Prometric Exam Questions for Clinical Biochemistry Specialists and Technologists 2026: 20 MCQs with Answers on Pre-analytical Errors, Quality Control, Renal and Liver Profiles, Electrolytes and Acid-Base, Diabetes Testing, Lipids, Cardiac Markers, Thyroid, Tumour Markers, Therapeutic Drug Monitoring and Newborn Screening

Clinical biochemistry is licensed at three levels in the Gulf: the specialist clinical biochemist (BIO5900 at DHA, with BIO6100 for consultants), the clinical scientist (BIC5662) and the clinical biochemistry technologist (BIC5661), each with a Prometric paper of 100 to 150 single-best-answer questions in up to three hours and a pass mark of about 60%. The papers overlap heavily: all three test pre-analytical and analytical quality, interpretation of the common profiles and the laboratory's governance role; the specialist paper adds clinical interpretation and method evaluation depth. The Gulf's diabetes, kidney disease and inherited metabolic disorder burden shapes the emphasis. This set covers what recurs. The licensing routes are in laboratory scientist and technologist titles and the pathologist guide.

Pre-analytical and quality

Question 1

A serum sample from the emergency department shows potassium 6.8 mmol/L, LDH 900 U/L, AST 120 U/L and a visibly pink serum, in a patient with a normal ECG and a potassium of 4.2 the previous day. The most likely explanation and the correct action are:

1. True hyperkalaemia; phone as a critical value
2. In vitro haemolysis (from difficult venepuncture, small needles, syringe transfer or prolonged tourniquet), which releases intracellular potassium, LDH and AST; the laboratory measures the haemolysis index, reports the affected analytes as invalid or with a comment per policy, phones the ward to request a fresh, carefully collected sample, and does not report a potassium that could trigger inappropriate treatment
3. Rhabdomyolysis; check creatine kinase only
4. Dilution with intravenous fluid

Answer: B. Pseudohyperkalaemia also occurs with marked leukocytosis or thrombocytosis (serum higher than plasma), delayed separation, fist clenching and refrigerated unseparated samples; EDTA contamination gives high potassium with very low calcium and alkaline phosphatase.

Question 2

On a Levey-Jennings chart, the level 1 control for glucose has been above the mean on ten consecutive runs, all within 1 SD, while level 2 is within limits. According to Westgard rules the laboratory should:

1. Release results because all points are within 2 SD
2. Recognise a 10x rule violation indicating systematic error (shift), which under most multirule schemes is a rejection or at least a warning requiring investigation of calibration, reagent lot or instrument drift before continuing, with documentation of the corrective action; the 1-3s and 2-2s rules detect larger systematic errors, and R-4s detects random error
3. Change the control material
4. Widen the limits

Answer: B. Multirule QC increases error detection while limiting false rejections; sigma metrics guide how many rules a method needs.

Question 3

Before introducing a new creatinine method, the laboratory compares 100 patient samples with the existing method and finds a constant bias of +8 micromol/L. The appropriate steps are:

1. Go live immediately; bias is irrelevant
2. Complete verification per CLSI guidance: precision (repeatability and within-laboratory), accuracy or bias versus a reference method or certified material (creatinine should be IDMS-traceable), linearity and measuring range, limit of quantitation, interference studies (bilirubin, haemolysis, lipaemia), carryover, and reference interval verification; a clinically significant bias is corrected or the method recalibrated, and the eGFR equation used must match the traceable method
3. Only run three controls
4. Adopt the manufacturer's data without local testing

Answer: B. Total allowable error from biological variation databases defines whether a bias matters; accreditation inspections ask for the validation file.

Question 4

Which statement about reference intervals is correct?

