Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Typical features of hereditary vitamin D-dependent (pseudovitamin D-deficient) rickets were observed beginning at ages 20 and 5 months in a brother and sister. Both had calcium malabsorption correctable with high doses of 25-hydroxyvitamin D. During periods of hypocalcemia they both manifested secondary hyperparathyroidism with hypophosphatemia and high serum concentrations of endogenously produced 1,25-dihydroxyvitamin D. In each, normalization of serum calcium concentration and resolution of osteomalacia were obtained with continuous administration of high doses of ergocalciferol or high doses of 1,25-dihydroxycholecalciferol. Chemical features of vitamin D deficiency were corrected in the presence of high circulating concentrations of 1,25-dihydroxyvitamin D2, produced endogenously, or of 1,25-dihydroxyvitamin D3, administered by mouth. Serum concentrations of 25-hydroxyvitamin D2, 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D were normal in five first degree relatives. We conclude that in these five first degree relatives. We conclude that in these siblings, rickets and osteomalacia resulted from a hereditary decreased sensitivity to 1,25-dihydroxyvitamin D at the intestine and perhaps other vitamin D target tissues.
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PMID:A familial syndrome of decrease in sensitivity to 1,25-dihydroxyvitamin D. 23 95

Intestinal malabsorption of calcium and the development of osteomalacia in conservatively treated renal failure is explained by a quantitative deficiency of 1,25-dihydroxycholecalciferol, which also contributes to the development of hypocalcaemia. Excess of 25-hydroxycholecalciferol can substitute for this deficiency. The presence and healing of azotaemic osteomalacia is unrelated to the prevailing plasma [Ca] x [P] product. The data suggest that "vitamin D" acts directly on bone mineralisation, but the claim that this apparent effect is normally due to 25-hydroxycholecalciferol is considered unproven. Most of the phenomena of azotaemic osteodystrophy are encountered in simple vitamin D deficiency; as in that condition, deficiency of 1,25-dihydroxycholecalciferol may be of primary significance in causing secondary hyperparathyroidism in renal failure.
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PMID:Vitamin D and the syndromes of azotaemic osteodystrophy. 36 40

Serum 25-hydroxyvitamin D levels were measured in 36 thalassaemic children and 27 controls aged 5-15 years. Blood specimens were collected from the beginning of April until the end of October 1976. We considered as the winter period the first 3 months and the summer period the last 4 months. We found that (a) thalassaemic children had lower levels of serum 25-hydroxyvitamin D than controls: (b) there was a seasonal variation of serum 25-hydroxyvitamin D in both groups; and (c) the thalassaemic children had malabsorption of vitamin D. We suggest that the bone lesions in thalassaemic children are related to vitamin D deficiency.
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PMID:Serum 25-hydroxyvitamin D levels in thalassaemia. 64 52

Hepatic osteodystrophy consists of three types: osteomalacia, osteoporosis, and periosteal reaction with new bone formation. Secondary hyperparathyroidism is very rare, if it occurs at all. The cause of osteomalacia appears to be vitamin D deficiency due to a lack of vitamin D substrate. In the presence of adequate substrates, 25-OHD and dihydroxy vitamin D metabolites are formed. The vitamin D deficiency results in osteomalacia and malabsorption of calcium and phosphorus. The osteomalacia can be treated successfully with vitamin D supplements. In some patients calcium, phosphorus, and magnesium supplements may be required. The aetiology and treatment of the osteoporosis and the periosteal reactions remain obscure.
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PMID:Hepatic osteodystrophy. 70 74

In this 54 year old woman with celiac disease, osteomalacia developed while she was on a gluten-free diet which had caused regression of her steatorrhea. She was not responsive to large doses of parenterally administered dihydrotachysterol and calcium, but she was responsive to the oral administration of 25-hydroxyvitamin D3 (25-OHD3). The data suggest that 25-OHD3 is the treatment of choice for patients with vitamin D deficiency due to intestinal malabsorption.
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PMID:Osteomalacia and celiac disease: response to 25-hydroxyvitamin D. 74 23

The pathogenesis, clinical course and treatment of senile-postmenopausal osteoporosis are reviewed. It is likely that several factors, including genetic and racial determinants as well as nutritional calcium and/or vitamin D deficiency in the elderly play a pathogenic role. Available data are consistent with the possibility that the primary alteration of bone metabolism in senile-postmenopausal osteoporosis may be a decrease in de-novo bone formation below the level necessary to compensate for age-related bone loss. The second part of the study deals with the osteomalacia syndrome. The most common known causes of osteomalacia are vitamin D deficiency, especially secondary to malabsorption, and a defective vitamin D metabolism associated with chronic renal insufficiency or prolonged anticonvulsant therapy. The hypophosphatemic forms of osteomalacia may be induced by renal tubular dysfunction or by phosphate deficiency of other origin; in these disorders a pathogenic role of altered vitamin D metabolism has not yet been established.
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PMID:[Osteoporosis and osteomalacia]. 112 74

