PTH and Marchiafava-Bignami disease: Male Cy/+ rats experience a clear elevation in blood urea nitrogen (BUN) by 10 weeks of age23 and show all features of late stage CKD-MBD by 35 to 38 weeks of age, including changes in additional plasma biochemistries such as creatinine, hematocrit, phosphorus and calcium, regulatory hormones PTH and FGF23, bone abnormalities (particularly cortical porosity), and vascular calcification24,26,27.