Dentin Alteration of Deciduous Teeth in Human Hypophosphatemic Rickets

Familial hypophosphatemic rickets is in most cases transmitted as an X-linked dominant trait and results from mutation of the PHEX gene, predominantly expressed in osteoblast and odontoblast. Patients have been reported to display important dentin defects, and therefore, we explored the dentin structure, composition, and distribution of extracellular matrix (ECM) molecules in hypophosphatemic human deciduous teeth. Compared to age-matched controls, the dentin from hypophosphatemic patients exhibited major differences: presence of large interglobular spaces resulting from the lack of fusion of calcospherites in the circumpulpal dentin; defective mineralization in the interglobular spaces contrasting with normal Ca-P levels in the calcospherites on X-ray microanalysis; abnormal presence of low-molecular weight protein complexes recognized on Western blots by antibodies against matrix extracellular phosphoglycoprotein (MEPE), dentin sialoprotein, osteopontin, and reduced osteocalcin (OC) level; and accumulation in the interglobular spaces of immunolabeling with antibodies against DSP, dentin matrix protein, bone sialoprotein, MEPE and OC, while chondroitin/dermatan sulfate glycosaminoglycans were exclusively located inside calcospherites. Alterations of the post-translational processing or partial degradation of some ECM appear as key factors in the formation of the defective hypophosphatemic dentin.     

Difference in calcium metabolism following billroth-I and billroth-II procedures for gastric and duodenal ulcers

There have been 7 patients with postoperative osteomalacia in our series of 500 patients who had a gastrectomy for gastric or duodenal ulcers. All seven of these patients had a Billroth-II type gastrojejunostomy or esophagojejunostomy which caused food to bypass the duodenum and the upper part of the jejunum, and six of these patients showed milk intolerance and had diarrhea on food other than cow's milk. From this finding, it may be surmised that patients are predisposed to osteopenia after gastrectomy due to disorder in the process of calcium absorption and they develop osteomalacia when treated with the Billroth-II procedure, showing milk intolerance and diarrhea on food other than cow's milk.     

Stimulation of growth hormone secretion in children with X-linked hypophosphatemia

X-linked hypophosphatemia is characterized by low serum phosphorus, relative vitamin D deficiency and rickets. Despite adequate metabolic control with oral phosphate and vitamin D therapy, patients with X-linked hypophosphatemia have short stature. Whether growth hormone (GH) deficiency plays a role in short stature in patients with X-linked hypophosphatemia is not known. The purpose of this report was to investigate the response of GH to sequential paired pharmacological stimulation in patients with X-linked hypophosphatemia. Basal GH was 3.8±0.7 ng/ml, insulin-like growth factor-I (IGF-I) was 225±38 ng/ml and IGF binding protein-3 was 3.0±0.2 mg/l in 16 children studied with X-linked hypophosphatemia. In response tol-dopa and arginine hydrochloride stimulation, serum GH rose to above 7 mg/ml in all patients. Thus, the short stature in patients with X-linked hypophosphatemia is not due to a GH/IGF-I secretory defect.     

Effect of acute changes of serum phosphate on fibroblast growth factor (FGF)23 levels in humans

Fibroblast growth factor (FGF)23 was identified as a humoral factor involved in the development of several hypophosphatemic diseases. Subsequent studies indicated that FGF23 is a hormone regulating serum phosphate level. However, it is still unknown how the production and serum level of FGF23 are regulated. This study was designed to determine whether acute changes of serum phosphate modulate FGF23 levels in human. Four healthy volunteers participated in the study. In the phosphate infusion study, dibasic potassium phosphate was infused at a rate of 10 mEq/h for 4 h, and serum FGF23 levels were measured for up to 6 h after the start of the infusion. In the carbohydrate study, partially hydrolyzed starch corresponding to 150 g glucose was ingested and FGF23 levels were measured similarly for 6 h. Phosphate infusion significantly increased and carbohydrate ingestion decreased serum phosphate levels, respectively. However, FGF23 did not change by these maneuvers. It is concluded that acute changes of serum phosphate do not modify FGF23 levels in the healthy human.     

