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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This chapter reviews the pathogenesis of disordered divalent mineral and bone metabolism in alcoholism, emphasizing the role of impaired vitamin D physiology. Normally, vitamin D metabolites are derived principally from cholecalciferol, which is synthesized in the skin via the energy of sunlight. Most alcoholics have subnormal levels of 25-hydroxyvitamin D [25(OH)D]. Those with Laennec's cirrhosis also have low levels of vitamin D binding protein due to impaired hepatic protein synthesis and as a result, have low serum concentrations of total, but not free, 1,25-dihydroxyvitamin D. The causes of 25(OH)D deficiency in alcoholics include reduced hepatic 25-hydroxylase activity, lack of sun exposure, inadequate dietary intake, and malabsorption. Hypomagnesemia and hypophosphatemia, which are very common in hospitalized alcoholics, result from deficient intake, malabsorption, excessive renal losses, and cellular uptake of both ions. Hypocalcemia in alcoholics is caused primarily by hypoalbuminemia but can result also from deficient intake, malabsorption, hypomagnesemia, and renal calcium wastage. Low vitamin D activity may contribute significantly to the calcium and phosphate deficiencies. Osteoporosis is extremely common in alcoholics whereas osteomalacia is exceptional. However, both bone disorders respond well to vitamin D therapy. Thus, alcoholics should be screened periodically for vitamin D deficiency and osteopenia, and when either is detected they should receive vitamin D supplements.
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PMID:Disorders of divalent ions and vitamin D metabolism in chronic alcoholism. 375 48

A male born to first cousins presented at 12 months with hypocalcemic convulsions, rickets, epistaxis due to vitamin K deficiency, and extremely low serum levels of beta-carotene and vitamin A. Liver function was altered moderately (glutamic-oxaloacetic transaminase, 55 U/L; glutamic-pyruvic transaminase, 37 U/L; lactate dehydrogenase, 255 U/L; alkaline phosphatase, 437 U/L). To correct the deficiencies, 8,000 IU vitamin D/day, 10,000 IU vitamin A/day, and intramuscular administration of vitamin K1 were required. At 9 years, he presented signs of neuromuscular affection, and the serum vitamin E level (measured for the first time) was extremely low. Classic lipid malabsorption syndromes (abetalipoproteinemia, chronic cholestasis, mucoviscidosis, coeliac disease, Whipple's disease) were excluded by appropriate examinations. Composition of duodenal bile acids was characterized by undetectable levels of cholic acid metabolites, and only chenodeoxycholic acid metabolites were present. Serum total bile acid concentration was normal, with an atypical low cholic acid/chenodeoxycholic acid ratio and abnormal presence of 3 beta-OH-delta 5-cholenic acid and 6-OH-bile acids. Urinary bile acid composition was also characterized by elevated 6-OH-bile acids. Known enzymopathies of the bile acid synthetic pathway were excluded (cerebrotendinous xanthomatosis, cerebro-hepato-renal syndrome of Zellweger, coprostanic acidemia). Bile acid pool sizes were determined by using stable isotopes: cholic acid pool size [2.90 (N, 32 +/- 16) microM/kg] and chenodeoxycholic acid pool size [10.8 (N, 32.6 +/- 9.9) microM/kg] were extremely low; fractional turnover rates of both bile acids were in a normal range.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Malabsorption of liposoluble vitamins in a child with bile acid deficiency. 379 31

A 25-yr-old black man with cystic fibrosis and cirrhosis developed symptoms of osteomalacia and hypocalcemia, hypophosphatemia, secondary hyperparathyroidism, and low circulating 25-hydroxyvitamin D (25-OHD). Serum 1,25-dihydroxyvitamin D (1,25-[OH]2D) was within the normal range. Iliac crest bone biopsy confirmed the diagnosis of osteomalacia. Oral administration of 50,000 IU of vitamin D2 failed to relieve symptoms or raise serum 25-OHD levels to normal. Intramuscular vitamin D2, 10,000 IU every 8-12 week, improved symptoms, raised serum 25-OHD to normal, and increased circulating 1,25-[OH]2D to values five times normal. Over the next 10 mo circulating 1,25-[OH]2D remained elevated despite normalization of serum calcium, phosphorus, and parathyroid hormone. Repeat bone biopsy 1 yr after parenteral vitamin D showed healing of the osteomalacia. Malabsorption of vitamin D appears secondary to profound steatorrhea due to pancreatic insufficiency and secondary biliary cirrhosis. Although extensive hepatocellular disease was present, hepatic conversion of vitamin D to 25-OHD was intact. Both high and low circulating 1,25-[OH]2D levels during active osteomalacia have been reported; initially, the level was in the normal range and higher values in this patient occurred with repletion of 25-OHD substrate. This study shows that symptomatic osteomalacia may be a major manifestation of cystic fibrosis in those patients surviving into adulthood. Measurements of serum 25-OHD in cystic fibrosis patients may identify those who should receive supplemental vitamin D.
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PMID:Vitamin D metabolism and osteomalacia in cystic fibrosis. 387 14

