Osteomalacia as a very late manifestation of primary hyperparathyroidism

An 86-year-old woman with a history of treated hyperthyroidism and a 20-year history of untreated primary hyperparathyroidism developed generalized bone pain and a pseudofracture of the midshaft of the left femur. Laboratory examinations revealed elevated serum calcium, alkaline phosphatase, and C-terminal parathyroid hormone levels. Serum inorganic phosphate was below normal and 25-hydroxyvitamin D levels were low-normal. An undecalcified transiliac bone biopsy specimen following tetracycline double labeling revealed osteomalacia and osteitis fibrosa. Following treatment with vitamin D and phosphate, the serum inorganic phosphate level rose to normal. There was a decrease in bone pain, and the pseudofracture healed. However, the serum calcium, alkaline phosphatase, and C-terminal parathyroid hormone levels remained elevated. Longstanding primary hyperparathyroidism causes chronic hypophosphatemia and may lead to osteomalacia. Osteomalacia and its consequences may be part of the spectrum of bone disease seen in patients with longstanding primary hyperparathyroidism.     

Unusual presentation of altered bone metabolism with long-term antiepileptic therapy: pathological fracture of neck of femur due to brown tumor at calcer

The antiepileptic drugs are known to alter the bone metabolism and result in various range of pathological conditions (osteoporosis, osteomalacia, vitamin D deficiency, secondary hyperparathyroidism). These clinical conditions developed either due to direct effect of these therapeutic agents on bone or due to alteration in the homeostasis of other regulators of bone metabolism like serum calcium, vitamin D, and parathyroid hormone. Long-term therapy with antiepileptic agents results in higher incidence of pathological fracture, which is a consequence of either osteoporotic or osteomalasic (secondary to vitamin D deficiency) changes in bone produced by these drugs. Secondary hyperparathyroidism due to vitamin D deficiency following long-term polytherapy of antiepileptic drug ultimately leading to development of brown tumor and pathological fracture is very unusual.     

Osteomalacia in a patient with severe anorexia nervosa

A 27-year-old woman with anorexia nervosa since adolescence was referred to our unit for generalized bone pain most severe at the pelvis and an inability to stand. She reported a pelvic fracture diagnosed one year earlier, which had failed to heal. Laboratory tests showed low serum phosphate, normal total serum calcium corrected for serum albumin, and very low urinary calcium excretion. Serum bone alkaline phosphatase and parathyroid hormone levels were elevated, whereas 25-hydroxy-vitamin D was severely decreased. Multiple vertebral and rib fractures were seen on plain radiographs. Radiographic images consistent with osteomalacia were pseudofractures of the left inferior pubic ramus, a bilateral complete fracture of the superior pubic ramus, and a characteristic pseudofracture (Looser zone) in the lateral margin of the right scapula. Vitamin D-deficient osteomalacia with secondary hyperparathyroidism was strongly suspected at this point, but it was decided not to confirm this diagnosis by bone biopsy with histomorphometry and osteoid labeling because of the emotional instability of the patient. Dual-energy X-ray absorptiometry disclosed severe demineralization. After two months on calcium and vitamin D supplements, the bone pain had abated and the patient was able to stand. Serum calcium had increased; serum phosphate, 25-hydroxy-vitamin D, and parathyroid hormone had returned to normal, and the pseudofractures showed evidence of healing. Osteoporosis is a well-known complication of anorexia nervosa. This case shows that osteomalacia can also occur. Vitamin D status should be assessed in patients with long-standing severe anorexia nervosa.     

Acidosis-induced osteomalacia: metabolic studies and skeletal histomorphometry

The pathogenesis of osteomalacia was investigated in three patients with chronic metabolic acidosis. Serum levels of parathyroid hormone and vitamin D metabolites were measured, and bone biopsy specimens were analyzed after double tetracycline labeling. Parathyroid hormone concentrations were normal in patients 1 and 3 and slightly elevated in patient 2. Vitamin D metabolism was undisturbed. Static indicators of bone remodeling substantiated the diagnosis of osteomalacia in each case. In patient 1 fluorescent microscopy revealed no evidence of tetracycline uptake. In patients 2 and 3 active mineralization was evident at all osteoid seams, but because double labels were rare, the mineral apposition rate appears to have been substantially reduced in most bone-forming units. Our results indicate that acidosis-induced osteomalacia, unlike that due to vitamin D deficiency, may be associated with mineral deposition at every possible site. Nevertheless, like other causes of osteomalacia, metabolic acidosis prevents mineral apposition at a normal rate even if mineral deposition is ubiquitous. We suggest that titration of newly deposited phosphate causes the observed impairment of mineral apposition and ultimately leads to osteomalacia.     

