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At least 595 records · Page 33Linked to original sources
PubMed2001

Ossification of the posterior longitudinal ligament in vitamin D-resistant rickets: case report and review of the literature.

STUDY DESIGN: A case report of cervical myelopathy caused by ossification of the posterior longitudinal ligament in a patient with vitamin D-resistant rickets is presented together with a review of literature. OBJECTIVE: To report the diagnosis of ossification of the posterior longitudinal ligament in a white woman with vitamin D-resistant rickets. SUMMARY OF BACKGROUND DATA: The association between ossification of the posterior longitudinal ligament and untreated vitamin D-resistant rickets has been reported in Japan, but infrequently in white populations. In whites, ossification of the posterior longitudinal ligament is closely associated with diffuse idiopathic skeletal hyperostosis. A clear association between ossification of the posterior longitudinal ligament and vitamin D-resistant rickets in white populations has not yet been established. METHODS: The medical record and imaging studies of a patient treated at the authors' institution for cervical myelopathy caused by ossification of the posterior longitudinal ligament in the setting of treated vitamin D-resistant rickets were reviewed. A Medline search of the medical literature between 1966-1999 was performed to identify pertinent studies and similar case reports. RESULTS: The occurrence of spinal stenosis in untreated adults with vitamin D-resistant rickets has been reported in all regions of the spine in Japanese patients. The association between ossification of the posterior longitudinal ligament and untreated vitamin D-resistant rickets was first reported in Japan, where ossification of the posterior longitudinal ligament is endemic. This association may be incidental, because reports on ossification of the posterior longitudinal ligament in whites are not as frequent as in Japanese, reflecting the higher prevalence of this condition in Japan. CONCLUSION: Ossification of the posterior longitudinal ligament and ossification of the posterior longitudinal ligament associated with deranged calcium or phosphate metabolism may be different pathologic entities sharing a common outcome. Adequate treatment of vitamin D-resistant rickets may not always prevent or reverse ossification of the posterior longitudinal ligament.

Bone Density↗
PubMed2001

Ectopic cardiac calcification associated with hyperparathyroidism in a boy with hypophosphatemic rickets.

An adolescent with hypophosphatemic rickets developed cardiac calcifications in the absence of hypercalcemia or elevation of the phosphocalcic product (the product of the total serum calcium and phosphorus concentrations). Cardiac calcifications led to aortic and mitral valve dysfunction, myocardial calcification, and arrhythmia. Hyperparathyroidism probably played a significant role in the development of this complication, which emphasizes the necessity for intermittent assessment of parathyroid status in individuals receiving medical therapy for hypophosphatemic rickets.

Adolescent↗
PubMed1996

Regulation of renal phosphate handling: recent findings.

Our knowledge of renal phosphate handling and its regulation has expanded in the past 2 years because of the molecular identification of sodium-phosphate cotransport systems. New tools (molecular probes and antibodies) have allowed dissection out of some of the molecular and cellular mechanisms underlying the adaptation of phosphate transport to dietary content, the phosphaturic effect of parathyroid hormone or glucocorticoids and the renal phosphate leak in hypophosphataemic rickets.

Animals↗
PubMed1997

New insights into X-linked hypophosphatemia.

X-linked hypophosphatemia is a heritable form of rickets characterized biochemically by phosphaturia and abnormal bioactivation of vitamin D. Recent advances include the observation, using kidney cells from the X-linked hypophosphatemia mouse model (Hyp), that in-vitro renal phosphate transport is normal yet bone mineralization may be intrinsically abnormal. Of special interest is the identification of a gene (PEX) that is mutated in X-linked hypophosphatemic patients.

Genetic Linkage↗
PubMed1997

Sodium transporters in health and disease.

Our understanding of sodium transport defects has exploded in the past 18 months, and has provided unique insights into epithelial transport processes and unusual clinical syndromes resulting from mutations of specific transporters. These genetic disorders disturb sodium balance, with both sodium retaining and sodium wasting disorders as the consequence.

Animals↗
PubMedDate not supplied

Hypophosphatemic rickets: the role of hemiepiphysiodesis.

