Comparisons between X-ray photodensitometric and gamma-ray absorptiometric findings of bone mineral measurements, and the evidence of their convertibility.

Fifty-two bone mineral measurements were made in chronic renal failure patients using two different radiologic techniques concurrently: gamma-ray absorptiometry; and x-ray photodensitometry. Although the sites of measurements of the cortical bone mineral mass in radius were different (distal vs. proximal) and different parameters were determined (in units of gm/cm vs. gm/cm2), a moderately good correlation was found between measurements by the two techniques (r = 0.61, p less than 0.001). Using external bone width, it was possible to calculate from photodensitometric measurements the bone mass per unit length (gm/cm). This conversion improved the correlation with absorptiometry values considerably (r = 0.78, p less than 0.001). A similar correlation was found between the trabecular bone mass in the distal radius, measured by absorptiometry, and the cortical bone mass in the proximal radius, determined by photodensitometry (r = 0.79, p less than 0.001), the correlation between the cortical and trabecular bone masses by absorptiometry being only slightly higher (r = 0.84, p less than 0.001). The residual variations not explained by the correlations between the absorptiometric and photodensitometric techniques may be largely due to the real differences of bone mineral masses at the two measuring sites and by the inherent methodological errors.     

Preventive effect of estrogen on postmenopausal bone loss.

Follow-up studies of bone mineral content in the radius were done in 82 postmenopausal women 4 to 10 years after the first examination. These patients were subdivided into four groups depending on the type of menopause (artificial or natural) and estrogen administration (treated or untreated). Bone mineral mass and combined cortical thickness decreased significantly in both groups of untreated women. Both mineral loss per year for the untreated women was -9.1 mg/sq cm for castrates and -6.9 mg/sq cm for those with a natural menopause. In neither group was the rate of loss correlated with age. The change in bone mineral mass per year in the estrogen-treated subjects (mean +3.25 mg/sq cm) differed significantly from that of untreated subjects (mean -7.99 mg/sq cm). The findings suggest that postmenopausal osteoporosis could be prevented by estrogen treatment.     

Calcium metabolism in adult outpatients with epilepsy receiving long-term anticonvulsant therapy

Long-term anticonvulsant drug therapy may lead to abnormalities of calcium metabolism resulting in osteomalacia. The prevalence and severity of altered calcium metabolism was studied in an adult outpatient population of persons with epilepsy receiving anticonvulsant therapy for a minimum of 2 years. Assessment of calcium metabolism was based on serum concentrations of calcium, phosphorus, alkaline phosphatase and 25-hydroxycholecalciferol and of plasma parathyroid hormone, intestinal absorption of isotopic calcium and skeletal bone mineral mass as determined by in vivo neutron activation or x-ray photodensitometry.

Thirty-nine patients who had been receiving anticonvulsant therapy for an average of 20 years were studied; none had clinical evidence of metabolic bone disease. Decreased serum calcium concentration was noted in 10%, decreased serum phosphorus concentration in 10% and elevated serum alkaline phosphatase concentration in 44%. The mean serum 25-hydroxycholecalciferol concentration was significantly lower (P < 0.001) than in a control group (11.6 v. 19.6 mg/mL). None of 18 patients studied had an increased plasma concentration of parathyroid hormone, and only 1 of 17 patients had decreased intestinal absorption of isotopic calcium. Bone mineral mass was decreased in 44% of 32 patients studied.

It was concluded that long-term treatment with anticonvulsant drugs leads to mild abnormalities of calcium metabolism and decreased bone mineral mass in a substantial percentage of adult outpatients with epilepsy. These abnormalities probably predispose the patients to the development of clinically significant metabolic bone disease.

     

Longitudinal microradioscopic comparisons on endosteal and juxtaendosteal bone loss in premenopausal and postmenopausal women, and in those with end-stage renal disease

Endosteal bone resorption is the principal mechanism of bone loss in involutional osteoporosis and in renal osteodystrophy. In the cortical bone it is often accompanied by juxtaendostal bone resorption. Using finedetail radiographs and × 6 magnified viewing, longitudinal radiographie observations and measurements were made on these two forms of bone resorption in the metacarpals II, III, and IV in three groups of women: (1) premenopausal, (2) postmenopausal, and (3) patients with end-stage renal disease. Bone loss was found to be negligible in the premenopausal women, but in postmenopausal and renal patients both endosteal and Juxtaendosteal bone resorption were frequently demonstrable. It is suggested that when a base-line fine-detail hand radiograph is obtained at the time of the menopause, follow-up radiographs may permit detection of relatively early endosteal and Juxtaendosteal bone loss by comparing the respective areas in metacarpals with those of the original radiograph. Since the methodology does not require expensive equipment, has a low intraobserver error and is simple to perform, it may deserve to be further evaluated in studies aimed at developing a simple and inexpensive approach as a screening method for early detection of postmenopausal osteoporosis.     

