Low cobalamin (vitamin B12) levels are frequent, especially in the elderly, several million of whom are affected. Most often the low levels reflect """"""""subclinical cobalamin deficiency"""""""", an asymptomatic state marked only by metabolic evidence of cobalamin insufficiency. It is unclear if these persons need intervention because progression to clinical deficiency may be uncommon, and many people with low levels have no deficiency at all. The proposal aims to study whether nitrous oxide (N2O), used in most general anesthesia in the US, worsens cobalamin status in elderly people who have unrecognized subclinical cobalamin deficiency. The reason for concern is that N2O inactivates cobalamin and therefore can cause neurological dysfunction in some patients with underlying clinically expressed cobalamin deficiency. The elderly are known to have an increased risk of postoperative cognitive complications. The study will recruit patients >60 years old who are scheduled for elective surgery in which N2O use for more than 1 hour is planned. Patients will be randomized in a blinded fashion to receive a standard anesthetic regimen of several agents, in which N2O is either included or replaced by air; the two regimens are equally safe and effective. They will undergo cognitive function and depression scale testing, blood testing of cobalamin-related metabolism, and clinical evaluation before surgery and at 48 hours, 14 days and 28 days after surgery. Those with cognitive changes will be treated with cobalamin and reevaluated after 3 months. Statistical analysis will compare the subgroups' metabolic, neuropsychological, demographic, genetic and clinical data. The primary question is what effect routine N2O anesthesia has on metabolic and clinical status related to subclinical cobalamin deficiency. It will also resolve whether or not the combination of N2O and the deficiency can explain the increased rate of postoperative cognitive problems in the elderly, and thus if preoperative or postoperative attention to cobalamin is needed in the elderly. A secondary goal is to extensively study cobalamin-related and homocysteine-related metabolism in these patients and their conditions, particularly as changes evolve after N2O use and later improvement. The clinical study provides a unique opportunity to establish these metabolic details and to compare their interactions with common genetic mutations in the patients that affect enzymes relevant to cobalamin deficiency, N2O effects, and their contribution to the clinical outcomes. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK032640-19
Application #
7279797
Study Section
Nutrition Study Section (NTN)
Program Officer
May, Michael K
Project Start
1983-09-01
Project End
2010-08-31
Budget Start
2007-09-01
Budget End
2010-08-31
Support Year
19
Fiscal Year
2007
Total Cost
$359,737
Indirect Cost
Name
New York Methodist Hospital
Department
Type
DUNS #
052810801
City
New York
State
NY
Country
United States
Zip Code
11215
Carmel, Ralph (2012) Subclinical cobalamin deficiency. Curr Opin Gastroenterol 28:151-8
Carmel, Ralph (2011) Mandatory fortification of the food supply with cobalamin: an idea whose time has not yet come. J Inherit Metab Dis 34:67-73
Shao, J S; Carmel, R; Alpers, D H (2011) Production of ectopic gastric intrinsic factor in gastric mucosa of humans with chronic gastritis. Dig Dis Sci 56:3209-19
Bailey, Regan L; Carmel, Ralph; Green, Ralph et al. (2011) Monitoring of vitamin B-12 nutritional status in the United States by using plasma methylmalonic acid and serum vitamin B-12. Am J Clin Nutr 94:552-61
Carmel, Ralph (2011) Biomarkers of cobalamin (vitamin B-12) status in the epidemiologic setting: a critical overview of context, applications, and performance characteristics of cobalamin, methylmalonic acid, and holotranscobalamin II. Am J Clin Nutr 94:348S-358S
Carmel, Ralph; Bellevue, Rita; Kelman, Zvi (2010) Low cobalamin levels associated with sickle cell disease: Contrasting origins and clinical meanings in two instructive patients. Am J Hematol 85:436-9
Carmel, Ralph; Parker, James; Kelman, Zvi (2009) Genomic mutations associated with mild and severe deficiencies of transcobalamin I (haptocorrin) that cause mildly and severely low serum cobalamin levels. Br J Haematol 147:386-91
Carmel, Ralph (2008) How I treat cobalamin (vitamin B12) deficiency. Blood 112:2214-21
Carmel, Ralph (2008) Nutritional anemias and the elderly. Semin Hematol 45:225-34
Chen, Xinke; Remacha, Angel F; Sarda, M Pilar et al. (2005) Influence of cobalamin deficiency compared with that of cobalamin absorption on serum holo-transcobalamin II. Am J Clin Nutr 81:110-4

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