Master CPS - Endocrinology/Metabolic
for MSRA

What the MSRA Tests in CPS - Endocrinology/Metabolic

The MSRA CPS - Endocrinology/Metabolic section tests your ability to manage common endocrine and metabolic presentations in a UK primary care and emergency setting. You must demonstrate knowledge of diagnostic criteria (e.g., WHO for diabetes, NICE for osteoporosis), first-line pharmacological choices (e.g., metformin, levothyroxine, bisphosphonates), and acute management (e.g., DKA, adrenal crisis, thyrotoxic storm). Questions often present as clinical scenarios requiring you to select the most appropriate investigation, treatment escalation, or referral. Key guidelines include SIGN/NICE for diabetes, thyroid disease, and osteoporosis. You must also recognise red flags (e.g., pituitary apoplexy, phaeochromocytoma) and know when to refer to secondary care.

High-Yield Concepts

• Type 2 Diabetes Diagnosis and Management: Diagnosis: fasting glucose ≥7.0 mmol/L, HbA1c ≥48 mmol/mol (6.5%) on two occasions, or random glucose ≥11.1 mmol/L with symptoms. First-line: metformin (standard release 500 mg BD, titrate to 1 g BD) unless eGFR <30 or contraindicated. If HbA1c >58 mmol/mol (7.5%) on metformin, add SGLT2 inhibitor (e.g., dapagliflozin) or DPP-4 inhibitor (e.g., sitagliptin) based on comorbidities (NICE NG28).
• Diabetic Ketoacidosis (DKA) Management: Diagnosis: glucose >11.0 mmol/L, ketones >3.0 mmol/L (blood) or ++ on urine, pH <7.3. Fixed-rate insulin infusion 0.1 units/kg/hour (after 0.1 units/kg bolus if severe). Fluid: 1 L 0.9% NaCl over 1 hour, then 500 mL/hour for 4 hours, then 250 mL/hour. Monitor K+ hourly; replace if <5.5 mmol/L. Stop insulin when ketones <0.3 mmol/L and pH >7.3 (JBDS guidelines).
• Hypoglycaemia Management: Blood glucose <4.0 mmol/L. Conscious: 15-20 g fast-acting carbohydrate (e.g., 150-200 mL Lucozade, 5-6 dextrose tablets). Recheck in 10-15 minutes; repeat if still <4.0. Unconscious/convulsing: 1 mg glucagon IM/SC (if IV access, 50 mL 50% dextrose). Follow with long-acting carbohydrate (e.g., 2 biscuits, 200 mL milk) to prevent recurrence.
• Thyroid Function Interpretation: Primary hypothyroidism: high TSH, low FT4. Start levothyroxine 1.6 mcg/kg/day (typically 50-100 mcg daily in adults <60 years without heart disease). Target TSH 0.5-2.5 mIU/L. Subclinical hypothyroidism: TSH >10 mIU/L or TSH 4.5-10 with symptoms/positive TPO antibodies → treat. Hyperthyroidism: low TSH, high FT4/FT3. First-line: carbimazole 15-40 mg daily (or propylthiouracil in first trimester). Beta-blocker (propranolol 40 mg TDS) for symptoms.
• Osteoporosis Diagnosis and Treatment: Diagnosis: DXA scan T-score ≤ -2.5 at hip or spine (WHO). FRAX tool for 10-year fracture risk. Treatment: first-line oral bisphosphonate (alendronic acid 70 mg once weekly) with calcium/vitamin D supplementation. NICE TA464: denosumab 60 mg SC every 6 months if bisphosphonate intolerant/ineffective. Monitor with repeat DXA every 3-5 years.
• Adrenal Insufficiency and Crisis: Primary: low cortisol (<100 nmol/L at 8-9am), high ACTH, low aldosterone/renin. Short Synacthen test: 250 mcg tetracosactide IM/IV; cortisol <430 nmol/L at 30 min = failure. Crisis: hypotension, hypoglycaemia, hyponatraemia, hyperkalaemia. Treatment: hydrocortisone 100 mg IV stat, then 100 mg IV QDS; 0.9% NaCl 1 L over 1 hour, then 500 mL/hour. Always give steroids before ACTH stimulation in suspected crisis.
• Hypercalcaemia Workup: Most common cause: primary hyperparathyroidism (high PTH, low phosphate, normal/high calcium). Exclude malignancy (PTHrP, myeloma screen). Severe hypercalcaemia (corrected Ca >3.0 mmol/L): IV 0.9% NaCl 3-4 L/day, consider bisphosphonate (pamidronate 30-90 mg IV over 2-4 hours). Avoid thiazides and lithium. Check vitamin D levels; if low, treat after correcting calcium.
• Pituitary Tumours and Apoplexy: Prolactinoma: first-line dopamine agonist (cabergoline 0.25-0.5 mg twice weekly). Non-functioning adenoma: observe if <1 cm; surgery if >1 cm with chiasm compression. Apoplexy: sudden headache, visual loss, ophthalmoplegia, hypotension. Emergency: high-dose steroids (hydrocortisone 100 mg IV), urgent MRI, neurosurgical referral. Check all pituitary axes.

Common Traps in CPS - Endocrinology/Metabolic Questions

• Starting insulin in type 2 diabetes without first trying metformin and a second oral agent (e.g., SGLT2i/DPP-4i) unless HbA1c >86 mmol/mol (10%) with symptoms.
• Using urine ketones alone to rule out DKA; always check blood ketones (beta-hydroxybutyrate) for accuracy.
• Treating subclinical hypothyroidism with levothyroxine when TSH is 4.5-10 mIU/L and the patient is asymptomatic with negative TPO antibodies (NICE recommends monitoring only).
• Giving glucagon to a patient with known insulinoma or suspected sulphonylurea overdose without also giving IV dextrose (glucagon may be ineffective).
• Failing to give intravenous steroids before the ACTH stimulation test in suspected adrenal crisis (can precipitate crisis).
• Assuming a normal calcium level excludes hyperparathyroidism; check albumin-adjusted calcium and PTH simultaneously.

How to Revise CPS - Endocrinology/Metabolic for the MSRA

For CPS - Endocrinology/Metabolic on the MSRA, focus on acute presentations (DKA, hypoglycaemia, adrenal crisis, thyrotoxic storm) and chronic management algorithms (diabetes, thyroid, osteoporosis). Questions are typically scenario-based with multiple steps: you must choose the correct initial investigation (e.g., HbA1c vs OGTT), then the appropriate first-line drug, then the escalation pathway. Practise using NICE and SIGN guidelines for cut-off values (e.g., HbA1c thresholds for starting insulin, DXA T-scores for treatment). Also, be comfortable interpreting basic lab results (TSH, FT4, cortisol, calcium) and recognising red flags (e.g., visual field defects in pituitary tumours). Time management: allocate 1-2 minutes per question; skip and return if unsure.

Practise it: MedLumen has 50 CPS - Endocrinology/Metabolic questions for the MSRA, each with a full explanation and references.