MRCP Part 1 Clinical Sciences 2 — Questions and Answers
Question 1: A patient on warfarin has an INR of 8.5 with no active bleeding. According to NICE guidelines, what is the most appropriate management?
- Stop warfarin and give oral vitamin K 1-5 mg (Correct answer)
- Continue warfarin at a reduced dose
- Give fresh frozen plasma
- Give intravenous vitamin K 10 mg
Correct answer: Stop warfarin and give oral vitamin K 1-5 mg
For an INR >8.0 without major bleeding, NICE recommends stopping warfarin and administering 1-5 mg of oral vitamin K. FFP or IV vitamin K at high doses is reserved for major bleeding. The INR should be rechecked within 24 hours.
Question 2: Which acid-base disturbance is most commonly seen in pyloric stenosis?
- Hypochloraemic hypokalaemic metabolic alkalosis (Correct answer)
- Metabolic acidosis
- Respiratory alkalosis
- Mixed respiratory and metabolic acidosis
Correct answer: Hypochloraemic hypokalaemic metabolic alkalosis
Pyloric stenosis causes persistent vomiting of gastric acid (HCl), leading to loss of hydrogen and chloride ions. The kidneys compensate by retaining hydrogen ions and excreting potassium, resulting in hypochloraemic hypokalaemic metabolic alkalosis.
Question 3: In autosomal dominant polycystic kidney disease (ADPKD), which gene mutation accounts for approximately 85% of cases?
- PKD1 on chromosome 16 (Correct answer)
- PKD2 on chromosome 4
- WT1 on chromosome 11
- NPHS1 on chromosome 19
Correct answer: PKD1 on chromosome 16
PKD1 mutations on chromosome 16 account for approximately 85% of ADPKD cases and are associated with more severe disease and earlier onset of end-stage renal failure compared to PKD2 mutations on chromosome 4.
Question 4: Which cytokine is most important in the pathogenesis of septic shock?
- Tumour necrosis factor alpha (TNF-alpha) (Correct answer)
- Interleukin-4
- Interleukin-10
- Interferon-gamma
Correct answer: Tumour necrosis factor alpha (TNF-alpha)
TNF-alpha is the key pro-inflammatory cytokine released by macrophages in response to bacterial lipopolysaccharide. It triggers the inflammatory cascade leading to vasodilation, increased vascular permeability, myocardial depression, and multi-organ failure in septic shock.
Question 5: A 55-year-old man has a plasma osmolality of 295 mOsm/kg but his urine remains maximally dilute at 80 mOsm/kg despite water deprivation. After desmopressin administration, urine osmolality rises to 600 mOsm/kg. What is the diagnosis?
- Cranial diabetes insipidus (Correct answer)
- Nephrogenic diabetes insipidus
- Primary polydipsia
- SIADH
Correct answer: Cranial diabetes insipidus
The failure to concentrate urine despite water deprivation (raised plasma osmolality) indicates diabetes insipidus. The response to desmopressin (synthetic ADH) confirms the kidneys can respond, meaning the problem is insufficient ADH production — cranial diabetes insipidus.
Question 6: Which HLA type is most strongly associated with ankylosing spondylitis?
- HLA-B27 (Correct answer)
- HLA-DR4
- HLA-DR3
- HLA-B51
Correct answer: HLA-B27
HLA-B27 is present in over 90% of patients with ankylosing spondylitis, making it one of the strongest HLA-disease associations known. However, only about 5% of HLA-B27 positive individuals develop the condition.
MRCP Part 1 Clinical Sciences 2
A patient on warfarin has an INR of 8.5 with no active bleeding.
According to NICE guidelines, what is the most appropriate management?