Role of fibroblast growth factor 23 in phosphate homeostasis and pathogenesis of disordered mineral metabolism in chronic kidney disease

The discovery of fibroblast growth factor 23 (FGF23), a novel bone-derived hormone that inhibits phosphate reabsorption and calcitriol production by the kidney, has uncovered primary regulatory pathways and new systems biology governing bone mineralization, vitamin D metabolism, parathyroid gland function and renal phosphate handling. This phosphaturic hormone, which is made predominately by osteocytes in bone, appears to have a physiologic role as a counter-regulatory hormone for vitamin D. Evidence has also emerged to support the existence of a bone-kidney axis to coordinate the mineralization of bone with renal handling of phosphate. Pathologically, high circulating levels of FGF23 result in hypophosphatemia, decreased production of 1,25(OH)(2)D, elevated parathyroid hormone and rickets/osteomalacia in patients with functioning kidneys, whereas low levels are associated with tumoral calcinosis, hyperphosphatemia and elevated 1,25(OH)(2)D. In addition, patients with chronic kidney disease (CKD) exhibit marked elevations of circulating FGF23. While the significance of increased FGF23 levels in CKD remains to be defined, it might contribute to phosphate excretion and suppression of 1,25(OH)(2)D levels in CKD stages 3 and 4, as well as potentially contribute to secondary hyperparathyroidism through direct actions on the parathyroid gland in more advanced renal failure. As our knowledge expands regarding the regulation and functions of FGF23, the assessment of FGF23 will become an important diagnostic marker as well as a therapeutic target for management of disordered mineral metabolism in a variety of acquired and hereditary disorders.     

关注甲状旁腺功能增强和正常血钙型原发性甲状旁腺功能亢进症的防治

随着血钙及甲状旁腺素（PTH）等各种实验室检查技术的发展,大量无症状或正常血钙型原发性甲状旁腺功能亢进症（primary hyperparathyroidism,PHPT）得以早期诊断。PHPT已成为影响人类健康的第三大常见内分泌系统疾病。目前部分PHPT,尤其是多数正常血钙型PHPT,并非原发,可能是长期钙摄入不足和...     

The association of neurofibromatosis 1 and spinal deformity with primary hyperparathyroidism and osteomalacia: might melatonin have a role?

A 35-year-old woman with neurofibromatosis 1 and thoracic kyphoscoliosis had incomplete paraplegia. She had a history of hyperparathyroidism due to a parathyroid adenoma which had been excised 4 years previously. Plain radiographs of the spine revealed kyphoscoliosis from the third to sixth thoracic vertebrae. Kyphosis and scoliosis angles were 86° and 28°, respectively. Radiographs of the skull and hands showed radiological changes suggestive of hyperparathyroidism. Laboratory tests showed low-normal serum calcium, hypophosphatemia, elevated serum alkaline phosphatase, and low serum 25-hydroxyvitamin D. Retrospective review of the patient's laboratory data showed that she had osteomalacia at the time of diagnosis of primary hyperparathyroidism. The patient had been treated by anterior and posterior decompression and fusion with posterior instrumentation through a single posterior approach. The postoperative kyphosis and scoliosis angles were 30° and 12°, respectively. Neurological recovery and spinal fusion had been achieved. Osteomalacia responded well to vitamin D therapy. This is the first case of coexisting neurofibromatosis 1, primary hyperparathyroidism due to parathyroid adenoma and osteomalacia to be reported in the literature. The osteomalacia in this patient could be related to primary hyperparathyroidism, and not to neurofibromatosis 1. A drop in melatonin level after parathyroidectomy may have been the cause of spinal curvature progression in this patient. Received: June 28, 2000 / Accepted: November 21, 2000     

