NSA: Serum Proteins (2009)
Golner BB, Reinhold RB, Jacob RA, Sadowski JA, Russell RM. The short- and long-term effect of gastric partitioning surgery on serum protein levels. J Am Coll of Nutr. 1987: 6: 279-285.
PubMed ID: 3598025
The purpose of this study was to investigate the effects of stress and subsequent low-protein and low-calorie intake on several circulating proteins and the nutrients carried by these proteins at various time points throughout a six-month period after gastric partitioning surgery in obese patients.
Patients who were scheduled to undergo elective gastric partitioning surgery for morbid obesity.
None noted.
Design
- Baseline fasting blood specimens were drawn on 22 patients prior to gastric partitioning surgery, with follow-up measurements taken at one, three and seven days post-operatively and again at approximately 30, 90 and 180 days post-operatively
- At each of the time points, the following five serum proteins and micronutritents carried by these proteins were measured: Retinol binding protein levels, transferrin, ceruloplasmin, transthyretin, albumin, iron, copper and zinc.
Statistical Analysis
The mean of each parameter at each post-operative time point was compared by paired T-test to the pre-operative baseline mean of the corresponding parameter.
Timing of Measurements
Blood specimens were drawn prior to gastric partitioning surgery (baseline) at one, three and seven days post-operatively, and again at approximately 30, 90 and 180 days post-operatively.
Dependent Variables
- Variable 1: Retinol levels were determined by reverse phase liquid chromatoggraphy
- Variable 2: Transferrin levels were measured by rate nephelometry
- Variable 3: Ceruloplasmin levels were measured by rate nephelometry
- Variable 4: Transthyretin levels were measured by rate nephelometry
- Variable 5: Albumin levels were measured by rate nephelometry
- Variable 6: Iron levels were measured by flame atomic absorption spectroscopy
- Variable 7: Copper levels were measured by flame atomic absorption spectroscopy
- Variable 8: Zinc levels were measured by flame atomic absorption spectroscopy.
Independent Variables
Baseline or pre-operative measures of the corresponding dependent variables.
- Initial N: 22 (19 females, 3 males)
- Attrition (final N): None reported
- Age: 23 to 56 years
- Anthropometrics: All participants were either a minimum of 100 lbs overweight or at a weight that was more than double their reference weight standard
- Location: USDA Human Nutrition Research Center on Aging at Tufts University, Tufts New England Medical Center, Boston, Massachusetts.
- Serum retinol (figure 1):
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Serum retinol values were most significantly depressed at days one and three post-operatively (P<0.001 as compared to pre-operative baseline)
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Decreases in mean serum retinol binding protein virtually paralleled changes in retinol and transthyretin at all post-operative time points during which serum retinol binding protein reached pre-operative levels
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Serum retinol values were lowest in the period of one to seven days post-operatively (P<0.0001 as compared to baseline) and were only slightly higher (P<0.01) at the remaining time points
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- Serum iron and transferrin (figure 2):
- As with all parameters, mean serum iron and transferrin levels were significantly lower than pre-operative levels on the first day post-operatively (P<0.0001)
- Serum iron and transferrin remained low through post-operative day 30 and transferrin through post-operative day 90 transferrin, but rose thereafter
- By post-operative day 180, both mean serum iron and transferrin were not significantly different from baseline
- Serum copper and ceruloplasmin (figure 3):
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Serum copper and ceruloplasmin reacted similarly at most time points
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Both serum copper and ceruloplasmin dropped sharply at post-operative day one (copper P<0.05, ceruloplasmin P<0.01 as compared to baseline)
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On day three post-operative, mean ceruloplasmin alone was significantly lower than the pre-operative baseline (P<0.05)
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By post-op day seven, mean ceruloplasmin reached the pre-operative level and mean copper became significantly higher than pre-operative levels (P value not reported)
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Serum copper and ceruloplasmin mean values fell again by post-operative day 90 (P<0.05 and P<0.01, respectively, as compared to baseline) before becoming non-significantly different from baseline levels at post-operative day 180
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- Serum zinc and albumin (figure 4):
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Serum zinc reached its nadir on post-operative day one, while albumin reached its nadir on post-operative day three
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The mean serum zinc level rose to its baseline or pre-operative level by post-operative day seven, while albumin reached pre-operative levels by day 30
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Neither mean serum albumin nor zinc levels fell below baseline values at the remaining time points (after day 30).
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- The short-half-life proteins, transthyretin and retinol binding protein, are the most sensitive indicators for reflecting protein nutriture in patients who undergo gastric partitioning surgery for morbid obesity
- The responses of serum ceruloplasmin and transferrin to gradual refeeding show that these proteins are less responsive to lowered protein and caloric intakes
- The failure of serum albumin to respond negatively to protein calorie deprivation after gastric partitioning surgery indicates that albumin is not a sensitive indicator of protein status in these patients
- Since serum albumin is used as an indicator of severe malnutrition, the level of protein calorie deprivation experienced by gastric partitioning patients may not result in major malnutrition.
