Capillary rarefaction in advanced chronic kidney disease is associated with high phosphorus and bicarbonate levels

• Published in: Nephrology, dialysis, transplantation dialysis, transplantation, 2011-11, Vol.26 (11), p.3529-3536
• Main Authors: Thang, Oanh H.D., Serné, Erik H., Grooteman, Muriel P.C., Smulders, Yvo M., ter Wee, Piet M., Tangelder, Geert-Jan, Nubé, Menso J.
• Format: Article
• Language: English
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Bicarbonates - blood; Biological and medical sciences; Calcifediol - blood; Calcitriol - blood; Capillaries - abnormalities; Capillaries - physiopathology; Case-Control Studies; Emergency and intensive care: renal failure. Dialysis management; Female; Fibroblast Growth Factors - blood; Follow-Up Studies; Humans; Intensive care medicine; Kidney Failure, Chronic - complications; Kidneys; Male; Medical sciences; Middle Aged; Nephrology. Urinary tract diseases; Phosphorus - blood; Prognosis; Skin - blood supply; Tumors of the urinary system; Vascular Diseases - etiology; Vascular Diseases - metabolism
• ISSN: 0931-0509; 1460-2385
• DOI: 10.1093/ndt/gfr089

Background. In patients with chronic kidney disease (CKD), disorders of mineral metabolism are associated with vascular calcifications and mortality. Microvascular dysfunction, by affecting flow resistance and tissue perfusion, may explain the cardiovascular sequelae of CKD-associated disorders of mineral metabolism. We investigated whether advanced CKD is associated with a decrease in the functional and structural number of capillaries in skin and subsequently whether capillary rarefaction is related to mineral metabolism. Methods. Capillary density was measured by nailfold microscopy in 19 predialysis and 35 CKD Stage 5 (CKD5) patients and 19 controls. In CKD patients, calcium, phosphorus, parathyroid hormone, 25-hydroxyvitaminD3 (25vitD3) and 1,25-dihydroxyvitaminD3 (1,25vitD3) were analysed as well. Results. Capillary density at baseline was 42 ± 15/mm2 in predialysis patients, 45 ± 17/mm2 in CKD5 patients and 56 ± 20/mm2 in controls (patients versus controls, respectively, P < 0.05 and P = 0.05). Absolute capillary recruitment during post-occlusive reactive hyperaemia was 17 ± 7/mm2, 14 ± 6/mm2 and 23 ± 8/mm2, respectively (P < 0.05 for both patients and controls). Capillary density during venous occlusion was 59 ± 20/mm2, 59 ± 21/mm2 and 77 ± 21/mm2, respectively (P < 0.05 for both patients and controls). In multiple regression analysis, both serum phosphorus and bicarbonate values were independently and inversely associated with capillary density at baseline (r 2 of model = 19%) as well as during venous occlusion (r 2 of model = 28%). Furthermore, both serum phosphorus and bicarbonate were inversely and female gender positively correlated with capillary density during recruitment (r 2 of model = 37%). Conclusion. Advanced CKD is characterized by an impaired functional and structural capillary density in skin, which is related to both high phosphorus and bicarbonate values.