1/8. Disorders of maternal calcium metabolism implicated by abnormal calcium metabolism in the neonate.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.- - - - - - - - - - ranking = 1keywords = metabolism (Clic here for more details about this article) |
2/8. Curative effects of 1alpha-hydroxycholecalciferol on calcium metabolism and bone disease in patients with chronic renal failure.Synthetic 1alpha-hydroxycholecalciferol (1alpha-OH-D3) was given intravenously in a dose of 2.5-10 mug per day to three patients with chronic renal failure. As little as 10 mug of 1alpha-OH-D3 daily for a week improved intestinal calcium absorption to a normal level, raised serum calcium, and reduced serum alkaline phosphatase. Severe rickets which had not responded to large amounts (greater than 200 mg in total) of vitamin D2 was markedly cured with 2.5 mug of 1alpha-OH-D3 given daily for 3 weeks. These clinical data hold promise that is certainly useful in the improvement of intestinal malabsorption of calcium and bone diseases in renal failure.- - - - - - - - - - ranking = 0.44444444444444keywords = metabolism (Clic here for more details about this article) |
3/8. Examination of megalin in renal tubular epithelium from patients with dent disease.dent disease is characteristic for the urinary loss of low-molecular-weight proteins and calcium, leading to renal calcification and, in some patients, chronic renal failure. This disorder is caused by loss-of-function mutations in the renal chloride channel gene, CLCN5. The animal model of this disease has demonstrated the possible role of disturbed megalin expression, which is a member of the low-density lipoprotein receptor family and is associated with renal reabsorption of a variety of proteins, in dent disease. We examined the expression of megalin in the renal tubular epithelium of two unrelated patients with dent disease. One patient, whose CLCN5 gene was completely deleted, showed significantly decreased staining of megalin compared with controls, while there was no change in another patient with partial deletion of the gene. These results demonstrated that mutation of CLCN5 in some patients with dent disease may impair the expression of megalin, resulting in abnormal calcium metabolism, manifested as hypercalciuria and nephrocalcinosis.- - - - - - - - - - ranking = 0.11111111111111keywords = metabolism (Clic here for more details about this article) |
4/8. Syndrome of amelogenesis imperfecta, nephrocalcinosis, impaired renal concentration, and possible abnormality of calcium metabolism.We describe a brother and sister with amelogenesis imperfecta, nephrocalcinosis and impaired renal concentrating ability. This is the second sibship reported, further substantiating autosomal recessive inheritance of this condition. There is lack of enamel, lifelong nocturnal enuresis, progressive punctate nephrocalcinosis, and decreased calcium and phosphate excretion over 24 hours and after an acute load. Increased serum osteocalcin and decreased urine delta-carboxyglutamic acid suggest involvement of vitamin k-dependent calcium binding proteins, although this may represent a secondary finding. No other evidence of abnormal calcium metabolism was found. Renal function is stable in the early teens, but the previously reported patients went on to renal failure.- - - - - - - - - - ranking = 0.55555555555556keywords = metabolism (Clic here for more details about this article) |
5/8. hypercalciuria in idiopathic fanconi syndrome.A 9 year old girl with idiopathic fanconi syndrome and hypercalciuria is described. In order to determine whether the increased calcium excretion was directly or indirectly due to the disturbed phosphate metabolism, the behavior of the calcium excretion during therapy, the serum levels of 1,25-dihydroxyvitamin D and parathyroid hormone, and the effect of parathyroid hormone on the renal tubules were investigated. Normal serum 1,25-dihydroxyvitamin D and parathyroid hormone levels, lack of a correlation between the serum phosphate concentration and the degree of hypercalciuria, as well as unsuccessful therapy of the hypercalciuria with oral phosphate indicate that the increased calcium excretion cannot be explained by impaired renal phosphate reabsorption. The hypercalciuria in the patient was therefore regarded as being due to a primary decrease of tubular calcium reabsorption.- - - - - - - - - - ranking = 0.11111111111111keywords = metabolism (Clic here for more details about this article) |
6/8. Renal manifestations and abnormal calcium metabolism in sarcoidosis.Forty-two patients with sarcoidosis were studied with special attention to renal disease and disturbance of calcium metabolism. Abnormal calcium metabolism was found in 19 patients and prednisone corrected hypercalcaemia in those affected within two weeks, except in one patient who had concomitant primary hyperparathyroidism. Renal failure was found in 19 patients, 15 of whom had hypercalcaemia. prednisone had a beneficial effect on kidney function within four weeks in all patients except in one with co-existing glomerulonephritis. Arterial hypertension was found in six patients, proteinuria in six, and calcinosis in six. Among 14 patients who underwent renal biopsy, granulomas were found in five. In only one of these was granulomatosis extensive bringing out renal failure and death within two years after temporary remission with prednisone. Co-existent non-sarcoid diseases affecting the kidneys or calcium metabolism occurred in ten out of 23 patients with sarcoidosis and kidney disease/calcium abnormality. In most cases these conditions contributed more to the prognosis than did sarcoidosis. From the present series and review of the literature it appears that young males within the first two years of diagnosis are at the greatest risk of hypercalcaemia or kidney disease.- - - - - - - - - - ranking = 0.77777777777778keywords = metabolism (Clic here for more details about this article) |
7/8. hypercalciuria secondary to chronic hypophosphatemia.A 41-year-old man presented with back pain, osteoporosis and vertebral crushing. Laboratory studies revealed persistent hypophosphatemia, normocalcemia and elevated levels of 1,25-dihydroxy-vitamin d. Other mineral metabolism tests showed a low tubular maximal phosphate reabsorption per glomerular filtrate, an absorptive hypercalciuria and a normal intestinal absorption of phosphate. hyperparathyroidism was ruled out by an intravenous calcium loading test. Bone histopathology was consistent with osteomalacia. Treatment with phosphate supplements resulted in resolution of symptoms and normalization of laboratory parameters. To our knowledge, this can be a sporadic form of a disorder recently described: hereditary hypophosphatemic rickets with hypercalciuria.- - - - - - - - - - ranking = 0.11111111111111keywords = metabolism (Clic here for more details about this article) |
8/8. Disorders of calcium and phosphorus metabolism in adolescents.During adolescence, there are marked changes in the metabolism of calcium and phosphorus and a dramatic increase in the rate of bone mineralization under the influence of the sex hormones, growth hormone, and insulin-like growth factor-1. More than 50% of adult bone mass is accumulated during puberty; failure to achieve maximum bone mineralization at this time may lead to osteopenia and its complications in later adulthood. This article discusses the causes, evaluation, and management of adolescents with hypocalcemia, hypercalcemia, and disorders of bone mineralization.- - - - - - - - - - ranking = 0.55555555555556keywords = metabolism (Clic here for more details about this article) |