Government: | USDA Human Nutrition Research Center on Aging, Tufts University, Boston MA |
This study is an older study (1987) and used research methodology was considered less rigorous than today's standards:
- Funding source(s) were not disclosed
- Minimal discussion of subject demographics
- Small sample size
- Overall clinical outcomes (healing of surgical wounds, weight loss, maintenance of weight loss) were not discussed.
Quality Criteria Checklist: Primary Research
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Relevance Questions | |||
1. | Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) | N/A | |
2. | Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? | Yes | |
3. | Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? | Yes | |
4. | Is the intervention or procedure feasible? (NA for some epidemiological studies) | N/A | |
Validity Questions | |||
1. | Was the research question clearly stated? | Yes | |
1.1. | Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? | Yes | |
1.2. | Was (were) the outcome(s) [dependent variable(s)] clearly indicated? | Yes | |
1.3. | Were the target population and setting specified? | Yes | |
2. | Was the selection of study subjects/patients free from bias? | N/A | |
2.1. | Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? | N/A | |
2.2. | Were criteria applied equally to all study groups? | Yes | |
2.3. | Were health, demographics, and other characteristics of subjects described? | ??? | |
2.4. | Were the subjects/patients a representative sample of the relevant population? | ??? | |
3. | Were study groups comparable? | N/A | |
3.1. | Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) | N/A | |
3.2. | Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? | N/A | |
3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | N/A | |
3.4. | If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? | N/A | |
3.5. | If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) | N/A | |
3.6. | If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? | N/A | |
4. | Was method of handling withdrawals described? | ??? | |
4.1. | Were follow-up methods described and the same for all groups? | ??? | |
4.2. | Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) | ??? | |
4.3. | Were all enrolled subjects/patients (in the original sample) accounted for? | ??? | |
4.4. | Were reasons for withdrawals similar across groups? | ??? | |
4.5. | If diagnostic test, was decision to perform reference test not dependent on results of test under study? | ??? | |
5. | Was blinding used to prevent introduction of bias? | N/A | |
5.1. | In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? | N/A | |
5.2. | Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) | Yes | |
5.3. | In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? | N/A | |
5.4. | In case control study, was case definition explicit and case ascertainment not influenced by exposure status? | N/A | |
5.5. | In diagnostic study, were test results blinded to patient history and other test results? | N/A | |
6. | Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? | ??? | |
6.1. | In RCT or other intervention trial, were protocols described for all regimens studied? | N/A | |
6.2. | In observational study, were interventions, study settings, and clinicians/provider described? | N/A | |
6.3. | Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? | Yes | |
6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | Yes | |
6.5. | Were co-interventions (e.g., ancillary treatments, other therapies) described? | ??? | |
6.6. | Were extra or unplanned treatments described? | ??? | |
6.7. | Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? | N/A | |
6.8. | In diagnostic study, were details of test administration and replication sufficient? | N/A | |
7. | Were outcomes clearly defined and the measurements valid and reliable? | Yes | |
7.1. | Were primary and secondary endpoints described and relevant to the question? | Yes | |
7.2. | Were nutrition measures appropriate to question and outcomes of concern? | Yes | |
7.3. | Was the period of follow-up long enough for important outcome(s) to occur? | Yes | |
7.4. | Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? | Yes | |
7.5. | Was the measurement of effect at an appropriate level of precision? | Yes | |
7.6. | Were other factors accounted for (measured) that could affect outcomes? | ??? | |
7.7. | Were the measurements conducted consistently across groups? | Yes | |
8. | Was the statistical analysis appropriate for the study design and type of outcome indicators? | Yes | |
8.1. | Were statistical analyses adequately described and the results reported appropriately? | Yes | |
8.2. | Were correct statistical tests used and assumptions of test not violated? | Yes | |
8.3. | Were statistics reported with levels of significance and/or confidence intervals? | Yes | |
8.4. | Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? | N/A | |
8.5. | Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? | N/A | |
8.6. | Was clinical significance as well as statistical significance reported? | Yes | |
8.7. | If negative findings, was a power calculation reported to address type 2 error? | No | |
9. | Are conclusions supported by results with biases and limitations taken into consideration? | Yes | |
9.1. | Is there a discussion of findings? | Yes | |
9.2. | Are biases and study limitations identified and discussed? | Yes | |
10. | Is bias due to study's funding or sponsorship unlikely? | Yes | |
10.1. | Were sources of funding and investigators' affiliations described? | No | |
10.2. | Was the study free from apparent conflict of interest? | Yes | |