bc quiz

Question 1

Nutritional Assessment

Answer 1

A - Anthropometry
B - Biochemical
C - Clinical
D - Dietary Assessmen

Question 2

ANTHROPOMETRY

Answer 2

Measurements of the variations of physical dimensions and the gross composition of the human body at different age levels and degrees of nutrition

Weight • Height e.g., standing (stature), sitting • Length e.g., recumbent length, arm span, knee • Breadth e.g., wrist, elbow • Circumferences e.g., head, waist, hip, mid-ar

Question 3

BODY COMPOSITION

CAFE

Answer 3

SPECIFIC BODY COMPARTMENTS
• Investigating body composition involves subdividing body weight into 2 or more compartments according to elemental, chemical, anatomical, or fluid compartment

Question 4

2 Compartment Model

Answer 4

body fat – fat-free mass (FFM) • FFM = body wt – body fat (fat mass); LBM = body wt – adipose fat • LBM includes essential fat (e.g., cell membrane fat) • often FFM = LBM in literature

Question 5

4 Compartment Model

Answer 5

aqueous – mineral – protein (muscle) – faT

Question 6

6 Compartment Chemical Mode

Answer 6

– aqueous - includes ECW, ICW – mineral - osseous - extraosseous – organic - glycogen (negligible) - protein - fat

Question 7

Elemental Model

Answer 7

body weight consists of 11 elements which comprise >99% of body weight in living subjects i.e., C, N, Ca, Na, Cl, K, H, P, O, S, Mg

Question 8

Proportion of body weight:

Answer 8

Water 62.4 % Protein 16.4 % Fat 15.3 % Bone Mineral 4.8 % Non-Osseous Material 1.1 %

Question 9

SPECIFIC BODY COMPARTMENTS

Answer 9

Total fat, regional fat, fat-free mass (FFM), regional FFM, muscle (e.g., ptn, K), total body water (TBW), extracellular water (ECW), intracellular water (ICW), bone mineral density (BMD), bone mineral content (BMC), elemental composition (e.g., N Ca P Mg Na Cl)

Question 10

Statistical Treatment of Dat

Answer 10

Low accuracy, low precisio ECT.

Question 11

ANTHROPOMETRY: Measurement

Answer 11

Examples - some will differ for infants, children, nonambulatory persons
• Weight - electronic or balance-beam scale - calibrated
• Height - stadiometer - technique - e.g., Frankfort horizontal plane
• Circumferences - landmarking, tape measure - placement, two people
• Skinfolds - landmarking, equipment, technique (skill

Question 12

ANTHROPOMETRY Uses
Weigh
HEIGHT

Answer 12

• Useful for extremes – 300 lbs or 80 lbs for an adult female – 140 lbs ???
• Monitoring change – sudden gains or losses in weight

Useful for “stunting” – indicator for undernutrition – nutrient deficiencies e.g., Zn

Question 13

negative linear
curvilinear
positive
no 
r values (correlation coefficient

Answer 13

a. Negative linear correlation (r = -0.70)
b. Curvilinear correlation (r = 0.20)
c. Positive linear correlation (r = 0.80)
d. No correlation (r = 0.10)

Question 14

how do you deterine the variance

Answer 14

square of the CC (r2) represents the proportion of variance in one variable accounted for by the other i.e., coefficient of determination
e.g., x (height); y (weight); r = 0.7 r2 = 0.49 or 49%
– Therefore, 49% of the variability of weight can be accounted for by height – other 51% accounted for by other factors (tendency to eat fatty foods, resistance training ↑ muscle mass)
– remember, “variability” refers to how scores are spread out about the mean

Question 15

cORRELATION AND CAUSATION

Answer 15

Rule: High correlation between 2 variables does not necessarily imply causal relationship
e.g., smoking (x) and lung damage (y)
high +ve correlation could mean: 1. x causes y 2. y causes x 3. a 3rd variable causes both x and y (e.g., stress) 4. the correlation occurred by chance
- use correlations as a source for subsequent hypothese

Question 16

ANTHROPOMETRY: Uses

Answer 16

Weight Standards
• Height-Weight Tables – Guideline Tables • Weight for Height • Age-Specific Weight Standards – Metropolitan Life Insurance Company (1983) • Includes “frame size”

Question 17

Height-Weight Indices

Answer 17

Relative weight (i.e., Devine Formula) – (actual wt / reference wt) x 100% – Interpretation: <90% underweight, 90 - <110% normal weight, 110 - <120% overweight, >120% obese
• Body Mass Index (i.e., Quetelet’s Index) – wt/ht2
• CDC Growth Charts (children) – percentiles - weight, length, wt for ht, BMI for age

