Disease or condition	Laboratory tests	Radiographs
Back strain	No abnormalities	Usually negative
		Radiographs may show incidental spondylotic changes.
Acute disc herniation	If testing is timed properly, positive findings for electrodiagnostic studies in the presence of root entrapment	Possibly, narrowed intervertebral disc spaces on radiographs
		CT and MRI can reveal level and degree of herniation.
		Myelography localizes site of disc herniation and the presence of root entrapment.
Osteoarthritis	ESR and WBC count plus differential typically normal	Asymmetric narrowing of joint space
		Sclerotic subchondral bone
		Marginal osteophyte formation
Spondylolisthesis	No abnormalities	Abnormal intervertebral movement on radiographs obtained with spine in flexion and extension
		Radiographs may reveal pars defect.
		Bone scans can reveal pars defect not visible on radiographs.
Ankylosing spondylitis	ESR may be elevated	Radiographs of pelvis are positive for sacroiliac joint sclerosis and narrowing.
	Mild anemia possible
	Positive human leukocyte antigen-B27 assay in 90 percent of affected patients	Bone scans are useful for demonstrating increased activity in sacroiliac joints, facets or costovertebral joints.
Infection	Elevated ESR; WBC count may be normal	Radiographs may show vertebral end-plate erosion, decreased intervertebral disc height, changes indicative of bony erosion and reactive bone formation.
	Blood culture or tuberculin test may be positive
		Gallium citrate scanning or indium-labeled leukocyte imaging may be positive.
Malignancy	Anemia	Radiographs may show bony erosion or blastic lesions.
	Increased ESR	Bone scans are useful for early demonstration of blastic lesions.
	Prostate-specific antigen or alkaline phosphatase level may be elevated	CT localizes cortical lesions earlier than radiographs.
		MRI is useful for demonstrating soft tissue tumors involving the spinal cord.