LAB INVESTIGATIONS

Question 1

What is measured in the U&E panel?

Answer 1

Sodium, potassium, chloride, bicarbonate (indirect), urea (BUN), creatinine, and calcium.

Question 3

What is measured in the U&E panel?

Answer 3

Sodium, potassium, chloride, bicarbonate (indirect), urea (BUN), creatinine, and calcium.

Question 4

Where is sodium primarily found?

Answer 4

It is the major extracellular cation, regulates plasma osmolarity.

Question 5

What mechanisms regulate sodium?

Answer 5

Aldosterone: Increases sodium reabsorption
Natriuretic peptides: Promote sodium excretion

Question 6

Why are potassium shifts dangerous?

Answer 6

Small changes affect cardiac conduction, muscle contraction, and nerve function.

Question 7

How are potassium imbalances managed?

Answer 7

Hypo: Potassium supplements
Hyper: Insulin/dextrose, calcium gluconate, β₂-agonists, Kayexalate

Question 8

What is chloride’s role?

Answer 8

Primary extracellular anion, works with sodium to maintain osmotic balance.

Question 9

How is anion gap calculated?

Answer 9

Anion gap = (Na⁺ + K⁺) – (Cl⁻ + HCO₃⁻)

Question 10

What does a high anion gap suggest?

Answer 10

Metabolic acidosis due to unmeasured anions (e.g. lactate, ketones)

Question 11

What regulates serum calcium?

Answer 11

PTH: Increases calcium levels (↑ resorption, ↓ excretion)
Vitamin D: Enhances gut absorption

Question 12

What does BUN measure?

Answer 12

Urea from ammonia (protein catabolism), cleared by kidneys.

Question 13

Causes of increased BUN?

Answer 13

Dehydration, GI bleed, renal failure, high protein intake.

Question 14

What affects serum creatinine?

Answer 14

Muscle mass, age, gender, kidney function.

Question 15

What conditions alter glucose levels?

Answer 15

Diabetes (Type 1 & 2)
Cushing’s syndrome
Medications (steroids)
Stress-induced hyperglycemia

Question 16

What is MCV and its normal range?

Answer 16

Mean Corpuscular Volume (80–100 fL) — indicates RBC size.

Question 17

What does a high MCV indicate?

Answer 17

Macrocytosis — B12/folate deficiency, methotrexate, zidovudine.

Question 18

What does a low MCV indicate?

Answer 18

Microcytosis — iron deficiency.

Question 19

Hb normal values?

Answer 19

Males: 14–18 g/dL
Females: 12–16 g/dL

Question 20

What does decreased hematocrit suggest?

Answer 20

Anemia, fluid overload.

Question 21

What does increased WCC suggest?

Answer 21

Infection, inflammation, leukemia

Question 22

What does decreased WCC suggest?

Answer 22

Myelosuppression, autoimmune neutropenia

Question 23

Define thrombocytopenia and thrombocytothemia.

Answer 23

Thrombocytopenia: ↑ bleeding risk
Thrombocytothemia: ↑ clotting risk

Question 24

What affects albumin levels?

Answer 24

Liver function, renal loss, nutritional status, fluid overload

Question 25

Difference between direct and indirect bilirubin?

Answer 25

Indirect (unconjugated): Bound to albumin Direct (conjugated): Water-soluble, excreted via bile

Question 26

ALT/AST ratio interpretation?

Answer 26

ALT > AST → non-alcoholic injury AST > ALT → alcohol-related liver injury

Question 27

ALP interpretation?

Answer 27

ALP ↑ + GGT normal = Bone disorder ALP ↑ + GGT ↑ = Cholestasis

Question 28

Ammonia (9–33 µmol/L)

Answer 28

↑ in liver failure due to impaired urea cycle

Question 29

Why is a lipid profile important?

Answer 29

Detects hypercholesterolemia/dyslipidemia, risk factor for CVD.

Question 30

What is Creatine Kinase (CK)?

Answer 30

Released in muscle injury CK-MB specific to myocardium (MI indicator)

Question 31

What is troponin and why is it important?

Answer 31

Cardiac-specific marker for MI Troponin I (cTnI) is highly specific for myocardial injury

Question 32

What is MCS testing?

Answer 32

Microscopy, Culture, and Sensitivity — identifies pathogens and drug susceptibilities.

Question 33

What is PCR used for?

Answer 33

Detects microbial DNA for viruses like SARS-CoV-2, HIV, TB (GeneXpert).

Question 34

What is serology?

Answer 34

Detects host antibodies to confirm past or current infection.

Question 35

When is antigen testing preferred?

Answer 35

When cultures are impractical or slow — e.g., rapid tests for malaria, SARS-CoV-2.