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

To evaluate the dual-isotope Schilling test for the diagnosis of pernicious anemia or malabsorption syndrome, 65 studies were selected for clinical correlation. Criteria for pernicious anemia included mean corpuscular volume greater than 100 cu micrometer, serum B12 greater than 100 ng/l, megaloblastic marrow, achlorhydria, reticulocytes greater than 5% on B12 therapy, atrophic gastritis, and elevated serum antibodies to parietal cells or intrinsic factor. Criteria for malabsorption syndrome included: decreased serum B12, folate, and carotene; increased fecal fat; abnormal D-xylose absorption; abnormal radiographic and biopsy findings. 58Co-cyanocobalamin and 57Co-cyanocobalamin bound to intrinsic factor were given orally to fasting patients; 1 mg of nonradioactive B12 was injected intramuscularly within two hours. Aliquots of 24-hour urine samples were counted. If the excretion of 58Co was less than 7% and the 57Co/58Co ratio was greater than 1.7, the test indicated pernicious anemia; a ratio less than 1.7 indicated malabsorption syndrome. Sensitivity, specificity, and accuracy of the dual-isotope Schilling test were 83%, 98%, and 94% for pernicious anemia, and 67%, 90%, and 86% for malabsorption syndrome, respectively.
 ...
PMID:Reliability of the dual-isotope Schilling test for the diagnosis of pernicious anemia or malabsorption syndrome. 723 58

The megaloblastic anaemia observed in patients with chronic atrophic gastritis is usually due to malabsorption of vitamin B12. In some cases, the absence of intrinsic factor supports the diagnosis of pernicious anaemia but other factors, the importance of which varies from case to case, are also involved. They include proliferation of bacteria in the lumen of the gut, intestinal cell abnormalities resulting from lack of vitamin B12 and low hydrochloric acid output with subsequent reduction in the release of vitamin B12 from foodstuffs. With regard to treatment, it would seem justified to combine oral broad-spectrum antibiotics with parenteral administration of vitamin B12.
 ...
PMID:[Vitamin B12 deficiency in chronic atrophic gastritis. 3 cases (author's transl)]. 726 28

In vivo studies demonstrate that the pancreatic enzymes and the ionic environment in the upper gastrointestinal tract are essential determining factors for transport and absorption of cobalamin in man. Jejunal fluid was aspirated from healthy human volunteers after administration of cyano[57Co]cobalamin preparations. Immunochemical analysis of the aspirates demonstrated that all isotopic vitamin was transferred to a protein that is identical to the gastric intrinsic factor in terms of molecular mass (57,500), ionic nature (mean pI, 5.09), and reactivity with anti-intrinsic factor sera. However, in the aspirates from patients with exocrine pancreatic dysfunction the vitamin was found to be coupled > 60% to a protein identical to R proteins in terms of molecular mass (125,000), ionic nature (mean pI, 3.51), and reactivity with anti-R protein and anti-intrinsic factor sera. The preferential transfer of cobalamin to R proteins in the patients and to intrinsic factor in healthy subjects was associated, respectively, with low and normal levels of pancreatic enzymes in the intestine and these in turn were paralleled respectively by impaired and normal ileal absorption of cobalamin. These findings confirm the suggestion that the formation of unabsorbable cobalamin complexes may be the reason of impaired vitamin absorption in exocrine pancreatic insufficiency. Observations made with other selected patients demonstrate: (a) that decreased enzyme activity and nondegradation of R proteins may also be due to nonactivation of pancreatic zymogens in an acidic pH of the intestinal juice the vitamin transported to the jejunum couples to intrinsic factor when pancreatic function is normal, and to intrinsic factor and R protein in exocrine pancreatic insufficiency. The observations made with these selected patients may explain why not all patients with exocrine pancreatic insufficiency develop imparied cobalamin absorption, and also why the malabsorption is corrected by the administration of bicarbonate in certain patients.
 ...
PMID:Cobalamin malabsorption due to nondegradation of R proteins in the human intestine. Inhibited cobalamin absorption in exocrine pancreatic dysfunction. 740 Mar 24

