What labs should be checked in a patient with osteoporosis?

Laboratory Workup for Patients with Osteoporosis

In patients with osteoporosis, a comprehensive laboratory evaluation should include basic metabolic tests, vitamin D assessment, and targeted testing for secondary causes to guide appropriate management and treatment decisions.

Basic Laboratory Tests (First-Line)

• Serum calcium (corrected for albumin) and phosphate to assess bone metabolism and identify abnormalities 1, 2
• 25-hydroxyvitamin D level to identify vitamin D deficiency, which is common in osteoporosis 2
• Albumin or total protein to correctly interpret calcium levels 1, 2
• Serum creatinine to assess kidney function, particularly important before initiating certain osteoporosis medications 2
• Alkaline phosphatase (ALP) to evaluate bone turnover and identify potential metabolic bone disorders 1

Tests to Identify Secondary Causes

• Thyroid function tests (TSH) to rule out hyperthyroidism, which can accelerate bone loss 1, 2
• Intact parathyroid hormone (iPTH) if calcium levels are abnormal to evaluate for hyperparathyroidism 1, 2
• Sex hormone levels based on patient characteristics:
  • For men: testosterone, sex hormone-binding globulin (SHBG), luteinizing hormone (LH), follicle-stimulating hormone (FSH) 1, 2
  • For women with menstrual irregularities: estradiol, LH, FSH 1

Additional Tests Based on Clinical Suspicion

• Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) if inflammatory conditions are suspected 1, 2
• Liver function tests (GOT, GPT, gamma-GT) to identify liver disease 1, 2
• Celiac disease screening (anti-endomysial, anti-transglutaminase antibodies) in patients with risk factors or suspected malabsorption 1
• Serum protein electrophoresis to rule out multiple myeloma in patients with unexplained osteoporosis 3, 4
• Fasting glucose and HbA1c to evaluate for diabetes 1

Bone Turnover Markers (Optional)

• Serum procollagen type I N-terminal propeptide (s-PINP) as the preferred bone formation marker 1, 5
• Serum C-terminal telopeptide of type I collagen (s-CTX) as the preferred bone resorption marker 5, 4
• These markers may be useful for monitoring treatment response but are not routinely recommended for initial diagnosis 5, 4

Special Considerations

• More extensive laboratory evaluation is warranted in premenopausal women or men younger than 50 years with osteoporosis, as this often indicates an underlying secondary cause 1
• Patients with fragility fractures despite normal bone mineral density should be referred to a specialist for further evaluation 1
• Patients with unexplained laboratory abnormalities (high/low ALP, low phosphorus) should be referred to an osteoporosis specialist 1
• Patients with recurrent fractures or continued bone loss despite therapy should undergo more comprehensive evaluation 1

Diagnostic Imaging

• Dual-energy X-ray absorptiometry (DXA) of lumbar spine and femoral neck remains the gold standard for diagnosis of osteoporosis 1, 2
• Lateral spine imaging should be considered to identify vertebral fractures, which may be asymptomatic 2

Remember that laboratory testing should be interpreted in the context of the patient's clinical presentation, risk factors, and bone mineral density results to guide appropriate management decisions.