vitamin-b-12 and Acquired-Immunodeficiency-Syndrome

We detected in 1989, with the inhibitor test of proviral insertion into c-erb B erythroblastosis, two retrovirus integrase inhibitors: hydroxy-methyl-ellipticine and acriflavine. They have been used for ten years in AIDS patients with high efficacy and no toxicity. Since vitamin B12 and cobalt, which it contains, have been detected as HIV1-integrase inhibitors by an in-vitro test, we have also used vitamin B12 (combined with folic acid), whose clinical action has been remarkable. Ten or so other compounds have been detected by such in-vitro tests, among which there are many compounds (such as flavones) which are used in many conditions and are not toxic.

Topics: Acquired Immunodeficiency Syndrome; Acriflavine; Cobalt; Ellipticines; HIV Integrase; HIV Integrase Inhibitors; HIV-1; Humans; Vitamin B 12

Certain aspects of the clinical syndrome of dementia, cerebral atrophy, predominantly sensory neuropathy, and vacuolar myelopathy in AIDS resemble those seen in vitamin B12 deficiency. Pathologically, there are similarities not only in the changes in the spinal cord, but also in the brain and peripheral nerves. The pathogenesis of vacuolar myelopathy may be secondary to a combination of immune mediated myelin and oligodendrocyte injury, and simultaneous impairment of repair mechanisms due to a deficiency of S-adenosylmethionine (SAM). Products derived from macrophages may interfere directly with the methyl transfer cycle through the generation of reactive oxygen intermediates and reactions involving nitric oxide and peroxynitrite which may limit the supply of methionine for conversion to SAM, both by direct interaction as well as through inhibition of methionine synthase. Macrophage activation with secretion of cytokines and other biologically reactive substances within the nervous system is sustained in the late stages of HIV infection by the general effects of immune depletion, including loss of T cells (with concomitant reduction of macrophage regulatory molecules) and recurrent opportunistic infections, and may be further augmented by the local presence of the virus itself (or its surface glycoprotein gp120). This would account for the common, but not exclusive, occurrence of vacuolar myelopathy in AIDS. The ability of the virus and its products to stimulate macrophage and microglial activation may also explain the association between severity of vacuolar myelopathy and the presence of HIV encephalitis. A similar mechanism may underlie the pathogenesis of dementia, cerebral atrophy, and peripheral neuropathy. Local factors or differential susceptibility between the central and peripheral nervous system may determine whether myelinotoxic or neurotoxic processes predominate; the prominence of myelin involvement in the spinal cord, and axonal involvement peripherally may reflect both ends of this range, with the brain manifesting a more equal balance of both processes.

Topics: Acquired Immunodeficiency Syndrome; AIDS Dementia Complex; Cytokines; Demyelinating Diseases; Folic Acid; Glutathione; Humans; Macrophage Activation; Oligodendroglia; Peripheral Nervous System Diseases; S-Adenosylmethionine; Spinal Cord Diseases; Vacuoles; Vitamin B 12

A cohort of asymptomatic human immunodeficiency virus (HIV) seropositive patients was followed over a 2 1/2-year period, to establish changes in serum vitamin B12 (B12) concentrations. Serum B12, CD4 count, and clinical progression to acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) were measured. The unsaturated B12 binding capacities of the transcobalamins were also determined at the start of the study and compared to those from a homosexual HIV seronegative control group. The geometric mean of serum B12 in 218 asymptomatic HIV seropositive patients was significantly lower than of a homosexual HIV seronegative control group (P = 0.02) and the unsaturated B12 binding capacities of transcobalamins I and II were significantly higher in the asymptomatic patients compared with the same control group (P < 0.03, P < 0.0001, respectively). Fifty-nine of the asymptomatic HIV seropositive patients were followed over a 2 1/2-year period during which most had falling serum B12 levels (64%). Twelve patients progressed clinically to ARC or AIDS, of which nine had repeat serum B12 estimation prior to progression. All nine patients had or developed falling serum B12 levels without any evidence of an HIV-related bowel disorder. All patients progressing had falling CD4 counts. Subnormal serum B12 levels are common in HIV disease and occur at an early stage. B12 levels fall in most patients with time and may help predict those patients whose disease will progress the most rapidly.

