Medical Biochemistry Quiz

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Questions and Answers

What is the primary function of urea in the human body?

To regulate blood sugar levels

To synthesize hormones

To transport oxygen to cells

To remove waste products from protein metabolism (correct)

Which of the following conditions can lead to an elevated blood urea nitrogen (BUN) level?

Excessive fluid intake

Reduced red blood cell production

Increased protein intake (correct)

Low protein diet

Which of the following is TRUE about BUN?

BUN rises more slowly than serum creatinine.

BUN is primarily eliminated through the lungs.

A measurement of BUN is not a reliable indicator of renal function.

BUN is a more sensitive indicator of declining renal function compared to creatinine clearance test. (correct)

What is the medical term for an elevated concentration of urea in the blood?

Azotemia (D) Signup and view all the answers

Which of the following substances should NOT be used for collecting blood samples for urea analysis?

Citrate (B), Fluoride (C) Signup and view all the answers

What is the primary treatment for Cystic Fibrosis?

Dietary supplements, antibiotics and physiotherapy (C) Signup and view all the answers

Which of these conditions CANNOT be prevented or mitigated with early treatment?

Cystic Fibrosis (B) Signup and view all the answers

What is the primary impact of Galactosaemia on the body?

Inability to break down the galactose part of milk sugar (B) Signup and view all the answers

Which condition can lead to serious damage to the brain and liver within the first week of life if left untreated?

Galactosaemia (B) Signup and view all the answers

What is the purpose of the Guthrie Test?

To detect phenylketonuria (C) Signup and view all the answers

Which condition is treated with a special milk-free diet?

Galactosaemia (A) Signup and view all the answers

What is a common treatment strategy for Fatty acid oxidation disorders?

Low-fat diet and dietary supplements, avoiding fasting (D) Signup and view all the answers

Which of these conditions can cause mental retardation if left untreated?

All of the above (D) Signup and view all the answers

What is the primary function of transamination in amino acid metabolism?

The synthesis of new amino acids. (D) Signup and view all the answers

Which of these conditions are caused by a defect in amino acid metabolism?

All of the above. (D) Signup and view all the answers

What is the primary purpose of the Guthrie test?

To screen for genetic disorders. (A) Signup and view all the answers

What is the primary role of the liver in amino acid metabolism?

Synthesis of new amino acids. (C) Signup and view all the answers

Which of the following is NOT a characteristic of amino acid disorders?

They are always fatal. (B) Signup and view all the answers

What is the primary function of the keto acids produced from deamination?

To be converted into glucose for energy. (B) Signup and view all the answers

Which of the following factors can cause a falsely elevated creatinine level in a blood sample?

Prolonged delay of the sample to the laboratory (A) Signup and view all the answers

What is the relationship between creatinine clearance and glomerular filtration rate (GFR)?

Creatinine clearance is directly proportional to GFR. (D) Signup and view all the answers

What is the primary reason for collecting both urine and blood samples for a creatinine clearance test?

To compare the serum creatinine level with the amount of creatinine excreted in the urine. (A) Signup and view all the answers

Why is it important for patients to avoid vigorous exercise before a creatinine clearance test?

Exercise can increase muscle breakdown, leading to a temporary spike in creatinine levels and inaccurate results. (A) Signup and view all the answers

Which of the following statements accurately describes creatinine?

Creatinine is a breakdown product of muscle tissue that is filtered by the kidneys. (B) Signup and view all the answers

What is the main reason for refrigerating creatinine clearance samples?

To prevent the formation of ammonia, which can falsely elevate creatinine levels. (A) Signup and view all the answers

Why is it important for patients to avoid excessive intake of meat before a creatinine clearance test?

Meat contains creatine, which can temporarily increase blood creatinine levels, leading to inaccurate test results. (A) Signup and view all the answers

Which of the following factors can contribute to lower creatinine levels in vegetarians?

Meat contains creatine, which vegetarians do not consume, leading to lower creatinine levels. (B) Signup and view all the answers

Which lipoprotein has the lowest density due to its large size and high triglyceride content?

Chylomicrons (B) Signup and view all the answers

Which lipoprotein is primarily responsible for transporting cholesterol from cells back to the liver for excretion?

High-density lipoprotein (HDL) (C) Signup and view all the answers

What distinguishes chylomicrons from other lipoproteins?

They carry dietary triglycerides from the intestine to other cells. (B) Signup and view all the answers

Why do plasma specimens containing high levels of chylomicrons and VLDL appear turbid or milky?

These lipoproteins are large and scatter light due to their high triglyceride content. (D) Signup and view all the answers

Which lipoprotein is considered the major cholesterol carrier to peripheral tissues?