Calcium and bone metabolism in 29 rheumatoid arthritis (RA) patients were compared with those in 27 postmenopausal osteoporotic patients. Signs of vitamin D deficiency were found in 20 RA patients, including 12 who took recommended amounts of vitamin D in their diets and were exposed to sufficient sunlight, and in none of the osteoporotic patients. There were no signs of malabsorption. In six out of 15 patients we found increased liver enzyme activity, which may have a role in vitamin D metabolism. We propose the influence of non-steroidal anti-inflammatory drugs (NSAIDs) on vitamin D metabolism in the liver as a possible explanation.
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PMID:Bone metabolism in rheumatoid arthritis compared with postmenopausal osteoporosis. 394 43

In 16 children with malabsorption syndrome, out of which 5 had impaired lipid absorption or diarrhoea, and in 14 children in the control group the concentrations of vitamin D and 25 OH D3 were determined after oral administration of vitamin D in dose of 1200 U/kg.b.wt. or 12000 U/kg.b.wt. No decrease in initial 25 OH D3 concentrations was noted in children with malabsorption syndrome (40,5 +/- 0,7 ng/ml) in comparison with the control group (40,0 +/- 0,4 ng/ml). In children with impaired lipid absorption and diarrhoea the 25 OH D3 concentration was 33,6 +/- 2,4 ng/ml. After oral administration of vitamin D in small doses no differences were noted in the increase in vitamin D and 25 OH D3 concentrations in children with malabsorption syndrome or the control group. After administration of vitamin D in the dose 10 times higher no difference in the increase in vitamin D concentration was noted in children with malabsorption syndrome and the control group. However the increase in 25 OH D3 concentration in children with malabsorption syndrome was 49,8 +/- 1,2 ng/ml and 145,0 +/- 3,5 ng/ml in the control group. In the children with impaired lipid absorption and diarrhoea decreased vitamin D and 25 OH D3 concentrations were noted. This means that physiological doses of vitamin D in children with malabsorption syndrome are sufficient to supply vitamin D. Diarrhoea and impaired lipid absorption however, are indications for stimulation of skin synthesis of vitamin D.
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PMID:[Vitamin D metabolism in children with malabsorption syndrome]. 397 66

We developed a test procedure for the clinical evaluation of the absorption of vitamin D. Serum vitamin D concentrations were evaluated in seven patients with intestinal fat malabsorption syndromes and in seven healthy, normal subjects, after being given a single oral dose of 50,000 IU (1.25 mg) vitamin D2. In the normal subjects, serum vitamin D concentrations rose from a baseline of less than 5 ng/ml to a peak of over 50 ng/ml by 12 h, gradually falling to baseline levels by 3 days. In five of the seven patients with intestinal fat malabsorption, oral administration of 50,000 IU vitamin D2 did not raise serum vitamin D concentrations above 10 ng/ml. Two patients with severe inflammatory bowel disease had a normal absorption pattern, however. These findings suggest that an oral vitamin D absorption test may be of value for determination of patients at risk for development of vitamin D deficiency. They also raise questions about the efficacy of oral vitamin D preparations in patients with intestinal fat malabsorption.
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PMID:Vitamin D absorption in healthy subjects and in patients with intestinal malabsorption syndromes. 405 Jul 23

Approximately 20 inherited disorders of kidney transport occurring in man have so far been defined. Most of these diseases have characteristic clinical profiles. They can be divided into four groups: 1) the amino acid transport mutations which include the cystinurias, hyperdibasicaminoaciduria, Joseph syndrome, Hartnup disease, and the methionine malabsorption syndrome: 2) the sugar transport mutations characterized by glucose (renal glucosuria), and glucose-galactose malabsorption; 3) the electrolyte and water transport disorders, among which are familial hypophosphatemic rickets, vitamin D-dependent rickets, pseudohypoparathyroidism, proximal and distal renal tubular acidosis, and nephrogenic diabetes insipidus; and 4) the "mixed" kidney transport mutations such as the "Busby", Fanconi, Lowe, Luder-Sheldon syndromes, and glucoglycinuria.
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PMID:Clinical phenotypes in kidney transport disorders. 437 65

