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
What do both plasma and serum measure?
Acute changes, reflecting recent intake (fasting sample)
What are the confounders for both plasma and serum?
Recent meal Diurnal variation Homeostatic regulation Medications Infection Inflammation Stress Sample Contamination
What do we look at when collecting a fece sample?
Fecal fat test for fat soluble vitamins
Colour
Frequency
Constipation vs diarrhea
What is Steatorrhea?
Risk of fat soluble vitamin deficiencies
What are the different colours a fecal sample can be?
Bloody Red/ Black= GI bleed or fe deficiency
Why is hair used as a specimen?
Used for screening population groups and individuals for trace element deficiencies and exposure to heavy metals
Retrospective (chronic index of trace element status during period of hair growth)
Non invasive
Trace elements are more concentrated and stable in hair
How are hair specimens confounded?
Exogenous contaminants such as:
- Atmospheric pollutants
- Water
- Sweat
- Beauty treatments
What are the 2 main types of test available for assessing nutritional status?
Static
Functional
What is a static test?
Based on measurement of nutrient or its metal elite in blood, urine, or body tissue
- Serum [Albumin]
- readily available
What is the downfall of the static test?
Often fail to reflect overall nutrient statues of individual or whether the body as a whole is in a s Tate of nutrient depletion or excess
-serum [Ca]
What is a functional test?
Measure of body function based on the idea that the. final outcome of a nutrient deficiency and its biological importance are due to failure of one ore more physiological processes relying on that nutrient for optimal performance
What are examples of functional tests?
Enzyme activity measurement
Impairment of immune status due to PEM and nutrient deficiencies
Measurement of Abnormal metabolite excreted in urine
What are the limitations of functional tests?
Some are non specific
Not used as much as static
May indicate general nutritional status but not allow identification of specific nutrient deficiencies
- Ex: Hb=function measure of Fe status
- Hb=anemia but altered b12 and Folate can also lead to decrease Hb
- Functional marker but not specific
How do you assess protein status?
Uses a 2 compartment model which counsitis of the metabolically available protein
-Somatic and Visceral Protein
What is Somatic protein?
75% of the body cell mass
Found in Skeletal muscle
Serum creatinine reflective of NMM (for normal renal function
Homogeneous
What is Visceral Protein?
25% of the body cell mass
Found within organs of viscera of the body liver, the RBS and WBCs and serum proteins
Heterogenous (100’s of different proteins)
Increase Createnin, increased BUN (blood urine nitrogen) and decreased u/o= Renal failure
How do you assess Somatic protein status?
24hr urinary creatinine excretion
- Urinary creatinine is a product of skeletal muscle
- excreted in a fairly constant proportion to the muscle mass in the body
- Readily measured in the clinical lab
What is the excretion when measuring somatic protein status?
Each gram of creatinine exerted represents 18-20kg of LMM (not controlled for age, sex, physical training, metabolic state, recent diet)
What should be eliminated from the diet when doing a 24hr urine sample?
Meat because not will imact the accuracy of urinary creatinine
Whatare factors that affect daily creatinine excretion?
Diurnal and day to day variation (4-8%)
Strenuous exercise (increase 5-10%)
Dietary intakes of creatinine (increase with meat and other protein sources)
Age (decreases as you get older)
Infection/fever/trauma( increase excretion with stress response)
Chronic renal failure (decrease due to inadequate clearance)
What is the equation for estimation of protein status
24hr urine creatinine(mg)x100/(expected 24hr urine creatinine (mg)
How do you interpret the results of the estimation of protein status?
60-80%- mild protein depletion
40-60%- Moderate protein depletion
Less than 40%- Severe protein depletion
What is the equation for estimating protein status: Nitrogen Balance?
[Protein intake (g/24hr)/6.25gN/gprotein]-[Urinary Urea Nitrogen(g/24hrs)+4]
In the nitrogen balance equation what does the 4 stand for?
Accounts for losses in dermal and fecal Nitrogen losses and non-urea Nitrogen components of urine
- which are ammonia, uric acid, creatinine
- normal renal and hepatic function (need this to do test)
How do you interpret the results from the nitrogen equation?