Topics: Acquired Immunodeficiency Syndrome; CD4 Antigens; Cohort Studies; Disease Progression; Female; Follow-Up Studies; Humans; Longitudinal Studies; Male; Predictive Value of Tests; Time Factors; Transcobalamins; Vitamin B 12

We conducted a double-blind, placebo-controlled trial of oral azidothymidine (AZT) in 282 patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex. Although significant clinical benefit was documented (N Engl J Med 1987; 317:185-91), serious adverse reactions, particularly bone marrow suppression, were observed. Nausea, myalgia, insomnia, and severe headaches were reported more frequently by recipients of AZT; macrocytosis developed within weeks in most of the AZT group. Anemia with hemoglobin levels below 7.5 g per deciliter developed in 24 percent of AZT recipients and 4 percent of placebo recipients (P less than 0.001). Twenty-one percent of AZT recipients and 4 percent of placebo recipients required multiple red-cell transfusions (P less than 0.001). Neutropenia (less than 500 cells per cubic millimeter) occurred in 16 percent of AZT recipients, as compared with 2 percent of placebo recipients (P less than 0.001). Subjects who entered the study with low CD4 lymphocyte counts, low serum vitamin B12 levels, anemia, or low neutrophil counts were more likely to have hematologic toxic effects. Concurrent use of acetaminophen was also associated with a higher frequency of hematologic toxicity. Although a subset of patients tolerated AZT for an extended period with few toxic effects, the drug should be administered with caution because of its toxicity and the limited experience with it to date.

Topics: Acquired Immunodeficiency Syndrome; Administration, Oral; AIDS-Related Complex; Anemia; Antiviral Agents; Blood Transfusion; Bone Marrow; Clinical Trials as Topic; Double-Blind Method; Erythrocyte Count; Female; Hemoglobins; Humans; Leukocyte Count; Male; Neutropenia; Platelet Count; Random Allocation; Thymidine; Vitamin B 12; Zidovudine

To present the 4 to 9 years (median: 6 years) treatment follow up of 10 HIV1-AIDS patients, 9 at AIDS and 1 at A3 stages.. We have applied from 1992 to 1994, AZT combined with 2 integrase inhibitors, acriflavine and hydroxy-methyl-ellipticine. We could shift, in 1994, to combinations of 3 drugs including two more retrotranscriptase inhibitors (RTI), ddI and ddC, and, after 1995, to combinations of 4 drugs including also two other RTI, d4T and 3TC, and 3 protease inhibitors (PI), indinavir, ritonavir, and saquinavir. In 1998, as cobalamine was shown by an in vitro test, to act as integrase inhibitor, vitamin B12 was added in cycles of various lengths. Every three weeks, not only the investigations were repeated, but the virostatics were changed.. No grade 2 virostatics toxicity has been registered. The viral loads (VL) decreased according to exponential curves. Their initial parts obeyed first order kinetics. The second parts were and still are asymptotic. The first parts could be rectilinear or sinuous. The sinuosities were associated to cofactors present before treatment (chimerism, UV irradiation, hepatitis C or B and C, brain toxoplasmosis). The asymptotic parts, whose VL were below PCR detectable levels, presented discrete, reversible HIV1 rebounds, associated to other cofactors (such as herpes zoster, herpes 6, CMV, flat condyloma, and influenza). Among immunologic parameters, the monocyte and CTL numbers increased and presented, during the rapidly decreasing part of VL curve, a significant inverse correlation with it. Neither CD4+ nor suppressor T-cell (STC) numbers presented such correlation. Near 100 % of CTL were CD28+. Later, vitamin B12 applications increased monocyte and CD28+ CTL numbers, and appeared to reinforce VL stabilization.. The combinations of inhibitors affecting 3 retrovirus targets, retrotranscriptase, integrase, and protease have given to 10 out of 10 AIDS patients survivals varying today between 4 to 9 years, in excellent conditions. The UVA-pretreated patient is the only one presenting a not maximally reduced asymptotic VL, while his CD4+ and STC have been absent for 8 years. Other patient VL regressed exponentially to become asymptotic, below PCR detectable levels.