Low-density lipoprotein (LDL) (C) Signup and view all the answers

What is the main apolipoprotein associated with Very Low Density Lipoproteins (VLDL)?

Apolipoprotein B-100 (B) Signup and view all the answers

Which of the following statements is TRUE regarding lipoprotein metabolism?

LDL directly transports cholesterol from the intestine to cells. (B) Signup and view all the answers

The turbid appearance of plasma specimens containing high levels of chylomicrons and VLDL is due to:

the scattering of light by their large size and triglyceride content. (B) Signup and view all the answers

Which of the following lipoproteins is responsible for transporting dietary triglycerides to tissues?

Chylomicron (C) Signup and view all the answers

Which of these is a key characteristic of High-Density Lipoprotein (HDL)?

Primarily transports cholesterol from peripheral cells to the liver for excretion. (C) Signup and view all the answers

What is the primary role of bile salts in fat digestion?

Emulsifying fat into smaller micelles. (C) Signup and view all the answers

What is the primary source of triglycerides in the body?

From both dietary sources and synthesis in the liver. (C) Signup and view all the answers

Which of the following is NOT a component of lipoprotein particles?

Albumin (C) Signup and view all the answers

What is the relationship between LDL cholesterol levels and the risk of ischemic heart disease?

High LDL cholesterol levels are associated with an increased risk. (D) Signup and view all the answers

Which of the following statements regarding lipoprotein metabolism is TRUE?

Lipoproteins can be assembled in both the small intestine and the liver. (C) Signup and view all the answers

Which enzyme is primarily responsible for the breakdown of dietary triglycerides in the small intestine?

Lipase (C) Signup and view all the answers

Study Notes

Laboratory Testing Groups

Basic Metabolic Panel (BMP):
- Kidneys
- Acid/base balance
- Electrolytes
- Blood Glucose level
Comprehensive Metabolic Panel (CMP):
- Kidneys
- Liver
- Electrolytes
- Acid/base balance
- Blood glucose
- Blood proteins
Liver Tests:
- Proteins (total protein & albumin)
- ALP (alkaline phosphatase)
- ALT (alanine aminotransferase) (SGPT)
- AST (aspartate aminotransferase) (SGOT)
- Bilirubin (total & direct)
Renal Profile:
- Albumin
- Urea/BUN (blood urea nitrogen)
- Electrolytes and anion gap
  - Sodium
  - Potassium
  - Chloride
  - Bicarbonate
  - Phosphorus
  - Calcium

Cardiac Panel Profile/Coronary Risk Profile/Lipid Profile

Cholesterol
HDL-cholesterol
LDL-cholesterol
Triglycerides

Diabetes Mellitus Profile

Screening: Urinalysis
Confirmation:
- Fasting blood glucose = > 7.0 mmol/L
- Random glucose = > 11.0 mmol/L
- OGTT/MGTT = > 11.0 mmol/L
- Monitoring: HbA1c > 6.5%

Anemia Profile

Total iron binding capacity
Iron
Vitamin B12
Folate, RBC
Transferrin
Ferritin

Hypertension Profile

Urinalysis, urine protein
Urinary albumin, BUN, creatinine, eGFR
Calcium
TSH (thyroid stimulating hormone) and T4
Fasting glucose, A1c
Potassium
Basic metabolic panel (BMP)
Lipid profile

Aldosterone and Renin

Cortisol and dexamethasone test
Catecholamines and d metanephrines
Complete blood picture

Arthritis Profile

C-reactive protein (CRP)
Sedimentation rate
Uric Acid

Bone/Joint Profile

Calcium
Uric acid
RA Factor (rheumatoid arthritis)
Phosphate

Pancreatic Profile

Amylase
Insulin fasting
Lipase
C-peptide

Thyroid Profile

TSH Tests
- T3 bound to protein
- FT3

Parathyroid Profile

Vitamin D tests
Calcium
Phosphorus

Drug Toxicology Profile

Therapeutic drug monitoring
- Barbiturates
- Phencyclidine (PCP)
- Amphetamines
- Cocaine
- Methamphetamines
- Marijuana
- Opiates

Amino Acids and Proteins

Protein:
- Large molecules
- Made up of chains of amino acids
- Found in every body cell
- Involved in most body functions
- Sequence of amino acids determined by DNA
Amino Acid Structure:
- Amino group
- Carboxyl group
- R-group (side chain)
Amino Acid Properties:
- Building blocks of proteins
- Organic compounds
- Zwitterions and amphoterics
Types of Amino Acids:
- Non-essential
- Essential
Non-Essential Amino Acids:
- Body produces these
- Liver produces nearly 80% of amino acids
Essential Amino Acids:
- Body cannot produce them
- Must be supplied through diet
20 types of amino acids: -Glycine, alanine, proline, valine, leucine, isoleucine, methionine -Serine, threonine, cysteine, asparagine, glutamine -Phenylalanine, Tyrosine, tryptophan -Aspartate, glutamate -Lysine, arginine, histidine
Protein bonds: -Dipeptide, tripeptide, oligopeptide, polypeptide
Structure of protein: -Primary, secondary, tertiary, quaternary