Parathyroid growth and suppression in renal failure

In advanced uremia, parathyroid hormone (PTH) levels should be controlled at a moderately elevated level in order to promote normal bone turnover. As such, a certain degree of parathyroid hyperplasia has to be accepted. Uremia is associated with parathyroid growth. In experimental studies, proliferation of the parathyroid cells is induced by uremia and further promoted by hypocalcemia, phosphorus retention, and vitamin D deficiency. On the other hand, parathyroid cell proliferation might be arrested by treatment with a low-phosphate diet, vitamin D analogs, or calcimimetics. When established, parathyroid hyperplasia is poorly reversible. There exists no convincing evidence of programmed parathyroid cell death or apoptosis in hyperplastic parathyroid tissue or of involution of parathyroid hyperplasia. However, even considerable parathyroid hyperplasia can be controlled when the functional demand for increased PTH levels is removed by normalization of kidney function. Today, secondary hyperparathyroidism can be controlled in patients with long-term uremia in whom considerable parathyroid hyperplasia is to be expected. PTH levels can be suppressed in most uremic patients and this suppression can be maintained by continuous treatment with phosphate binders, vitamin D analogs, or calcimimetics. Thus modern therapy permits controlled development of parathyroid growth. When nonsuppressible secondary hyperparathyroidism is present, nodular hyperplasia with suppressed expression of the calcium-sensing receptor (CaR) and vitamin D receptor (VDR) has been found in most cases. An altered expression of some autocrine/paracrine factors has been demonstrated in the nodules. The altered quality of the parathyroid mass, and not only the increased parathyroid mass per se, might be responsible for uncontrollable hyperparathyroidism in uremia and after kidney transplantation.     

Primary hyperparathyroidism associated with hypocalcemia in a patient presenting with kidney disease

Elevated serum parathyroid hormone (PTH) level together with hypocalcemia in chronic kidney disease usually suggests secondary hyperparathyroidism. However, primary hyperparathyroidism should also be considered, especially if concomitant vitamin D deficiency is suspected. We report a case of parathyroid adenoma associated with hypocalcemia and metabolic bone disease in a patient presenting with kidney disorder. The patient was successfully treated by parathyroidectomy that was preceded and followed by intensive calcium and vitamin D supplementation.     

Renal osteodystrophy: some new questions on an old disorder

The two major lesions of renal osteodystrophy are osteitis fibrosa cystica (OFC) and osteomalacia (OM). OFC is the characteristic bone lesion of uremic hyperparathyroidism. Although renal failure causes predictable parathyroid hyperplasia, the precise pathogenetic mechanism is still not defined. The "hyperphosphatemia-hypocalcemia-parathyroid hormone (PTH) hypersecretion" sequence of events is no longer an adequate model for the pathogenesis of uremic hyperparathyroidism. Other abnormalities associated with uremia include reduced 1,25-dihydroxyvitamin D (1,25D) synthesis, changes in intracellular phosphorus content or transcellular phosphate fluxes, or alteration in PTH metabolism, eg, change in set-point for PTH secretion. Each abnormality interacts with others and contributes to PTH hypersecretion, but none can completely account for the development and persistence of hyperparathyroidism in renal failure. The possibility that uremia may directly cause parathyroid hyperplasia remains open. It is also possible that factor(s) that initiate hyperparathyroidism may turn out to be quite different from that which sustains the hyperparathyroid state. Although both vitamin D-deficient and vitamin D-resistant OM may develop in patients with renal failure, the majority of uremic OM seen currently is "vitamin D-refractory." Although now there is persuasive evidence implicating aluminum (Al) accumulation as the major pathogenetic cause for the mineralization defect seen in this disorder, additional disturbances may play important contributory roles. Such factors would include extraskeletal effects of Al, differences in host-susceptibility to this element, the localization of Al within bone, uremia per se, and the participation of other metals and toxins. Finally, possible interactions between hyperparathyroidism and OM of uremia are speculated on.     

Emerging role of fibroblast growth factor 23 in a bone-kidney axis regulating systemic phosphate homeostasis and extracellular matrix mineralization

PURPOSE OF REVIEW: To describe emerging understanding of fibroblast growth factor 23 (FGF23) - a bone-derived hormone that inhibits phosphate reabsorption and calcitriol production by kidney and participates as the principle phosphaturic factor in a bone-kidney axis coordinating systemic phosphate homeostasis and bone mineralization. RECENT FINDINGS: FGF23 (a circulating factor made by osteocytes in bone) inhibits phosphate reabsorption and 1,25(OH)2D production by kidney. Physiologically, FGF23 is a counter-regulatory phosphaturic hormone for vitamin D and coordinates systemic phosphate homeostasis with skeletal mineralization. Pathologically, high circulating FGF23 levels cause hypophosphatemia, decreased 1,25(OH)2D production, elevated parathyroid hormone and rickets/osteomalacia. FGF23 mutations impairing its degradation cause autosomal dominant hypophosphatemic rickets. Respective loss-of-function mutations of osteocyte gene products DMP1 and Phex cause autosomal recessive hypophosphatemic rickets and X-linked hypophosphatemic rickets, initiating increased FGF23 production. Low FGF23 levels lead to hyperphosphatemia, elevated 1,25(OH)2D, and soft-tissue calcifications. FGF23 is markedly increased in chronic renal disease, but its role remains undefined. SUMMARY: FGF23 discovery has uncovered primary regulatory pathways and new systems biology governing bone mineralization, vitamin D metabolism, parathyroid gland function, and renal phosphate handling. FGF23 assessment will become important in diagnosing hypophosphatemic and hyperphosphatemic disorders, for which pharmacological regulation of FGF23 levels may provide novel treatments.     

