[Hyperparathyroidism. Quantitative determination of specific skeletal changes in the radiography of the hand]

1. The extent to which skeletal involvement in hyperparathyroidism can be detected by X-ray remains an unsolved issue. The present investigation, aimed at resolving this problem, was carried out in 44 patients with primary (PHPT) and 57 subjects with secondary hyperparathyroidism (SHPT) due to terminal renal insufficiency. For comparison, 49 age-matched controls were included in this series. Subperiostal resorption of the phalanges of the hand was considered pathognomonic and graded according to a semiquantitative system using a magnifying lens. The data were compared with the serum calcium and alkaline phosphatase values. 2. Pathological subperiostal resorption was detected in 38.5% of the PHPT and in 56% of the SHPT patients while the controls showed 4% (false) positive results. A highly significant correlation between the extent of bone resorption and alkaline phosphatase was found (PHPT: r=0.80, SHPT: r=0.71, p less than 0.001). No correlation of the X-ray findings to the serum calcium could be detected. Compared to the degree of skeletal involvement demonstrated by X-ray, the alkaline phosphatase was significantly lower in SHPT than in PHPT. In PHPT on the other hand, subperiostal resorption was prominent among female patients aged over 40 years, while no prevalence for sex and age was found in the SHPT group. 3. These results demonstrate that a clinically relevant degree of bone involvement in hyperparathyroidism may be easily and reliability assessed by evaluating X-rays of the hands by means of a magnifying lens. Increased bone resorption in hyperparathyroidism appears to be paralleled by an increase of osteoblastic activity as assessed by elevation of alkaline phosphatase. In SHPT due to chronic renal failure, however, a relative osteoblastic insufficiency seems to exist. In PHPT, the prevalence of subperiostal bone resorption in women aged over 40 years may be compatible with a skeletal protecting effect of intact ovarian function (estrogens).