Cystic fibrosis is an inherited, multisystem disorder characterized by an abnormality in exocrine gland function. It leads to chronic pulmonary disease in most cases and pancreatic insufficiency in 85 percent of patients. Although this disease is not uncommon in Caucasians, it has been considered very rare among Japanese. The majority of patients are diagnosed in infancy or childhood. The patient in this case report was a 45-year-old Japanese man who had not been diagnosed as having cystic fibrosis. This patient had recurrent episodes of pulmonary infection that started in childhood, and plain films of the chest showed increased interstitial markings, hyperaeration, and bronchiectasis. CT of the upper abdomen showed a generally enlarged pancreas with complete fatty replacement. Serum and urine pancreatic enzyme levels were low, suggesting pancreatic insufficiency. Repeated sweat tests were positive. A roentgenologic skeletal survey showed general demineralization, which may be multifactorial. In this case, it was concluded that vitamin D deficiency caused by vitamin D malabsorption and/or insufficient sunlight exposure was mainly responsible for the demineralization and that chronic respiratory acidosis might also be partially responsible.
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PMID:A Japanese adult case of cystic fibrosis causing bone demineralization. 141 May 64

Serum 25-hydroxyvitamin D declines in elderly subjects. This decrease reflects, in part, a lower vitamin D intake. But changes in serum 25-hydroxyvitamin D are more marked in the northern latitudes of the world because less vitamin D synthesis occurs n the skin as a result of a reduced amount of ultraviolet light. Consequently, vitamin D deficiency leading to osteomalacia is more common in thr northern latitudes, particularly among the elderly. The Recommended Daily Allowance of 200 IU of vitamin D in the elderly may be insufficient, since higher doses of 800 IU/day have been shown to reduce the incidence of osteoporotic fractures. The use of more potent analogues of vitamin D, such as calcitriol (Rocaltrol), should be reserved only for those patients who have established vertebral osteoporosis and who generally have more pronounced malabsorption of calcium.
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PMID:Vitamin D metabolism and therapy in elderly subjects. 150 13

The synthesis of osteocalcin or bone gla protein by osteoblasts is markedly stimulated by 1,25-(OH)2D, a key hormone in the regulation of bone mineralization. The circulating levels of osteocalcin have been shown to reflect both the osteoid matrix production and the formation rate of mineralized bone in several metabolic bone diseases (osteoporosis, thyrotoxicosis, primary hyperparathyroidism) in which both mechanisms are tightly coupled because of the absence of mineralization defect. In this study, we measured in 12 patients (7 women, 5 men, 56 +/- 15 yr old) with untreated osteomalacia serum osteocalcin and vitamin D metabolites (25OHD and 1,25-(OH)2D). The results were correlated with biochemical and histomorphometric assessment of bone remodeling. Osteomalacia was due to vitamin D deficiency (5 cases), to vitamin D malabsorption (6 cases), and to hypophosphataemia in 1 case. When compared to control values, serum osteocalcin was increased in patients with osteomalacia (7.4 +/- 4 vs. 3.7 +/- 1.3 ng/mL; P less than 0.001) and was positively correlated with serum alkaline phosphatase (r = 0.65; P = 0.03) and negatively with 25 OHD (r = -0.61; P = 0.04). Serum osteocalcin was not correlated with 1,25-(OH)2D [r = -0.45; not significant (NS)] even after exclusion of the patient with hypophosphataemia. Serum osteocalcin was positively correlated with the osteoid volume and osteoid perimeter (r = 0.71 and 0.69 respectively; P less than 0.01) but not with any of the tetracycline-based parameter of bone mineralization at the tissue level (r ranging from -0.41 to +0.42, NS). Serum 25 OHD, but not 1,25-(OH)2D, was positively correlated with the mineralization rate (r = 0.59; P less than 0.05 and r = 0.54; NS). We conclude that in patients with osteomalacia, a condition which is characterized by an increased osteoid accumulation due to a decreased mineralization rate, the increased level of serum osteocalcin reflects the increased osteoid synthesis but not the mineralization defect. In this disease, serum osteocalcin is inversely correlated to the severity of vitamin D deficiency reflected by serum 25 OHD, but not to the serum levels of 1,25-(OH)2D.
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PMID:Serum osteocalcin is increased in patients with osteomalacia: correlations with biochemical and histomorphometric findings. 156 62

Vitamin D has certain clearly defined effects on bone: vitamin D deficiency results in defective bone mineralization, whereas 1,25-dihydroxy-vitamin D3 (1,25-(OH)2D3) stimulates bone resorption. Studies of the use of 1,25-(OH)2D3 to prevent or treat osteoporosis have given conflicting results concerning bone remodeling. However, 1,25-(OH)2D3 or other vitamin D metabolites seem to play a role in the correction of calcium malabsorption, which is a common feature in osteoporosis.
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PMID:Is there a role for vitamin D in osteoporosis? 193 97


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