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Query: UMLS:C0005940 (bone disease)
 7,459 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Normal fetal and neonatal calcium homeostasis is dependent upon an adequate supply of calcium from maternal sources. Both maternal hypercalcemia and hypocalcemia can cause metabolic bone disease or disorders of calcium homeostasis in neonates. Maternal hypercalcemia can suppress fetal parathyroid function and cause neonatal hypocalcemia. Conversely, maternal hypocalcemia can stimulate fetal parathyroid tissue causing bone demineralization. We report two asymptomatic women, one with previously unrecognized hypoparathyroidism and the other with unrecognized familial benign hypercalcemia, who were diagnosed when their newborn infants presented with abnormalities of calcium metabolism. J.B. was born at 34 weeks' gestation with transient hyperbilirubinemia and thrombocytopenia. At 1 month of age he had severe bone demineralization, cortical irregularities, widening and cupping of the metaphyses, and lucent bands in the scapulae. The total serum calcium and phosphorus were normal with an ionized calcium of 5.4 mg/dL (4.6-5.4). His alkaline phosphatase, parathyroid hormone, and 1,25-dihydroxyvitamin D levels were all increased. P.B., mother of J.B., had no symptoms of hypocalcemia either prior to, or during this pregnancy. She had severe hypocalcemia and hyperphosphatemia, laboratory values typical of hypoparathyroidism. J.N. presented at 6 weeks of age with new onset of seizures and tetany secondary to severe hypocalcemia. The serum phosphorus, creatinine, alkaline phosphatase, and parathyroid hormone levels were normal. At 15 weeks of age his calcium was slightly elevated with a low fractional excretion of calcium. P.N., mother of J.N., had no symptoms of hypercalcemia either prior to, or during this pregnancy. Her serum calcium was 12.7 mg/dL and urine calcium was 66.5 mg/24 hr, with a low fractional excretion of calcium ranging from 0.0064 to 0.0073. P.N. has a brother who previously had parathyroid surgery. Both J.N. and P.N. meet the diagnostic criteria for familial benign hypercalcemia. These cases illustrate the important relationships between maternal serum calcium levels and neonatal calcium homeostasis. They emphasize the need to assess maternal calcium levels when infants are born with abnormal serum calcium levels or metabolic bone disease.
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PMID:Disorders of maternal calcium metabolism implicated by abnormal calcium metabolism in the neonate. 1087 87

Pseudohypoparathyroidism (PHP) is a disorder characterized by hypocalcemia and secondary hyperparathyroidism caused by primarily renal resistance to the effects of parathyroid hormone (PTH). However, as an indication of normal PTH responsiveness in bone, some patients with PHP develop skeletal disease because of longstanding secondary hyperparathyroidism. A patient is described with hypocalcemia, hyperphosphatemia, marked secondary hyperparathyroidism, and an increased alkaline phosphatase level. Subsequent evaluation revealed a diagnosis of PHP type Ib. The patient had radiographic evidence of skeletal disease caused by secondary hyperparathyroidism. A urinary level of N-telopeptide cross-links of type I collagen (NTX) was elevated markedly. Bone mineral density (BMD) was in the normal range at all measured sites, with BMD at the spine being higher than at the femur and distal radius. Treatment was initiated with calcium and calcitriol. Seven months later, calcium and PTH levels had normalized. The level of urinary NTX fell by 83%. Spinal BMD improved by 15%, and BMD at the femoral neck improved by 11%. Radial BMD was unchanged. This case emphasizes the importance of evaluating patients with PHP for hyperparathyroid bone disease and shows that correction of secondary hyperparathyroidism in patients with PHP can result in a significant suppression of previously accelerated bone turnover and to substantial gains in BMD at sites containing a major percentage of cancellous bone. The case also implies that assessment of bone turnover with urinary NTX and measurement of BMD with dual-energy X-ray absorptiometry (DEXA) may be useful in following the response of the skeleton to therapy in these patients and suggests the need for more studies of both NTX and BMD in patients with PHP.
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PMID:Serial changes in bone mineral density and bone turnover after correction of secondary hyperparathyroidism in a patient with pseudohypoparathyroidism type Ib. 1089 92