Management of disturbances of calcium and phosphate metabolism in chronic renal insufficiency, with emphasis on the control of hyperphosphataemia.

BACKGROUND: Disturbances of calcium-phosphate (Ca-P) metabolism in chronic renal insufficiency (CRI) play an important role not only in bone disease (renal osteodystrophy) but also in soft tissue calcification, with an increased risk of vascular calcification, arterial stiffness, and worsening of atherosclerosis. METHODS: Discussion in order to achieve a consensus on key points relating to pathogenesis, clinical assessment, and management of renal osteodystrophy in dialysis patients. RESULTS: Secondary hyperparathyroidism develops primarily as a consequence of reduced active vitamin D production by the kidneys and phosphate retention, with the development of hyperphosphataemia, hypocalcaemia, and increased parathyroid hormone (PTH) levels. The same factors over the long term cause parathyroid gland hyperplasia and autonomous PTH production (tertiary hyperparathyroidism). As hyperphosphataemia and increased CaxP product have been associated with increased mortality in dialysis patients, hyperparathyroidism should be prevented and managed, starting in the pre-dialysis period, by calcium/vitamin D supplementation. Hyperphosphataemia is usually treated by means of intestinal phosphate binders, but different types of binders have been used. The traditional aluminium-based phosphate binders are certainly effective, but have the drawback of side effects due to aluminium absorption (osteomalacia, encephalopathy, microcytic anaemia). Calcium-containing phosphate binders (calcium carbonate or calcium acetate) have mainly been used for the last 10-15 years. However, they aggravate metastatic calcification, particularly if they are taken together with vitamin D analogues and a high calcium dialysate concentration. New calcium- and aluminium-free phosphate binders have recently been developed and may be useful, particularly in patients with metastatic calcification and/or hypercalcaemic episodes, in order to reduce the phosphate burden in the absence of an additional calcium load. New vitamin D analogues and calcimimetic drugs are also being developed for PTH suppression, with the goal to minimize or even entirely avoid hypercalcaemia and/or hyperphosphataemia. A suitable dialysate calcium concentration is important and must take into consideration the medical therapy and the calcium balance on an individual patient basis. Surgical parathyroidectomy is the ultimate means of treating hypercalcaemic hyperparathyroidism, when medical therapy has failed. CONCLUSION: Achieving an evidence-based consensus can give clinicians a useful tool for the treatment of disturbances of Ca-P metabolism in CRI: this has become an important objective in nephrological care, particularly as ageing and increased risk of atherosclerosis have become major issues in the dialysis population.     

Parathyroidectomy in chronic renal failure

Parathyroidectomy was carried out in 26 patients over a 14-year period. Excellent results were obtained in patients with severe hyperparathyroidism. Vascular calcification, hypercalcaemia and pruritus did not justify surgery unless associated with unequivocal hyperparathyroidism. 13 patients required intravenous calcium infusion for up to 2 weeks to control post-operative hypocalcaemia. Calcium requirements could be predicted from the pre-operative plasma alkaline phosphatase level. Following operation continued treatment with vitamin D was necessary to prevent hypocalcaemia. Hyperparathyroidism recurred in 1 patient after 8 years and 4 patients developed osteomalacia. Since parathyroid hormone may have toxic effects other than those on bone, maintenance of normal levels should be a long-term objective in the treatment of patients with chronic renal failure. Where large parathyroid glands are present, surgical reduction in gland mass is a logical prelude to long-term suppression of parathyroid hormone with vitamin D and phosphate-binding agents.     