Despite early medical intervention, children with hypophosphatemic rickets often have progressive deformities in the lower extremities. With the forces imparted by gravity and weight bearing, varus or valgus deformities that might otherwise have been physiological are likely to progress, causing gait disturbance and pain. Proper medical management is important and may theoretically slow or prevent the progression of varus or valgus, but is ineffective at correcting deformity once established. We have reviewed the literature and gathered a series of 10 patients, most of whom underwent hemiepiphysiodesis. We are presenting the rationale for, and the results of, that surgery, in an effort to define the role of this minimally invasive procedure.

Adolescent↗
PubMed2004

What have we learnt about the regulation of phosphate metabolism?

PURPOSE OF REVIEW: The search for hormones which specifically regulate phosphate metabolism has fuelled recent tantalizing studies. These studies have been motivated by diseases involving renal phosphate wasting, including tumor-induced osteomalacia, X-linked hypophosphatemic rickets, and autosomal dominant hypophosphatemia. This review focuses on likely candidate 'phosphatonins' and their possible physiological significance. RECENT FINDINGS: Candidate phosphatonins include fibroblast growth factor 23, matrix extracellular phosphoglycoprotein, stanniocalcin, and Frizzled-related protein 4. Fibroblast growth factor 23 has emerged as the prime candidate explaining pathophysiology of these diseases. FGF-23 is expressed in most tumors in tumor-induced osteomalacia. Serum fibroblast growth factor 23 is increased in most patients with X-linked hypophosphatemic rickets and tumor-induced osteomalacia. Injection of recombinant fibroblast growth factor 23 induces phosphaturia, hypophosphatemia, and suppression of 1,25-dihydroxyvitamin D in animals. Many unanswered questions remain, including the relationship between PHEX (phosphate-regulating gene with homologies to endopeptidases on the X chromosome) mutations and elevated fibroblast growth factor 23. It is also not clear whether these candidate phosphatonins play a role in phosphate or vitamin D metabolism in healthy humans, or that this role is endocrine. The most compelling evidence derives from the fibroblast growth factor 23-knockout mouse which shows hyperphosphatemia and increased serum 1,25-dihydroxyvitamin D. A physiologically relevant phosphatonin should explain renal adaptation to variable dietary phosphate intake. The tissue source and determinants of serum fibroblast growth factor 23 are unknown. SUMMARY: Pathophysiological and animal studies serve as a logical foundation on which to base further questions of human physiology. The definition of what is or is not a phosphatonin may need to be refined. There is a need to return to 'old-fashioned' human physiology studies to place recent findings in perspective.

Animals↗
PubMed2005

Recent findings in phosphate homeostasis.

PURPOSE OF REVIEW: We summarize the most recent findings on the proteins that interact with sodium/inorganic phosphate (Na/Pi) cotransporters, the factors that regulate Pi homeostasis and their role in pathology. RECENT FINDINGS: Studies in animal models and cell lines identified proteins mandatory to correct trafficking of the kidney-specific Na/Pi cotransporter NPT2a and its control by the parathyroid hormone. Expression of the intestinal cotransporter NPT2b is controlled by calcitriol, the ubiquitin ligase Nedd-4 and the serum glucocorticoid inducible kinase. Recent data confirm that fibroblast growth factor 23 plays a central role in the control of Pi homeostasis. Mice disrupted for or overexpressing this gene exhibit significant alteration of Pi transport and calcitriol metabolism. In humans, fibroblast growth factor 23 mutations are responsible for autosomal hypophosphataemic rickets or tumoral calcinosis. This gene also seems to be involved in hyperparathyroidism in patients with chronic kidney disease. Several new phosphaturic factors have been identified. Moderate increases in serum Pi concentration may have deleterious effects on lifespan in humans with chronic kidney disease. Disruption of the Klotho gene in mice is associated with hyperphosphataemia and decreased lifespan. Polymorphisms in this gene, in humans and in mice, influence vascular calcification and survival. SUMMARY: Pi homeostasis depends on the activity of Na/Pi cotransporters in intestine and kidney. Na/Pi transporter activity is regulated by cellular and endocrine factors, among which fibroblast growth factor 23 plays a central role. Adequate control of Pi homeostasis is crucial, as a moderate increase in serum Pi concentration and polymorphisms in genes involved in Pi metabolism may influence the aging process and lifespan.

Animals↗
PubMedDate not supplied

Acquired vitamin D-resistant rickets caused by aggressive osteoblastoma in the pelvis: a case report with ten years' follow-up and review of the literature.

