30th April 2024

A 17-year-old male with known sickle cell disease presents with severe pain in his lower back and legs, which started a few hours ago.

A 17-year-old male with known sickle cell disease presents with severe pain in his lower back and legs, which started a few hours ago. He has no fever or other symptoms. His last pain crisis was 6 months ago. He has been taking hydroxyurea regularly.

Investigations:

Haemoglobin: 75 g/L (130–170)

White cell count: 15 × 10⁹/L (4.0–11.0)

Platelets: 350 × 10⁹/L (150–400)

Reticulocyte count: 10% (0.5–2.0%)

Serum bilirubin: 30 μmol/L (< 21)

Lactate dehydrogenase (LDH): 450 IU/L (135–225)

Blood film: Numerous sickle cells, Howell-Jolly bodies

Which additional investigation is most appropriate to assess his current condition?