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Serum immunoreactive parathyroid hormone and 25-hydroxyvitamin D in patients with uremic bone diseases.

Bone histologic parameters and serum iPTH and 25-OHD were measured in 20 patients with end-stage renal failure treated with hemodialysis. By bone histologic criteria, the patients were divided into three groups: mild, osteomalacic, and fibrotic. The increase in serum iPTH was much greater in the fibrotic group than in the mild or osteomalacic groups. In the uremic patients as a group, there were significant correlations between serum iPTH and both percent marrow fibrosis and percent resorbing surface. In the mild and fibrotic groups together, serum iPTH was also correlated with percent forming surface. This and other findings suggested that most of the bone changes in the mild and fibrotic groups could be explained by excess PTH. The difference in bone changes and in serum iPTH between the mild and fibrotic groups could be related to our eariler findings that duration of renal disease was much greater in the fibrotic than in the mild group. The lowest increment in serum iPTH was found in the osteomalacic group. In this group, percent resorbing surface was not increased and there was only a slight increase in marrow fibrosis. Thus in all three groups, serum iPTH appeared to reflect parathyroid status. The cause of the elevated serum iPTH and for the intergroup differences was not apparent inasmuch as serum calcium was normal in all three groups. Serum 25-OHD was significantly elevated in the osteomalacic and fibrotic groups. Because none of our patients had received preparations containing vitamin D, the elevated serum 25-OHD in the osteomalacic and fibrotic groups is consistent with altered vitamin D metabolism in these two groups. There was a direct relationship between percent osteroid area and serum 25-OHD. However, whether or not altered vitamin D metabolism contributed to the mineralization defect in uremic bone disease could not be established.

Adult

Serum 1,25-dihydroxyvitamin D levels in normal subjects and in patients with hereditary rickets or bone disease.

The serum concentration of 1,25-dihydroxylvitamin D (1,25-[OH]2D) in normal children and in children with inherited diseases of bone was compared by use of a competitive binding assay. Observed values were: in 12 normal children and adolescents, 37.1 +/- 1.9 pg per milliliter (mean +/- S.D.); in 14 patients with X-linked hypophosphatemic rickets treated with vitamin D2 and phosphate supplements, 15.6 +/- 7.8 (P less than 0.01 versus control); in six patients with autosomal recessive vitamin D dependency treated with vitamin D2, 9.5 +/- 2.9 (P less than 0.01 versus control); and in four untreated patients with autosomal dominant hypophosphatemic (non-rachitic) bone disease, 30.2 +/- 6.3 (not significantly different from the controls). The difference in bone disease between X-linked hypophosphatemia (severe) and hypophosphatemic bone disease (mild) at comparable low serum levels of phosphate implies that 1,25-(OH)2D and phosphate may have independent roles in the pathogenesis of defective bone mineralization.

Adolescent

Effect of dialysate calcium concentration on bone disease in patients on hemodialysis.

Plasma biochemistry, bone radiology and morphometry were studied in a group of 20 patients receiving maintenance hemodialysis. The aim was to determine if increasing the dialysate calcium concentration would decrease plasma parathyroid hormone and improve the radiologic appearances of bone in patients without producing serious side effects. Dialysate calcium concentration was increased stepwise from 4.5 to 6.0 and then to 7.0 mg/100 ml. Mean predialysis plasma calcium concentration increased from 9.4 to 9.7 and then to 10.0 mg/100 ml and mean predialysis phosphate concentration increased from 5.3 to 5.6 mg/100 ml. Parathyroid hormone concentration was elevated in all patients but the mean concentration did not change significantly although in seven patients a decrease occurred. Six patients had radiologic signs of renal bone disease, two patients showed improvement and three patients developed bone disease during the study. The patients with radiologic bone disease had the highest parathyroid hormone concentrations and the majority were female. Morphometric bone measurements showed that bone loss during the study occurred mainly in the male patients. Soft tissue calcification continued to appear during the study. Although the response to some patients to an increased dialysate calcium concentration was favorable, it was impossible to predict which types of patient would benefit from the use of a dialysate calcium concentration of 7.0 mg/100 ml.

Adult

The actions of parathyroid hormone on bone: relation to bone remodeling and turnover, calcium homeostasis, and metabolic bone diseases. II. PTH and bone cells: bone turnover and plasma calcium regulation.

