In this study, 26 patients (60.46%) were seropositive (ANA+) and 17 patients (39.53%) were seronegative (ANA−). The frequency of seronegative patients in our study was somewhat more than other previous studies because this research was conducted in long period of time at the Ali Asghar Pediatric Hospital, a referral center in Iran in which many patients even from neighboring countries are referred for diagnostic and treatment procedures. Furthermore, we compared the clinical and laboratory findings of patients at the time of diagnosis and we didn’t intend ANA− patients who had been changed to ANA+ in the course of the disease because the purpose of this study was to identify the underlying factors for the diagnose of the disease and seroconversion was not the purpose of this study. We also found that the proportion of female patients in both groups was nearly twice as high as that of boys, indicating a higher incidence of Lupus in girls than boys. Many studies reported that the incidence of lupus in girls is higher than boys [6, 12, 14]. For example, Murashima et al., , showed that the incidence of ANA+ was significantly higher in girls than boys; and 9 out of 10 patients who had ANA+ at the second visit were girl. In another study, Moradinejad et al.,  reported that the ratio of female to male with SLE was 8 to 1 and aged between o 3 to 16 years(sample size=45). In another study, Hiraki et al., examined 256 children with SLE and revealed that the ratio of girls to boys with SLE was 4.7, which is somewhat consistent with the results of our study. Salah et al.,  showed that the ration of girls to boys with SLE was 2.7 which is in line with our results. In our study, although the percentage of girls with SLE was higher than boys, there was no significant difference in sex distribution between ANA+ and ANA− groups.
So far, very few studies have compared the results of clinical and laboratory findings between patients with lupus, especially between seropositive and seropositive children. The results of our study didn’t show a significant difference in general symptoms such as fatigue, anorexia, weight loss, fever and lymphadenopathy between the ANA+ and ANA− groups. The frequency of general symptoms in ANA+ and ANA− patients was 53.84% and 64.7%, respectively. Our study also did not show a significant difference in the frequency of skin symptoms between the two groups. Interestingly, the results of our study showed a significant difference in the frequency of neuropsychiatric symptoms, including convulsion, psychosis, headache, depression, anxiety, and between the two groups. The incidence of neurological symptoms in ANA+ group was approximately twice that of the ANA− group. The frequency of neurological symptoms in patients in ANA+ and ANA− groups was 38.46% and 17.64%, respectively. Thus, the results of this study suggest that neuropsychiatric manifestations can be one of the diagnostic tools used in the differentiation of seropositive and seronegative SLE patients.
The results of our study did not show a significant difference in the frequency of gastrointestinal involvement, including HSM, intestinal vasculitis, pancreatitis, abdominal pain. The frequency of gastrointestinal presentations in ANA+ and ANA− groups was 38.46% and 41.17%, respectively. Although there was no significant difference in the frequency of musculoskeletal symptoms between two groups, its prevalence was somewhat higher in ANA− patients (64.7%) than ANA+ (46.15%). Therefore, it seems that musculoskeletal symptoms may also be a useful diagnostic tool for the differentiation of seropositive and seropositive patients; however, further studies with larger sample sizes are needed to confirm it. The frequency of renal complaints, including edema, nausea, vomiting, ascites, and oliguria in ANA+ and ANA− groups was 38.46% and 41.17%, respectively, and didn’t show a significant difference.
Numerous studies have investigated the prevalence of clinical symptoms in patients with SLE. Moradinejad et al.,  reported that the most common type of symptoms in children with SLE was skin and musculoskeletal involvements, kidney problems and hematologic abnormalities by 88.8%, 77.7%, 64.4% and 55.5%, respectively. The prevalence of heart disease, central neurological involvement and lung disease was 26%, 17%, and 11%, respectively. Hiraki et al., (18) reported that the most common clinical findings in children with SLE were arthritis (67%), malarial rash (66%), nephritis (55%), systemic involvement, and central nervous system (27%). In another study, Ramírez Gómez et al., examined 230 children under the age of 18 with SLE and reported that malarial rash, fever, oral ulcers, thrombocytopenia and hemolytic anemia and neuropsychiatric problems were the most common clinical symptoms in these patients. Salah et al., (19) considered 207 children aged 2 to 16 years with SLE and showed that nephritis (67%), hematological findings (44.9%), photosynthesis (44%), arthritis (39%), malarial rash (38.2%), cervicitis (32.9%), and neurological findings (24.25%) were significantly increased during the follow-up. Sibbitt et al., (11) demonstrated that the most common clinical symptoms in children with SLE were headache (72%), mental disorders (57%), consciousness disorders (55%), seizures (51%), acute perturbation (35%), emotional disorders (21%), central nervous system involvement (15%), cerebrovascular disease (12%), psychosis (12%), chorea (7%), syndrome Demineralization (4%), and myelopathy (1%). Deborah et al.,  reported that the most common clinical findings in children with SLE included fever (37- 100%), lymphadenopathy (13-45%), weight loss (-32%). 21%), mucocutaneous (60-90%), musculoskeletal (60-90%), nephritis (48-78%), NPSLE (15-95%), gastrointestinal problems (24-40%), hematological disorders (50%-100%), heart problems (25-60%), and pulmonary problems (18-81%).
Another finding of our study was related to the history of autoimmune disease between two groups. Patients in ANA− group had higher autoimmune disease history compared to ANA+ group (42.85% vs 15.0%). It is clinically valuable and can be helpful for the prognosis and distinguish of seronegative from seropositive patients. However, further studies with larger sample size should be undertaken. In our study, although there was no significant difference in the family history of the disease between two groups, patients in ANA− group had somewhat higher family history of the disease (50% compared to 23.52%).
Interestingly, the results of our study showed a significant difference in the frequency of hypertension between two groups. The frequency of hypertensive patients in ANA− group (52.94%) was significantly higher than those in ANA+ group (26.92%). This data suggests that a history of hypertension can be considered as one of the risk factors for the possibility of lupus seronegative. Along with hypertension, our results showed that the prevalence of serositis ANA− group (41.17%) was significantly higher than patients in ANA+ group (23.07%). We didn’t find significant difference in other parameters such as CBC, complements levels, direct coombs, renal biopsy result, prevalence of proteinuria and hematuria, as well as prevalence of leukopenia and lymphopenia between two groups; however, the prevalence of patients with thrombocytopenia in ANA+ group was significantly higher than those in ANA− group (32% vs. 12.5%). There was no significant difference in the serum antibodies levels including anti-dsDNA, antiphospholipid antibodies, p-ANCA and c-ANCA between two groups. Similarly, Murashima et al., found non-significant difference in the prevalence of anti-DNA and anti-phospholipid antibodies in children with SLE and the control group. Therefore, it seems that investigating several risk factors such as autoimmune and family history of the disease together, hypertension, serositis and musculoskeletal symptoms can be considered for the diagnosis seronegative patients from seropositive patients.