The treating team, after taking a thorough medical history and making a thorough examination

of the patient, should undertake the following investigations under the guidance of a haematologist.

Tests that are always indicated

Blood and urine tests to assess for MM and MM- defining events:

• full blood count, differential and blood film
• urea and electrolytes, calcium, phosphate, magnesium, urate
• liver function test, albumin
• beta-2 microglobulin, LDH, C-reactive protein
• serum protein electrophoresis and immunofixation
• serum free light chain
• 24-hour urine collection: protein excretion, creatinine clearance, Bence Jones protein
• bone marrow aspirate and trephine with:
  • morphology; immunohistochemistry: CD138
  • cytogenetic assessment (success rate of cytogenetic assessment falls at lower levels of marrow plasmacytosis e.g. < 15%)
  • FISH, the minimum requested panel should include: t(4;14), t(14;16), t(11;14), 17p del, 1q21 amplification
  • flow cytometry with the following minimal panel: CD138, CD19, CD56, kappa and lambda light chain expression.

Whole-body low-dose CT skeletal survey

Whole-body low-dose CT skeletal survey is recommended as the first-line imagery in all MM cases (both suspected and confirmed). It is more sensitive than an x-ray skeletal survey at detecting bone lytic lesions, and recent improvements in CT technology mean that the effective radiation doses are now similar to x-ray (Hillengass et al. 2019).

Tests that are indicated in selected cases

• Whole body (if not whole spine and pelvis) MRI
• To assess for MM lesions in patients with a histological diagnosis of MM but negative or inconclusive CT skeletal survey
• To confirm suspected spinal cord compression, nerve impingement or paraspinal soft tissue plasmacytoma in patients with back pain
• PET-CT

– Is particularly useful for patients with extramedullary disease or oligo/non-secretory myeloma

• Bone densitometry

– When osteoporosis is suspected

• Image-guided biopsy of the affected bone or soft tissue area

– Use if bone marrow aspirate and trephine shows less than 5 per cent of clonal plasma cells