Non-protein Nitrogenous Compounds

Amino Acid Functions:
- Energy use
- Vitamin 65 and coenzyme A constituent -Immune function (tumor & cancer retardation, healing) -Liver detoxification -Muscle metabolism -Stamina -Protective liver function -Production of collagen, elasticity, and skin texture
Transamination:
- Transfer of amino group from amino acid to keto acid to form new amino acid and keto acid
- Catalyzed by transaminases (aminotransferases)
- Kidney function -regulating acid-base balance and excreting nitrogenous waste
- Brain function -synthesis of neurotransmitters (glutamate, aspartate, GABA)
Deamination:
- Removal of amino group from amino acid
Defects in amino acid metabolism:
- Phenylketonuria (PKU)
- Tyrosinemia, alkaptonuria, and albinism
- Homocystinuria and hypermethioninemia
- Cystinuria and cystinosis and sulfite oxidase deficiency
- Hartnup's disorder
- Maple syrup urine disease (MSUD)
- Nonketotic hyperglycinemia (glycine encephalopathy)
Aminoaciduria:
- Presence of elevated amino acids in urine
- Can be primary (inherited enzyme deficiency or inborn error) or secondary (due to kidney/liver dysfunction)

Newborn Screening Tests

Guthrie Test:
- Detects phenylketonuria (PKU)
- Involves placing a blood sample on filter paper
- Bacterial growth indicates elevated phenylalanine levels (positive result

Urea/Blood Urea Nitrogen (BUN)

BUN measures the amount of urea nitrogen in blood.
Indication of kidney function.
Rises more rapidly than serum creatinine (Less sensitive indicator of declining renal function).
Normal values differ based on gender and age.

Azotemia

Elevated urea concentration in blood.
Often caused by: impaired renal function, congestive heart failure, dehydration, shock etc.

Uric Acid

Waste product produced from protein metabolism.
Excreted by kidneys & bowels.
Increased levels can lead to gout and other issues.
Normal values vary.

Chronic Kidney Disease (CKD) Stages

Lipid and Fatty Acids

Lipid - various molecules, insoluble in water. Types - triglycerides, cholesterol, phospholipids
Fatty acids - mostly straight-chain monocarboxylic acids. Saturated fatty acids, Unsaturated fatty acids.
Triglycerides - fatty acids esters of glycerol, Main lipids in diets.
Cholesterol - steroid present in the diet and liver that's part of cell membranes, steroid hormone synthesis.
Phospholipids - similar structure to triglycerides, major component of cell membranes.

Lipoproteins

Lipoproteins - transport cholesterol, triglycerides, and phospholipids in plasma.
Chylomicron = largest, carries dietary triglycerides
VLDL = endogenously produced triglycerides
LDL = carries cholesterol to tissues
HDL = carries cholesterol from tissues to liver
Enzyme Systems (LPL, LCAT) crucial in lipoprotein metabolism

Glucose Metabolism

Homeostasis:
- Pancreas release insulin in response to high blood sugar
- Insulin helps regulate blood glucose levels
- Conversely, glucagon increase blood sugar when levels decrease.
Hypoglycemia: Very low blood sugar level, can be caused by prolonged fasting, excessive physical activity, and insulin overdose.

Hormones (Insulin, Glucagon) & Other factors affecting Glucose Regulation

-Insulin: Reduces blood sugar.

Glucagon: Increases blood sugar.
Hypoglycemia: Low blood sugar.

Thyroid Hormone

Main function = regulate metabolism, growth, and energy balance.
Thyroid hormone (T3, T4)
TRH (thyrotropin-releasing hormone) stimulates pituitary to release TSH (thyroid-stimulating hormone) which stimulates thyroid.
Negative feedback loops help to maintain homeostasis in thyroid hormone balance.
Goiters - swelling of the thyroid gland.

Hyperthyroidism & Hypothyroidism

Hyperthyroidism - overactive thyroid gland (symptoms - Weight loss, increased appetite, heart palpitations, nervousness etc.)
Hypothyroidism - underactive thyroid gland (symptoms - Weight gain, fatigue, depression etc.)

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Description

Test your knowledge on medical biochemistry topics such as urea functions, blood urea nitrogen levels, and various metabolic disorders. This quiz covers essential concepts critical for understanding human metabolism and related health conditions. Challenge yourself to see how well you understand these critical biochemical processes.