What lab tests would you expect to be elevated in a patient with right hip pain, difficulty walking that improves with activity and worsens at night?

Laboratory Testing for Hip Pain with Night Worsening

In a patient with right hip pain, difficulty walking that improves with activity and worsens at night, you would NOT expect any specific lab elevation in the most common diagnoses (hip osteoarthritis, labral tears, or FAI syndrome), as these are primarily diagnosed through imaging and clinical examination rather than laboratory studies.

When Laboratory Testing IS Indicated

Laboratory tests are not routinely necessary for isolated hip pain unless systemic illness, infection, or inflammatory conditions are suspected 1. The clinical presentation described—pain improving with activity and worsening at night—is atypical for most hip pathology and should raise suspicion for alternative diagnoses.

Red Flag Scenarios Requiring Labs

If infection is suspected (septic arthritis or osteomyelitis), the following labs would be elevated:

• White blood cell count (WBC): Elevated in infectious processes 2, 3
• Erythrocyte sedimentation rate (ESR): Significantly elevated in septic arthritis 2, 3
• C-reactive protein (CRP): Markedly elevated in infection; CRP showed the highest sensitivity (1.00) for diagnosing infectious hip pathology 2, 3
• CRP/albumin ratio (CAR): Significantly higher in infectious rapid hip destruction, with specificity of 0.92 when combined 3

Clinical pearl: All children with septic arthritis had at least two of the following: fever, elevated ESR, and elevated CRP 2. This principle applies to adults as well.

If inflammatory arthropathy is suspected, obtain:

• ESR and CRP: Elevated in inflammatory conditions 1, 4
• Autoimmune serology (ANA, anti-dsDNA, rheumatoid factor): For systemic lupus erythematosus or rheumatoid arthritis 4

Nutritional Markers in Infectious Hip Disease

In cases of rapid hip destruction with suspected infection, nutritional markers show significant changes 3:

• Albumin: Significantly lower in infectious cases (sensitivity 1.00, specificity 0.73) 3
• Albumin to globulin ratio (AGR): Significantly lower 3
• Prognostic nutritional index (PNI): Significantly lower 3
• Geriatric nutritional risk index (GNRI): Significantly lower 3

The Typical Hip Osteoarthritis Scenario

For mechanical hip pathology (osteoarthritis, labral tears, FAI syndrome)—which is the most likely diagnosis given chronic hip pain—no laboratory abnormalities are expected 5, 6. These conditions are diagnosed through:

• Plain radiographs (AP pelvis and lateral hip): First-line imaging 5, 6, 1
• MRI without contrast: When radiographs are negative or equivocal 5, 6
• Physical examination: Pain with internal rotation strongly suggests intra-articular pathology 6, 1

Critical Diagnostic Pitfall

The pattern described (pain improving with activity, worse at night) is atypical for hip osteoarthritis, which typically worsens with activity and improves with rest 6. This presentation should prompt consideration of:

• Inflammatory arthropathy: Requires ESR, CRP, and autoimmune workup 1, 4
• Infection: Requires WBC, ESR, CRP, and possibly joint aspiration 1, 2
• Referred pain from spine: May require lumbar spine evaluation 6, 7
• Bone tumor or metastasis: May require advanced imaging 7

Practical Algorithm

1. Obtain inflammatory markers (ESR, CRP) and CBC if the clinical presentation is atypical or suggests systemic disease 1, 4
2. Start with plain radiographs regardless of lab results, as imaging is essential for diagnosis 5, 6, 1
3. Consider joint aspiration if fever, elevated WBC, ESR >40, or CRP >20 are present 2, 3
4. Proceed to MRI if radiographs are negative but clinical suspicion remains high 5, 6