الفهرس 
HISTORICAL BACKGROUNDOnly 14 pages are availabe for public view
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Abstract
Cystic fibrosis (CF) is the most common inherited disorder in childhood being caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR gene). It is a chronic condition involving several organ systems that results in life-long morbidity and premature mortality. Lung disease in CF is the major cause of death through a complex process involving impairmant of mucociliary clearance, infection, inflammation, and structural injury.
For a long time, CF was thought to be a rarity in the Arab world. Recently, case reports from several Arabic countries have been published. Environmental, nutritional, and socioeconomic factors as well as modifier genes may affect the clinical manifestations of the disorder.
CF patients have decreased vitamin D synthesis. CF patients who are exposed to the sun may have little body fat and may store less vitamin D, further exacerbating the problem. Decreased storage of both produced and consumed vitamin D may also be due to decreased levels of vitamin D binding protein. In children, severe vitamin D deficiency results in rickets, but its clinical presentation in CF is more subtle.
Systemic levels of inflammation are important in CF for their impact on both pulmonary inflammation and other CF comorbidities. Individuals with CF are at increased risk for both low bone mineral density and diabetes which is both related to increased inflammation. chronic inflammation has a negative impact on bone metabolism and has been linked to impaired linear growth and bone mineral accrual. Vitamin D does modulate the immune response and has been shown to have anti-inflammatory effects. Given the growing understanding of the importance of this vitamin in the regulation of multiple biological functions beyond skeletal health and the importance of vitamin D in relation to severity of lung disease which is closely correlated with total immunoglobulin G (IgG) levels in children, we sought to investigate the levels of vitamin D-binding protein (DBP), circulating 25-OHD vitamin D (25OHD) and total immunoglobulin G (IgG) in CFpatients and their correlation to different parameters measured and clinical data presented.
In this cross sectional case control observational study, we measured the levels of DBP, total 25OHD and IgG in the sera of 50 patients clinically diagnosed as CF and referred to the Allergy and Pulmonology Unit, Aboreesh Children’s Hospital, Cairo University, for diagnosis, investigations and follow up. Both genders were included with age range from 18 months till 13 years and a group of 20 age-matched healthy children was used as a control group.
The present study showed that CF group had significant lower serum concentrations of DBP (p<0.012) and 25OHD (p<0.001) while IgG levels were within normal values (p<0.216) compared to the control group. Significant positive correlations were observed between IgG and age (r=0.528), (p<0.01) weight (r=0.480), (p<0.001) and height(r=0.509), (p<0.001). Significant positive relations were observed between failure to thrive and DBP (p=0.023) and 25OHD (p=0.003). Also the study showed a significant positive relation between DBP and pancreatic insufficiency (p=0.039). No significant correlations were observed between DBP and age (r= 0.030) (p= 0.836), weight (r=-0.045) (p=0.758) and height (r=-0.040) (p=0.785). No significant correlations were observed between 25OHD and age (r=0.126), (p=0.301), weight (r=-0.099), (p=0.493) and height (r=-0.033), (p=0.821). No significant correlations were observed between DBP and 25OHD (r=-0.224), (p=0.118), between DBP and IgG (r=0.195), (p =0.176), between DBP and sweat chloride test (r=0.201), (p=0.162) and between 25OHD and IgG(r=0.195), (p=0.176). No significant relations were observed between pancreatic insufficiency, and 25OHD (p=0.944) and IgG (p=0.332) and between failure to thrive and IgG (p=0.898).
Therefore, the present study showed a significant relation of 25OHD with failure to thrive and significant relations of DBP with failure to thrive and pancreatic insufficiency emphasizing its role as a marker for the nutritional status in CF patients.
Adressing the presence of low 25OHD emphasizes the continued inadequate supplementation despite increased awareness. Many of the documented 25OHD levels over the last few decades suggest a trend toward higher 25OHD levels over recent years especially among larger studies, which likely reflect increased attention to 25OHD levels by most large CF centers .