1. Evaluation of tracer labelled methionine load test in vitamin B-12 deficient adolescent women
- Author
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Satish C. Kalhan, Anura V Kurpad, Chittaranjan S. Yajnik, Dattatray S. Bhat, Carole Bennett, Lourdes L. Gruca, and Prachi Katre
- Subjects
0301 basic medicine ,Vitamin b ,Homocysteine ,Physiology ,Administration, Oral ,lcsh:Medicine ,Transsulfuration ,Biochemistry ,Body Mass Index ,chemistry.chemical_compound ,Methionine ,Medicine and Health Sciences ,Amino Acids ,lcsh:Science ,Carbon Isotopes ,Multidisciplinary ,biology ,Organic Compounds ,Nutritional Deficiencies ,Anemia ,Megaloblastic anemia ,Fasting ,Vitamins ,Hematology ,Glutathione ,3. Good health ,Body Fluids ,Vitamin B 12 ,Chemistry ,Blood ,Vitamin B12 deficiency ,Micronutrient Deficiencies ,Physical Sciences ,Methionine loading ,Female ,Anatomy ,Research Article ,Vitamin ,medicine.medical_specialty ,Adolescent ,Iron ,Blood Plasma ,03 medical and health sciences ,Folic Acid ,Internal medicine ,TRACER ,medicine ,Humans ,Sulfur Containing Amino Acids ,Serologic Tests ,Cysteine ,Nutrition ,030109 nutrition & dietetics ,Organic Chemistry ,lcsh:R ,Chemical Compounds ,Biology and Life Sciences ,Proteins ,Vitamin B 12 Deficiency ,Carbon Dioxide ,Cystathionine beta synthase ,Amino Acid Metabolism ,030104 developmental biology ,Endocrinology ,Metabolism ,chemistry ,Dietary Supplements ,biology.protein ,lcsh:Q ,Peptides - Abstract
Background Methionine loading test (MLT) has been used primarily to identify defects in transsulfuration of homocysteine in cystathionine beta synthase deficiency. It may not be as useful to evaluate remethylation pathway, in vitamin B-12 and folate deficiencies. Objective We used tracer isotope labelled MLT to interrogate transsulfuration and remethylation independently in vitamin B-12 deficiency. Design We studied vitamin B-12 deficient women with a tracer labelled MLT before and eleven months after treatment with vitamin B-12. The fractional contribution of [13C]homocysteine to breath CO2 was used as a measure of transsulfuration, and difference in the intracellular enrichment of [13C]methionine and that of [C2H3]methionine as a measure of remethylation of homocysteine. Combined pre- and post-treatment results were analyzed to investigate the association between plasma vitamin B-12 concentrations and measures of homocysteine metabolism. Results The subjects were 17 years old, with a BMI of 19.4 kg/m2. Treatment with vitamin B-12, 2µg/day increased plasma B-12 from 93 (78.7, 106.2) [median (25th, 75th centiles)] to 161.5 (125.5, 226.2) pmol/L; 44% were below 150pmol/L. The tracer estimated transsulfuration of homocysteine was lower and remethylation higher with B-12 levels >150pmol/L when compared with those
- Published
- 2018