Introduction to Clinical Chemistry

Question 1

homeostasis

Answer 1

the tendency toward steady state or equilibrium of body processes

Question 2

analyte

Answer 2

a chemical substance that is the subject of chemical analysis

Question 3

preanalytical phase

Answer 3

the collection, handling and storing correctly until tests are performed

Question 4

analytical phase

Answer 4

using correct procedures and appropriate quality assessment measures to analyze specimens

AKA quality control

Question 5

postanalytical phase

Answer 5

reporting accurate and calculated test results

Question 6

routine chemistry tests

Answer 6

AKA complete metabolic profile, is a group of tests performed simultaneously on a patient specimen to provide an assessment of the patient’s general condition.

ie. state of carbohydrate and lipid metabolism, liver and kidney tests

Question 7

Special chemistry tests

Answer 7

tests that are ordered less frequently

ie. hormones or certain drug levels

Question 8

Chemistry profiles or panels

Answer 8

• reflect general state of health

- evaluate particular organ systems

Question 9

Specimens used for chemical analysis

Answer 9

blood and urine

Question 10

Reference range

Answer 10

• determined by measuring the level of the substance in a portion of the general population and applying statistical methods to the data.
  ie. when establishing reference range for total protein, a lab might test 100 random samples from the population and calculate the mean value and the standard deviation of the set of values.
• the reference range is then determine by adding +-2
  ie. the mean is 7g/dL therefore the reference range is 6-8 g/dL

NOTE: * reference value(s) can differ from recommended values

Question 11

factors affecting reference range

Answer 11

• differ slightly according to the population sample’s geographical area and age of population.
• reference range for a substance measured in plasma vs. serum
• types of analyzers used, testing methods

Note*: each lab must supply its reference range when a test result is reported

Question 12

reference range for Total Protein

Answer 12

60-80 g/L

albumins(60%) + globulins (40%)

Question 13

Albumins

Answer 13

-the most abundant protein in normal plasma (60%); a homogeneous group of plasma proteins that are made in the liver and help maintain osmotic balance

Reference range for albumins 38-50g/L

Question 14

hypoalbuminemia

Answer 14

low level of albumin

Question 15

Globulins

Answer 15

a heterogeneous group of serum proteins with varied functions, 40% of total protein in serum

(total protein-albumin = globulin)

Question 16

electrolytes

Answer 16

the cations and anions important in maintaining fluid and acid-base balance

Cation-a positively charged ion
Sodium, Na+ (135-148 mmol/L)
potassium, K+ (3.8-5.5 mmol/L

Anion- a negatively charged ion
Chloride, Cl- (98-108 mmol/L)
Bicarbonate HCO3- (2-28 mmol/L)

Note*- inform provider if sodium result is outside of reference range bc it is related to the relaxation and contraction of the muscle

Question 17

Mineral metabolism

Answer 17

• Calcium, Ca (1.15-1.33 mmol/L)
• phosphorus (0.96-1.44 mmol/L)
• Iron (11.6-29.5 mmol/L)

Question 18

hypercalcemia

Answer 18

blood calcium levels above normal

1.15-1.33 mmol/L

Question 19

hypocalcemia

Answer 19

blood levels below normal

1.15-1.33 mmol/L

Question 20

Kidney Function

Answer 20

-Creatinine (62-125 mmol/L)
-Blood Urea Nitrogen, BUN (2.9-6.4 mmol/L)
-Glomerular filtration rate, GFR
-Uric Acid (0.21-0.44 mmol/L)
Note*- elevated uric acid causes Gout

Question 21

Glomerular filtration rate

Answer 21

an estimation of how much blood passes through the glomeruli per unit of time (minute); an estimate of the number of functioning nephrons made by using the rate at which molecules such as creatinine and urea are filtered by the kidneys

Question 22

Gout

Answer 22

a painful condition in which blood uric acid is elevated and urates precipitate in joints

Question 23

Liver Function

Answer 23

Bilibrubin- a product formed in the liver from the breakdown of hemoglobin
(2.0-21.0 umol/L)

Enzymes

• Alkaline phosphatase (ALP) (20-130 U/L)
• Aminotransferases (ALT 3-30 I/L) (AST 10-37 U/L)
• Gamma glutamyltransferase (GGT 3-40 U/L)
• Lactate dehydrogenase (LDH 110-230 U/L)