Metabolic bone disease occurring in renal or intestinal disorders has been reviewed with particular reference to etiological factors. Hyperparathyroidism is seen as a recurring cycle of renal damage-hyperphosphatemia-hypocalcemia-parathyroid stimulation-mobilization of bone calcium and phosphate-renal tubular phosphate rejection. In intestinal cases, the initial stimulus is presumably hypocalcemia. Osteomalacia is seen as resulting from phosphate depletion for the following reasons:1. Experimentally, rickets results from dietary phosphate restriction in rats.2. Such rickets is not prevented by the presence of normally adequate amounts of dietary vitamin D, and may therefore be termed "resistant" in the clinical sense.3. Osteomalacia or rickets in intestinal malabsorption and renal tubular disorders is associated with hypophosphatemia due to excessive fecal or urinary loss.4. Renal tubular rickets has been healed by oral phosphate loading in some studies.5. Acidosis may induce osteomalacic changes, experimentally and clinically (for example, in uretero-sigmoidostomy). Reversal of systemic acidosis with oral bicarbonate has resulted in phosphate retention and a rising serum phosphate in one such case.6. Preliminary data from analysis of full-thickness bone biopsy in two osteomalacic patients shows a significant reduction in calcium and phosphate content.7. Despite the hyperphosphatemia of azotemic renal failure, over-all phosphate depletion may be present in this situation also due to: * Diminished dietary phosphate in low protein diets * Nausea and vomiting * Occasional diarrhea * The use of oral phosphatebinding antacids * Perpetuation of urinary phosphate losses by reduction in proportion of tubular reabsorbed phosphate (secondary hyperparathyroidism) and possibly high filtered load per nephron * Repeated losses of phosphate to bath fluid during dialysis.
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PMID:Metabolic bone disease secondary to renal and intestinal disorders. 489 May 32

As measured by whole body retention of isotopic calcium given in milk, absorption of calcium was impaired in 10 patients with chronic parenchymal non-biliary liver disease who were icteric. Mean absorption was normal in 15 patients with parenchymal liver disease who were anicteric although some individual patients absorbed less than any of the controls. Depressed absorption of calcium was seen in 10 patients with primary biliary cirrhosis and seven patients with intra- or extra-hepatic biliary obstructive disease. The most likely cause for this malabsorption is reduced bile salt secretion into the intestinal lumen which impairs vitamin D and fat absorption. The finding that parenteral vitamin D increased calcium absorption to normal levels in five patients with primary biliary cirrhosis suggests that deficiency of this vitamin is a major and correctable factor leading to calcium malabsorption in such patients. Precipitation of calcium salts by excess intraluminal fat appears to be a further possible factor reducing calcium absorption in these patients. These findings emphasize the importance of parenteral vitamin D therapy in patients with chronic obstructive biliary diseases. They also suggest that certain patients with chronic parenchymatous liver disease, particularly those who are icteric, may also occasionally require therapy with vitamin D.
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PMID:47 Calcium abosrption in parenchymatous and biliary liver disease. 517 34

The intestinal absorption of calcium is often depressed in patients with chronic renal insufficiency. Furthermore, the malabsorption of calcium and the osteodystrophy which occur in association with chronic renal disease are often "resistant" to vitamin D; the basis for this resistance remains uncertain however. Recent studies by others have emphasized the role of an abnormality in the metabolism of vitamin D in accounting for the alterations in the calcium absorption and the apparent vitamin D-resistance which accompany the uremic syndrome. The present studies with an experimentally uremic animal model demonstrate a defect in the active transport of calcium by duodenal gut sacs in vitro. This abnormality is not due to the semistarvation associated with renal insufficiency and cannot be corrected by the administration of physiologic amounts of vitamin D(3): it is reversed by massive doses of the vitamin. Neither the metabolism of vitamin D(3) nor the levels of calcium binding protein activity in the duodenal mucosa are affected by renal insufficiency under the conditions employed in the present studies. The results of the present studies strongly suggest that in addition to the recently proposed mechanism involving an interference with the metabolism of vitamin D renal insufficiency also affects the cellular mechanisms for calcium transport in a manner which, while opposite in direction to that of vitamin D, is independent of a direct interaction with the vitamin or its metabolites.
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PMID:Effect of renal insufficiency on the active transport of calcium by the small intestine. 542 27


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