Vitamin D Deficiency and Its Influence on Bone Metabolism and Density in a Brazilian Population of Healthy Men

Vitamin D supplementation is universal for postmenopausal women, but not for elderly men, in whom osteoporosis is also commonly neglected. This study aimed to evaluate vitamin D deficiency and its association with secondary hyperparathyroidism, bone resorption, and bone density in Brazilian men. A total of 120 men, 20–93 years, were evaluated for serum calcium, phosphorus, creatinine, 25-hydroxyvitamin D (25(OH)D), parathyroid hormone, biochemical markers of bone resorption (carboxy-terminal telopeptide, carboxy-terminal peptide of type I collagen), and bone mineral density (dual-energy X-ray absorptiometry). Glomerular filtration rate (GFR) below 30?mL/min/1.73?m², chronic diseases, and medications affecting bone were the exclusion criteria. No participant reported previous low-impact fractures. In the overall population, 25(OH)D levels were below 30?ng/mL in 46.7%, and below 20?ng/mL in 27.6%. Among the 93 patients 50 years and older, 28 had osteoporosis. In those 70 years and older, the prevalence of vitamin D deficiency (42.1%), secondary hyperparathyroidism (46.4%), high bone resorption (39.6%), decreased GFR (39.2%), and osteoporosis (41.4%) was significantly higher than in the younger subjects (p?<?0.005 for all comparisons). Serum parathyroid hormone increased with aging and declining GFR, but was not significantly associated with 25(OH)D or bone mineral density. There was a clear contribution of vitamin D deficiency to increased bone resorption and osteoporosis. Binary logistic regression model considering age, 25(OH)D, and bone resorption identified age ≥70 years as the main determinant of osteoporosis. Our data demonstrate a high prevalence of vitamin D deficiency in a male population living in Rio de Janeiro, and emphasize its participation on the pathogenesis of age-related bone loss. (Vitamin D deficiency and osteoporosis are common in elderly Brazilian men.)     

Pathogenesis of parathyroid hyperplasia in renal failure

In chronic kidney disease, secondary hyperparathyroidism (HPTH) is characterized by parathyroid hyperplasia and enhanced synthesis and secretion of parathyroid hormone (PTH). Elevated PTH levels cause renal osteodistrophy and cardiovascular complications, with significantly increased morbidity and mortality in renal failure. The three main direct causes of renal HPTH are hypocalcemia, hyperphosphatemia and vitamin D deficiency. A link between the mechanisms controlling proliferation and hormonal production also exists in normal parathyroid cells which respond to the stimulus of chronic hypocalcemia, not only by an increase in PTH release but also with a consequent parathyroid cell proliferation. The mechanisms responsible for this link, however, remain poorly understood. In this review, we analyze the current understanding concerning the new insights into the molecular mechanisms of parathyroid hyperplasia and PTH secretion in renal failure regulated by calcium, phosphate and vitamin D.     

Secondary hyperparathyroidism as a palpable intrathyroid parathyroid gland in a patient with hypophosphatemic osteomalacia

Secondary hyperparathyroidism is sometimes seen in patients with hypophosphatemic osteomalacia after long-term oral phosphate therapy. Parathyroidectomy is sometimes needed for the correction of hypercalcemia in these patients, and is rarely performed in patients without hypercalcemia. A 46-year-old female patient had hypophosphatemic osteomalacia with unknown cause and secondary hyperparathyroidism. A palpable neck mass developed after long-term oral phosphate therapy. An intrathyroid parathyroid gland was confirmed through partial thyroidectomy and parathyroidectomy. Renal phosphate wasting decreased strongly, and serum parathyroid hormone was in the normal range after the operation. A correction of secondary hyperparathyroidism may partially overcome hyperphosphaturia in some patients with hypophosphatemic rickets.     

The mineralization index--a new approach to the histomorphometric appraisal of osteomalacia