Serum magnesium level and arterial calcification in end-stage renal disease

In this paper we examine the relationship of serum levels of Ca, P, Ca X P, P/Mg, Ca X P/Mg, alkaline phosphatase, and iPTH to the development or regression of peripheral arterial calcifications (AC) in 44 patients with end-stage renal disease being treated by continuous ambulatory peritoneal dialysis (CAPD). The average follow-up time of this longitudinal study was 27 months (range 6-67 months). The patients were divided into two groups: Group A, those showing one or more increases of AC; and Group B, patients in whom AC either did not develop or decreased during the follow-up. There was no significant difference in serum Ca, P, Ca X P, alkaline phosphatase of iPTH between the two groups. However, serum Mg was significantly lower in Group A than in Group B (2.69 +/- 0.52 and 3.02 +/- 0.51 mg/dl, respectively, P less than 0.001), while the ratios P/Mg and Ca X P/Mg were significantly higher. Our observations suggest that in end-stage renal disease hypermagnesemia may retard the development of arterial calcifications.     

Radiologic study of endosteal, intracortical, and periosteal surfaces of hand bones in metabolic bone diseases

In metabolic bone diseases, subtle abnormalities occur on the three surfaces of bone, the recognition of which is important for diagnosis, as well as in follow-up studies, to recognize progression or regression. These resorptive and formative changes are best studied in fine-detail hand radiographs under 6 to 8 times magnification by a relatively simple radiologic method (microradioscopy). The periosteal resorption of hyperparathyroidism is thus recognized earlier than by regular radiography, and intracortical resorption, not detectable by the naked eye, can be visualized. The latter is also seen frequently in nutritional osteomalcia, renal osteodystrophy, and thyrotoxicosis, and sometimes in acromegaly. Endosteal resorption in developing involutional osteoporosis can also be recognized more efficiently by microradioscopy than by ordinary radiographs without magnification. Fine-detail hand radiographs may thus be used as an inexpensive preliminary measurement for diagnosis of osteoporosis.     

Radiographically detectable intracortical porosity. The dimensions and frequencies of its components in hand bones of normal men and women

Since the measurement of intracortical resorptive spaces by histologic methods is difficult and very few data are available in normal humans, we have measured their lengths and widths and calculated the intracortical porosity in metacarpals and phalanges of 79 normal women and 69 normal men, using fine-detail radiographs of the hands and a computerized semi-automatic image analysis system (Zeiss MOP-3), this being the first study of this kind. Several methodological problems were solved satisfactorily, and the results of this study could serve as a data bank for further investigations concerned with intracortical resorption. Significant differences were found between age and sex versus several intracortical resorptive parameters; also significant correlations were found with age in some cases. Normal intracortical porosity was found to be about three times greater in the proximal phalanges than in the metacarpals. It is concluded that this methodology could be used for further studies of intracortical resorption in osteoporosis and other metabolic bone diseases.     

The influence of age and sex on bone resorption of secondary hyperparathyroidism in renal osteodystrophy

Summary The severity and incidence of subperiosteal and intracortical bone resorption were evaluated from fine-detail hand radiographs at × 8 magnification in relation to age and sex in 239 chronically dialyzed adult renal failure patients. The severity of subperiosteal resorption decreased significantly with advancing age in both sexes and the incidence decreased somewhat more in males than in females; no such trends were apparent for intracortical resorption. Although the mean values for the grades of subperiosteal and intracortical resorption were significantly higher in females than in males, when the effect of age and duration of follow-up were taken into consideration, this sex difference remained significant only for intracortical resorption. It is concluded that when studying certain aspects of renal osteodystrophy, differences due to age, sex, and duration of follow-up should be considered in the final interpretation of data.     

The Relationship of Diabetes Mellitus and Body Weight to Osteoporosis in Elderly Females

Assessment of roentgenographic measurements of cortical bone of the radius in 196 elderly females, including 63 diabetics, revealed that: (1) in the non-diabetic group there was a significant loss of cortical bone relative to the number of years after the menopause and to body weight; (2) although there was a significant loss of cortical bone relative to years postmenopausal in a group of diabetic patients the cortex in the diabetic group was better preserved than in those non-diabetic controls in whom no vertebral compressions were diagnosed in the roentgenograms; no correlation between bone loss and body weight was found among the diabetics; (3) the thinnest cortical bone and the lowest average body weight was found in the 34 non-diabetics with vertebral compression deformities. It thus appears that involutional osteoporosis will be less prevalent among old women suffering from diabetes mellitus than in comparable non-diabetic subjects, and more prevalent among non-diabetics of low body weight than in old women who are obese or of normal weight.