Kinetic and morphologic studies in patients with parathyroid disease, and a wide variety of studies in experimental animals indicate that one major effect of PTH is to increase the proliferation of osteoprogenitor cells into osteoclasts and so to increase bone turnover. PTH stimulates bone cells by increasing cell membrane permeability to calcium and consequently increasing calcium influx and by activating membrane-bound adenyl-cyclase. It is likely that the former event precedes the latter and that calcium is the second messenger and cyclic AMP the third messenger. PTH increases the production by bone cells of lactate, citric and carbonic acids, lysosomal enzymes, collagenase, and hyaluronic acid, some or all of which are concerned in the mechanism of bone resorption. With the exception of lactate which probably comes mainly from osteocytes, the increase in metabolic activity is largely due to the increase in the number of osteoclasts. There is also ultrastructural, biochemical, and biophysical evidence that PTH stimulates existing osteoclasts, but this most likely represents the transformation of inactive cells into an active state, and is a transient and nonsustainable effect. As yet, there is no evidence that either increased osteoprogenitor cell proliferation or increased osteoclast activity is mediated by adenyl-cyclase activation. PTH also acts on the deep osteocyte to cause rapid mobilization of calcium from the zone of hypomineralized metabolically active perilacunar bone. This effect is mediated by adenyl-cyclase activation and is preceded by a slight fall in plasma calcium probably due to the movement of calcium into bone cells. The function of this rapid hypercalcemic response to PTH is correct errors in the prevailing steady-state level of plasma calcium...

Animals

Correlation of clinical, biochemical and skeletal responses to 1alpha-hydroxyvitamin D3 in renal bone disease.

Thirty-five patients with bone disease and chronic renal failure (twenty-four on maintenance haemodialysis) were treated for 7--39 months with 1alpha-hydroxyvitamin D3, 2--2.5 microgram daily by mouth. Symptoms (bone pain and muscle weakness) and radiographic appearances improved and plasma alkaline phosphatase returned to normal in the majority of patients (87, 76 and 75% respectively). In contrast, histological appearances in bone improved in only 46% twenty-three patients from whom paired biopsies were available, and this change was not greatly different from that seen in a comparable group of untreated patients. Significant correlations were noted in individual patients between the changes in symptoms, X-rays, plasma alkaline phosphatase and immunoreactive parathyroid hormone and these, in turn, were related to histological changes in bone, although these latter changes were often small. It is concluded that 1alpha-hydroxyvitamin D3 is a useful new drug in the treatment of renal bone disease, but that the evaluation of the response depends critically on the method of assessment used.

Adolescent

Destructive bone disease in early syphilis.

Although destructive bone disease is a well-known complication of tertiary syphilis, osteitis or osteomyelitis are not commonly recognized as complications of early (primary or secondary) syphillis. A patient with secondary syphilis characterized by generalized lymphadenopathy, perianal condyloma lata, and positive rapid plasma reagin (RPR) and fluorescent treponemal antibody-absorption (FTA-ABS) tests also complained of headache, right should pain, and right anterior chest pain and swelling. Roentgenograms showed mottled osteolytic lesions consistent with previously described luetic bone disease. Biopsy confirmed the diagnosis of syphilitic osteomyelitis, and treatment with penicillin resulted in prompt resolution of symptoms.

Adult

The actions of parathyroid hormone on bone: relation to bone remodeling and turnover, calcium homeostasis, and metabolic bone disease. Part IV of IV parts: The state of the bones in uremic hyperaparathyroidism--the mechanisms of skeletal resistance to PTH in renal failure and pseudohypoparathyroidism and the role of PTH in osteoporosis, osteopetrosis, and osteofluorosis.

In early chronic renal failure, the state of the bones resembles that of type II primary hyperparathyroidism. Cortical bone becomes thinner and more porous, and there is increased extent of surface remodeling. These changes are followed in turn by osteomalacia and osteitis fibrosa, although sometimes these may be alternate rather than successive stages. Bone turnover is less than would be expected for the elevation of PTH level, probably because of 1,25 (OH)2D3 deficiency. The resorption velocity and lamellar bone appositional rates are depressed, but woven bone appositional rate may be increased, possibly because of hyperphosphatemia. Bone mass reflects the summation of three independent processes: loss of lamellar bone due to hyperparathyroidism (depending on the extent of insulation by osteoid); accumulation of partly mineralized osteoid because of osteomalacia; accumulation of woven bone because of osteitis fibrosa. Osteosclerosis may be growth-related metaphyseal, subchondral or diffuse axial, and periosteal neostosis may also occur. Some patients on hemodialysis lose bone because of planing rather than lacunar or dissecting resorption, combined with depression of both lamellar and woven bone formation. Hyperparathyroid bone disease tends to improve slowly after renal transplantation. Persistent hypocalcemia reflects a defect in the calcium homeostatic system and cannot be explained solely by the known stimuli to secondary hyperparathyroidism. The increment in plasma calcium in response to PTH infusion is subnormal, both in early chronic and in acute renal failure, probably because of 1,25(OH)2D3 deficiency. This is also the most likely explanation for the depressed level of blood-bone equilibrium. The activity of all three of the PTH responsive cell systems in bone is depressed in renal failure, probably because all three require 1,25(OH)2D3 in order to function normally. In pseudohypoparathyroidism, as in chronic renal failure, hypocalcemia results from a defect in the regulation of the blood-bone equilibrium. The bone-remodeling system shows all gradations of response, from slight depression of bone turnover to overt osteitis fibrosa, but bone turnover is never as low as in PTH deficiency. These differences may reflect the presence or absence of resistance to PTH of the osteoprogenitor cell as well as of the calcium homeostatic system, or may be due to varying degrees of 1,25(OH)2D3 deficiency, as in chronic renal failure. An increase in plasma calcium in response to PTH can occur either in the untreated state or after treatment with vitamin D because either the error-correcting or remodeling system remains responsive to PTH. Pseudohypoparathyroidism may be subdivided into three types, depending on whether the urinary cyclic-AMP response to PTH remains defective despite treatment with vitamin D, improves with treatment, or is normal before treatment. Only the former is associated with the genetic syndrome of Albright's hereditary osteodystrophy...

