ASCP- Clinical Chemistry

Diurnal variation

Changes in concentration of an analyte based on the time of the day (measured at day vs. night time)

What is increased in the AM? (b/c of diurnal variation)

ACTH, Cortisol, Iron

ACTH role

adrenocorticotropic hormone- stimulates adrenal cortex to secrete CORTISOL

How does stress affect chemistry values?

Increase in ACTH, cortisol, and catecholamines

Catecholamines

Hormones made by adrenal glands during stress.

Ex. dopamine, epinephrine, norepinephrine

Which analyte values are affected if delay in processing b/c serum/plasma is not separated in time?

Ammonia, lactic acid, K, Mg, LD, glucose

Components of Spectrophotometry (in order)

Light source- monochromator- cuvette- photodetector- readout

Fluorometry components (in order)

Light source- primary monochromator- cuvette- secondary monochromator- detector- readout

When is thin-layer chromatography primarily used?

Screening test for drugs of abuse in urine

When is high-performance liquid chromatography (HPLC) used?

Separation of thermolabile compounds

When is gas chromatography used?

Separation of volatile compounds (therapeutic & toxic drugs)

what is Glucose and when does it decrease

major source of cellular energy. Levels decrease if sample sits at RT.

What are the common methods to measure glucose?

Glucose oxidase & hexokinase= most common (hexokinase is more accurate)

Is cholesterol a risk factor for coronary artery disease (CAD)?

not by itself (must be analyzed with HDL & LDL)

HDL

"good fat"- levels should be >60 mg/dL

LDL

"bad fat"- calculated via Friedwald formula

Risk factor for coronary artery disease

levels should be <100 mg/dL

Triglycerides

Main form of lipid storage- need fasting specimen

levels should be <150 mg/dL

What method is used to measure total protein?

Biuret method

Biuret method depends on the presence of what?- (detection of total protein levels)

Amount of PEPTIDE BONDS

What plasma protein is the most abundant?

albumin (synthesized in the liver)

Albumin levels if dehydrated

Increased

Which hormone is responsible for the entry of glucose into cells and decreases blood glucose levels?

Insulin

Which hormone stimulates glycogenolysis (breakdown of glycogen-stored glucose) & gluconeogenesis?

Glucagon

Cortisol & epinephrine effect on glucose

increases it

Stress hormone

Insulin antagonist- stimulates glucose production

Thyroxine effect on glucose

increase

Increases glucose absorption from GI tract

Stimulates glyocogenolysis- breakdown of glycogen into glucose

Disease characterized by increased blood glucose, >40 years old, obesity, NO KETOACIDOSIS, no ketones or glucose in urine

Type 2 diabetes mellitus (non-insulin dependent)

What fasting plasma glucose level is considered positive for diabetes mellitus?

>126 mg/dL (on 2 occasions)

Which test gives the long-term results of blood glucose?

HbA1c

What is a metabolic syndrome

Group of conditions that increase risk of developing atherosclerotic cardiovascular disease & Type 2 diabetes mellitus

Metabolic syndrome risk factors?

Decreased HDL

Increase LDL

Increased triglycerides

Increased blood pressure

Increased blood glucose

What is phenylketonuria?

what does it cause

Deficiency of the enzyme that converts phenylalanine to tyrosine.

Causes mental retardation and urine has "mousy" odor

what is Tyrosinemia and what does it cause

Disorder of tyrosine catabolism.

Causes liver and kidney disease

what is Alkaptonuria and what does it cause

Deficiency of enzyme needed in metabolism of phenylalanine & tyrosine. Causes of buildup of acid.

what is Homocystinuria and what does it cause

Deficiency of enzyme needed for metabolism of methionine.

Methionine & homocysteine build up in plasma & urine.

Causes osteoporosis, mental retardation, and thromboembolic events

what is it Maple syrup urine disease (MSUD) and what does it cause

Enzyme deficiency leading to buildup of leucine, isoleucine, and valine.

