Detection of early renal osteodystrophy

Quantitative bone histology, serum biochemistry and skeletal survey were studied in 21 children aged 6-18 years with moderate renal impairment (glomerular filtration rate (GFR) 20-50 ml/min/1.73 m2) but no previous history of bone disease to try and identify early markers of the disease simpler and less invasive than histomorphometry. Ninety percent of the 20 biopsies studied exhibited abnormal quantitative bone histology. Predominant hyperparathyroidism was noted in 30%; osteomalacia in 5%, mixed picture in 55%. Parathyroid hormone (PTH) levels were elevated in all the patients. Alkaline phosphatase bone isoenzyme was elevated in 95% of the patients. X-ray was relatively insensitive showing mild changes of hyperparathyroidism in only 3 patients (14.3%), all of whom had GFR less than 30 ml/min/1.73 m2. We feel that the elevated PTH levels denote a true state of hyperparathyroidism which probably precedes histological derangement in chronic renal failure, and may justify prophylactic treatment of renal osteodystrophy in children with moderate renal impairment.