Renal secondary hyperparathyroidism in aged Sprague-Dawley rats.

Fourteen aged Sprague-Dawley rats had typical renal secondary hyperparathyroidism. The renal disease was severe glomerulosclerosis with tubular dilation. The parathyroid glands were enlarged and had hyperplasia of chief cells. Bone lesions were generalized osteodystrophia fibrosa and osteosclerosis. All rats had osteodystrophia fibrosa and it was severe in 10 rats. Only four rats had osteosclerosis and it was moderate. Metastatic calcification was seen in various soft tissues in 13 rats.