20th August 2020

A 45-year old man comes to visit his GP complaining of tiredness and lethargy for 3 months

A 45-year old man comes to visit his GP complaining of tiredness and lethargy for 3 months. His GP decides to do some blood tests. The relevant results are below:

• Hb: 120 (115-165g/L)
• WCC: 5.2×10⁹ (3.6-11.0×10⁹/L)
• Platelets: 144×10⁹ (140-400×10⁹/L)
• Na: 135 (133-146mmol/L)
• K: 4.2 (3.5-5.3mmol/L)
• Ca (adjusted): 2.4 (2.2-2.6mmol/L)
• Urea: 7.2 (2.5-7.8mmol/L)
• Creatinine: 48 (45-84μmol/L)
• HbA1c: 35 (<42mmol/mol)
• Vitamin B12: 650 (180-1000pg/ml)
• Folate: 5.3 (>4.0 ng/ml)
• Transferrin saturation: 75 (25-45%)
• TSH: 2.3 (0.4-4.0mU/L)
• Free T4: 12 (9-24pmol/L)
• Free T3: 4.8 (3.5-7.8pmol/L)
• Cortisol (random): 338 (137-429 nmol/L)

Given the blood test results, which is the most likely diagnosis?

Select the SINGLE most appropriate option from the list below. Select ONE option only.