MSRA MSRA Data Interpretation 1 — Questions and Answers
Question 1: A patient has Na⁺ 128 mmol/L, serum osmolality 258 mOsm/kg, urine osmolality 620 mOsm/kg, and urine Na⁺ 55 mmol/L. She takes an SSRI. What is the most likely cause?
- Psychogenic polydipsia
- Hypothyroidism
- SIADH (Correct answer)
- Adrenal insufficiency
Correct answer: SIADH
Low serum osmolality with inappropriately concentrated urine and elevated urine sodium in the context of SSRI use is diagnostic of SIADH.
Question 2: ABG shows: pH 7.28, PaCO₂ 52 mmHg, HCO₃⁻ 24 mmol/L, PaO₂ 58 mmHg on air. What is the primary disorder?
- Metabolic acidosis
- Respiratory alkalosis
- Respiratory acidosis (Correct answer)
- Mixed metabolic and respiratory acidosis
Correct answer: Respiratory acidosis
The low pH with elevated PaCO₂ and normal bicarbonate indicates an acute respiratory acidosis with inadequate renal compensation, consistent with acute respiratory failure.
Question 3: A 60-year-old woman has K⁺ 2.8 mmol/L, Na⁺ 142 mmol/L, Cl⁻ 88 mmol/L, and HCO₃⁻ 38 mmol/L. She takes furosemide. What is the diagnosis?
- Renal tubular acidosis
- Metabolic alkalosis with hypokalaemia (Correct answer)
- Respiratory alkalosis
- Normal anion gap metabolic acidosis
Correct answer: Metabolic alkalosis with hypokalaemia
Elevated bicarbonate with hypokalaemia and hypochloraemia in a patient on loop diuretics is classic contraction metabolic alkalosis from volume and chloride loss.
Question 4: A 50-year-old male has: Hb 95 g/L, MCV 72 fL, serum ferritin 8 µg/L, TIBC 68 µmol/L. What is the diagnosis?
- Anaemia of chronic disease
- Vitamin B12 deficiency
- Iron deficiency anaemia (Correct answer)
- Thalassaemia trait
Correct answer: Iron deficiency anaemia
Microcytic anaemia with low ferritin and elevated TIBC confirms iron deficiency anaemia; ferritin is the most sensitive marker of iron stores.
Question 5: Troponin I at 3 hours is 0.06 µg/L (reference <0.04) and at 6 hours is 0.22 µg/L. ECG shows no ST changes. How should this rise be interpreted?
- Likely type 2 MI from demand ischaemia only
- Non-ST elevation myocardial infarction (NSTEMI) requiring ACS management (Correct answer)
- Laboratory error — repeat in 24 hours
- Stable angina — discharge with outpatient follow-up
Correct answer: Non-ST elevation myocardial infarction (NSTEMI) requiring ACS management
A rising troponin pattern (delta change >20% over 3–6 hours) with symptoms consistent with ACS confirms NSTEMI requiring antiplatelet therapy and cardiology input.
Question 6: LFTs show: ALP 480 U/L, GGT 510 U/L, ALT 65 U/L, bilirubin 55 µmol/L, albumin 38 g/L. What pattern do these results suggest?
- Hepatocellular injury
- Cholestatic liver disease (Correct answer)
- Acute hepatitis
- Hepatic synthetic failure
Correct answer: Cholestatic liver disease
Disproportionate elevation of ALP and GGT relative to aminotransferases, with raised bilirubin, is the hallmark of a cholestatic (obstructive) pattern of liver disease.
MSRA MSRA Data Interpretation 1
A patient has Na⁺ 128 mmol/L, serum osmolality 258 mOsm/kg, urine osmolality 620 mOsm/kg, and urine Na⁺ 55 mmol/L.
She takes an SSRI.
What is the most likely cause?