Longitudinal growth; bone and growth zone histology; growth cartilage and bone mineralization (tetracycline technique); bone Ca content (neutron activation analysis); bone radiology; serum and urine chemistry; urinary cAMP and serum 25-OH-vitamin D₃ were studied in a long-term model of experimental uremia in the rat. Uremia was induced by two-stage subtotal nephrectomy with irradiation of the remaining parenchyma. Ccr in the experimental group was 113 ± 5.8 µl/min × 100 g (19.8% of controls) and serum creatinine 1.67 ± 0.04 mg% (5.1 × control value). Uremic animals were pair-fed with sham-operated controls. In the proximal tibia delayed transformation of cartilage into primary spongiosa with appearance of chondro-osteoid and delayed transformation of primary spongiosa into secondary spongiosa was observed (rickets). Increased amounts of osteoid were present although 25-OH-vitamin D₃-levels were high. There were only modest signs of secondary hyperparathyroidism (osteoclast counts; urinary cAMP). In spite of the presence of bone disease, longitudinal growth was not reduced in uremic animals as compared with pair-fed sham-operated animals, but was significantly reduced as compared with ad lib fed control animals. In contrast, weight gain was significantly diminished in uremic animals as compared with pair-fed sham-operated control animals. It is concluded that diminished intake of food is the major determinant of growth retardation in preterminal experimental renal failure.

X-ray films of the hand skeleton (mammography technique), serum chemistry, and quantitative bone histology (micromorphometry of undecalcified sections, iliac crest spongiosa) were compared in 25 patients on maintenance hemodialysis. The X-ray findings correlated better with serum PTH levels than with bone histology. Of all radiological signs of renal osteodystrophy, pronounced subperiosteal resorption (radial aspect, second finger, middle phalanx) and periosteal new bone formation (middle phalanx) correlated best with histological indicators of osteitis fibrosa. These signs were never seen in control patients. Acroosteolysis (endphalanx) and intracortical or endosteal resorption (middle phalanx) were less specific (i.e., seen even in the absence of metabolic bone disease) and correlated less with bone histology. Osteosclerosis in iliac cancellous bone was paralleled by abnormal texture of spongy bone in the proximal metaphysis of the middle phalanx (second finger).