Intake>loss=Anabolism
-+Nbalance
Intake
When do we see a +NBalance?
During growth
Late pregnancy
recovery from illness
In athletic training
When do we see -Nbalance?
Inadequate protein and or energy intake
Imbalance in EAA:NEAA
Catabolic states (trauma, infection, sepsis burns)
Excessive protein loss burns. excessive diarrhea)
In terms of N, what should we do to monitor the effectiveness of nutritional therapy?
An estimate of the change in N balance rather than a single measurement is preferred
How do you measure visceral protein status?
serum proteins
- measure is considered simple and accurate
- Liver site of synthesis (liver failure=decreased albumin)
- Many confounding factors
- Low sensitivity and specificity
When measuring visceral protein status, which marker can we use?
Serum albumin (main protein in serum)
- Made by liver
- poor prognostic associated with [low]
What are the interpretation ranges for Sarum albumin?
30-35g/l= Mild deficit
24-29g/l= Moderate deficit
Less than 24= Severe deficit
What is the half life of serum albumin?
14-20 days
-not sensitive to acute nutritional changes
What kind of body pool does serum albumin has?
Large 3-5g/kgBW
What does serum albumin reflect in the body?
Changes in intra-vascular space, however ext5ra vascular space will supply to intra scalar space during deficiency
-Serum Albumin may increase ins semi starvation (Anorexia)
What will serum albumin increase with?
Dehydration
What will swum albumin decrease with?
Low protein intake Over hydration Malabsorption Acute catabolic states/infection Chronic losses Agining Edema Disease Poor synthesis -overall poor specificity to nutritional status
What is serum transferrin used for?
Biochemical measure of visceral protein status
What does serum transferrin do?
Binds and transports Fe (concentration increases in Fe deficiency)
-made by liver
What is the half life of serum transferrin?
8-10 days
-better sensitivity than serum albumin
Serum transferrin is bacteriostatic, what does that mean?
Prevents bacteria from reproducing
-Renders Fe unavailable to bacteria
What kind of body pool does serum transferrin have?
Small body pool
Less than 100mg/kgBW
What does serum transferrin increase with?
Fe deficiency
Pregnancy
Estrogen Tx
What does serum transferrin decrease with?
Acute catabolic states Chronic infection PEM Some disease states: -diseases of liver decreases synthesis -diseases of kidney, heart and GI
How can we assess health status off serum transferrin? (ranges)
1.5-2g/l= Mild deficit
1-1.5g/l= Moderates deficit
Less than 1 g/l= Severe deficit
What is thyroxine binding prealbumin used to measure?
Biochemical measure of visceral protein status
- thyroxine transport protein
- retinol binding protein (carrier protein)
What is the half life of thyroxine binding prealbumin?
2-3 days
-more sensitive to acute nutritional changes than albumin
What is the other name for thyroxine binding prealbumin?
Transthyretin
-not a precursor to albumin
Where is thyroxine binding prealbumin made and what is the body pool?
Liver
Small pool 10mg/kgBW
What re the ranges for interpreting thyroxine binding prealbumin levels?
1-1.5g/l= Mild deficit
0.5-1g/l= Moderate
Less than 0.5= severe deficit
What does thyroxine binding prealbumin increase with?
Renal disease (chronic kidney disease)
Hodgkins disease
What does thyroxine binding prealbumin decrease with?
Liver disease/damage decreases synthesis Malabsorption/malnutriiton Chronic losses Hyperthyroidism Acute catabolic states
What is C-reactive protein?
Produced by liver in repose to inflammation
-inflammartory cytokines (interleukin-6)
When do we see increased serum [C-reactive protein]?
In acute or chronic clinical stress
- abdominal obesity, atherosclerosis
- Acute pancreatitis
- Cancer
- Sepsi
What is BUN?
Urea is the end product of protein metabolism and the primary method of N excretion
-ammonia converted to urea by liver and excreted by kidney in urine
When do we see a decrease in BUN?
PEM
Liver disease
Overhydration
Anabolic Steroid use
When do we see increases in BUN?
