Monitoring Parameters for Growth Hormone Replacement Therapy
Regular monitoring of specific clinical and laboratory parameters is essential for patients on growth hormone replacement therapy to ensure safety and efficacy.
Key Monitoring Parameters
Clinical Parameters (Every 3-6 Months)
- Growth and Development
- Stature/height
- Height velocity (particularly important in first year of treatment)
- Pubertal development
- Skeletal maturation (wrist radiography)
Laboratory Parameters (Every 3-6 Months)
- Metabolic Parameters
- Fasting blood glucose (monitor for glucose intolerance)
- Insulin levels (hyperinsulinemia may develop in first year)
- Thyroid function (TSH and free T3)
- Calcium and phosphate levels
- Bicarbonate levels
- Parathyroid hormone (PTH) levels
Additional Monitoring
Renal Function
- eGFR (estimated glomerular filtration rate)
- Watch for unexplained decreases in renal function
Treatment Response
- Serum insulin-like growth factor 1 (IGF-1) levels
- Weight-adjusted GH dosage assessment
Special Considerations
Fluid Retention
- Monitor for signs of fluid retention, especially during initial treatment 1, 2
- Weight gain
- Edema
- This is often a physiological normalization rather than a true adverse effect
Intracranial Hypertension
- Baseline fundoscopy before initiating GH therapy
- Immediate evaluation including fundoscopy if persistent headache or vomiting occurs 3
Secondary Hyperparathyroidism
- GH may stimulate parathyroid gland activity
- Monitor calcium, phosphate, and PTH levels
- Consider discontinuing GH if PTH >500 pg/ml 3
Orthopedic Complications
- Watch for symptoms of slipped capital femoral epiphysis
- Obtain bone radiographs if symptoms occur 3
Monitoring Frequency
- More frequent monitoring recommended for:
- Young patients
- Patients with advanced CKD
- Initial months of therapy (when dose adjustments are common)
- Standard interval: every 3-6 months 3
When to Consider Discontinuing GH Therapy
- Epiphyseal closure
- Persistent severe secondary hyperparathyroidism (PTH >500 pg/ml)
- Intracranial hypertension
- Slipped capital femoral epiphysis
- Inadequate response despite optimal management
- Accelerated bone maturation
- Unexplained decrease in eGFR 3
Poor Response Assessment
If height velocity in first year is less than 2 cm/year over baseline:
- Assess adherence to therapy
- Measure serum IGF-1 levels
- Review weight-adjusted GH dosage
- Evaluate nutritional and metabolic factors 3
Dosing Considerations
- Adult GH replacement should be initiated at low doses (approximately 1.0 IU/day)
- Increase gradually by about 0.5 IU per month until target dose is reached
- Maintenance dose typically should not exceed:
- 1.0 IU/m²/day for patients 40-60 years old
- 1.5 IU/m²/day for patients 20-40 years old 4
- Women may require higher replacement doses 4
Following these monitoring guidelines helps optimize the safety and efficacy of GH replacement therapy while minimizing potential adverse effects.