Histopathological and pathophysiological investigations including the genetic approach have been contributing to management of renal hyperparathyroidism (HPT). In renal failure, parathyroid glands initially proliferate diffusely and polyclonally, and then are transformed to monoclonal nodular hyperplasia with aggressive growth potential and diminished expression of both the vitamin D receptor and calcium-sensing receptor. When more than one parathyroid gland progresses to nodular hyperplasia, HPT is refractory to medical treatment. To prevent advanced renal HPT, progression to nodular hyperplasia should be avoided. Control of hyperphosphatemia is very important to prevent advanced renal HPT, but it is usually difficult. Administration of vitamin D metabolites constitutes the most promising form of prophylaxis and should be performed with monitoring of the PTH level to avoid adynamic bone disease. Calcitriol pulse therapy is effective for advanced renal HPT; however, when parathyroid glands progress to nodular hyperplasia, surgical treatment should be considered. Measuring parathyroid volume by ultrasonography is useful for detecting nodular glands and deciding treatment options. Parathyroidectomy (PTx) is an effective treatment for advanced renal HPT. However, the timing of the operation is important, because the improvement of skeletal deformity and vessel calcification inducing high mortality risk cannot be expected even after successful surgery. Total PTx with forearm autograft is a suitable procedure for renal HPT. Recently. selective percutaneous ethanol injection therapy has been adopted as an alternative treatment to PTx, and new vitamin D analogues, phosphate binders without calcium, and calcimimetics have been developed as new options for management of renal HPT.
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PMID:Management of renal hyperparathyroidism. 1091 87

Control of serum phosphorus continues to be of utmost importance in renal replacement therapy, due to the high prevalence of hyperphosphatemia in the dialysis population. Hyperphosphatemia has traditionally been associated with secondary hyperparathyroidism, soft tissue calcification, and renal osteodystrophy. Recent evidence implicates poor phosphorus control as an important factor in the development of cardiovascular calcification, cardiac disease, and death in patients with chronic renal failure. Dietary restriction of phosphorus, while an important factor in the control of serum phosphorus, has practical problems that limit its success in most patients. Aluminum was used in the past to inhibit phosphorus absorption, but its accumulation has serious, toxic effects on bone. Calcium-based binders have largely replaced aluminum; however, these binders are limited by the excessive amounts of calcium absorbed, which can frequently lead to positive calcium balance, suppression of bone turnover, and hypercalcemia. Calcium overloading is also associated with soft tissue and cardiovascular calcification. More recent strategies for managing hyperphosphatemia and renal bone disease include the use of nonabsorbed phosphate binders that are aluminum- and calcium-free and the development of vitamin D analogs that control parathyroid hormone activity with less calcemic effects. Future goals include defining optimal target levels of phosphorus, calcium, and parathyroid hormone and developing clinical approaches that will promote parathyroid glands, bone, and cardiac health.
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PMID:Hyperphosphatemia: pharmacologic intervention yesterday, today and tomorrow. 1107 7

Secondary hyperparathyroidism (SH) and hyperplasia of the parathyroid glands (PTG) are universal complications in patients with CRF. In early renal failure, reduction in serum calcitriol and moderate decreases in ionized calcium contribute to greater synthesis and secretion of PTH. As renal disease progresses, a reduction in parathyroid expression of vitamin D receptor and calcium receptor renders the PTG more resistant to both calcitriol and calcium. High dietary phosphorus (P), independent of calcium and calcitriol, further enhances uremia-induced PTG hyperplasia and PTH synthesis and secretion, the latter by posttranscriptional mechanisms. Once SH develops, dietary P restriction can return the high serum PTH levels toward normal, however, parathyroid hyperplasia persists. Studies in our laboratory identified 2 of the mechanisms involved in the opposing effects of high and low dietary P content on PTG growth. Whereas high dietary P increases parathyroid expression of transforming growth factor alpha (TGFalpha), a growth promoter, P restriction induces the cyclin-dependent kinase inhibitor p21, an inducer of growth arrest. Both effects of P are specific for the PTG. No increase in either protein was observed in liver or intestine. TGFalpha induction of hyperplasia involves binding to the epidermal growth factor receptor and activation of mitogen activated protein (MAP) kinases cascades. p21 blocks progression through the cycle and cell division by inactivating cyclin/cyclin-dependent kinase complexes. Preventing hyperphosphatemia and elevated Ca x P product in renal failure not only ameliorates the progression of SH and bone disease but also the morbidity and mortality resulting from vascular calcification.
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PMID:Role of phosphorus in the pathogenesis of secondary hyperparathyroidism. 1115 62

