Lecture 7 Flashcards
What is the purpose of biochemical lab data?
- Detect clinical and subclinical nutrient deficiencies
- Collect objective and quantitative data about nutrition status
- Evaluate tissue stores or function of a nutrient
- Monitoring response to treatment, including medical nutrition therapy
- Estimate risk of morbidity or mortality
What are the advantages of biochemical lab data?
- Allow collection of subclinical nutrient deficiencies
- Collection of objective and quantitative data about nutritional status
- Only objective data used in assessment which are CONTROLLED FOR VALIDITY of the method of measurement
- Can be used to test validity of dietary intake measurements
What is a control?
Each time samples are taste a specimen of known value is assayed
What are the limitations of biochemical lab data?
Altered by nutritional an non nutritional factors such as:
- Intake of nutrients
- Intake of non nutrients
- Fluid status
How does the intake of carbs, saturated fat, alcohol and dehydration affect lab data?
Carb intake increase blood glucose
Fat increases blood cholesterol
Alcohol decreased blood glucose
Dehydration increases blood albumin, hemoglobin and urea
How are medical treatment and procedures affect lab data?
High dextrose dialysate fluid increases blood glucose
Physical activity decreases blood glucose and can increase or decrease Na
How does medication affect lab data?
Thiazide diuretics decrease blood K,MG and P
How does illness and disease affect lab data?
Renal failure increase blood creatinine
Infections increase blood glucose
What are the limitations to substances altered by nutrition and nonnutritioall factors?
Many factors can confound the interpretation of biochemical lab measurements
- confounding factors
- inverse relationship between CRP and albumin
Biochemical Assay methods/techniques vary
Many test are not specific
Reference values difference between labs
Reference values different based on sex, age and physiological state
Technical problems in. sample collection or performing test
What is the best test to measure biochemical lab data?
There is no single test, index for group of tests by itself is sufficient to evaluate and monitor nutritional status or more a diagnosis of nutrient deficiency
When using lab data what should you be cautious about using?
Single isolated lab test values to make a diagnosis
- reviewing all lab data is recommended
- Look at direction and speed of change
what happens if you lab data seems to be off in a value?
Retake it immediately
What is a summary of confounding factors for biochemical lab data?
Tight homeostatic regulation Diurnal variation Sample Contamination Physiological state Infection Hormonal Status Physical exercise Age, sex, ethnic group Accuracy and precision of method Drugs Recent Dietary intake Hemolysis Disease state Nutrient interactions Inflammaroty stress Weight loss Sampling and collection procedures Sensitivity and specificity
In lab data what are the common sources/specimen types?
Whole blood Urine Blood Cells/White blood cells Plasma Serum Feces Hair Saliva Breast Milk Sweat Nails adipose tissue Organ biopsy
How is whole blood collected and what are the characteristics of it?
With and anticoagulant (EDTA, Heparin)
- readily accessibly
- relatively noninvasive
- easily analyzed
- affected by acute changes
What is urine used to examine?
Excreted minerals
Water soluble vitamins (B&C)
Protein
What are the conditions that need to be met for Urine samples to be used?
Requires complete 24hr collection
Renal function normal
Affected by acute changes
How are blood cells obtained?
Separated from anti-coagulated whole blood to get erythrocytes
What is the foes-an of erythrocytes?
120 days
- good measure of chronic nutrient status
- depending on nutrition abc may only contain a small % of the total body nutrient content
What is the lifespan of white blood cells?
13-20 days
what are the 3 kinds of leukocytes?
Lymphocytes
Monocytes
Neutrophils
How are leukocytes elevated?
Infection
Stress response
How is plasma obtained?
Uncoagulated fluid that bathes blood cells
Fluid (with EDTA/heparin) collected aft blood cells a have been removed or separated by centrifuge
How is serum obtained?
Flui (w/o fibrinogen) remaining after whole blood has coagulated