Rickets or osteomalacia secondary to tumor in either bone or soft tissue is rare and interesting in that it can be cured after removal of the tumor. The majority of the reported cases occurred in adults older than 30 years, and the most commonly associated types were vascular and fibrous tumors. We present a new case of aggressive osteoblastoma in the ilium, which induced vitamin D-resistant rickets in an 8-year, 9-month-old boy. Radiographs and blood chemistry findings on admission showed typical features of active hypophosphatemic ricketts. He underwent three local excisions of the tumor. At 10-year follow-up, the patient was symptom free but short. When a child has symptoms of rickets that develop relatively later than ordinary vitamin D-resistant rickets, every effort should be made to search out a tumorous lesion before attributing it to a renal origin.

Bone Neoplasms↗
PubMed1978

Mild phosphate diabetes in adults.

Phosphate diabetes has been considered as rare and to occur almost exclusively in children. Upon examination of adult patients with rheumatic or kidney diseases it has, however, been found that the combination of hypophosphataemia and hyperphosphaturia is not so rare. This paper deals with 24 adult patients of this type, whom we have found during 6 months. Their mean serum phosphorus concentration was 0.7 mmol/l (range 0.5--0.8). Mean phosphate clearance was 31 ml/min/1.73 m2 (range 16--51). The diagnoses were myalgia, dorsalgia (n = 7), papillitis calcificans (n = 5), prostatitis or prostate accretions (n = 4), dizziness (n = 2), kidney stones, tubular defect, interstitial nephritis, medullary sponge kidney (1 case each), two patients had transplanted kidneys. Asthenia was a common additional diagnosis. The patients' complaints have been pain in the muscles, joints, bones (18 cases), tiredness (10 cases), dizziness (8 cases), shakyness, numbness, burning sensation (7 cases), tenderness in the muscles and bones ("the princess-on-the-pea syndrome") (7 cases). The most common findings upon examination were bone tenderness (13 cases), reduced manual power (8 cases), positive Romberg test (3 cases), slight muscle atrophy (2 cases), waddling gait (2 cases). The most common findings encountered in the laboratory, besides hypophosphataemia and hyperphosphaturia, were high pH in the urine, hyperaminoaciduria, and phosphate crystals in dried urine.

Adult↗
PubMed1980

Hyperaminoaciduria in mild phosphate diabetes in adults.

Quantitative urinary amino acid excretion has been studied in 23 adult patients with mild phosphate diabetes (MPD), in 22 adult control patients with various renal disorders and in 15 children, 7--19 years old, with atopic disorders (normal controls). Statistically significant increases in urinary excretion of glutamine (p < 0.01), glycine (p < 0.01) and cystine (p < 0.05) were found in the MPD patients compared to the normal controls. The urinary excretion of glutamine was significantly increased while the increases in cystine and glycine excretions were non-significant when MPD patients were compared to the control patients. In addition to clinical signs and analyses of plasma and urinary phosphate, a quantitative evaluation of urinary amino acids might be a tool in the diagnosis of MPD. The significance of the increased urinary amino acid excretion in MPD is discussed.

Adult↗
PubMed1987

Myeloid progenitors from the bone marrow of patients with vitamin D resistant rickets (type II) fail to respond to 1,25(OH)2D3.