Bone Diseases

The use of whole-body retention of Tc-99m diphosphonate in the diagnosis of metabolic bone disease.

The limited role of bone scanning in the diagnosis of metabolic bone disease might be considerably improved by accurate quantification of skeletal uptake of the radiopharmaceutical. Using a standard shadow-shield whole-body monitor, we have measured whole-body retention (WBR) of Tc-99m HEDP up to 24 hr in 11 patients with renal osteodystrophy (mean WBR 88.6% at 24 hr); in ten patients with Paget's disease (mean 56.9%); in seven patients with osteomalacia (mean 40.7%); in five patients with primary hyperparathyroidism (mean 50.7%); in four patients with osteoporosis (mean 21.2%); and in 12 normals (mean 19.2%). The osteoporotic group could not be differentiated from the normal group, but the other groups were significantly different from the normal group at 24 hr (p less than 0.002), and each individual rest for the 24-hr WBR of Tc-99m HEDP in these groups lay outside our normal range. This test may, therefore, provide a sensitive means of detecting conditions with increased bone turnover. We obtained measurements of plasma activity of Tc-99m HEDP in these patients up to 24 hr, and 4-hr bone to soft-tissue ratios from bonescan images, but little additional information resulted.

Adolescent

Long term therapy with 1,25(OH)2D3 in dialysis bone disease.

Five patients with haemodialysis bone disease were treated with 1 to 1.5 mug of 1,25 (OH)2D3 daily for periods ranging from 6 -8 months. There was a significant improvement in calcium absorption but no troublesome hypercalcaemia was encountered. Secondary hyperparathyroidism improved, both histologically and radiologically, and there was a fall in serum PTH and return of serum alkaline phosphatase to within normal limits. There was also improvement in the patients' mineralisation status, but this change was slower and less marked. Muscle power improved significantly, both clinically and electromyographically.

Calcium

Changes in protein-bound calcium during haemodialysis in relation to bone disease.

29 patients receiving haemodialysis treatment for chronic renal failure were divided into two groups on the basis of the presence or absence of bone disease as defined by radiology and bone alkaline phosphatase. The group of patient with bone disease showed a significantly greater increase in protein-bound calcium during dialysis compared with the control group. There were no significant differences in the changes in total calcium, albumin or hydrogen ion concentration during dialysis between each group. The data suggest that there is a relationship between the increase in protein-bound calcium during dialysis and the incidence of bone disease.

Alkaline Phosphatase

Metabolic bone disease in chronic renal failure. I. Dialyzed uremics.

Garner and ball's point counting technic was used to compare metabolic bone disease in dialyzed and nondialyzed uremic patients. Histologic measurements of bone from dialyzed and nondialyzed uremic patients dying between 1966 and 1971 showed that dialyzed patients have quantitatively more severe bone resorption, distortion of trabecular architecture and mineralization defects. Mineralization defects become more severe as the duration of dialysis increases but are not related to serum calcium and phosphorus levels. Bone volume in both groups is normal or increased and in dialysis patients increases in proportion to the elevation of serum phosphorus. Mean serum phosphorus and calcium levels, bone volume, and volume: surface ratios all decreased in dialysis patients between 1966 and 1971, while bone resorption and mineralization defects did not change. These results suggest that lowering of serum phosphorus without increasing serum calcium may aggrevate the uremic bone disease by reducing bone volume without improvement of mineralization and resorption defects.

Adult

Polyphosphate bone scanning of non-malignant bone disease in children.

The advent of 99mTechnetium phosphate bone scanning radiopharmaceuticals has opened new methods of investigation of pediatric bone diseases. In axial skeleton pain, suspected osteomyelitis, evaluation of vascular integrity and suspected but undetected fractures, the bone scan has proved to be a highly complementary study to the radiologic examination.

Adolescent

Bone disease after jejuno-ileal bypass for obesity.

Bone tissue was examined in 21 patients who had undergone jejuno-ileal bypass for obesity between 1971 and 1974. 10 patients had osteomalacia with evidence of secondary hyperparathyroidism. Clinical symptoms and biochemical and radiological investigations were often unreliable in diagnosing bone disease, although plasma-25-hydroxyvitamin-D and plasma-phosphate concentrations were significantly lower and plasma-parathyroid-hormone concentrations were significantly higher in the patients with bone disease. The presence of osteomalacia was unrelated to age, length of time since bypass, or post-bypass weight-loss, and plasma-25-hydroxyvitamin-D levels did not correlate closely with bone histological changes. It is concluded that osteomalacia is common after jejuno-ileal bypass and that factors other than simple vitamin-D deficiency may contribute to its development.

Adult