Topics: Acquired Immunodeficiency Syndrome; Acriflavine; Adult; Anti-HIV Agents; Antiviral Agents; CD4-CD8 Ratio; Didanosine; Drug Therapy, Combination; Ellipticines; Female; Follow-Up Studies; HIV-1; Humans; Integrase Inhibitors; Male; Middle Aged; Protease Inhibitors; Stavudine; Vitamin B 12; Zalcitabine; Zidovudine

A Johns Hopkins University study reveals that HIV-infected men with abnormally low B vitamin blood levels progressed to AIDS twice as fast as those with normal levels. Low levels of B12 have also been found in persons with Chronic Fatigue Immune Dysfunction Syndrome (CFID). Since both ailments have a common virus in HHV-6A, the virus is suspected, although unproven, of causing the inability of the intestines to absorb B12 by affecting intrinsic factor levels.

Topics: Acquired Immunodeficiency Syndrome; Cognition Disorders; Fatigue Syndrome, Chronic; Herpesvirus 6, Human; Humans; Intrinsic Factor; Vitamin B 12; Vitamin B 12 Deficiency

A Johns Hopkins study of more than 300 men indicated that those with an abnormally low level of vitamin B-12 in their blood serum progressed to AIDS almost twice as fast as those with normal levels. In contrast to vitamin B-12, serum levels of vitamin B-6 or folic acid did not appear to correlate with disease progression. The almost twofold increase in progression to AIDS in those with low B-12 levels was found after adjusting for HIV-1-related symptoms, CD4+ cell count, age, serum albumin, use of antiretroviral therapy before AIDS, serum folate concentration, and frequency of alcohol consumption. This may indicate that serum vitamin B-12 concentrations are an early and independent marker of HIV-1 disease progression.

Topics: Acquired Immunodeficiency Syndrome; CD4 Lymphocyte Count; Cohort Studies; Disease Progression; Humans; Male; Retrospective Studies; Vitamin B 12

The mechanisms underlying acid secretory failure in patients with HIV disease are unknown. We evaluated, in a series of preliminary studies, changes associated with parietal cell structure and function in early and late HIV disease, in an attempt to elucidate possible underlying mechanisms. Gastric acid and intrinsic factor secretion, vitamin B12 absorption, and light and electron microscopic evaluation of gastric mucosa were evaluated in patients with early and late HIV infection (AIDS) and compared to non-HIV-infected controls. Immunolocalization of HIV-related antigens in gastric mucosa was also examined. Fasting gastric juice pH and intrinsic factor (IF) concentration in AIDS and HIV infected subjects were significantly different from controls (P = 0.012 and P = 0.025, respectively for pH, and 0.029 and 0.035 for IF; ANOVA LSD test). By contrast, maximal acid output (MAO) was significantly lower in AIDS, but not HIV-infected subjects (P = 0.043 and P = 0.322, respectively). Similarly, Schilling test phases 1 and 2 results were significantly lower in AIDS, but not HIV-infected subjects. Varying degrees of vacuolar degeneration of parietal cells were seen on light microscopy. On electron microscopy (EM), tubulovesicles were reduced and intracellular canaliculi dilated with striking loss of microvilli. Immunofluorescent staining with antibodies to gp120, gp41, p24, and p17 demonstrated positive punctate signals in the cytoplasm of gastric glands, which includes parietal cells. Immunogold EM with anti-gp120, localized predominantly to the microvilli of intracellular canaliculi in parietal cells. Abnormal secretory function of parietal cells occurs early in HIV disease, affects acid as well as intrinsic factor secretion, and is associated with morphological changes in the acid secretory apparatus.

Topics: Acquired Immunodeficiency Syndrome; Adult; Fluorescent Antibody Technique; Gastric Juice; Gastric Mucosa; HIV Antigens; HIV Enteropathy; HIV Infections; Humans; Intestinal Absorption; Intrinsic Factor; Lymphocytes; Male; Middle Aged; Parietal Cells, Gastric; Vitamin B 12

To define the clinical syndrome, nutritional status and malabsorptive status in patients with HIV and chronic diarrhea and either microsporidia or no identified pathogen.. HIV-positive patients from an urban, hospital-based infectious disease clinic with chronic diarrhea who had undergone exhaustive gastrointestinal and stool studies for enteric pathogens and were found to have either microsporidia or no pathogen.. Patients were evaluated for clinical history, physical, body composition, nutritional and malabsorptive studies including D-xylose, Schilling test, determinations of 24 h stool fat, weight and nitrogen, and 24 h urea nitrogen.. Ten patients with microsporidia were studied, four of whom were infected with Septata intestinalis, six with Enterocytozoon bieneusi; nine patients had no identified pathogen. Patients in both groups were comparable in stage of HIV disease, and demonstrated abnormal nutritional status and malabsorptive parameters. Patients with no pathogen had significantly longer duration of symptoms prior to presentation; however, patients with microsporidia had significantly greater malabsorption of fat, D-xylose, vitamin B12, and significantly lower serum levels of zinc. Nutritional status and malabsorption were similarly depressed in patients infected with either species of microsporidia.. HIV-infected patients with chronic diarrhea associated with either microsporidial infection or with no identified pathogen had abnormal parameters of absorption and malnutrition, and those infected with microsporidia demonstrated more severe malabsorption.