Renal failure
Dehydration
GI bleed
High protein intake
What is Azotemia?
When you have elevated Urea
What is renal failure the result of?
Serum creatinine increases (low urine creatinine)
Serum urea increases (low urine urea)
In renal failure what happens the ruin output decreases, retaining or remains adequate?
Decreases
- anuric= no ruin or oliguric=~500ml
- would need to increase K,Mg, P
Retaining
-decrease in serum Na (due to fluid overload)
Remains adequate
- K,Mg,P and Na may remain low
- Creatinine and Urea remain elevated
What does renal failure cause when looking at the skin?
Pedal pitting edema
- due to loss of electrolytes through urine via kidney
- don’t have u/o (anuric)
- increase in K, Mg and PO4
Whats phosphors’s role in the body?
Structural components Enzyme cofactor Energy metabolism Component of cell membranes -controlled by parathyroid
Where do we find Phosphorus in the body?
Bones 80-85%
Muscles 14%
Extracellular Fluids 1%
What is the serum concretion of phosphorus?
Inorganic phosphorus
Does not reflect total body status
Closely related to serum [Ca]
What does Phosphorus increase with?
Hypoparathyroidism Hyperthryroidism Acidosis Hypocalcemia Renal failure Excess use of laxatives and enemas containing phosphate
-Ca binds P in the GI
What does Phosphorus decrease with?
Alcoholism Hypokalemia Hemodialysis Hyperparathyroidism Rickets Osteomalacia Refeeding Synfrome Excess use of antacids
-binds P in GI and decreases absorption
Whats Magnesiums role in thee body?
Catalyst in metabolic pathways
Where do you find magnesium in the body?
Bones 60%
Muscles 25%
Extracellular fluids less than 1%
Other tissues 10%
What does magnesium increase with?
Some renal disease
Dehydration
Hypothyroidism
-High GI losses decreased K, Mg PO4 Na
What does Magnesium decrease with?
Malabsorption Alcoholism Burns Emesis antibiotics Diuretics POancreatitis Some renal Disease Liver disease
What is potassiums role in the body?
Major intracellular cation
Acid base balance
Body fluid Balance
Nerve impuse transmission
Where do you find potassium in the body?
Muscles 80%
Extracellular fluids 10-20%
What happens when you have an increase in potassium?
results in hyperkalemia
-danger of heart problems because too much K in blood
What increases potassium?
Acidosis Renal failure Hemolysis Addisons disease Severe burns Crushing injuries Some Meds
What does potassium decrease with?
Diarrhea Vomiting Diuretics Alcoholism Alkalosis (increase blood pH) Bulimia Some meds
What is sodiums role in the body?
MAJOR extracellular cation
Maintenance of fluid balance and acid base rxns
Where is sodium found int he body?
Extracellular fluids 80%
Bones 20%
What is Serum [Na] sensitive too?
Na intake
Na excretion
Fkuid metabolism
What happens when you have an increase in Na?
Hypernatremia
-increase Na in the blood
What increases Na?
Dehydration
renal disease
Aldostreonism
-increase Na reabsorption in the distal renal tubule
What does Na decrease with?
Diarrhea Vomitting Diuretics Gastric Suctioning Congestive heart failure Edema
What does hepatic failure increase in?
Liver function tests
- AST aspartate transaminase
- ALT alanine tranaminase
- Alk Phos
- GGT
- Bilirubin
Clotting factors
- INR
- PPT
Ammonia
What does hepatic failure decrease in?
Albumin
Transferring
What is Hepatic encephalopathy?
Confusion with an altered level of consciousness and possibly leading to coma and death
-accumulation of took substances (ammonia) in blood which is normally removed by the liver
What is ascites?
Accumulation of protein containing fluid in the peritoneal cavity seen in liver failure
What is muscle wasting?
Loss of protein synthesis (somatic proteins)
When you have hepatic failure what side effects fo you usually see in the later stages of liver disease?
GI bleeds
-Coagulopathic (high PPT) due to decreased clotting factors made by liver
Jaundice
-Conjunctival membranes over sclera caused by hyperbilirubinemia