阿德福韦酯导致胸痛、低磷血症2例报告

阿德福韦酯是一种单磷酸腺苷的无环核苷类似物,用于慢性乙型肝炎的抗病毒治疗。关于它引起低磷血症的报道较少,国内外也罕见以胸痛为首发症状和低磷血症的报道。本文报告2例患者服用阿德福韦酯后出现胸痛为首发症状和低磷血症。     

Calcitriol dosage in osteomalacia,hypoparathyroidism and attempted treatment of myositis ossificans progressiva

Summary

Mineral retention was measured during 39 metabolic balance studies in 34 patients with nutritional osteomalacia or late rickets; they were divided into 5 treatment groups consisting of oral vitamin D, artificial ultra-violet irradiation, 25-hydroxychole-calciferol {calcifediol), 1 α-hydroxycholecalciferol (alfacalcidol) and 1α,25-dihydroxy-cholecalciferol (calcitriol). With the 1 α-hydroxylated derivatives, initial dosage of 2 to 6 μg daily was required to achieve optimal healing rates by comparison with other responses. Mineral retention was markedly enhanced by supplementation with micro-crystalline hydroxyapatite compound (MCHC); untreated X-linked hypophosphataemic rickets healed in 7 weeks on 10 μg alfacalcidol daily and 6?g MCHC daily without developing hypercalcaemia. By contrast, adult-presenting hypophosphataemic osteomalacia developed early hypercalcaemia on the same treatment; additional phosphate supplementation, without changing other treatment, abolished hypercalcaemia and improved calcium retention. A long-term crossover trial of the vitamins D in 6 patients with hypoparathyroidism suggested that relative potencies were as follows {assigning to vitamin D an arbitrary potency of 1): vitamin D₂ (or D₃) 1: dihydrotachysterol (DHT) 3: calcifediol 10: alfacalcidol 750: calcitriol 1500. The two-fold superiority of calcitriol over alfacalcidol was evident. Calcifediol and vitamin D controlled plasma calcium at comparable levels of circulating 25-hydroxyvitamin D (25-OH-D), elevated 25-OH-D persisting at least 1 to 2 years after discontinuing long-term (>4 years) vitamin D. In 2 patients with myositis ossificans progessiva treated with 10 to 20 μg calcitriol daily, hypercalcaemia was minimized by a low-calcium diet supplemented with cellulose phosphate, suggesting that bone resorption did not play a major role in vitamin D intoxication. Net mineral loss was documented in a young male patient but not in a menopausal female, suggesting that calcitriol treatment was not likely to produce post-menopausal osteoporosis.     

Phosphaturic mesenchymal tumor diagnosed by fine-needle aspiration and core biopsy: a case report and review of literature

Oncogenic (tumor-induced) osteomalacia is a rare paraneoplastic syndrome of phosphate wasting that is frequently associated with phosphaturic mesenchymal tumor (PMT). As the cytologic features of this tumor apparently have not been reported, we describe the fine-needle aspiration (FNA) findings for PMT that arose from the gluteal soft tissue in a patient with hypophosphatemia and multiple fractures secondary to osteomalacia. Smears from the computerized tomography (CT)-guided FNA showed groups of spindle cells having elongated nuclei, fine to moderately coarsely granular chromatin, inconspicuous nucleoli, and delicate cytoplasm. Marked nuclear atypia, mitotic figures, and necrosis were absent. The differential diagnosis included a variety of benign and malignant spindle cell neoplasms such as monophasic synovial sarcoma, leiomyoma, peripheral nerve sheath tumor, fibrosarcoma, and, less likely, metastatic melanoma and sarcomatoid carcinoma. The bland-appearing cytologic features of a spindle cell tumor in a patient with osteomalacia should suggest the diagnosis of PMT.     

Positive HLA‐B27 and sacroiliitis is not always spondyloarthritis

A 36‐year‐old man was treated for several years with multiple agents for ankylosing spondylitis based on positive human leukocyte antigen‐B27 and sacroiliitis. He was also diagnosed with osteoporosis and hypophosphatemia. Over these years, from being an avid runner, he became dependent on a walker for ambulation. The lack of treatment response and the low phosphorus were clues that eventually led to a diagnosis of tumor‐induced osteomalacia. This case discusses the importance of not solely relying on genetic markers and sacroiliitis for diagnosing ankylosing spondylitis as other conditions can cause similar presentations.