FP060SERUM VITAMIN D LEVELS AND EXPRESSION OF VITAMIN D RECEPTOR (VDR) IN PATIENTS WITH AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE(ADPKD)

Abstract

Introduction and Aims: The progression of Autosomal Dominant Polycystic Kidney Disease (ADPKD) is associated with kidney enlargement due to cyst growth and activation of the Renin‐Angiotensin‐Aldosterone system (RAAS), which may lead to hypertension and cell proliferation. Recent observational studies in the general population have shown that serum levels of vitamin D [25(OH)D] are negatively associated with arterial blood pressure and the active form of vitamin D [1,25(OH) 2D3] is known as a suppressor of renin biosynthesis. The aim of the present study was to assess vitamin D status, the expression of vitamin D receptor (VDR), blood pressure and related parameters and their association with kidney volume in ADPKD patients. Methods: Blood samples were obtained from 68 ADPKD patients (27M/41F, 40+/‐12 years old) for serum biochemistry and hormonal determinations. VDR expression in peripheral blood monocytes was determined by flow cytometry and Magnetic Resonance Imaging (MRI) was performed to determine the total kidney volume (TKV). Hypertension was considered on the basis of a history of hypertension, present blood pressure measurements, or use of antihypertensive medications. Results: The studied population consisted of 71% of hypertensive patients with 46 % of them with chronic kidney disease (CKD) stage 1, 31% stage 2, 17% stage 3 and 6% stage 4. Forty‐two (42) out of 68 (62%) presented insufficient levels of 25(OH)D (< 30 ng/mL). There has been no statistical differences in the comparison with patients who were vitamin D‐sufficient (n=26) with respect to renal function, microalbuminuria, serum PTH, FGF‐23, Alkaline Phosphatase, Aldosterone and Plasma Renin. The mean TKV was higher in vitamin D‐insufficient patients but did not reached statistical significance (1377 +/‐966 vs 1042 +/‐730 mL) and the % of hypertensive patients was not statistically different between groups (73 vs 69 %, respectively. As shown in the table, a significant and negative correlation was found between serum vitamin D levels and TKV and between VDR expression and plasma Renin. (Table presented) Conclusions: Present findings indicate that lower levels of vitamin D were associated with larger kidneys in this population of ADPKD patients and the negative association between expression of VDR and plasma renin further suggested a lack of downregulation of renin in the kidney. The high percentage of hypertensive patients under treatment might have been responsible for the absence of association between blood pressure and vitamin D.