Evaluation of Holotranscobalamin as an Indicator of Vitamin B12 Absorption

NCT ID: NCT00235573

Last Updated: 2011-12-22

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 21 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2005-10-31
• Study Completion Date: 2005-11-30

Brief Summary

Vitamin B12 is an essential nutrient that the body needs for cells to divide and function normally. Individuals may develop a deficiency of vitamin B12 by either limiting the amount in the diet or by decreased vitamin B12 intake into the body (absorption). Keeping adequate B12 blood levels is important for health. Vitamin B12 deficiency may increase one's risk for developing anemia and can even lead to neurological problems and paralysis if the deficiency is severe and lasts a long time. It is very important for doctors to have accurate tests to determine if people are absorbing vitamin B12 normally so that treatment can be started before severe clinical problems occur.

The purpose of this research is to provide new information that may help scientists develop a better method to test for problems with absorbing vitamin B12. In this study, changes in the amounts of vitamin B12 bound to protein (transcobalamin) in the blood will be measured after doses of vitamin B12 are taken. If the amounts of this vitamin B12-protein complex (called holo-transcobalamin) change in response to taking a vitamin B12 supplement in normal individuals, it may be possible to use this information to develop a new sensitive test to identify individuals who have problems absorbing vitamin B12. This new vitamin B12 absorption test may be a better clinical test for vitamin B12 absorption than those now available for doctors to use.

Detailed Description

Part I Screening: Individuals who meet initial screening criteria will be scheduled to have fasting blood samples drawn in the General Clinical Research Center (GCRC). All participants will sign informed consent forms approved by the UF Institutional Review Board prior to the initiation of this part of the study. Subjects' heights and weights will be measured and subjects will be asked to complete a medical history questionnaire. Blood analyses will include serum B12, blood chemistry, and hematological indices. Females will be given a pregnancy test. Subjects eligible for Part II of the study (Intervention) will have serum B12 concentrations that are ≥444 pmol/L; will be non-anemic; and will have normal general blood chemistry (all values within or near the normal range), and no history of chronic disease (e.g., pernicious anemia, cancer, diabetes, renal disease, hypertension, neurological abnormalities, gastrointestinal disorders). Any subject with deficient (<148 pmol/L) serum B12 concentration [18] will not be eligible for participation and will be instructed to see their personal physician for complete follow-up and treatment.

Part II Intervention: Changes in B12 status assessment indicators in response to B12 supplementation will be evaluated.

Subjects will come to the GCRC the night before (Day 1) the intervention protocol. The next morning (Day 1) following an overnight fast, an indwelling catheter will be inserted from which repeated blood samples will be drawn throughout Day 1. A baseline fasting blood sample (#1) will be drawn. Subjects will then consume a light breakfast (including 1 piece of bread and 8 oz of orange juice) and will take a 9 ug dose of B12 (Dose 1). Thirty minutes after completion of the meal and consumption of the B12 supplement, a second blood sample (#2) will be drawn. Five subsequent hourly blood samples (# 3-7) will be drawn. After the 7th blood sample the subjects will consume one piece of bread and 8 ounces of orange juice and will take a second 9 ug dose of B12 (Dose 2) and have a blood sample (#8) drawn 30 minutes after consumption of the meal and the B12 dose. Five subsequent hourly blood samples (#9-13) will be drawn. The subjects will then consume one piece of bread and 8 ounces of orange juice and take a 9 ug dose of B12 (Dose 3). Another blood sample (#14) will be drawn 30 minutes after the meal and the B12 dose. One hour later, a final (Day 1) blood sample (#15) will be drawn followed by removal of the catheter. In addition to the bread and juice consumed with each B12 supplement, subjects will receive a mid-morning snack 2 hours after Dose 1 of the B12 supplement, lunch 3.5 hrs after Dose 1 of the B12 supplement, dinner at 4 hours after Dose 2 of the B12 supplement, and an evening snack at 3 hours after Dose 3. Low B12-containing foods will be provided in the GCRC. Water and non-caffeinated, non-caloric beverages will be allowed ad libitum.

The subjects will remain in the GCRC overnight and a fasting blood sample (#16) will be drawn in the morning on Day 2. On Day 2 participants will be provided breakfast following the blood draw, after which they will be free to leave the GCRC. Subjects will be provided with take-away meals and snacks (lunch, dinner, snacks) consisting of low-B12 containing foods.

Subjects will be instructed to return on the morning of Day 3 at which time they will have one am fasting blood sample (#17) drawn and will be provided with breakfast before they leave the GCRC. All overnight fasts will be from 10 pm the previous night. The following B12 indicators will be measured at each blood draw (a) holo-TC; (b) total-TC; (c) holo-HC and total HC; (d) serum B12; and (e) plasma albumin. Additional B12 status indicators (e.g. homocysteine, methylmalonic acid, RBC B12) will be measured at select blood draw intervals. A baseline folate analysis will be done.

