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Vitamin D Deficiency- Tiredness with Abnormal Blood Results: A PLAB 2 Mock

Summary:

This scenario involves a 55-year-old female patient presenting with tiredness and test results showing vitamin D and calcium deficiency. The candidate must take a structured history, interpret blood tests, rule out differentials, and formulate an appropriate management plan while addressing patient concerns about hypothyroidism.



Key Points:


Presenting Complaint & Differential Diagnosis

  • Main symptom: Tiredness

  • Differentials to consider:

    • Anemia (check Hb levels)

    • Hypothyroidism (check TSH, T4)

    • Depression

    • Electrolyte imbalance (e.g. hyponatremia)

    • Vitamin deficiencies (B12, D)

    • Chronic kidney disease, malignancy


History Taking

  • Confirm full name and age as per candidate information.

  • Ask:

    • Onset, duration, diurnal variation of tiredness

    • Impact on daily life and activities

    • Mood changes (to rule out depression)

    • Dietary habits (vitamin D, calcium-rich foods)

    • Sunlight exposure

    • Past medical history (CKD, liver disease, malabsorption conditions)

    • Neurological symptoms (tingling, numbness, muscle weakness or spasms)

    • Bowel habits (constipation – rule out colon cancer or malabsorption causes)

    • Any recent weight changes


Blood Results Interpretation

  • Normal results: Hb, TSH, B12

  • Abnormal results:

    • Low vitamin D (25-hydroxy vitamin D)

    • Low calcium


Important Considerations:

  • Vitamin D metabolism:

    • Requires dietary intake (oily fish, egg yolk, fortified cereals) and sunlight exposure for activation.

    • Hydroxylated in the liver (25-hydroxylation) then activated in the kidney (1-hydroxylation).

  • Vitamin D deficiency leads to reduced calcium absorption from the gut → secondary hypocalcemia.

  • Rule out causes such as:

    • Poor dietary intake

    • Lack of sun exposure

    • Liver or kidney dysfunction

    • Malabsorption conditions (e.g. IBD, celiac disease)

  • Always explain all blood results to the patient, not just abnormal ones.



Diagnostic Approach:

  1. Confirm full identity.

  2. Elicit presenting symptoms, duration, and impact.

  3. Ask targeted systemic review:

    • Mood and sleep pattern

    • GI symptoms: constipation, appetite changes

    • Neurological symptoms

    • Musculoskeletal symptoms: bone pain, falls

  4. Interpret blood tests systematically:

    • Hb → Anemia

    • TSH → Hypothyroidism

    • B12 → Neurological causes

    • Sodium → Electrolyte imbalance

    • Calcium & Vitamin D → Bone metabolism



Management:


Immediate Plan

  • Explain findings clearly and sequentially:

    • “Your hemoglobin, thyroid and B12 levels are normal, ruling out anemia and hypothyroidism. However, your vitamin D and calcium are low.”

  • Education & Advice:

    • Role of vitamin D in bone health and calcium absorption.

    • Sources: Diet (oily fish, egg yolk, fortified foods), sunlight exposure (15-20 mins daily).

  • Treatment:

    • Loading dose of vitamin D for 6 weeks followed by maintenance dose.

    • Calcium supplementation if symptomatic or persistently low.

  • Safety Netting:

    • Warn about worsening tiredness, confusion, muscle cramps, severe constipation, unsteadiness.

  • Follow Up:

    • Recheck vitamin D and calcium levels after treatment.

    • If persistent deficiency despite treatment → refer to gastroenterology to rule out malabsorption or gut pathology.

  • Provide information leaflets and ensure understanding.


Communication Skills:

  • Warm greeting and professional introduction.

  • Clarify patient’s concerns about hypothyroidism with reassurance.

  • Use simple language to explain metabolism and treatment plans.

  • Empathy: Validate concerns, address misconceptions sensitively.

  • Signposting before changing questions or moving to management.

  • Maintain non-verbal attentiveness and active listening throughout.


Ethical Considerations:

  • Maintain patient autonomy with informed decision-making.

  • Avoid over-promising investigations or referrals without indication.

  • Refer to seniors or specialists if uncertain about the cause of deficiency.


Additional Resources:

  • NICE guidelines on Vitamin D deficiency management

  • GMC Good Medical Practice for safe prescribing

  • RCGP guidelines on chronic tiredness and differential diagnosis

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