I RUDERMAN1, T HEWITSON1,2, E D SMITH1,2, S HOLT1,2, B WIGG1, N TOUSSAINT1,2
1Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia, 2Department of Medicine, The University of Melbourne, Parkville, Australia
Background: Vascular calcification (VC) is well described in large- and medium-sized vessels in patients with chronic kidney disease (CKD), especially in those with end-stage kidney disease (ESKD) on dialysis. Medial calcification is particularly prevalent in this population and contributes to arterial stiffness and increased cardiovascular mortality and morbidity. Apart from in the setting of calciphylaxis, few studies have assessed skin and subcutaneous calcification and associations with abnormalities of bone and mineral metabolism in patients with CKD.
Methods: single-centre observational study to evaluate incisional skin tissue samples from anatomical sites in patients with different stages of CKD undergoing elective surgery. Skin samples compared to control cohort without CKD. Staining for calcification was performed with von Kossa method. A subgroup of skin samples were assessed by RT-PCR for upregulation of pro-calcific gene transcripts for tissue non-specific alkaline phosphatase (TNAP) and Runt-related transcription factor 2 (RUNX2).
Results: 45 patients were evaluated, 34 with CKD and 11 control patients. VC identified in 15 skin samples (13 CKD and 2 controls). VC present in dermal and subcutaneous tissues of the neck, abdomen and arm samples. Two different histological types of VC were identified: medial calcification and internal elastic lamina calcification. Presence of perieccrine calcification was identified in 14 samples. There were no significant differences in serum parathyroid hormone, phosphate or calcium in patients with or without VC. Expression of TNAP or RUNX2 was not increased in samples from patients with ESKD or those with histological evidence of calcification.
Conclusion: This study reports the novel finding of dermal and subcutaneous calcification in multiple anatomical locations in 38% of patients with advanced CKD/ESKD undergoing elective surgery but free from calciphylaxis.
Irene Ruderman works as a Nephrologist at The Royal Melbourne Hospital. She recently completed her postdoctoral studies and has an interest in Chronic Kidney Disease Mineral Bone Disorder and vascular calcification.