The active metabolite of vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), has been shown to enhance the growth of human granulocyte/macrophage haemopoietic progenitors in vitro and to induce these cells to differentiate along the monocyte/macrophage pathway. In order to evaluate the relationship between specific receptors for 1,25(OH)2D3 and the role of 1,25(OH2D3 in the regulation of haemopoietic cell differentiation, we examined the effect of haemopoietic cell differentiation, we examined the effect of 1,25(OH)2D3 on the in vitro growth and differentiation patterns of marrow myeloid progenitor cells from two patients with 1,25(OH)2D3 resistant rickets, resulting from defective receptors to vitamin D. A significant rise in the frequency of myeloid colonies in control marrow cell cultures was induced by 2 X 10(-9) to 2 X 10(-7)M 1,25(OH)2D3. This rise reached a plateau at 2 X 10(-9)_2 X 10(-8) M 1,25(OH)2D3, resulting in a maximal 54 +/- 9% increase in colony numbers. In contrast, no stimulatory effect could be detected when 1,25(OH)2D3 was added to cultured marrow cells from the patients with 1,25(OH)2D3 resistance. Analysis of colony composition revealed that 2 X 10(-8) and 2 X 10(-7) M, 1,25(OH)2D3 induced a 50 +/- 26% increase in the frequency of colonies composed only of monocytes/macrophages in control, but not in the patients' marrow cell cultures. The effect of 2 X 10(-8) and 2 X 10(-7) M 1,25(OH)2D3 on progenitor cell differentiation towards monocytes/macrophages was also observed in marrow cell suspension cultures. Whereas 1,25(OH)2D3 induced a 81-136% increase in the frequency of monocytes in control marrow cells, no effect could be detected on the generation of mature monocytes in marrow cells of the 1,25(OH)2D3 resistant patients. Our results show that marrow granulocyte/macrophage progenitor cells from patients with 1,25(OH)2D3 resistance fail to respond to 1,25(OH)2D3. We thus demonstrate that the effect of 1,25(OH)2D3 on the proliferation and differentiation of haemopoietic progenitor cells is mediated through its binding to specific cytoplasmic receptors.

Bone Marrow↗
PubMed1977

Vitamin D resistant hypophosphataemic osteomalacia: treatment with 1alpha-hydroxyvitamin D3.

Ten patients with vitamin D resistant hypophosphataemic osteomalacia are described. They had hypophosphataemia with a decreased tubular reabsorption of phosphate, malabsorption of calcium and phosphorus, proximal myopathy and extensive osteomalacic changes on iliac crest bone biopsy. The plasma alkaline phosphatase and urine hydroxyproline, however, were raised in only some of the patients. Treatment with 1alpha-hydroxyvitamin D3 in high doses rapidly cured the myopathy, increased calcium and phosphorus absorption and retention and healed the osteomalacia. Phosphorus supplements were not required.

Adolescent↗
PubMed1977

1alpha-hydroxyvitamin D3 in the treatment of nutritional and metabolic rickets and osteomalacia.

Five patients with nutritional osteomalacia or rickets and six children with rickets unresponsive to physiological doses of vitamin D were treated with 1alpha-hydroxyvitamin D3 (1alpha-OHD3). Patients with nutritional osteomalacia responded to 1--2 microgram/day of 1alpha-OHD3. The most striking findings were rises in plasma calcium and, in one case, a decrease in faecal calcium. In some cases there was a rise in plasma phosphorus, alkaline phosphatase remained unchanged. There was radiological healing. In three patients with cystinosis and one with hypophosphataemia and Barrter's syndrome 2 microgram of 1alpha-OHD3 produced healing of rickets. Plasma phosphate rose on treatment, possibly by a suppression of parathyroid activity. The response to such low doses of 1alpha-OHD3 suggests impaired 1alpha-hydroxylation of 25-hydroxyvitamin D in these patients. A patient with intestinal malabsorption was resistant to high doses of 1alpha-OHD3 by mouth but responded to parenteral administration. A boy with osteopetrosis and the biochemical changes of rickets was resistant to large doses of 1alpha-OHD3 presumably because of failure of osseous response.

Adolescent↗
PubMed1981

Vitamin D resistant rickets with alopecia: a form of end organ resistance to 1,25 dihydroxy vitamin D.

A 4-year-old girl presented with severe clinical and radiological rickets, and alopecia since the age of 1 year. Laboratory studies revealed: hypocalcaemia, hypophosphataemia, secondary hyperparathyroidism, abnormally low intestinal calcium absorption, and markedly elevated circulating 1,25(OH)2D3 levels. A normal calcaemic response to parathyroid extract was obtained. Treatment attempts with vitamin D2, 1 alpha (OH)D3 and 1,25(OH)2D3 were totally ineffective. Intestinal resistance to the action of 1,25(OH)2D3 appeared well established in this case. Refractoriness of bone to this hormone seems less certain. From this new entity of 'Vitamin D resistant rickets due to end organ unresponsiveness', six cases have been hitherto reported in the literature. However, only two have enough resemblance to our case, to constitute a distinct and well defined nosologic subunit. The molecular basis of this disorder(s) remains to be elucidated.

Alopecia↗