The prevalence and the clinical gravity of the various histopathological varieties of renal osteodystrophy in dialysis patients depends on the severity of both the aluminium intoxication and that of hyperparathyroidism. The prevalence of bone pains, fractures and hypercalcemias are the highest in adynamic bone diseases (ABD) with severe aluminium intoxication, then in osteitis fibrosa and mixed osteopathy, in the ABD with moderate aluminium intoxication and rare in the mild lesion in spite of similar moderate aluminium intoxication. In the absence of aluminium intoxication, hypercalcemia and hyperphosphatemia prevalence is higher only when intact PTH is more that 4 times the upper limit of normal. When PTH is between 1 and 2 folds the ULN this prevalence is null and bone mineral density is the highest. 2. The low turnover aluminic bone diseases (osteomalacic or adynamic) will be cured by long term deferoxamine treatment. The hazards of such treatment justify the performance of a bone biopsy to ensure the diagnosis. Their prevention relies on adequate treatment of tapwater and definitive exclusion of long term administration of aluminum phosphate binders. 3. Non aluminic osteomalacia will be treated according to the same guidelines given for the uremic patients before dialysis. 4. Non aluminic adynamic bone disease will be cured by means aiming at stimulating PTH secretion as discontinuing 1 alpha hydroxylated vitamin D derivatives, and, if there is no hyperphosphatemia by discontinuation of calcium supplement. In case of hyperphosphatemia in dialysis patients CaCO3 doses have to be nevertheless increased after the dialysate calcium concentration (DCa) has been decreased in order to induce a negative perdialytic calcium balance for PTH secretion stimulation. In the near future substitution of CaCO3 by non calcemic non aluminic phosphate binders will suffice. 5. Osteitis fibrosa due to hyperparathyroidism will be treated first by securing an optimal vitamin D repletion (bringing plasma 25OH vitamin D around 30 and 60 ng/ml or 75-150 nmol/l) and by correcting hypocalcemia and hyperphosphatemia by CaCO3 at high doses (3-12 g/day) taken with the meals. In case of hypercalcemia dialysate calcium concentration will be decreased to correct it or, in a near future, CaCO3 will be decreased to 3 g/day and hyperphosphatemia will be controlled by non calcemic, non aluminic phosphate binders. When hyperphosphatemia is controlled whereas plasma calcium is normal or low, 1 alpha hydroxylated vitamin D derivatives can be administered. 6. Instrumental parathyroidectomy should be considered when plasma levels of intact PTH remain above 7 folds the upper limit of normal whereas hyperphosphatemia persists and hypercalcemia occurs in order to prevent thining of the corticals and subsequent fracture risk. In case of previous exposition to aluminum, a deferoxamine test and/or a bone biopsy will be performed to decide a long term DFO treatment before the parathyroidectomy in order to prevent the transformation of a mixed osteopathy into an aluminic adynamic bone disease. 7. The difficulty of hyperparathyroidism control in dialysis patients is due to poor compliance to phosphate binders and to irreversible parathyroid hyperplasia with occured before the dialysis stage. This stress the primary importance if its early prevention without iatrogenia by first CaCO3 and vitamin D repletion, as soon as the creatinine clearance decreases below 60 ml/min/1.73 m2.
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PMID:[Renal osteodystrophy (3); its treatment in dialysis patients]. 1121 85

There is mounting evidence that elevated serum phosphorus is an important cardiovascular risk factor in patients with end stage renal disease. Recent work has shown that vascular smooth muscle cells have the ability to undergo osteoblastic differentiation and produce an environment conducive to mineralization. Serum phosphorus is an important stimulator of this process and the adverse cardiovascular effects of hyperphosphatemia are most likely mediated via its ability to enhance the development of vascular calcification. Arterial calcification, whether it is intimal or medial in location, is a strong independent risk factor for cardiovascular morbidity and mortality. Both coronary artery calcification and calciphylaxis are prototypical examples of arterial calcification that have been associated with poor phosphate control. Furthermore, several investigators have recently suggested that the prescription of large doses of calcium to achieve phosphate control may augment, rather than diminish, the risk of vascular calcification. This is more likely to be true in the presence of low turnover bone disease, a diagnosis difficult to make with routine laboratory testing. A brief review of the molecular biology of vascular calcification supports the concept that warfarin administration may exacerbate the calcific process, particularly in the setting of hyperphosphatemia, as has been reported in patients with calciphylaxis. Recognizing the consequences of poor phosphate control, it is time to adopt strict target levels that aim to normalize serum phosphorus levels. The available evidence supports that this control should not be achieved through the use of supraphysiologic doses of supplemental calcium.
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PMID:Control of serum phosphorus: implications for coronary artery calcification and calcific uremic arteriolopathy (calciphylaxis). 1170