1. Manufacturer intervals can be used without any local checks
2. Reference intervals are typically the central 95% of results from a healthy reference population, so 5% of healthy people fall outside them; laboratories verify transferred intervals with at least 20 local reference samples, and must consider age, sex, ethnicity and pregnancy partitions (for example different ALP, creatinine and vitamin D distributions in Gulf populations); clinical decision limits (such as HbA1c 6.5% or LDL targets) differ from reference intervals
3. Reference intervals are the same worldwide
4. Any result outside the interval indicates disease

Answer: B. Reference change values based on biological variation help decide whether serial results differ significantly.

Renal and liver

Question 5

A 45-year-old man of African descent has a creatinine of 130 micromol/L. Which statement about estimating kidney function is correct?

1. Creatinine alone is sufficient without an estimated GFR
2. The laboratory reports eGFR using a validated equation such as CKD-EPI 2021 (which no longer applies a race coefficient), recognising that creatinine depends on muscle mass, diet and some drugs (trimethoprim, cimetidine), and that cystatin C-based or combined equations improve accuracy in patients with abnormal muscle mass; eGFR is interpreted with urine albumin-to-creatinine ratio for CKD staging, and measured GFR or timed clearances are reserved for specific situations
3. Urea is a better marker than creatinine
4. eGFR is valid in acute kidney injury

Answer: B. eGFR assumes a steady state and is not valid in AKI, where changes in creatinine and urine output define the stage.

Question 6

A liver profile shows ALT 1,800 U/L, AST 1,400 U/L, ALP 140 U/L, bilirubin 60 micromol/L and GGT 90 U/L in a 30-year-old. The pattern and the most useful next tests are:

1. Cholestatic pattern; biliary imaging
2. A hepatocellular pattern with marked transaminase elevation suggesting acute hepatitis (viral, drug-induced such as paracetamol, ischaemic or autoimmune); the laboratory supports testing for hepatitis A IgM, HBsAg and anti-HBc IgM, hepatitis C RNA, hepatitis E where relevant, paracetamol level, and prothrombin time as the key marker of synthetic function and severity
3. Alcoholic hepatitis; AST:ALT ratio above 2
4. Haemolysis; haptoglobin

Answer: B. A cholestatic pattern has ALP raised proportionally more than transaminases, with GGT confirming the hepatic origin of ALP (bone ALP rises in growth, Paget's disease and vitamin D deficiency, the last extremely common in the Gulf).

Question 7

Which urine test is recommended to screen for and stage diabetic kidney disease?

1. Dipstick protein only
2. Urine albumin-to-creatinine ratio on a first-morning or random spot sample, with results categorised A1 (under 3 mg/mmol), A2 (3 to 30) and A3 (over 30), confirmed on two of three samples over three to six months because of biological variation, exercise, infection and menstrual contamination; dipstick protein misses moderately increased albuminuria
3. 24-hour urine protein in every patient
4. Urine microscopy alone

Answer: B. Albuminuria predicts cardiovascular as well as renal outcomes; the Gulf's diabetes prevalence makes annual ACR screening a quality indicator.

Electrolytes and acid-base

Question 8

A sample from a patient with a paraprotein of 60 g/L gives a sodium of 122 mmol/L on the indirect ion-selective electrode of the main analyser, but 138 mmol/L on the blood gas analyser's direct electrode. The explanation is:

1. The blood gas analyser is faulty
2. Pseudohyponatraemia from the electrolyte exclusion effect: indirect ISE methods dilute the sample and assume a normal plasma water fraction, so severe hyperproteinaemia or hyperlipidaemia gives a falsely low sodium, whereas direct ISE measures sodium activity in plasma water and is correct; the laboratory reports the direct result or a comment, and the same artefact affects hypertriglyceridaemic samples
3. True hyponatraemia; fluid restriction
4. Sample mix-up

Answer: B. Hyperglycaemia causes true dilutional hyponatraemia (sodium falls about 2.4 mmol/L per 5.5 mmol/L rise in glucose above normal), which is corrected by calculation, not by changing the method.