Topics: Acquired Immunodeficiency Syndrome; Adult; Animals; CD4 Lymphocyte Count; Diarrhea; Dietary Fats; HIV Wasting Syndrome; Humans; Malabsorption Syndromes; Male; Microsporida; Protozoan Infections; Vitamin B 12; Xylose; Zinc

This study examines small intestinal absorption-permeability, intestinal inflammation and ileal structure and function in HIV-positive male homosexuals.. Thirty HIV-seropositive male homosexuals at various stages of disease underwent intestinal absorption permeability and 111indium leukocyte studies (for quantification of intestinal inflammation). Twenty-six men with AIDS had a dual radioisotopic ileal function test (whole body retention of tauro 23-[75Se]-selena 25-homocholic acid and 58cobalt-labelled cyanocobalamine), and 17 underwent ileocolonoscopy with terminal ileal biopsy.. Well, HIV-infected, subjects had normal intestinal absorption-permeability, but both functions were impaired upon the development of AIDS. The median faecal excretion of 111indium in well patients (0.66%) did not differ significantly (P > 0.5) from controls (0.46%), but subjects with AIDS who were well or who had diarrhoea had significant (P < 0.005) intestinal inflammation (1.33% and 2.18%, respectively). The median 7-day retention of tauro 23-[75Se]-selena 25-homocholic acid in well patients with AIDS (38.9%) did not differ significantly (P > 0.2) from controls (39.3%), whereas the absorption of 58cobalt-labelled cyanocobalamine was significantly (P < 0.05) lower than controls (32.1% and 59.4%). Patients with AIDS-diarrhoea had significant (P < 0.001) malabsorption of both the bile acid (7.7%) and vitamin B12 (8.9%) which was more severe than in Crohn's ileitis (14.2% and 30.3%, respectively). Morphometric analyses of ileal biopsies were unremarkable in AIDS.. These studies demonstrate a low-grade enteropathy in patients with AIDS, severe ileal malabsorption in patients with AIDS diarrhoea and relatively minor ileal morphologic changes. Malabsorption of bile acids may play a pathogenic role in patients with AIDS and diarrhoea.

Topics: Acquired Immunodeficiency Syndrome; Adult; CD4 Lymphocyte Count; Crohn Disease; Diarrhea; HIV Seropositivity; Humans; Ileum; Inflammatory Bowel Diseases; Intestinal Absorption; Male; Middle Aged; Vitamin B 12

To determine the prevalence and describe the clinical correlates of subnormal cobalamin levels in subjects infected with the human immunodeficiency virus (HIV), and to assess its relationship to virus-mediated immunosuppression and/or anti-viral therapy.. Outpatient referral clinic in tertiary care hospital.. 200 HIV infected individuals.. Descriptive cross sectional survey, with prospective follow-up in a subgroup of patients before and after initiation of zidovudine therapy.. Routine complete blood count, serum B12 assay, CD4 counts. Serum homocysteine levels, and Schilling tests were performed on subgroups of study subjects.. Subnormal serum B12 levels were found in 61 subjects (30.5%). B12 deficient subjects were more likely to be taking zidovudine. (P = .007). Serum homocysteine levels were significantly higher in patients with subnormal cobalamin levels but were unrelated to CD4 counts or zidovudine use, and were rarely outside of the normal range. Malabsorption of vitamin B12 as evidenced by abnormal Schilling tests was more likely among patients with more advanced HIV disease, or gastrointestinal symptoms but was not necessarily associated with low B12 levels.. Decreased cobalamin levels are found frequently in HIV disease, especially among those treated with zidovudine. Evidence of B12 malabsorption is found among those with more advanced disease and gastrointestinal symptoms.