Hyperphosphatemia directly or indirectly contributes to the progression of chronic renal disease and is an important factor in the development of secondary hyperparathyroidism and uremic bone disease. New therapeutic advances include the development of calcium-free intestinal phosphate binders, calcimimetics to control parathyroid hormone secretion and non-calcemic vitamin D analogs.
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PMID:Disorders of phosphate metabolism in chronic renal disease. 1195 Jun 29

Vitamin D derivatives correct high bone remodeling by decreasing plasma iPTH concentration in uremic patients with secondary hyperparathyroidism. However, without bone biopsy, plasma iPTH alone might not provide sufficient information regarding vitamin D-induced bone changes. Plasma bone-specific alkaline phosphatase (bAP) seems more sensitive than iPTH in assessing the degree of bone remodeling. We prospectively studied the evolution of iPTH and bAP in 14 adult hemodialysis patients treated for 1 year by i.v. alfacalcidol pulses. The mean total alfacalcidol dose was 0.08 +/- 0.02 g/kg/week. Ten patients completed the study, 2 patients had to be parathyroidectomized before week 24 because of hypercalcemia and uncontrolled hyperphosphatemia, and 2 other patients died before week 36. Mean iPTH levels diminished from 826 +/- 300 pg/ml (range 507 - 1,500 pg/ml) at baseline to 436 +/- 371 pg/ml (range 18 - 1,095 pg/ml) after 52 weeks of treatment (48% of decrease). Only 2 patients normalized plasma iPTH levels while 8/10 normalized bAP. Five patients remained with plasma iPTH concentrations higher than 5-fold the normal value. In contrast, plasma bAP levels declined from 47.6 +/- 32.2 ng/ml (range 15.4 - 130.0 ng/ml) at baseline to 17.8 +/- 9.9 ng/ml (range 8.0 +/- 38.0 ng/ml) at week 52 (63% of decrease). Bone histomorphometry was available in 6 patients after 15.8 +/- 5.1 months of alfacalcidol treatment. None of them met the criteria of adynamic bone disease as they had increased bone resorption and marrow bone fibrosis. Bone formation rate was normal in 2 patients and unmeasurable in the other 4. Two patients showed signs of osteomalacia. In conclusion, alfacalcidol preferentially reduced bone formation rate rather than the other histological parameters of secondary hyperparathyroidism. It reduced plasma bAP more efficiently than iPTH.
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PMID:Plasma bone-specific alkaline phosphatase changes in hemodialysis patients treated by alfacalcidol. 1200 42

End-Stage Renal Disease Network 11 initiated a renal osteodystrophy quality improvement activity in 1999. One component was the collection and assessment of dialysis facility renal osteodystrophy protocols, whereas another component was the analysis of bone disease-related medication use. Two hundred eighty-eight facilities were invited to submit protocols. A model bone disease and mineral metabolism protocol was developed as the standard for comparison. From the model protocol, an instrument was created to evaluate eight key areas (baseline screening of key laboratory data, dietary intervention, phosphate-binder use, vitamin D use, monitoring of key laboratory indicators, management of hypercalcemia, oversuppression of parathyroid hormone [PTH], and guidelines for both hemodialysis and peritoneal dialysis patients). A bone disease-related prescription survey was completed for 749 randomly selected patients. Survey information included vitamin D and phosphate-binder use and related laboratory values (calcium, phosphorus, intact PTH [iPTH], and calcium x phosphorus product). Although 45% of facilities had six or more points on the evaluation tool, protocols were still incomplete compared with the model. Mean facility-specific scores among the five states in the Network ranged from 1.0 to 5.9 (possible scores, 0 to 8). Most patients were prescribed a phosphate binder; however, 31.8% had average phosphorus levels greater than 6.0 mg/dL during the 3-month period. Only 58% of patients with average iPTH concentrations greater than 260 pg/mL were prescribed vitamin D. Of patients treated with vitamin D, 39% had iPTH concentrations less than 130 pg/mL. There is opportunity to improve renal osteodystrophy protocols in Network 11 and reinforce potential hazards of sustained hyperphosphatemia and hyperparathyroidism.
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PMID:Analysis of renal bone disease treatment in dialysis patients. 1204 41


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