In addition, many of these cytokines have pleiotropic functions and their role in bone remodeling is cell type and concentration dependent and also influenced by the variable cytokine network involved in different physiological and pathological conditions [11]. Local production of eicosanoids and IL is thought to participate in the regulation of bone turnover, and excess or reduced production of these mediators may underlie the development of OP [11]. This study was conducted to assess serum level of IL 31 in postmenopausal osteoporotic patient and healthy control and to determine optimal cutoff value for IL31 to differentiate between study groups. METHODS Study design This case–control study was conducted at the Rheumatology Consultation Clinic of Baghdad Teaching Hospital/Medical City from July 2016 to November 2016. Ethical permission to conduct the research was obtained from rheumatology unit/department of medicine and a signed consent was taken from each participant. Participants A total of 50 Iraqi postmenopausal female’s patients with OP diagnosed by dual X-ray absorptiometry (DXA) spine and DXA hip which was diagnosed by rheumatologist according to the current criteria of the World Health Organization [12]. Females ages ranged from 55 to 76 years. Another 30 healthy volunteer female’s subjects were taken as controls. They have no OP by DXA study and non-significant medical history. Data collection Full history was taken and complete clinical examination was done for all participants in the study. Data collected included age, weight, height, body mass index (BMI), smoking status, and the recent relevant investigations were recorded inform of C-reactive protein and erythrocyte sedimentation rate. None of the studied participants had pathologies causing secondary OP or took drugs that could affect bone metabolism. Measurements 4 ml of venous blood sample was obtained from each subject and collected in a non-heparinized plain tube, then centrifuged at 1800× g for 10 min to separate serum. The obtained serum labeled and stored at −20°C until use, no preservative was added. IL31 was detected by enzyme-linked immunosorbent assay technique at immunology department/teaching laboratories. Statistical analysis Statistical analysis was done using the Statistical Package for the Social Sciences version 20 IMB. Anderson–Darling normality test was used to test the distribution of variables by a Minitab version 17 software. Continuous variables were reported as mean ± standard deviation © 2018 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ajpcr.2018.v11i11.29647 Research Article