Lim is a 65-year-old business owner who presents for review of blue fingers and nails, which he has become increasingly aware of over the past few months. 

Test your clinical know-how by taking the quiz below. If you select the wrong answer, have another go — you can try as many times as you like!

<p>Lim is a 65-year-old business owner who presents for review of blue fingers and nails, which he has become increasingly aware of over the past few months.</p><p>Lim is otherwise well. He has hypertension that is well controlled with ramipril.</p><p>Since the COVID-19 pandemic, he has also been taking regular supplements from a herbal medicine practitioner to help ward off infections and for joint health support, but he is not sure of the constituents.</p><p>He has no past history or known risk factors for VTE.</p><p>On examination, Lim appears well and comfortable, although the blue–grey discolouration is noted on his face, as well as his fingers and nails (pictured).</p><p>Vital signs are within normal limits. Cardiorespiratory examination is unremarkable; there is no calf tenderness or lower limb oedema.</p><p>ECG is normal as is initial FBC, biochemistry and chest X-ray.</p>

Dr Kate Kelso is a GP and medical editor at Australian Doctor.