A master's thesis at the University of Basrah at the College of Medicine discusses Assessment of 1,25-Dihydroxyvitamin D in Patients with Chronic Kidney Disease .The research presented by the student, Rafel Haider Hussein, aims to evaluate the difference in the levels of 1,25 (OH)2 D, 25 (OH)2 D, iPTH, and 1,25 (OH)2 D/iPTH across different stages of chronic kidney disease and to explore the relationships between biomarkers, focusing on the association of 1,25 (OH)2 D with estimated glomerular filtration rate (EGF), the association of 25 (OH)2 D with EGF, the association of iPTH with EGF, and the association of 1,25 (OH)2 D with IpTH. The study concluded that there was a statistically significant decline in 25-hydroxyvitamin D (25OH) and 1,25-dihydroxyvitamin D (1,25(OH)₂ D) levels with the progression of chronic kidney disease (CKD). Conversely, intact parathyroid hormone (iPTH) levels significantly increased  across the CK Dstage . The ratio of 1,25(OH)₂ D to iPTH decteased progressively. Correlation analysis revealed a negative correlation between iPTH and 1,25(OH)₂ D levels, as well as a positive correlation between estimated glomerular filtration rate (eGFR) and 25(OH)₂ and 1,25(OH)₂ D levels. Furthermore, a negative correlation was observed between eGFR and iPTH levels. Ordinal regression analysis indicated a significant negative estimate, indicating that lower levels of 1,25(OH)₂ D and 25(OH)₂ D are associated with more advanced stages of CKD. Conversely, iPTH has a positive estimate suggesting that higher levels of iPTH correlate with disease progression.