Question 18

android vs gynoid

Answer 18

android typical in men and aroind the belly, gynoid is the pear shape

Question 19

Body Fat Distributio

Answer 19

Waist Circumference – measure waist at iliac crest • men > 40 inches • women > 35 inches
• Waist to Hip Ratio - measure waist at mid-point between inferior margin of ribs & iliac crest • men > 1.0 • women > 0.8
Skinfold Measurements – Various sites and predictive equationsTriceps • Common: biceps, triceps, subscapular, suprailiac
• Percentile Charts – e.g., tricep skinfold

Question 20

BODY COMPOSITION Measurement

Direct Measures

Answer 20

Cadaveric (Dissection) Studies – fat, muscle (ptn), K, water? – assume cadavers similar to living subjects

Question 21

BODY COMPOSITION

Indirect Measures

Answer 21

Indirect Measures (measures which predict)
• Densitometry (underwater weighing) – body fat, FFM
• Dilution techniques – total body water TBW, extracellular water ECW
• TBK – FFM
Absorptiometry (single-photon, dual-photon, DXA) – total or regional FFM (LBM), total or regional bone mineral
• Ultrasound – regional fat (tissue thickness)
• Computerized tomography (CT) – regional body composition (fat, lean tissue, bone)
• Magnetic resonance imaging (MRI) – fat, water
Neutron activation analysis – multielemental composition - N Ca P Mg Na Cl
• Skinfolds (anthropometry) – body fat (density eqn.), FFM, muscle size
• Electrical conductance (TOBEC, BIA or BIS) – FFM, TBW, ECW
• Infrared interactance – body fat

Question 22

Biochemical parameter

Answer 22

– Urinary creatinine excretion → muscle mass – Total plasma creatinine → skeletal mass (muscle) – 3-methyl histidine → muscle mass

Question 23

BODY COMPOSITION

ASSUMPTIONS

Answer 23

Direct measures used to validate indirect measures e.g., neutron activation analysis – Are direct measures valid?
• Indirect measures used to validate other indirect measures e.g., BIA validated using dilution techniques since cannot perform BIA on cadavers
“Is there a GOLD STANDARD?”

Question 24

Compartment Analysis

Answer 24

Normality (compare to standards) – Change over time

Question 25

Cadaveric (Dissection) Studies

Answer 25

Only direct measure of body composition – Brussels Cadaver Analysis Study (CAS) n>30 (Drinkwater) – Garrow (1983) n=6 adults – Widdowson (1950s) human fetus • fat (skinfolds and chemical analysis), muscle (ptn), K, water? • used to validate various in vivo methods ADVANTAGES - most direct measure available DISADVANTAGES - limited # of studies (ages, weights etc) - assume cadavers have similar characteristics to living subjects (e.g., H2O) -cause of death often illness "Question whether representative sample"

Question 26

Densitometry what is it what 2 measurements are calculated, what are advantages and disadvantages

Answer 26

measurement of total body density through determination of body volume e.g., underwater weighing, helium displacement, partial water displacement and air displacement • therefore, body fat & FFM (2 compartment model) are calculated using density equation (like skinfolds) ADVANTAGES - measurements are precise (repeatable) DISADVANTAGES - subject cooperation is necessary - not practical for large groups - unsuitable for young children, elderly etc (underwater weighing) - accuracy ↓ due to "lung volume" (estimate) - density in fat-free component (bone & muscle

Question 27

Hydrostatic Weighin

Answer 27

Errors – Equations – Residual lung volume – Water density – Consistency of tissues across races, gender, age • Recommended Technique. – Water tank – Nitrogen wash out • Residual volume – Weight belt – Maximal exhalation – Repeat 8-12 times • r = 0.94

Question 28

Dilution Techniques advantages and disadvantages

Answer 28

TBW measured in FFM (no water in fat) by dilution with D2O, 3H2O or H218O • ECW measured by dilution of NaBr (Br does not enter cell) • a known amount of isotope is given (C and V), steady state reached, biological fluid sampled (e.g., blood, urine, or saliva) C1V1 = C2V2 solve for V2 ADVANTAGES - gives TBW, ECW (thus ICW) - stable isotopes can now be used DISADVANTAGES - difficult procedure with limited precision - cost (isotopes expensive)

Question 29

Total Body Potassium (TBK what does is measure advantages and disadvantages

Answer 29

40K is found in a known amount (0.012%) in ICW and not present in stored triglycerides • therefore, FFM is estimated by external counting of gamma rays emitted by 40K ADVANTAGES - ↑ precision DISADVANTAGES - assumes FF tissue has known/constant K content (differs gender, obesity, age) e.g., older and obese overestimate fat - accuracy ??? - high cost & limited locations

