student

1. A M A N D A M U R U N G I
Biochemical Assessment

2. Session outline
 Define Biochemical assessment
 Describe the advantages and limitations of
biochemical assessment
 Describe the types of biochemical assessments

3. What is Biochemical Assessment?
 Biochemical assessment means checking levels of
nutrients in a person’s blood, urine, or stools.
 Laboratory test results can give trained medical
professionals useful information about medical
problems that may affect appetite or nutritional
status

4. Importances of biochemical assessent
 It is useful in detecting early changes in body
metabolism & nutrition before the
appearance of overt clinical signs.
 It is precise, accurate and reproducible.
 Useful to validate data obtained from dietary
methods e.g. comparing salt intake with 24-
hour urinary excretion.

5. Limitations of biochemical assessment
Time consuming
Expensive
They cannot be applied on large scale
Needs trained personnel & facilities

6. Two types of Tests
• Static- measure of a nutrient or its metabolite in blood,
urine, or body tissue (actual measure of the nutrient) e.g
Iron or vit A
Limitations: may fail to reflect the overall nutrient status
(serum may not reflect level of nutrient in tissues)
• Functional - reflects the failure of function or physiologic
process of the body as a result of nutritional deficiency
(indirect measure)
Examples: Immune response will be compromised by
protein deficiency; visual adaption to dark will be
compromised by vit. A deficiency
Limitations: May be nonspecific; indicates a general
nutritional status, but may not allow id of specific
nutrients

7. Protein Status Evaluation
Types of Proteins:
1)Somatic or skeletal muscle (about 75% of body’s
protein)
2)Visceral in organs or viscera, erythrocytes,
lymphocytes (about 25% of body’s protein)
 Evaluation of “protein status” is challenging; no
one test or indicator is perfect or without limitation.
 It is best to evaluate in addition to other nutrition
status indicators (anthropometric, clinical, dietary)

8. Methods to evaluate protein
 Creatinine Height Index (CHI):The body excretes creatinine in the urine
as a by-product of skeletal muscle. The amount that is produced is relative to
height. This amount can be looked up in references.
 Nitrogen Balance: Nitrogen is a by-product of protein breakdown from
food we ingest or from our body’s own turnover/breakdown of protein
 A person is said to be in “positive nitrogen balance” (a good thing!) when
nitrogen intake (from dietary protein intake) exceeds (or is >) than nitrogen
loss.
 A person is said to be in “negative nitrogen balance” (a serious concern!)
when nitrogen losses (from losses of the body’s protein breakdown) exceed
nitrogen intake (dietary protein intake).
 Blood Albumin (Alb) used in clinical settings to “evaluate” protein status;
has half life of 14-20 days (it takes longer to determine if the patient’s diet is
adequate in protein).
 Albumin may “drop” during infection, and can appear low during over
hydration. Albumin may appear high during dehydration.

9. Evaluating Iron (Fe) Status
 TIBC (total iron binding capacity): Most
sensitive and best test to detect early iron deficiency!
Transferrin carries Fe in blood.
When TIBC goes up, iron level is low. When TIBC
goes down, iron level is high.
 Hemoglobin (Hb) is the molecule in RBC (red
blood cells) that holds iron, and allows the cells to
carry oxygen to the body tissues.
 Hematocrit (Hct) expressed as a percentage of
RBCs as compared to entire volume of blood

10.  Mean Corpuscular Hemoglobin (MCH) is the
amount of hemoglobin in RBCs
 Mean Corpuscular Volume (MCV) is the
volume of the average RBC; Cell size may go up or
down Low MCV (microcytic anemia or “small red
blood cells) is a sign of iron deficiency or even lead
poisoning High MCV (macrocytic anemia or “large
red blood cells) is a sign of folate or vitamin B12
deficiency

11. Liver function tests
 Metabolic Panel ALT (alanine
aminotransferase) is a liver enzyme; when
elevated may signal a liver problem or disease
 Alkaline Phosphatase (ALP) enzyme indicating a
problem in liver, bone, placenta, intestine
 AST (aspartate aminotransferase) indicates,
liver disease, drug exposure, musculoskeletal injuries
 Bilirubin is the pigment in bile, produced from the
breakdown of hemoglobin; when elevated may
indicate liver problem and results in jaundice

12. Blood glucose
 Random blood sugar
 Fasting blood sugar
 HbA1C/ glycated hemoglobintest is a common blood
test used to diagnose type 1 and type 2 diabetes.
 The test reflects the average blood sugar level for the past three months
and measures the percentage of your hemoglobin (protein in RBC that
carries oxygen) is coated with sugar (glycated).
 Normal A1C 4.5-6% (5% = 97 mg/dL as estimated average blood glucose
level)
 Prediabetes A1C 5.7-6.4% (6% = 126 mg/dL as estimated average BG
level)
 Diabetes A1C >6.5% (7%= 154 mg/dL as estimated average BG level)

13. Biochemical Tests of Nutrients
 Zinc (Zn) is involved in enzymes; immune function and
wound healing. If depleted can result in growth
retardation; if severe may cause dwarfism. Possible
tests: metallothionen, hair zinc, urinary zinc
 Vitamin C, in reduced form, is ascorbic acid; used in
formation of collage, promotion of Fe absorption. Tests:
serum, leukocyte levels
 Vitamin B6 serves as a coenzyme in reactions; of most
concern in elderly and alcoholism; Tests-PLP, plasma
PL, total B6 using microbiological assay, Tryptophan
Load test (most widely used), Methionine Load test
 Folate serves as a coenzyme that transports carbon
groups in amino acid metabolism and nucleic acid
synthesis.

14.  Vitamin B12 is involved and active in human
metabolism. Sources include animal products and
fortified grain, soy and plant based meat substitutes.