Burnt sugar odor to urine, breath, and skin.

Failure to thrive, mental retardation, acidosis

what is Cystinuria and what does it cause

Increased excretion of cystine due to defect in renal reabsorption.

Leads to recurring kidney stones

What is the pH of protein electrophoresis barbital buffer?

8.6

What is the most common protein electrophoresis stain?

Ponceau S then coomassie brilliant blue

How many serum proteins are seen in electrophoresis?

5

Which serum protein has the largest fraction and moves the fastest?

Albumin

What are the 5 serum proteins in electrophoresis?

Albumin

alpha-1 globulin

alpha-2 globulin

beta globulin

gamma globulin

Which direction do serum proteins in buffer flow?

Anode (+) --> cathode (-)

gamma globulins are cathodic then

Where do bence jones proteins migrate to in urine electrophoresis?

gamma region

Which proteins spike on electrophoresis in acute inflammation?

Increase in alpha-1 and alpha-2 globulins

Which proteins spike on electrophoresis in chronic infection?

Increase in alpha-1, alpha-2, and gamma globulins

Which proteins spike on electrophoresis in cirrhosis?

Polyclonal increase (all increased) with beta-gamma bridging

What is a monoclonal gammopathy?

sharp increase in 1 immunoglobulin and a decrease in other globulins

Nephrotic syndrome serum protein electrophoresis pattern

Decrease in albumin

Increase in alpha-2 globulin

BUN

where is it made and excreted

what happens during kidney disease

Synthesized by liver from ammonia, excreted by kidneys.

Increased levels in kidney disease

Creatinine is a waste product of....

muscle metabolism

Which method is used to determine creatinine levels?

Jaffe's reaction (nonspecific)

when does Uric acid increase and decrease

Increased levels in gout, renal failure, ketoacidosis, lactate excess.

Decreased when ACTH is administered or renal tubular defects.

Where is ammonia produced? and when does it increase?

Produced in GI tract, high levels are neurotoxic.

Increased in liver disease, Reye's syndrome.

Sodium (Na+)

what is it

what is it's role

and what is it regulated by?

Major extracellular cation.

Contributes almost half to plasma osmolality.

Maintains normal distribution of water & osmotic pressure.

Levels are regulated by ALDOSTERONE

Potassium (K+)

what is it

what causes it to increase

what causes high/low levels

Major intracellular cation.

High levels b/c crush injuries, metabolic acidosis.

Low levels b/c urinary loss, use of diuretics, metabolic alkalosis.

What should the Na+/K+ ratio be?

30:1

Chloride (Cl-)

what is it

what is it's role

and what is it regulated by?

Major extracellular anion.

Helps maintain osmolality, blood volume, electric neutrality.

PASSIVELY FOLLOWS Na+

What is sweat chloride test used for?

Cystic fibrosis

Increased CO2 is caused by what

metabolic alkalosis (compensated respiratory acidosis)

Decreased CO2 is caused by what

Metabolic acidosis (compensated respiratory alkalosis)

Calcium (Ca2+)

what is it

what is it's role

what is it regulated by?

what is it affected by

most abundant mineral in the body.

99% in the bones.

REGULATED BY PTH, vitamin D, and calcitonin.

Affected by pH and temp.

Magnesium (Mg2+)

what is it

what causes increased levels

Essential cofactor for many enzymes. Avoid hemolysis.

Increased levels due to renal failure.

Phosphorus (phosphate)

what is it

what is it's role

what are the sample insturctions

Major intracellular anion, mostly in bones, component of nucleic acids, many coenzymes.

Important reservoir or energy.

Avoid hemolysis and separate serum/plasma promptly.

Lactate (lactic acid)

what is it

specimen collection

By-product of anaerobic metabolism.

Sign of decreased O2 to tissues.

Iron

what type of sample is preferred and why (time of day)

how is it measured

what causes it to increase

Early morning specimen preferred b/c of diurnal variation.

