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100+ Free CMSA FC Path(SA) Chemical Pathology Practice Questions

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Sample CMSA FC Path(SA) Chemical Pathology Practice Questions

Try these sample questions to test your CMSA FC Path(SA) Chemical Pathology exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1A 45-year-old male with severe diarrhoea presents with serum sodium 138 mmol/L, potassium 3.1 mmol/L, chloride 112 mmol/L, and bicarbonate 14 mmol/L. What is the serum anion gap in mmol/L?
A.8
B.12
C.16
D.20
Explanation: The serum anion gap is calculated as [Na+] − ([Cl-] + [HCO3-]). Substituting the given values: 138 − (112 + 14) = 138 − 126 = 12 mmol/L. A gap of about 12 mmol/L is normal and fits hyperchloraemic metabolic acidosis from gastrointestinal bicarbonate loss in severe diarrhoea.
2A 52-year-old man with type 2 diabetes presents with confusion. Serum sodium 128 mmol/L, glucose 38 mmol/L. Using the correction of 2.4 mmol/L per 10 mmol/L glucose above 5.6 mmol/L, what is the corrected sodium in mmol/L?
A.132
B.134
C.136
D.138
Explanation: Corrected Na+ = measured Na+ + 2.4 × (glucose − 5.6)/10 = 128 + 2.4 × 32.4/10 = 128 + 7.8 ≈ 136 mmol/L, indicating mild true hyponatraemia beyond pseudohyponatraemia from hyperglycaemia.
3A patient with ethylene glycol poisoning has serum sodium 140 mmol/L, glucose 5 mmol/L, urea 6 mmol/L, and measured serum osmolality 360 mOsm/kg. Estimated osmolality (2×Na + glucose + urea) is 292 mOsm/kg. What is the osmolal gap in mOsm/kg?
A.48
B.58
C.68
D.78
Explanation: Osmolal gap = measured osmolality − calculated osmolality = 360 − 292 = 68 mOsm/kg. An elevated osmolal gap (>10–15 mOsm/kg) with high anion gap metabolic acidosis suggests toxic alcohol ingestion.
4Arterial blood gas: pH 7.28, PaCO2 22 mmHg, HCO3− 10 mmol/L. Using Winter's formula, what is the expected PaCO2 (±2 mmHg)?
A.18–22 mmHg
B.22–26 mmHg
C.26–30 mmHg
D.30–34 mmHg
Explanation: Winter's formula: expected PaCO2 = 1.5 × [HCO3−] + 8 (±2) = 1.5 × 10 + 8 = 23 mmHg (range 21–25). Measured PaCO2 of 22 mmHg indicates appropriate respiratory compensation for primary metabolic acidosis.
5A patient with diabetic ketoacidosis has Na+ 140, Cl− 100, HCO3− 10 mmol/L. What is the serum anion gap in mmol/L?
A.20
B.24
C.28
D.30
Explanation: Anion gap = [Na+] − ([Cl−] + [HCO3−]) = 140 − 110 = 30 mmol/L, consistent with high anion gap metabolic acidosis in DKA.
6In metabolic acidosis, anion gap is 24 mmol/L (baseline 12) and bicarbonate fell from 24 to 12 mmol/L. What is the delta ratio (ΔAG/ΔHCO3−)?
A.0.5
B.1.0
C.1.5
D.2.0
Explanation: Delta ratio = (24−12)/(24−12) = 12/12 = 1.0, indicating pure high anion gap metabolic acidosis. Ratios <0.4 suggest concurrent normal AG acidosis; >2 suggest concurrent metabolic alkalosis.
7A 70-year-old on thiazides has Na+ 118 mmol/L, serum osmolality 250 mOsm/kg, urine osmolality 450 mOsm/kg. Which diagnosis is most likely?
A.Psychogenic polydipsia
B.SIADH
C.Diabetes insipidus
D.Addison disease
Explanation: Hyponatraemia with inappropriately concentrated urine (>100 mOsm/kg) in a euvolaemic patient suggests SIADH or thiazide-associated hyponatraemia. Psychogenic polydipsia causes dilute urine; DI causes hypernatraemia; Addison causes hyperkalaemia and volume depletion.
8Which finding best distinguishes renal tubular acidosis from diarrhoea as the cause of hyperchloraemic metabolic acidosis?
A.Urine pH >5.5 in type 1 RTA despite systemic acidosis
B.Urine anion gap >0 in diarrhoea
C.Urine potassium <20 mmol/L in all RTA types
D.Urine osmolality <100 mOsm/kg in RTA
Explanation: In distal (type 1) RTA, the kidney cannot acidify urine despite systemic acidosis (urine pH >5.5). In diarrhoea, appropriate renal acid excretion produces urine pH <5.5 and negative urine anion gap.
9A patient has potassium 6.8 mmol/L with peaked T waves. Which treatment lowers serum potassium fastest by intracellular shift?
A.Calcium gluconate IV
B.Insulin-dextrose infusion
C.Sodium polystyrene sulfonate
D.Calcium resonium enema
Explanation: Insulin with dextrose drives K+ intracellularly via Na+/K+-ATPase, producing the fastest reduction in extracellular K+. Calcium gluconate stabilises myocardium but does not lower K+. Resonium removes K+ via the gut over hours.
10Serum albumin 20 g/L, total calcium 1.95 mmol/L. Using correction (add 0.02 mmol/L per 1 g/L albumin below 40 g/L), what is corrected calcium in mmol/L?
A.2.15
B.2.25
C.2.35
D.2.45
Explanation: Corrected Ca = 1.95 + 0.02 × (40−20) = 1.95 + 0.40 = 2.35 mmol/L, revealing true hypocalcaemia masked by hypoalbuminaemia.