Topics: Acquired Immunodeficiency Syndrome; Adult; Aged; Antigens, CD; Cross-Sectional Studies; Female; Follow-Up Studies; Humans; Male; Middle Aged; Prospective Studies; Vitamin B 12; Zidovudine

The replication of human immunodeficiency virus (HIV) may be modulated in part by host factors such as DNA methylation. Hypermethylation of the HIV provirus may suppress viral replication and play a role in the establishment of latency. HIV seropositive individuals have decreased levels of metabolites involved in methylation. It is proposed that metabolites such as S-adenosylmethionine (SAM), methylcobalamin and methyltetrahydrofolate be explored as potential therapeutic agents in HIV infected individuals.

Topics: Acquired Immunodeficiency Syndrome; DNA, Viral; HIV; HIV Infections; HIV Seropositivity; Humans; Methylation; Proviruses; S-Adenosylmethionine; Tetrahydrofolates; Virus Replication; Vitamin B 12

AIDS-associated gastric secretory failure has been characterized by decreased secretion of acid, pepsin, and gastric juice volume. To determine whether decreased intrinsic factor secretion and vitamin B12 malabsorption occur in this entity, we performed prospective measurements of maximal acid output, intrinsic factor output, vitamin B12 absorption, serum vitamin B12, and holotranscobalamin II in 10 consecutive AIDS patients. Four of 10 patients had low maximal acid output, i.e., < or = 1.5 mEq/h (control = 12.8 +/- 9.0, range 2.5-25 mEq/h). Four patients had low intrinsic factor output, i.e., < or = 1.1 microgram/h (control = 8.2 +/- 6.9, range 3.1-19.4 micrograms/h). One patient with low intrinsic factor output had low serum vitamin B12 and a Schilling test consistent with pernicious anemia. A second patient with very low intrinsic factor output (0.16 micrograms/h) had low parts I and II Schilling tests; malabsorption most likely resulted from both low intrinsic factor secretion and ileal disease. One of three vitamin B12 malabsorbing patients, with normal serum vitamin B12, had low holotranscobalamin II, 25 pg/ml (control holotranscobalamin II = 76 +/- 44, range 44-152 pg/ml). Maximal acid output and intrinsic factor output did not correlate in AIDS (r = 0.36, p = 0.30) in contrast to the expected correlation in controls (r = 0.91, p = 0.03). We conclude that low intrinsic factor secretion is common in AIDS and contributes to vitamin B12 malabsorption. Decreased parietal cell secretion of intrinsic factor and acid may occur independently in human immunodeficiency virus-associated gastric secretory failure. Low holotranscobalamin II, an early manifestation of vitamin B12 malabsorption, results in decreased delivery to vitamin B12-dependent tissues prior to depletion of serum vitamin B12. Regular supplementation with vitamin B12 may therefore be warranted in patients with advanced HIV infection.

Topics: Acquired Immunodeficiency Syndrome; Adult; Female; Gastric Acid; Humans; Intrinsic Factor; Malabsorption Syndromes; Male; Parietal Cells, Gastric; Prospective Studies; Vitamin B 12

In AIDS, as previously found in pernicious anemia (PA), the earliest serum marker of subnormal vitamin B12 (cobalamin) absorption, and therefore of negative B12 balance, is low serum holotranscobalamin II (holo-TC II; B12-TC II) despite normal total serum B12 level, normal serum homocysteine, and normal classic (oral free radio-B12) Schilling test. This may be accompanied by subtle and insidious damage to hematopoietic, immunologic, neuropsychiatric, nutritional and alimentary systems, confirmed by correction on therapeutic trial with B12 therapy. Our studies suggest such selective B12 deficiency occurs in about half of the HIV-1 infected, in part due to frequent depression of B12 absorption by HIV-1 attack on the gastric mucosa and/or opportunistic infection attack on the small bowel, and in part due to a telescoping of the continuum of the stages of negative B12 balance in relation to damage to B12 delivery by the infective and/or systemic disease process. In AIDS, when total serum B12 is normal despite tissue depletion of B12, if the classic Schilling test does not reveal subnormal food B12 absorption, the food Schilling test does. We hypothesize that DNA-synthesizing cells of the hematopoietic, immunologic, neurologic and other systems which have surface receptors solely for holo-TC II, and which have low B12 stores, rapidly become dysfunctional due to B12 deficiency when holo-TC II is low, while cells (such as liver cells) which also have surface receptors for holohaptocorrin (B12-haptocorrin) remain B12-replete. We believe this to be another example of the concept of selective nutrient deficiency in one cell line but not another.