Conditions

Disorder of Vitamin B12

Keywords

Vitamin B12 absorption; Holo-transcobalamin

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: DIAGNOSTIC
• Blinding Strategy: NONE

Study Groups

Vitamin B12 supplement

After taking a fasting blood sample, all subjects were given a light breakfast plus 9 micrograms of vitamin B12. Two more doses of vitamin B12 were administered 6 hours apart.

Group Type: EXPERIMENTAL

Vitamin B12

Intervention Type: DIETARY_SUPPLEMENT

After taking a fasting blood sample, all subjects were given a light breakfast plus 9 micrograms of vitamin B12. Two more doses of vitamin B12, 9 micrograms each, were administered 6 hours apart.

Interventions

Vitamin B12

After taking a fasting blood sample, all subjects were given a light breakfast plus 9 micrograms of vitamin B12. Two more doses of vitamin B12, 9 micrograms each, were administered 6 hours apart.

Intervention Type: DIETARY_SUPPLEMENT

Eligibility Criteria

Inclusion Criteria

• No vitamin B12-containing supplement use within past year
• No vitamin B12 injections within past year
• No use of tobacco products
• No chronic use of prescription medications except oral contraceptives
• No history of chronic disease (e.g., pernicious anemia, cancer, diabetes, renal disease, hypertension, neurological abnormalities, gastrointestinal disorders)
• BMI between 18.5-29.9
• General Chemistry Blood Tests (all values within or near normal range; hemoglobin if female ≥ 11.0 g/dL; if male ≥ 12 g/dL)
• B12 status (Serum B12 ≥ 444 pmol/L)
• Capable of understanding the informed consent form
• Agrees to comply with protocol requirements

Exclusion Criteria

• History of pernicious anemia, cancer, diabetes, renal disease, hypertension, heart disease, neurological abnormalities, gastrointestinal disorders, lung disease, hepatic disease, hematologic, or other metabolic diseases that, in the opinion of the Co-Principal Investigators, would affect safety or compliance
• Vitamin B12 supplement use or injections within past year
• Pregnant or breast feeding
• Has BMI <18.5 or >29.9
• Has donated or lost a significant volume (>450 mL) of blood or plasma within 30 days of the study
• General chemistry lab values outside of ranges
• Serum B12 outside of range listed above
• Use of tobacco products
• Chronic use of prescription medications except oral contraceptives
• Does not understand the informed consent form
• Does not agree to comply with protocol requirements

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 49 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

National Center for Research Resources (NCRR)

NIH

Sponsor Role: collaborator

University of Florida

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Principal Investigators

Lynn B Bailey, PhD

Role: PRINCIPAL_INVESTIGATOR

University of Florida

Gail PA Kauwell, PhD

Role: PRINCIPAL_INVESTIGATOR

University of Florida

Locations

General Clinical Research Center, Shands Hospital, University of Florida

Gainesville, Florida, United States

Countries

United States

References

von Castel-Dunwoody KM, Kauwell GP, Shelnutt KP, Vaughn JD, Griffin ER, Maneval DR, Theriaque DW, Bailey LB. Transcobalamin 776C->G polymorphism negatively affects vitamin B-12 metabolism. Am J Clin Nutr. 2005 Jun;81(6):1436-41. doi: 10.1093/ajcn/81.6.1436.

Reference Type: BACKGROUND

PMID: 15941899 (View on PubMed)

Bor MV, Nexo E, Hvas AM. Holo-transcobalamin concentration and transcobalamin saturation reflect recent vitamin B12 absorption better than does serum vitamin B12. Clin Chem. 2004 Jun;50(6):1043-9. doi: 10.1373/clinchem.2003.027458. Epub 2004 Mar 25.

Reference Type: BACKGROUND

PMID: 15044317 (View on PubMed)

Bor MV, Cetin M, Aytac S, Altay C, Nexo E. Nonradioactive vitamin B12 absorption test evaluated in controls and in patients with inherited malabsorption of vitamin B12. Clin Chem. 2005 Nov;51(11):2151-5. doi: 10.1373/clinchem.2005.055509. Epub 2005 Sep 15.

Reference Type: BACKGROUND

PMID: 16166166 (View on PubMed)

Related Links

http://www.ctsi.ufl.edu/research/clinical-research-units/uf-clinical-research-center/

The website for the UF General Clinical Research Center Clinical and Translational Science Institute

Other Identifiers

7591

Identifier Type: OTHER_GRANT

Identifier Source: secondary_id

M01RR000082

Identifier Type: NIH

Identifier Source: secondary_id

View Link

433-2005

Identifier Type: -

Identifier Source: org_study_id