Question 9

Arterial blood gas: pH 7.25, PaCO₂ 3.2 kPa, bicarbonate 10 mmol/L, sodium 140, chloride 102, potassium 5.2, glucose 6, lactate 1.0, urea 30 mmol/L, creatinine 600 micromol/L. The interpretation is:

1. Normal anion gap acidosis from diarrhoea
2. High anion gap metabolic acidosis (gap 28) with appropriate respiratory compensation (expected PaCO₂ by Winter's formula about 3.0 to 3.5 kPa), most consistent with uraemic acidosis from renal failure given the normal glucose and lactate; other high-gap causes are ketoacidosis, lactic acidosis and toxic alcohols, for which an osmolal gap is calculated
3. Metabolic alkalosis
4. Mixed respiratory and metabolic acidosis

Answer: B. The osmolal gap (measured minus calculated osmolality, where calculated = 2Na + glucose + urea) above about 10 mOsm/kg suggests methanol or ethylene glycol; the delta ratio helps detect mixed disorders.

Question 10

A patient has a calcium of 1.95 mmol/L with an albumin of 22 g/L. The laboratory's interpretation and preferred follow-up are:

1. True hypocalcaemia; give intravenous calcium
2. Adjusted calcium of about 2.31 mmol/L (adding 0.02 mmol/L for each g/L of albumin below 40, using the laboratory's own validated formula), so the total calcium is low because of hypoalbuminaemia; ionised calcium on a blood gas analyser is the preferred measurement in critical illness, abnormal pH and after transfusion, since adjustment formulas perform poorly there
3. Hyperparathyroidism; PTH
4. Vitamin D deficiency; no action

Answer: B. PTH, phosphate, magnesium, vitamin D and alkaline phosphatase complete the work-up of true hypocalcaemia; magnesium deficiency causes resistant hypocalcaemia.

Diabetes, lipids and cardiac markers

Question 11

A patient with sickle cell trait has an HbA1c of 5.2% but fasting glucose values of 9 to 11 mmol/L. The laboratory should advise:

1. The patient does not have diabetes
2. That HbA1c may be unreliable in haemoglobin variants, haemolytic anaemia, recent transfusion, iron deficiency (falsely high) and reduced red cell survival (falsely low), depending on the assay method; the laboratory's HbA1c method interference profile is checked, and diagnosis relies on glucose criteria (fasting glucose of 7.0 mmol/L or more, or an oral glucose tolerance test), with fructosamine or glycated albumin as alternative monitoring markers; HbA1c assays should be NGSP-certified and IFCC-traceable and reported in both % and mmol/mol
3. Repeat HbA1c in a month
4. Use random glucose only

Answer: B. Haemoglobinopathy prevalence in the Gulf makes this a regular question; some boronate-affinity and HPLC methods handle variants differently.

Question 12

Which statement about lipid testing and reporting is correct?

1. Fasting is mandatory for every lipid profile
2. Non-fasting samples are acceptable for routine risk assessment, with fasting repeated if triglycerides exceed about 4.5 mmol/L; LDL cholesterol is calculated (Friedewald, or newer equations such as Sampson or Martin-Hopkins that remain valid at higher triglycerides) or measured directly, non-HDL cholesterol is reported as a secondary target, and lipoprotein(a) is measured at least once in a lifetime for risk assessment; results are interpreted against risk-based targets, not reference intervals
3. Friedewald is valid at any triglyceride level
4. HDL is the primary treatment target

Answer: B. Familial hypercholesterolaemia is more common in consanguineous Gulf populations, so very high LDL in young adults prompts family cascade testing.

Question 13

A patient with chest pain has a high-sensitivity troponin T of 9 ng/L at presentation and 11 ng/L at one hour, with a 99th percentile of 14 ng/L. The laboratory's role in the interpretation is:

1. Reporting the result as positive because it rose
2. Supporting a validated rapid rule-out algorithm (for example ESC 0/1-hour), in which very low baseline values or small absolute changes below the assay-specific delta make myocardial infarction unlikely, while values above the 99th percentile with a significant rise or fall indicate acute myocardial injury; the laboratory reports in whole ng/L, defines sex-specific 99th percentiles where validated, ensures turnaround within 60 minutes, and advises on chronic elevations in renal failure, heart failure and myocarditis
3. Using CK-MB instead
4. Repeating at 24 hours only

Answer: B. Macrotroponin and heterophile antibodies cause persistent unexplained elevations that the laboratory investigates with dilution or blocking studies.

