The clinical and metabolic effects of porcine calcitonin on Paget's disease of bone

The clinical and metabolic effects of porcine calcitonin were assessed in six patients with Paget's disease and two patients with osteoporosis under metabolic balance conditions. The administration of calcitonin for 4-17 wk resulted in an amelioration of the clinical phenomena associated with Paget's disease, including bone pain, increased skeletal vascularity, congestive heart failure, and neurologic deficits secondary to skeletal impingement. The major metabolic effects of calcitonin in Paget's disease included the induction of positive calcium balance of +50 to +240 mg/day, reduction in hyperphosphatasia and hydroxyprolinuria of 15 to 60%, and a deceleration of radiocalcium turnover by 12 to 46%. Natriuresis, phosphaturia, and reduced urinary calcium excretion were observed, whereas sustained hypocalcemia and hypophosphatemia did not occur. The administration of porcine calcitonin was not associated with adverse objective or subjective reactions, toxic effects, or allergic phenomena. There was no evidence of antibody formation or loss of therapeutic potency. Although the response of individual patients with Paget's disease varied widely, the data indicate that calcitonin, presumably through its skeletal anti-resorptive action, is able to reduce skeletal turnover and volume in Paget's disease, and thereby improve the associated clinical and metabolic abnormalities. Long term therapeutic studies in progress suggest that prolonged periods of control of the generalized condition may be feasible. In osteoporosis, neither clinical improvement nor consistent metabolic changes indicative of amelioration of the skeletal disease were observed.

Juvenile osteoporosis

Two cases of idiopathic juvenile osteoporosis are described; one with the mild form of the disease, and the other with the severe form. The common findings were pain in the feet or in the lumbar spine, with a negative calcium balance. Phosphorus balance was negative only in the child with the severe form of the disease.

Osteoporosis, skin collagen, and androgen

Total skin collagen was found to be decreased in untreated patients with osteoporosis, particularly women, but increased after treatment with androgens in women. Decreased body collagen may possibly be a primary defect in osteoporosis, while androgens may increase total skin collagen.

Evaluation of theoretical renal phosphorus threshold as an index of renal phosphorus handling

1. A simple phosphate infusion technique was employed to produce a linear elevation of plasma phosphorus levels with time. Using this technique theoretical renal phosphorus threshold (TRPT) was determined from sixty-seven infusions performed in fifty subjects in order to evaluate this measure of the renal excretion of phosphorus.

2. Glomerular filtration rate (GFR) was determined from phosphate data, and the maximum tubular reabsorptive capacity for phosphate (TmP) was obtained as the product of TRPT and GFR. Results obtained by simple graphic derivation of TRPT and GFR compared well with those obtained by regression analysis.

3. The normal adult range of TRPT was 2·7–4·1 mg/100 ml with a mean of 3·4 ± 0·4 (SD) mg/100 ml while adolescents had higher values. Results were compared in subjects with various disturbances of calcium and phosphorus metabolism. In primary hyperparathyroidism with and without bone disease the range of TRPT was 0·5–2·8 mg/100 ml with a mean of 2·0 ± 0·7 (SD) mg/100 ml (difference from normals P < 0·0125); in osteomalacia before and during treatment the range of TRPT was 0·3–1·9 mg/100 ml with a mean of 1·0 ± 0·6 (SD) mg/100 ml (difference from normals P < 0·0005). The standard deviation in repeated tests in the same individual was ±0·28 mg/100 ml.

4. There was a significant positive correlation between TRPT (TmP/GFR) and GFR. Changes in GFR of 10 ml/min were associated with absolute changes in TRPT of 0·08–0·19 mg/100 ml. Thus TRPT showed very much less dependence on GFR than TmP and appeared the more consistent index of renal phosphate handling.

5. The technique has proved valuable in monitoring the response to treatment in different forms of osteomalacia. It has provided evidence of increased urinary phosphate excretion in some patients with idiopathic osteoporosis. Lysine and probably certain other amino acids may be infused by the same technique for the more precise study of the renal excretion of these compounds.