Question 30

Absorptiometry (single-photon, dual-photon DEXA [dual energy Xray absorptiometry] or DXA) what is it- what element advantage disadvantage

Answer 30

body (region) is scanned transversely in small steps by radiation from gadolinium-153 • 153Gd emits 2 gamma rays of different energies for quantitation of bone mineral/soft tissue (FFM/LBM) ADVANTAGES - DEXA allows for regional body composition (body sections differences) measurements - small error = ±1-5% - quick, subject friendly DISADVANTAGES - expensive equipment & limited locations - calibration and mathematical treatment of data is complicated - x-ray

Question 31

ultrasound

Answer 31

electrical energy is converted to high-frequency ultrasonic energy in a probe • transmission of sounds waves through various tissues (fat and muscle tissue have differing densities) can be used to calculate tissue thickness (e.g., subcutaneous fat) ADVANTAGES - portable equipment available - safe & non-invasive - compares well with skinfolds DISADVANTAGES - constant pressure of probe is difficult, thus prejudicing determination of fat thickness i.e., resolution not as good as with CT - validity for wide range of body fatness unknown

Question 32

Computerized tomography (CT

Answer 32

Method measures attenuation (consistency) of X-rays as they pass through tissues • degree of attenuation is related to density of tissue • an image is generated by computerized processing of density-frequency distribution data • regional body composition (fat, lean tissue, bone) ADVANTAGES - additional use, organ size (liver, spleen, kidneys) can be measured DISADVANTAGES - exposure risk (X-rays), limits use for whole-body and multiple scans - no chemical composition information - expensive & limited locations

Question 33

Magnetic resonance imaging (MRI) | measures what

Answer 33

based on the fact that atomic nuclei can behave like magnets • external magnetic field is applied across body and nuclei attempt to align with the external field • radio-frequency is directed into the body & nuclei absorb energy (change in positioning of magnetic field) • radio-frequency turned off (return to orginal state) • emit signal which is imaged by computer (level of hydration and fat content) ADVANTAGES - safe (e.g., children etc, multiple studies) & noninvasive - both amount and distribution of body fat obtained - high quality images of the body (better than CT) - can currently image hydrogen and phosphorous (will soon image C, N, Na, Cl) DISADVANTAGES -limited locations & high cost

Question 34

Neutron activation analysis

Answer 34

radioisotopes of N, P, Na, Cl, Ca are created by irradiating the subject • radioactivity of element is measure using a whole body counter and is related to content ADVANTAGES - only technique currently available for measurement of multielemental composition of the human body (Ca P Mg Na Cl) in addition to muscle mass (N) DISADVANTAGES - subjects exposed to radioactivity - elements not uniformly activated, thus sensitivity varies - expensive & limited locations

Question 35

Skinfolds (anthropometry)

Answer 35

covered in detail in in anthropometry section and laboratory SOME ADVANTAGES - measurements (for fat etc) can be made in field but require skilled technicians for accuracy SOME DISADVANTAGES - dependence on technicians skill - not applicable to all population groups for exmple black people harder to distinguish fat from muscle

Question 36

11. Electrical Conductance (TOBEC, BIA/BIS/BEI)

Answer 36

based on the difference in electrolyte content between fat and fatfree tissue • electrolytes in water are capable of conducting electricity better than its fat mass • determinations of resistance and reactance are made, and used to calculate conductance and to predict LBM/FFM, TBW, ECW from "various" equations ADVANTAGES - safe, convenient to use, portable, rapid, and non-invasive - BIA (measures extremities) less expensive than TOBEC (whole body) DISADVANTAGES - affected by conditions (fed, fasted, edema, dehydration etc.) - extent to which variation in body shape and size affects readings not yet known

Question 37

Infrared Interactanc

Answer 37

recently developed to estimate fat • measurement of body fat is made at various sites on the extremities through use of short wavelengths of infrared light • fat is calculated from the absorption spectra • predictive equations used to estimate total fat ADVANTAGES - safe, non-invasive, rapid, convenient (used in health clubs and weight loss clinics) DISADVANTAGES - validation studies (comparing with other techniques) have not been favourable - depends upon regional fat distribution to predict TBF - believed to be inferior to skinfolds - not a recommended approach for determining body composition

Question 38

Biochemical Parameter what is measured

Answer 38

Urinary creatinine excretion – muscle mass • Total plasma creatinine – skeletal mass (muscle) • 3-methylhistidine – muscle mass • major problem is accounting for amounts found in diet