Endocrine and tumour markers

Question 14

Thyroid function tests show TSH 0.05 mU/L, free T4 28 pmol/L and free T3 9 pmol/L in a patient taking biotin supplements. The laboratory should consider:

1. Reporting overt hyperthyroidism without comment
2. Biotin interference in streptavidin-biotin immunoassays, which produces falsely low TSH and falsely high free hormones mimicking hyperthyroidism (and false results in troponin, hCG and other assays); the laboratory asks about supplements, repeats testing after biotin is stopped for 48 to 72 hours or uses an unaffected method, and comments on the result; other interferences include heterophile antibodies, macro-TSH and assay-specific thyroid hormone autoantibodies
3. Thyroid storm
4. Pituitary adenoma

Answer: B. A low TSH with low free T4 suggests central hypothyroidism or non-thyroidal illness; a raised TSH with raised free T4 suggests a TSH-secreting adenoma, thyroid hormone resistance or interference.

Question 15

Which statement about tumour markers reflects appropriate laboratory and clinical use?

1. CA 125 is a reliable screening test for ovarian cancer in the general population
2. Most tumour markers (CEA, CA 125, CA 19-9, CA 15-3) lack the sensitivity and specificity for population screening and are used for monitoring treatment response and recurrence in diagnosed cancer, with PSA used in shared-decision screening and AFP with ultrasound for hepatocellular carcinoma surveillance in cirrhosis; results are interpreted on the same assay over time because methods differ, and benign causes (cholestasis for CA 19-9, endometriosis for CA 125, smoking for CEA) are recognised; hCG is used for germ cell tumours and gestational trophoblastic disease
3. CA 19-9 is diagnostic of pancreatic cancer
4. Markers from different assays are interchangeable

Answer: B. The hook effect in sandwich immunoassays can give falsely low results at very high concentrations (hCG, PSA, prolactin), detected by dilution.

Question 16

A woman has a prolactin of 2,500 mU/L with no symptoms, normal menses and a normal pituitary MRI. The laboratory investigation is:

1. Report hyperprolactinaemia and refer for dopamine agonist therapy
2. Screen for macroprolactin by polyethylene glycol precipitation, because biologically inactive prolactin-immunoglobulin complexes cause raised results in a significant minority of samples and lead to unnecessary imaging and treatment; the laboratory reports monomeric prolactin after precipitation, and also considers stress, drugs (antipsychotics, metoclopramide), hypothyroidism and renal failure as causes of true elevation
3. Repeat the same assay
4. Measure growth hormone

Answer: B. Macroprolactin screening is recommended for all hyperprolactinaemic samples in many guidelines.

Therapeutic drugs, point-of-care and screening

Question 17

A trough vancomycin level is requested. The laboratory should advise on sampling and interpretation as follows:

1. Any random time is acceptable
2. Sample immediately before the next dose at steady state (after about four doses), document the exact time of the last dose and the sample, and interpret with renal function; current guidance favours AUC-guided dosing (AUC/MIC 400 to 600) using Bayesian software, with troughs of 15 to 20 mg/L as the older target; similar timing rules apply to aminoglycosides (peak and trough or extended-interval nomograms), digoxin (at least six hours post-dose), lithium (12 hours post-dose), phenytoin (with albumin correction) and tacrolimus (trough)
3. Peak levels are more useful than troughs for vancomycin
4. Sampling time does not affect interpretation

Answer: B. Mistimed samples are the commonest cause of misleading drug levels; the laboratory rejects or comments on samples without timing information.

