Can You Start Forteo in a Patient with Elevated Alkaline Phosphatase?
You should NOT start Forteo (teriparatide) in a patient with elevated alkaline phosphatase until you have determined the cause of the elevation and ruled out contraindications, particularly Paget's disease and bone malignancy. 1
Critical Contraindications Related to Elevated ALP
Teriparatide is absolutely contraindicated in several conditions that present with elevated alkaline phosphatase:
- Paget's disease of bone is an absolute contraindication to teriparatide therapy, as the drug's anabolic effects could worsen the already excessive bone turnover characteristic of this condition 2, 1
- Bone malignancy or skeletal metastases represent absolute contraindications due to teriparatide's black box warning for potential osteosarcoma risk 1
- Unexplained elevation of alkaline phosphatase itself is listed as a contraindication in FDA labeling, as it may indicate underlying Paget's disease or malignancy 1
Mandatory Workup Before Considering Teriparatide
Before initiating teriparatide in any patient with elevated ALP, you must complete this diagnostic evaluation:
Determine the Source of ALP Elevation
- Measure bone-specific alkaline phosphatase (B-ALP) to confirm bone origin, as this is more specific than total ALP 2
- Obtain liver function tests including GGT—if GGT is normal, this strongly indicates a non-hepatic (bone) source 2
- Check serum calcium, phosphate, and PTH to assess for metabolic bone disorders 2
- Measure 25-hydroxyvitamin D levels to evaluate for vitamin D deficiency and osteomalacia 3, 2
Rule Out Malignancy
- Perform bone scintigraphy as the primary imaging modality if malignancy is suspected or if ALP remains unexplained 2, 4
- Obtain targeted radiographs to assess for lytic lesions or other concerning bone pathology 2, 4
- Measure lactate dehydrogenase (LDH) as elevated levels correlate with bone malignancy and metastatic disease 4
Rule Out Paget's Disease
- Clinical assessment for bone pain, deformity, or warmth over affected bones 5
- Radiographic evaluation for characteristic findings of Paget's disease (cortical thickening, trabecular coarsening) 5
- Bone scan if Paget's disease is suspected clinically 2
When Teriparatide May Be Appropriate
If your workup reveals a benign cause of elevated ALP, teriparatide may be considered:
- Post-fracture healing causes physiologic ALP elevation that typically normalizes within 2-3 months; teriparatide can be initiated once healing is confirmed and ALP is trending down 2
- Vitamin D deficiency/osteomalacia should be corrected first with vitamin D supplementation before starting teriparatide 3, 2
- Hypophosphatasia is a rare exception where teriparatide has been used successfully despite low baseline ALP, though this represents a unique clinical scenario 6
Important Clinical Caveat
One case report documented extreme ALP elevation (6480 U/L) during teriparatide treatment in a young patient with glucocorticoid-induced osteoporosis, suggesting potential osteoblast hyperactivation 7. While this is rare, it underscores the importance of:
- Monitoring ALP levels every 4-6 weeks during the first few months of teriparatide therapy 2
- Discontinuing teriparatide immediately if ALP rises dramatically or unexpectedly during treatment 7
- Exercising particular caution in younger patients or those with complex medical conditions 7
Alternative Treatment Options
If teriparatide is contraindicated or the elevated ALP remains unexplained, consider these alternatives:
- Bisphosphonates (alendronate 70mg weekly, risedronate 35mg weekly, or zoledronic acid 5mg IV annually) are first-line therapy for osteoporosis and do not carry the same contraindications 1
- Denosumab (60mg subcutaneous every 6 months) works through a different mechanism and may be appropriate 1
Bottom line: Do not start Forteo until you have a clear explanation for the elevated ALP and have definitively ruled out Paget's disease and malignancy.