The clinical and laboratory data from 75 patients with altered vitamin B 12 absorption were reviewed. In 36 cases the diagnosis of pernicious anaemia had been established. Of these, 14 patients showed malabsorption of radiolabelled vitamin B 12, but the absorption of vitamin B 12 bound to the intrinsic factor (IF) was normal (Group A). The other 22 patients with pernicious anaemia showed altered free and IF-bound vitamin B 12 absorption (Group B). Laboratory and clinical data and the absorption tests (xylose and fat excretion) were more abnormal in group B than in group A. Finally, 39 patients (Group C) with general malabsorption showed alternation of the absorption of free and IF-bound vitamin B 12 (Group C). The clinical nd biological data were different in these patients from that found in groups A and B. It is possible that in patients with pernicious anaemia who are untreated an alteration of the intestinal mucosa may produce a malabsorption of vitamin B 12 even in the presence of intrinsic factor.
 ...
PMID:Clinical evaluation of simultaneously administered 58Co labelled vitamin B12 and 57Co labelled vitamin B12 bound to intrinsic factor in patients with pernicious anaemia. 747 Jun 41

Food-cobalamin absorption depends on the initial release of cobalamin from its binders in food. Therefore, the characterization of patients' gastric juices and their behavior in this process was undertaken. Pentagastrin-stimulated gastric juice specimens from three patients with severe food-cobalamin malabsorption, six patients with mild malabsorption, and five patients with normal absorption were tested for pH, pepsin, intrinsic factor content, and an in vitro method that quantitates transfer of cobalamin from egg yolk to gastric R binder. Transfer of cobalamin correlated best with in vivo egg yolk-cobalamin absorption test results in the 14 patients (r = 0.731, P < 0.005). Transfer also correlated inversely with gastric juice pH (r = -0.619, P < 0.02). Basal gastric juice specimens, with their higher pH, from the same subjects failed to promote cobalamin transfer until their pH was lowered to 1.0-1.3. Pepsin levels did not correlate with in vitro transfer or with absorption in vivo; nevertheless, raising the low pepsin concentration of one stimulated gastric juice improved transfer, while inhibiting pepsin activity with pepstatin A inhibited transfer. Mixing experiments with selected stimulated gastric juices demonstrated that poor in vitro transfer, which in a few cases seemed unrelated to pH or pepsin levels, was not due to any inhibitory activity of such gastric juices. These studies confirm that gastric acid and pepsin play a central role in releasing food-bound cobalamin and transferring it to R binder, but suggest that other, still unidentified gastric defects occasionally contribute to impaired transfer; the latter defects are not inhibitory in nature but seem to involve the absence of a permissive activity.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:In vitro studies of gastric juice in patients with food-cobalamin malabsorption. 799 73

Imerslund-Najman-Grasbeck disease is a rare inherited megaloblastic anaemia secondary to a selective malabsorption of vitamin B12 by ileal enterocytes. The authors report on a 4 year-old tunisian girl who presented as visceral infantile leishmaniasis because of huge splenomegaly and major anaemia. The diagnosis of Imerslund disease was performed on the basis of the association of typical megaloblastic cells in the marrow, permanent proteinuria and favourable outcome under parenteral B12 administration. In addition, ther were no folate deficiency, no anti-intrinsic factor antibodies and no intrinsic factor deficiency. The outcome of the disease is always favourable if parenteral administration of vitamin B12 maintained.
 ...
PMID:[Imerslund-Najman-Grasbeck anemia. Apropos of a case]. 801 68

We have described the first case, to our knowledge, in which recurrent respiratory tract infections were the primary manifestation of thymoma with immunodeficiency (Good's syndrome) associated with cobalamin malabsorption and immunoglobulin M-kappa (IgM-kappa) M component. The intrinsic factor receptor activity was dramatically decreased in a mucosal homogenate prepared from ileal biopsies. This decreased activity could be the principal cause of the malabsorption of labelled cobalamin which was observed in the presence of intrinsic factor. However, it could be the consequence of the cobalamin deficiency, as it is known that a cobalamin deficiency can affect the assimilation of cobalamin, even in presence of exogenous intrinsic factor.
 ...
PMID:Thymoma with immunodeficiency (Good's syndrome) associated with selective cobalamin malabsorption and benign IgM-kappa gammopathy. 830 82

