Investigation is warranted if there is clinical concern, or symptoms are worsening or interfering with function.
Blood tests and radiographs will be normal with mechanical back pain.
HLA B27 has an association with inflammatory back pain but is present in many healthy individuals and is therefore not diagnostic.
MRI scan of the spine to include sacroiliac joints and using Gadolinium may be indicated to exclude pathology and is more useful in adolescents as radiographs may be normal.
Radiographs including oblique views may be indicated to exclude spondylolysis / listhesis although further imaging may be needed. Radiographs are not helpful to exclude sacroiliitis and may be normal.
Management of mechanical back pain is physiotherapy, advice on posture and carrying heavy loads (e.g. school bags) and encouraging activity (swimming is ideal) and weight loss if appropriate. Hamstring stretches and advice on foot wear may be helpful.