Question 18

The hospital wants to deploy point-of-care glucose and blood gas analysers on wards. The laboratory's governance role includes:

1. No role; the ward owns the devices
2. A point-of-care committee led by the laboratory with device selection and validation against the central laboratory, operator training and competency with lockout for untrained users, quality control schedules and external quality assessment, connectivity to the laboratory information system for result capture and patient identification, maintenance and reagent lot management, incident reporting and audit, in line with ISO 22870 and accreditation requirements; glucose meters are restricted in critically ill patients where interferences and perfusion affect accuracy
3. Training only
4. Purchasing only

Answer: B. Point-of-care errors are a recognised patient safety risk; Gulf accreditation bodies inspect POCT programmes as part of laboratory accreditation.

Question 19

A newborn screening result shows a markedly raised TSH on a dried blood spot taken at 72 hours. The laboratory's responsibilities are:

1. Wait for the routine clinic visit
2. Immediate recall of the infant through the screening programme for confirmatory serum TSH and free T4, with treatment of congenital hypothyroidism started within the first two weeks of life to protect neurodevelopment; the laboratory manages the screening algorithm, cut-offs and timeliness indicators, and Gulf programmes screen for an expanded panel including congenital hypothyroidism, congenital adrenal hyperplasia, phenylketonuria and other amino acid, organic acid and fatty acid oxidation disorders by tandem mass spectrometry, G6PD deficiency and haemoglobinopathies, because consanguinity raises the prevalence of inherited metabolic disorders
3. Repeat the dried blood spot in a month
4. No action; TSH is unreliable in newborns

Answer: B. Samples taken before 24 to 48 hours of age give false TSH results; preterm infants need repeat screening.

Question 20

A critical value of glucose 1.6 mmol/L is obtained from a ward sample at 02:00. The correct laboratory procedure is:

1. Report electronically and continue
2. Verify the result (sample integrity, delta check, repeat if indicated), telephone the result immediately to a responsible clinician, use read-back to confirm the value and patient identity, document the time, the person informed and the caller, and escalate if no responsible person is reached within the defined time; critical value lists and times are set with clinicians and audited under accreditation standards
3. Leave a message for the morning staff
4. Report only to the pathologist

Answer: B. Critical value communication is a patient safety goal; failures are among the commonest findings in laboratory accreditation surveys.

How to practise

• Know the artefacts and interferences: haemolysis, EDTA contamination, pseudohyponatraemia, biotin, heterophile antibodies, macroprolactin, HbA1c variants, the hook effect.
• Master quality control and method evaluation: Westgard rules, sigma metrics, verification elements, reference intervals, POCT governance.
• Interpret the common profiles: renal, liver, electrolytes and acid-base, diabetes, lipids, troponin algorithms, thyroid patterns, tumour markers, drug levels.
• Practise under time in the Clinical Biochemistry Specialist bank, the Clinical Scientist bank or the Clinical Biochemistry Technologist bank (5,000 explained questions in 24 chapters), using the error-log method.

Related sets: lab technologist questions, haematopathology questions, medical microbiology questions and fluid and electrolyte questions.

Frequently asked questions

How many questions are in the Prometric clinical biochemistry exam?

Typically 100 to 150 single-best-answer MCQs in up to three hours, with a pass mark of about 60%, varying by authority and title.

Which clinical chemistry topics come up most?

Pre-analytical errors and interferences, quality control and method validation, renal and liver profiles, electrolytes and acid-base, HbA1c and diabetes testing, troponin, thyroid patterns and critical value communication.

Is the technologist exam different from the specialist exam?

The technologist paper emphasises analysers, sample handling, quality control and safety; the specialist paper adds clinical interpretation, method evaluation and laboratory management. The core content overlaps.

Does the exam include calculations?

Yes. Expect anion gap, osmolal gap, adjusted calcium, eGFR interpretation, LDL calculation, sigma metrics and dilution calculations.

Are these real exam questions?

No. They are original practice questions written to the published blueprint. Real exam content is confidential.