*note- enzymes in the blood are unstable

Question 24

Alkaline phosphatase(ALP)

Answer 24

20-130 U/L - an enzyme widely distributed in the body, especially in the liver and bone

note liver and bone

Question 25

Aminotransferases

Answer 25

(ALT 3-30 U/L) (AST 10-37 U/L)

Question 26

Alanine aminotransferase (ALT)

Answer 26

an enzyme presents in high concentration in the liver and measured to assess liver function; formerly called SGPT (3-30 U/L)

Question 27

aspartate aminotransferase (AST)

Answer 27

an enzyme presents in many tissues, including cardiac, muscle and liver and measured to assess liver function; formerly called SGOT (10-37 U/L) note* also used to assess heart

Question 28

difference between ALT and AST

Answer 28

ALT is measured to assess liver function, and AST is measured to assess liver function and heart

Question 29

Cardiac Markers

Answer 29

``` Creatine kinase (CK-MB) troponins B-type natriuretic peptide (BNP) C-reactive protein (CRP) Homocysteine ```

Question 30

Creatine Kinase (CK-MB)

Answer 30

an enzyme presents in large amounts in brain tissue, heart and skeletal muscle and a form of which is measured to aid in diagnosing heart attach within 24 hour Total CK 30-170 U/L

Question 31

Troponins

Answer 31

intracellular proteins that are present in skeletal and heart muscle and are released when muscle is injured

Question 32

B-Type natriuretic peptide (BNP)

Answer 32

a peptide hormone released primarily from the ventricles of the heart and used as a marker for cardiac function note*- released from the ventricles of the heart

Question 33

What is the similarity between skeletal muscle and heart muscle?

Answer 33

they are striated

Question 34

If a patient is walking with chest pain, what can we measure to see if there is a heart problem?

Answer 34

troponins

Question 35

homocysteine

Answer 35

an amino acid, elevated blood levels of which are associated with increased risk for vascular and cardiovascular disease

Question 36

Lipids

Answer 36

any one of a group of fats or fat-like substances

Question 37

Lipid metabolism

Answer 37

- Total Cholesterol (3.6 -6.5 mmol/L) and fractions LDL, HDL, VLDL - Triglycerides (0.11-2.15 mmol/L - hyperlipidemia

Question 38

Triglycerides

Answer 38

the major storage form of lipids; lipid molecules formed from glycerol and fatty acids. fasting for 12-14 hr (0.11-2.15 mmol/L)

Question 39

hyperlipidemia

Answer 39

excessive amount of fat in the blood plasma is milky appearance

Question 40

Carbohydrate metabolism

Answer 40

glucose (3.9 -6.2 mmol/L) Glucose metabolism is largely regulated by insulin, which is produced by the pancreas. Also influenced by glucagon, growth hormone, and cortisol

Question 41

Thyroid Function

Answer 41

-Thyroid-stimulating Hormone (TSH) (0.35-5.0 mIU/L -Thyroxine (T4) Triiodothyronine (T3) Other Tests: Insulin growth hormone adrenocorticotropic hormone (ACTH)

Question 42

Thyroid stimulating Hormone (TSH)

Answer 42

a hormone that is synthesized by the anterior pituitary gland and regulates the activity of the thyroid gland (0.35-5.0 mIU/L)

Question 43

hyperthyroidism

Answer 43

excessive functional activity of the thyroid gland; excessive secretion of thyroid hormones Grave's disease

Question 44

hypothyroidism

Answer 44

underactive function of the thyroid gland; abnormally low production of thyroid hormones

Question 45

What are the most common specimens used to analyze chemical chemistry?

Answer 45

blood (serum) and urine

Question 46

how long do we wait before centrifuge SST? Why?

Answer 46

30 MINUTES to let clotting activator mix well and to avoid the buildup of membrane layer note*- the automated machine will not collect serum if membrane layer detected

Question 47

Why do we perform the glucose test when checking kidney performance?

Answer 47

Elevated sugar levels signal a variety of metabolic and structural changes in the nephrons preventing them from functioning properly

Question 48

Will we use whole blood sample in clinical chemistry department?

Answer 48

yes, we use whole blood in the lavender tube for the HBA1C test

Question 49

Problems in specimen collection and processing

Answer 49

- hemolysis (elevate LD, AST, K) - hemoconcentration - over centrifugation - evaporation - microbial contamination - anticoagulant contamination