Bone Mineral Density in Patients With Childhood-onset Systemic Lupus Erythematous, in Relation to Disease Clinical Criteria

Childhood-onset systemic lupus erythematosus (CSLE) is a chronic, inflammatory, autoimmune disease that is characterized by multisystemic involvement with diverse clinical presentation and can involve one or more organ (1).This condition has a broad spectrum of clinical features ranging from mild cutaneous involvement to severe organ damage, such as kidney failure, pulmonary hypertension, and cardiac failure. The diagnosis of SLE is based on clinical and laboratory findings (2).The disease has a variable prevalence across the globe, with higher prevalence in low to middle income Asian and African countries than previously thought (3,4). Despite being common in young age females of reproductive age, the pediatric populations also suffer from lupus, where it has more aggressive disease course and complications (5).

Over the years, the management of CSLE has improved significantly, increasing the life expectancy of affected individuals however, CSLE patients still face numerous challenges, such as the increased risk of developing secondary complications like osteoporosis(6).

Osteoporosis, a skeletal disorder characterized by compromised bone strength and an increased risk of fractures, is a major public health concern worldwide (7). The association between CSLE and osteoporosis has been studied extensively and there is evidence suggesting an increased risk of osteoporosis in patients with CSLE (8) ,Possible factors contributing to low bone mineral density in CSLE patients include chronic inflammation, glucocorticoid therapy, and the presence of various cytokines produced by immune cells that interfere with bone homeostasis. Lifestyle factors and low vitamin D levels in CSLE patients may further contribute to the risk of osteoporosis (9,10).

Among children and adolescents, the recommended technology for clinical measurement of bone mineral density (BMD) and bone mineral content (BMC) is dual energy X-ray absorptiometry (DXA). It is a radiological method that detects the attenuation of two photon beams of different energies as they pass through the soft tissue and bone. DXA remains a method of choice because of its availability, low ionising radiation exposure, precision, scan speed(11). Mostly, the posteroanterior lumbar spine (L1-L4) and the total body less head (TBLH) are the skeletal sites of choice. Other sites such as the proximal femur, distal radius and lateral distal femur can be used to measure BMD if assessing standard sites are not feasible, and appropriate reference DXA data are available (12).

In recent years, studies have shown that vitamin D deficiency in patients with CSLE is strongly associated with reduced bone mineral density (BMD) determined by (DXA)(13).Vitamin D inadequacy is highly prevalent in CSLE patients due to the avoidance of sunshine, photoprotection, renal insufciency and the use of medications such as glucocorticoids, anticonvulsants, antimalarials and the calcineurin inhibitors, which alter the metabolism of vitamin D or down regulate the functions of the vitamin D receptor (14).

This study aims to disscus the clinical criteria in patients diagnosed as CSLE at Assiut University Children's Hospital ,and to asses bone mineral density based on (DXA) and 25(OH) vitamin D levels.

Inclusion criteria

• Age of patients below 18 years old.
• Both sexes.
• The Patients should be diagnosed as SLE, according to 2019 European league against rheumatism (EULAR)/ American college of rheumatology (ACR) SLE classification criteria from >6 months ago.

Exclusion criteria

• Patients with autoimmune diseases other than CSLE.
• Patients not fulfilling the criteria for diagnosis of CSLE.
• Active infections.
• Malignancies.
• Patients with other diseases which decrease vitamin D levels as malabsorption, cholestatic jaundice and chronic kidney disease.