About the CMSA FC Path(SA) Chemical Pathology Exam

FC Path(SA) Chemical Pathology is the fellowship qualification awarded by the College of Pathologists of South Africa, certifying specialist chemical pathologists for clinical laboratory leadership and diagnostic consultation across South Africa.

Assessment

The CMSA FC Path(SA) Chemical Pathology examination comprises Part I and Part II components featuring written papers, laboratory practical interpretation, data analysis, and oral examinations covering clinical biochemistry, metabolic pathology, laboratory management, quality assurance, and analytical techniques.

Time Limit

3 hours per written paper

Passing Score

Overall 50% with written/practical subminimums

Exam Fee

R24 650 (Colleges of Medicine of South Africa (CMSA) — College of Pathologists)

CMSA FC Path(SA) Chemical Pathology Exam Content Outline

15%

Acid-Base and Electrolytes

Anion gap, osmolal gap, arterial blood gas interpretation, sodium/potassium disorders.

20%

Endocrinology

Thyroid, adrenal, pituitary, calcium/bone, diabetes diagnostic testing and dynamic function tests.

15%

Lipid & Metabolic Pathology

Familial dyslipidaemias, Friedewald LDL estimation, metabolic syndrome, cardiac biomarkers.

15%

Liver & Kidney Testing

Hepatic panel interpretation, clearance calculations, eGFR equations, proteinuria, tubular defects.

10%

TDM & Toxicology

Pharmacokinetics, toxic screen interpretation, specific antidote/trough monitoring.

15%

Instrumentation & Quality Control

Westgard rules, immunoassay interference, LC-MS/MS, analytical validation, reference intervals.

10%

Inborn Errors of Metabolism

Newborn screening, organic acidurias, amino acid disorders, lysosomal storage diseases.

How to Pass the CMSA FC Path(SA) Chemical Pathology Exam

What You Need to Know

  • Passing score: Overall 50% with written/practical subminimums
  • Assessment: The CMSA FC Path(SA) Chemical Pathology examination comprises Part I and Part II components featuring written papers, laboratory practical interpretation, data analysis, and oral examinations covering clinical biochemistry, metabolic pathology, laboratory management, quality assurance, and analytical techniques.
  • Time limit: 3 hours per written paper
  • Exam fee: R24 650

Keys to Passing

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

CMSA FC Path(SA) Chemical Pathology Study Tips from Top Performers

1Master numerical calculations: practice anion gap, osmolal gap, corrected calcium, creatinine clearance, and Friedewald equation rapidly and accurately.
2Understand laboratory methods and analytical interferences (e.g. heterophile antibodies, hook effect, haemolysis/icterus/lipaemia indices).
3Apply Westgard rules and quality management concepts to practical clinical laboratory scenarios.
4Review clinical case vignettes combining laboratory data with clinical presentation for dynamic function tests and inborn errors of metabolism.

Frequently Asked Questions

What is the examination structure of FC Path(SA) Chemical Pathology?

The examination consists of written papers, practical laboratory interpretation (data interpretation, unknown specimen analysis, quality control analysis), and oral examinations before a board of CMSA chemical pathology examiners.

What is the passing score and fee for FC Path(SA) Chemical Pathology?

The FC Path(SA) Chemical Pathology Part II examination fee is R24 650 (SS2026, inclusive of VAT). Candidates must attain an overall mark of at least 50% with subminimum requirements in written, practical, and oral components as specified in CMSA regulations.

What topics are covered in this 100-question practice bank?

The bank covers acid-base/electrolytes, endocrinology, lipid disorders, liver/kidney biochemical testing, therapeutic drug monitoring, laboratory instrumentation/quality control, and inborn errors of metabolism.