The histomorphometric diagnosis of osteomalacia depends on the conjunction of two or three independent criteria but for several reasons, both clinical and pathophysiologic, it would be useful to have a single index of severity. Accordingly, using an extensive library of normal values in 143 healthy women, we constructed the mineralization index (MI), defined as [osteoid thickness (O.Th) (microm) + osteoid volume/bone volume (OV/BV) (%)] x 1.15 - osteoid mineralization rate (%/day) - [bone formation rate/bone surface (BFR/BS) (microm3/microm2/year) x 0.15]. MI was normally distributed with mean 8.0, SD 3.3, and range 0-15 (arbitrary units); it was unaffected by race, menopausal status, age or bone turnover, and was slightly lower in osteoporotic patients with nontraumatic vertebral fracture than in healthy white postmenopausal women (6.83 vs. 7.95). In hypovitaminosis D osteopathy (HVO) stage I, MI was normal in 18/26 cases (70%; HVOia), demonstrating more rigorously than before that osteoid accumulation is initially due entirely to secondary hyperparathyroidism and increased bone turnover. In the remaining 30% (HVOib), MI was increased, indicating the onset of impaired mineralization while bone formation was still increased and before the appearance of osteomalacia. In secondary hyperparathyroidism due to renal bone disease, 10/20 cases (50%) had normal MI and higher BFR than in HVOia (93 vs. 32), and there was a significant inverse correlation between MI and BFR. In patients with osteomalacia according to current criteria, MI ranged from 29.2 to 166.5; an MI of 30 had high sensitivity and specificity for the diagnosis of osteomalacia. Including all patients with HVO, there was a significant (P < 0.001) inverse correlation between MI and calcium x phosphate product, but the unexplained variance of >70% suggests that vitamin D deficiency impairs mineralization by multiple mechanisms. We conclude that the MI clarifies the early effects of vitamin D deficiency on bone and the relationship between different components of renal bone disease simplifies the histologic diagnosis of osteomalacia and may contribute to its management, and explicates the mechanisms of mineralization.     

Parathyroid function in chronic vitamin D deficiency in man: A model for comparison with chronic renal failure

Summary It has become obvious, from the elegantin vitro studies of Cohnet al. (3) and of others, that calcium may act at various steps in the biosynthesis, storage, degradation and secretory release of parathyroid hormone. It would be premature to attempt to interpret our simple clinical observations in terms of these still incompletely defined mechanisms. These clinical studies have, however, identified several different components in the overall pattern of parathyroid response in chronic vitamin D deficiency. In significantly hypocalcaemic patients there was an inverse proportional relationship between serum calcium and serum iPTH, both in the steady-state (9) and during calcium infusion (Fig. 2A); a similar pattern was seen in primary hyperparathyroidism (Fig. 2B). One is tempted to regard this relationship as reflecting an action of calcium on hormonal biosynthesis. There is the further suggestion that profound hypocalcaemia in vitamin D deficiency might limit the capacity of the parathyroid gland to release its hormone (Figs. 3, 4). In the majority of cases of chronic vitamin D deficiency, the serum calcium is maintained close to normal but varying between 8.1 and 11.1 mg/dl in different individual patients of the present series; and in all these cases there is very obvious evidence of increased parathyroid activity. In such patients, it appears that the serum iPTH represents the maximum rate of secretion that the parathyroid gland can currently produce; and the level of serum calcium reflects the extent to which that parathyroid secretion compensates for lack of vitamin D action on gut, bone and kidney. If this equilibrium state is disturbed by an induced, barely detectable, increment in serum calcium there appears to be an immediate inhibition of parathyroid secretion (Fig. 5). There is nothing in the data to suggest that a direct action of vitamin D on the parathyroid glands is required for any of these patterns of parathyroid response, since all were observed in patients with clinical vitamin D deficiency. Only the very slow decay in the steady-state concentration of serum iPTH after correction of vitamin D deficiency in the two hypercalcaemic patients (Fig. 6) suggests a possible direct action of vitamin D on the parathyroid glands. The very slowness of this decay must imply a process of structural involution. Is it possible that vitamin D is involved in some way in coupling the calcium dependent processes of hormonal synthesis and secretion with a calcium dependent mechanism controlling cell division? At present one can do little more than ask the question and wonder it it is a disturbance of such coupling that permits the development of hypercalcaemic secondary hyperparathyroidism.     

Management of calcium and bone abnormalities in hemodialysis patients

In chronic renal failure, hyperphosphatemia, hypocalcemia, hyperparathyroidism, reduced activation of vitamin D, decreased level of calcium-sensing receptor, osteitis fibrosa, and osteomalacia are features related to calcium abnormalities. Hyperparathyroidism is a risk factor for survival of hemodialysis patients as well as hypoparathyroidism, which is another feature in hemodialysis patients. Treatment of these abnormalities includes control of parathyroid hormone (PTH) secretion, counteracting hyperphosphatemia, correction of hypocalcemia, and others. Various kinds of vitamin D analogs have been introduced recently in addition to calcitriol and alfacalcidol, which have a rather long history (eg, maxacalcitol and falecalcitriol). Sevelamer is a newly developed phosphate binder to treat soft-tissue calcification.