Topics: Absorption; Acquired Immunodeficiency Syndrome; Adult; Biomarkers; Humans; Male; Transcobalamins; Vitamin B 12

Small intestinal absorptive function was investigated in six patients with the acquired immunodeficiency syndrome (AIDS) who had diarrhoea and weight loss. Proximal function was assessed by [14C]Triolein test of fat absorption. Distal function was determined by a test of bile acid absorption in which the loss of radio-labelled synthetic bile acid, 75seleno-23-homocholic acid-taurine ([75Se]HCAT), from the enterohepatic circulation was quantified by abdominal gamma-scanning and by a vitamin B12-intrinsic factor absorption test. Concurrently indirect tests of small intestinal bacterial overgrowth ([14C]glycocholate and breath hydrogen) were carried out. In addition, jejunal histological examination and stool microscopy and culture for enteropathogens were performed. Fat absorption was reduced in all six patients, four of whom had jejunal villous atrophy. Bile acid and vitamin B12 absorption were normal in four subjects. Enteropathogens were not detected in any of the four subjects with normal terminal ileal absorptive function. In contrast, reduced bile acid and vitamin B12 absorption were detected in two of six subjects. Both patients had an enteropathogen (Cryptosporidium spp. and Isospora belli) present on stool and jejunal histological examination. Neither subject had evidence of small-intestinal bacterial overgrowth. AIDS patients therefore may have normal ileal absorptive function in the presence of jejunal disease. Infection with Cryptosporidium spp. or I. belli may however, be associated with severe ileal dysfunction.

Topics: Acquired Immunodeficiency Syndrome; Adult; Atrophy; Cryptosporidiosis; Dietary Fats; Female; Humans; Hyperplasia; Ileal Diseases; Intestinal Absorption; Jejunal Diseases; Malabsorption Syndromes; Male; Middle Aged; Vitamin B 12; Weight Loss

Topics: Acquired Immunodeficiency Syndrome; Agranulocytosis; Folic Acid; Humans; Lithium; Neutropenia; Vitamin B 12; Zidovudine

We have examined 11 patients with the acquired immunodeficiency syndrome (AIDS) for evidence of subclinical vitamin B12 malabsorption. Three subjects (27%) had low levels of vitamin B12. Eight subjects (73%), including these 3 subjects plus 5 others with normal vitamin B12 levels, had abnormal Schilling test results. In addition, 15% of an unselected population of 121 patients with AIDS and 7% of 27 patients without AIDS who were seropositive for human immunodeficiency virus type 1 (HIV-1) had low serum vitamin B12 levels. Stool cultures from the 8 subjects with abnormal Schilling test results revealed no pathogens. Intestinal involvement by Kaposi's sarcoma was found in only 1 patient. Biopsy specimens from 5 of 6 patients with vitamin B12 malabsorption, however, contained mononuclear cells harboring HIV-1, as indicated by in situ hybridization studies. Our observations suggest that vitamin B12 malabsorption is common in patients with AIDS and may be a very early manifestation of infection with HIV-1.

Topics: Acquired Immunodeficiency Syndrome; Adult; Humans; Malabsorption Syndromes; Male; Middle Aged; Vitamin B 12

Low serum cobalamin levels in 10 patients with AIDS or AIDS-related complex led us to also prospectively survey 40 homosexual men in our AIDS clinic. 8 of the latter (20%) had low cobalamin values. We found no evidence of megaloblastic changes in the blood or bone marrow. Assessment disclosed malabsorption of cobalamin in only 1 of 6 cases tested for it. 6 of the patients were treated with cobalamin and had no hematologic response. It appears that low serum cobalamin levels in AIDS and related disorders do not usually represent overt cobalamin deficiency. While malabsorption is occasionally responsible for the low cobalamin level, in most cases the cause is unknown and may reflect a serum abnormality similar to that in multiple myeloma. AIDS and related disorders should be considered in the differential diagnosis of unexplained low cobalamin levels.

Topics: Acquired Immunodeficiency Syndrome; Adult; AIDS-Related Complex; Homosexuality; Humans; Male; Middle Aged; Schilling Test; T-Lymphocytes, Helper-Inducer; T-Lymphocytes, Regulatory; Vitamin B 12