Clinical Chemistry Exam 2

What is activation energy?

The excess energy needed to induce the transition state.

Energy required to raise all molecules in one molecule of a compound at a certain temperature to the transition state at the peak of the energy barrier.

What do enzymes do to activation energy?

Enzymes catalyze physiologic reactions by lowering the activation energy level that the reactants require to for the transition state.

What are enzymes?

Specific proteins that catalyze biochemical reactions without altering the equilibrium point of the reaction or being consumed or changed in composition

Uric acid levels help detect what diseases?

Gout and disorders related to purine metabolism

Serum urea levels are influenced by what factors (know at least 3)

All of the above

What is Alanine aminotransferase (ALT)?

A transferase with an enzymatic reaction that catlyzes the transfer of an amino group from alanine to a-ketoglutarate with the formation of glutamate and pyruvate.

What does Aspartate Aminotransferase help detect?

All of the above

What is Aspartate aminotransferase (AST)?

An enzyme belonging to the class of transferases involved in the transfer of an amino group between aspartate and a-keto acids

What does Alanine Aminotranserfase help detect?

Hepatic disorders

What is Alkaline phosphate (ALP)?

Enzymes that catalyze the hydrolysis of various phosphomonoesters at an alkaline pH

What does Alkaline phosphatase help detect?

Bone disorders and hepatic disorders

What is Gamma-glutamyltransferase (GGT)?

Enzyme involved in the transfer of gamma-glutamyl reside from gamma-glutamyl peptides to amino acids, H2O and other small peptides

What does gamma-glutamyltransferase help detect?

Alcoholism, diabetes mellitus, hepatobiliary disease, and myocardial infarction

What is Lactate dehydrogenase (LD)?

Enzyme that catalyzes the interconversion of lactic to pyruvic acid

What does Lactate dehydrogenase help detect?

Hepatic disorder, myocardial infarction,carcinoma and hemolysis

Uric acid is the ___ ______ of purine metabolism. Uric acid is produced in the _____, circulates in plasma and excreted primarily by the ____ and also in the GI tract.

End product; liver; kidneys

During the biosynthesis and excretion of urea, ammonia is produced from _____ _____ ______ binds with CO2 to form ________ ________ entering the urea cycle in the liver, resulting in urea production. Urea is carried in the blood to the kidneys, filtered by glomeruli, and mostly excreted in urine. Some reabsorption occurs depending on dehydration

amino acid deamination; carbamoyl phosphate

During the biosynthesis and excretion of urea, urea is carried in the blood to the ______, filtered by ______, and mostly excreted in _______. Some reabsorption occurs depending on dehydration

Kidneys; glomeruli; urine

Why is nitrogen released and converted into urea, what is breaking down to form this nitrogen?

Urea cannot be properly stored. During protein metabolism, nitrogen is released as ammonia from protein metabolism, converted to urea in the liver, and excreted from the kidneys as a waste product

What is fixed time?

Measurement of product or substrate concentration at a specific time point

What is continuous monitoring?

Measuring the reaction rate continuously over time

What is zero-order kinetics?

Reaction rate is independent of substrate concentration (enzyme saturated)

What is first-order kinetics?

Reaction rate is directly proportional to substrate concentration

An increased serum level of which of the following analytes is commonly associated with decreased glomerular filtration?

Creatinine

What is noncompetitive inhibitor?

Bind elsewhere, altering enzyme activity without competing for the active site

What is competitive inhibitor?

Binds to active site and compete with substrate

What enzyme is used in coupled enzymatic method for urea quantification?

Glutamate dehydrogenase (GLDH)

What does ammonia help aid in the diagnosis of?

All of the above

Elevated concentration of uric acid in blood and acidic urine yields:

Uric acid crystals

From what precursor is creatinine formed?

Creatine phosphate + creatine

What should be monitored in patients with chemotherapy to avoid nephrotoxicity?

Blood urea nitrogen (BUN)

What is the most common method to quantify uric acid?

Uricase Method

What is preazotemia?

Decreased renal blood flow (high protein diet and decreased protein metabolism) BUN increase Creatinine ←→ ration >20:1

What is renal azotemia

Decreased renal function (renal failure, glomerulobephritis, tubular necrosis) BUN increase creatine increase ratio ← →

What is postrenal azotemia

Obstruction of urine flow (tumors, stones, severe infection)

Significance of lipase

Enzyme that hydrolyzes the ester linkages of fats to produce alcohols and fatty acids of triglycerides

What excretes lipase?

Pancreas

Significance of amalyse

Enzyme belonging to the class of hydrolases that catalyzes the breakdown of starch and glycogen

What excretes amalyse?

Salivary glands and pancreas

What is the greatest tissue source of CK?

Skeletal tissue

Where does acid phosphatase activity mainly come from?

Prostate

Amyloclastic methods for amylase determination

Measure the decrease in starch concentration,

Saccharogenic methods for amylase determination

Measures formation of reducing sugars from starch breakdown

BUN concentration is dependent on what?

Protein in diet, rate of protein catabolism, and renal function

(T/F) Elevated levels of creatine is associated with renal disease?

False

What does uric acid levels help detect?

Kidney dysfunction

What do increased serum enzyme levels indicate?