Colorimetric methods used to measure.

Increased in hemolytic anemia & sideroblastic anemia.

TIBC (Total iron binding capacity)

when is it increased/decreased

Increased in iron deficiency anemia.

Decreased in iron overdose

What is the normal range of TIBC

250-425 micrograms/dL

% saturation (transferrin saturation)

equation

when is it increased/decreased

Serum iron/ TIBC x100

Increased in iron overdose, sideroblastic anemia.

Decreased in iron deficiency anemia

Transferrin

what is it

when is it increased/decreased

Complex of apotransferrin (protein that transports iron) & iron.

Increased in iron deficiency anemia.

Decreased in iron overdose, chronic infections, malignancies.

Ferritin

Most common form of iron storage, rough estimate of body iron content.

Acid phosphatase (ACP)

Old marker for prostate cancer. PSA is now used (more specific).

when is Alkaline phosphatase (ALP) increased

Increased in liver obstruction & bone disease.

when is Aspartate aminotransferase (AST) increased

Increased in liver disease (especially hepatitis), myocardial infarction, and muscular dystrophy.

when is Alanine aminotransferase (ALT) increased

Increased in liver disease.

More specific for liver disease than AST.

Marked increase in hepatitis.

In RBCs also.

when is Gamma-glutamyl transferase (GGT) increased

Most sensitive enzyme for all types of liver disease.

High in chronic alcoholism (used to monitor alcohol levels).

Highest levels w/ obstructive disorders.

Lactate dehydrogenase (LD)

what is it

when is it increased

Catalyzes lactic acid <--> pyruvic acid

Increased in AMI, liver disease, and pernicious anemia.

Creatine Kinase (CK)

what is it

when is it increased

Most sensitive enzyme for skeletal muscle disease.

Need heparin tube sample.

Increased in AMI and muscular dystrophy.

Amylase

what is it

when is it increased

Breaks down starch to simple sugars.

Increased in acute pancreatitis and other abdominal disorders.

Lipase

what is it

when is it increased

Breaks down triglycerides into fatty acids & glycerol.

Levels are similar to amylase, but stay increased longer.

More specific than amylase for pancreatic disease.

Glucose-6-phosphate dehydrogenase (G6PD)

what is it

what does deficiency lead to

An enzyme that aids in the proper functioning of red blood cells.

Deficiency leads to hemolytic anemia.

Cardiac disorder enzymes

CK-MB

Hepatocellular disorder enzymes

AST, ALT, LD

Biliary tract obstruction enzymes

ALP, GGT

Skeletal muscle disorder enzymes

CK, AST, LD

Bone disorder enzymes

ALP

Acute pancreatitis enzymes

Amylase and lipase

What is the order of enzymes that increase after AMI from earliest to latest?

Myoglobin-- CK-MB -- Troponin

Which cardiac enzyme can you expect to stay increased up to 10 days after AMI?

Troponin

If this enzyme is NOT increased within 8 hours of chest pain, AMI is ruled out. Which enzyme is it?

Myoglobin

Which enzyme is a definitive marker for AMI?

Cardiac troponins

Which test is used to indicate heart failure?

BNP- acts on kidneys to increase excretion of fluid

Which test is used to assess the risk of coronary artery disease (CAD)

Cardiac C-reactive protein (cCRP)

Biliary obstruction leads to an increase in which type of bilirubin?

Conjugated bilirubin

Does bilirubin sample need to be protected from light?

YES

Which test method is used to measure total bilirubin?

Jendrassik-Grof method.

Diazo reagent

Which bilirubin is bound to protein (albumin)

Unconjugated bilirubin

Is unconjugated bilirubin fat or water soluble?

Fat soluble

Is unconjugated bilirubin present in urine?

No

ACTH is increased in which disease?

Cushings disease

what is FSH

Regulates sperm & egg production.

Sharp increase just before ovulation