MRCP Biochemistry: Vitamins & Trace Elements

TL;DR

For MRCP Part 1, vitamins and trace elements are tested through clinical recognition, not biochemical trivia. Focus on classic deficiency syndromes, fat-soluble vitamin toxicity, trace-element associations, and drug interactions. This guide summarises the examinable scope, common traps, and how to revise efficiently.

Why this matters

Vitamins and trace elements are often underestimated in MRCP Part 1 preparation, yet they appear regularly as short, clinically framed questions. The exam favours pattern recognition: unexplained anaemia, neuropathy, bone pain, cardiomyopathy, or bleeding disorders linked to nutritional deficiencies or excess states.

Unlike undergraduate biochemistry, MRCP Part 1 does not reward memorising pathways or daily requirements. Instead, it tests whether you can identify the right diagnosis from a vignette and understand how nutrition, disease, and drugs intersect. This article supports the core MRCP Part 1 overview and links directly to question practice using Free MRCP MCQs.

Scope of vitamins & trace elements in MRCP Part 1

You should expect questions in three main areas:

1. Deficiency syndromes – the most common format

2. Toxicity and excess – especially fat-soluble vitamins

3. Physiological roles and interactions – enzymes, transport, and drugs

Laboratory cut-offs are rarely required. Interpretation and association matter far more than numbers.

Five most tested subtopics

1. Fat-soluble vitamins (A, D, E, K)

Fat-soluble vitamins accumulate in the body, making toxicity a favourite exam theme.

• Vitamin A

  • Deficiency: night blindness, xerophthalmia

  • Excess: headache, hepatotoxicity, alopecia, pseudotumour cerebri

  • Key association: teratogenicity in pregnancy

• Vitamin D

  • Deficiency: osteomalacia, hypocalcaemia, secondary hyperparathyroidism

  • Excess: hypercalcaemia, nephrocalcinosis

  • Classic stem: chronic kidney disease with bone pain

• Vitamin K

  • Role: γ-carboxylation of clotting factors II, VII, IX, X

  • Deficiency: prolonged prothrombin time

  • Risk groups: neonates, cholestasis, prolonged antibiotic use

2. Water-soluble vitamins (B-complex and C)

These are commonly tested through neurological, dermatological, and haematological clues.

• Vitamin B1 (Thiamine)

  • Deficiency: Wernicke–Korsakoff syndrome

  • Associations: alcohol dependence, refeeding syndrome

• Vitamin B6 (Pyridoxine)

  • Deficiency: sideroblastic anaemia, peripheral neuropathy

  • Drug link: isoniazid

• Vitamin B12 vs folate

  • Both cause megaloblastic anaemia

  • Only B12 causes neurological deficits and raised methylmalonic acid

• Vitamin C

  • Deficiency: scurvy (bleeding gums, poor wound healing)

  • Role: collagen synthesis and iron absorption

3. Trace elements and enzymes

Trace elements are tested through their functional consequences, not absorption pathways.

Trace element	Main role	Classic association
Iron	Haemoglobin synthesis	Microcytic anaemia
Zinc	Wound healing, taste	Perioral rash, alopecia
Copper	Oxidative enzymes	Menkes (deficiency), Wilson disease (excess)
Selenium	Antioxidant enzymes	Cardiomyopathy
Iodine	Thyroid hormone synthesis	Goitre, hypothyroidism

4. Nutrition-related clinical scenarios

Common exam stems include:

• Long-term total parenteral nutrition → zinc, selenium, copper deficiency

• Alcohol dependence → thiamine and folate deficiency

• Malabsorption (coeliac disease, cholestasis) → fat-soluble vitamin deficiency

• Bariatric surgery → vitamin B12, iron, and vitamin D deficiency

5. Drug–vitamin interactions

These are frequent traps in MRCP Part 1.

• Isoniazid → vitamin B6 deficiency

• Methotrexate → folate antagonism

• Warfarin → vitamin K pathway interference

• Long-term proton-pump inhibitors → reduced vitamin B12 absorption

High-yield revision list

1. One signature symptom per vitamin

2. One toxicity clue for fat-soluble vitamins

3. One drug interaction per commonly tested vitamin

4. One trace element–disease link

5. One risk group for each major deficiency

Mastering these five layers covers the majority of exam questions.

Practical example (mini-case)

A 55-year-old man with chronic alcohol use presents with confusion, ataxia, and ophthalmoplegia. Blood tests show mild macrocytosis. What is the most appropriate immediate management?

Answer: Intravenous thiamine before glucose.

Explanation: This presentation is classic Wernicke encephalopathy due to vitamin B1 deficiency. Administering glucose before thiamine worsens neuronal injury. This scenario is repeatedly tested in MRCP Part 1.

Common pitfalls

• Confusing folate deficiency with vitamin B12 deficiency when neurological signs are present

• Forgetting that fat-soluble vitamins cause toxicity as well as deficiency

• Missing drug-induced deficiencies (e.g. isoniazid and B6)

• Over-focusing on laboratory values rather than clinical features

• Ignoring malabsorption as the unifying mechanism

Practical study-tip checklist

• Revise vitamins clinically, not biochemically

• Pair each vitamin with one disease and one drug

• Practise mixed questions using MRCP mock tests

• Review explanations carefully to spot recurring patterns

• Consolidate weak areas with targeted revision sessions

FAQs

Are vitamins and trace elements high yield for MRCP Part 1?

Yes. They appear frequently as short, clinically framed questions and are relatively easy marks with focused revision.

Do I need to memorise recommended daily allowances?

No. The exam focuses on deficiency, toxicity, and associations rather than nutritional guidelines.

How do I differentiate vitamin B12 from folate deficiency in questions?

Look for neurological features and risk factors such as pernicious anaemia or gastric surgery, which point to B12 deficiency.

Are trace elements tested on their own?

Usually not. They are integrated into clinical vignettes involving anaemia, cardiomyopathy, or poor wound healing.

Ready to start?

Use this guide as a framework, then reinforce it with question-based learning. Start from the MRCP Part 1 overview, practise systematically with Free MRCP MCQs, and assess readiness using full-length MRCP mock tests.

Sources

• MRCP(UK) Examination Blueprint: https://www.mrcpuk.org/mrcpuk-examinations/part-1

• British National Formulary (BNF): https://bnf.nice.org.uk

• NICE Clinical Knowledge Summaries: https://cks.nice.org.uk

• Kumar & Clark’s Clinical Medicine, Elsevier