Tissue damage or disease

Which CK is elevated in muscle disease

CK-MM

How do you handle ammonia testing in the lab (know the steps)

Collect venous blood without trauma, keep on ice, and test immediately after collection to avoid degradation. Use heparin or EDTA anticoagulant, avoid hemolyzed samples, and process quikly or freeze if delayed.

Which enzyme activity can use olive oil as a substrate?

Lipase

NPN compounds

Urea, amino acids, uric acid, creatinine, creatine, and ammonia

Urea

Nitrogenous compound and product of protein metabolism enzymatically formed during the urea cycle

Amino acids

Organic compounds that serve as the building blocks of proteins, formed from the combination of amine and carboxylic acid functional groups.

Uric acid

A naturally occuring nitrogenous compound produced during purine nucleotide metabolism

Creatine

A compound formed from amino acids and synthesized primarily in the liver, important for energy production in muscle cells.

Creatinine

A naturally occurring metabolic waste product generated during creatine metabolism

Ammonia

A colorless gas that is a byproduct of protein metabolism and is converted to urea in the liver.

ALP should increase in bone disease

True

What may falsely increase ammonia levels?

In vitro amino acid deamination post-collection , hemolysis, and raised GGT

What is the process of a OGTT?

Patients fast overnight and then consume a glucose solution; blood sugar levels are measured at intervals afterward.

What does HgbA1C test?

Average blood glucose level at any one time reflects the average blood glucose level over the previous 2 to 3 months

ALP is significantly increased in what disorders?

Paget’s osteomalacia, rickets hyperparathyroidism, and osteogenic sarcoma

What is the function of insulin in relation to glycogenesis, glycolysis, lipogenesis, and glycogenolysis.

Increases glycogenesis, lipogenesis. an glycolysis but Inhibits glycogenolysis.

What are the symptoms for diabetes mellitus?

Polydipsia, polyphagia, polyuria, rapid weight loss, hyperventilation, mental confusion, and possible loss of consiousness

Which hormones can increase blood sugar levels?

Glucagon → a cells of islet of langerhans

Blood ammonia levels are used to evaluate which conditions?

Hepatic failure, Reye’s syndrome, and inherited deficiencies of urea cycle enzymes

Autoimmune diabetes is what type of diabetes?

Type 1 diabetes

What HgbA1C levels and what fasting glucose levels indicate diabetes mellitus?

HbA1c >6.5% and fasting plasma glucose >126 mg/dL

Lipogenesis

Conversion of carbohydrates to fatty acids

Gluconeogensis

Formation of glucose-6-phosphate from noncarbohydrate sources

Glycogenolysis

Breakdown of glycogen to glucose for use as energy

Glycolysis

Metabolism of a glucose molecule to pyruvate or lactate for production of energy

Glycogenesis

Breakdown of glucose to glycogen for use as energy

Lipolysis

Decomposition of fat

The estimated glomerular filtration rate (eGFR) is calculated based on age, gender, race and what additional parameter?

Serum creatinine concentration

The process by which glycogen is converted back to glucose-6-phosphate (G6P) for entry into the glycolytic pathway is:

Glycogenolysis

What enzyme catalyzes this reaction?

Glucose oxidase; peroxidase

What liver enzyme detects liver damage from chronic alcoholism?

Gamma-Glutamyltransferase (GGT)

What is the reference method used for glucose determination due to its specificity?

Hexokinase

What type of chemical bond links two monosaccharides to form a disaccharide?

A glycosidic bond

Which diabetes is insulin resistance?

Type 2

What sugar is a non-reducing sugar?

Sucrose

What causes a low plasma urea concentration?

Severe liver disease, malnutrition, or overhydration. It indicates reduced protein intake or metabolism.

What is uremia?

A very high plasma urea concentration accompanied by renal renal failure

Which enzymes have a cardiac origin

CK-MB and CK-MM

What method for glucose results in the formation of NADPH for measurement?

Hexokinase coupled with G6PD

Oxidoreductase

Catalyze an oxidation reduction reaction between two substrates

Transferases

Catalyze the transfer of a group other than hydrogen from one substrate to another

Hydrolases

Catalyze the hydrolysis of chemical bonds

Lyases

Catalyze removal of groups from substrates without hydrolysis; the product contains double bonds

Isomerases

Catalyze the interconversion of geometric, optical, or positional isomers

Ligases

Catalyze the joining of two substrate molecules, coupled with breaking of the pyro-phosphate bond in adenosine triphosphate or similar compound

How is urea formed?

Formed in the liver from amino groups (NH2) and free ammonia generated during protein catabolism

What specimen should be collected for HgbA1C?

Whole blood or plasma

Know how to calculate glucose concentration using Hgb A1C

eAG (mg/dL) = 28.7 x HbA1c-46.7

What is produced when there is carbohydrate deprivation or low carb diet?

Ketones

When should we test for albumin in a urine sample?

An annual assessment of kidney function by the determination of urinary albumin excretion and glomerular filtration rate is recommended for diabetic patients

At what glucose level do symptoms of hypoglycemia start to appear?

50-55 mg/dL

When a patient is going through a hypoglycemic period, what mechanisms can activate to help increase glucose levels in circulation?

Release of glucagon, epinephrine, cortisol, and growth hormone

Which enzyme is used for enzymatic assay for ammonia?

Glutamate dehydrogenase (GLDH)