The human immunodeficiency virus (HIV)-associated dementia complex is characterized by difficulties in concentration and memory followed by apathy, social withdrawal and motor dysfunction. Decreased serum vitamin B12 levels occur in up to 20% of patients with acquired immune deficiency syndrome (AIDS) and may adversely contribute to the haematologic and neurologic dysfunction which is frequently attributed to the human immunodeficiency virus. We describe a patient with AIDS who presented with an apparent advanced AIDS dementia complex. There was an associated low serum vitamin B12 resulting from malabsorption due to low gastric intrinsic factor secretion. Following treatment with vitamin B12 the symptoms resolved over a 2-month period. We believe that the AIDS dementia complex represented a reversible adverse synergistic interaction between the human immunodeficiency virus and vitamin B12 deficiency.
 ...
PMID:Reversal of apparent AIDS dementia complex following treatment with vitamin B12. 850 20

Food-cobalamin malabsorption is marked by the inability to release cobalamin from food, which therefore cannot be taken up by intrinsic factor for absorption. The defect is not detectable by classical clinical tests like the Schilling test which are all based on the absorption of free, crystalline cobalamin. Tests of food-cobalamin absorption have been devised, the most popular ones using cobalamin bound to eggs or to chicken serum. The disparity between the abnormal results of these tests and the normal results with the Schilling test defines the disorder of food-cobalamin malabsorption. Release of cobalamin from food requires acid and pepsin, and most food-cobalamin malabsorptive states can be traced to gastric defects. However, other mechanisms may also play a role. The malabsorption is limited to food cobalamin and any free cobalamin, presumably including recycled biliary cobalamin, will be absorbed normally, which may explain its frequently insidious nature. The effect on cobalamin status covers a broad spectrum. At one extreme, some individuals, perhaps in the earliest stages, have normal cobalamin status, while at the other extreme may be found deficiency every bit as severe as in the most florid case of pernicious anaemia. Most often, however, the deficiency is mild, frequently marked by only a low serum cobalamin level, mild evidence of metabolic insufficiency and, sometimes, minimal clinical sequelae. Moreover, in some cases the gastric defect progresses and intrinsic factor secretion is affected, thus transforming into classical pernicious anaemia; this is not inevitable, however, and probably occurs in only a minority of patients. The course of food-cobalamin malabsorption is therefore a varied one. Nevertheless, it may be the most common cause of subtle or mild cobalamin deficiency and it is also sometimes associated with severe deficiency. Its identification and treatment need to be considered more widely in the clinical setting.
 ...
PMID:Malabsorption of food cobalamin. 853 65

In approximately 2 to 4 percent of patients, laboratory evidence of macrocytosis is found. Macrocytic anemias are classified as those resulting from disorders of DNA synthesis of erythrocyte precursors in bone marrow (megaloblastic anemias) or those caused primarily by alcoholism, liver disease and hypothyroidism (nonmegaloblastic anemias). A blood smear should be performed to differentiate the two forms. Neutrophil hypersegmentation is one of the most sensitive and specific signs of megaloblastic anemia. Other testing should include vitamin B12 and red blood cell folate levels, reticulocyte count, and thyroid and liver function tests. The Schilling test can determine if B12 can be absorbed and, if not, whether adding intrinsic factor corrects the malabsorption. The most common form of nonmegaloblastic macrocytic anemia results from alcoholism. Nonmegaloblastic macrocytic anemias may be accompanied by increased reticulocyte counts (hemolysis, hemorrhage) or by normal or decreased reticulocyte counts (alcoholism, liver disease, hypothyroidism and various bone marrow disorders).
 ...
PMID:Macrocytic anemia. 870 32


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>