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Conjunctival and corneal calcification and bone metabolism in hemodialysis patients
Takanobu Tokuyama1, Tomohiro Ikeda, Keiko Sato
1Department of Ophthalmology, Inoue Hospital, Osaka, Japan. ttokuyama@nifty.com
Insights
Conjunctival and corneal calcification in hemodialysis patients correlates with longer treatment duration and abnormal mineral metabolism, not age or lumbar bone density. This suggests excessive calcium and phosphorus levels contribute to eye calcification.
Area of Science:
- Ophthalmology
- Nephrology
- Bone Metabolism
Background:
- Conjunctival and corneal calcification is a known metastatic calcification in hemodialysis patients.
- Understanding the factors contributing to this ocular complication is crucial for patient management.
Purpose of the Study:
- To investigate the relationship between the severity of conjunctival and corneal calcification and various clinical and biochemical parameters in male hemodialysis patients.
- To identify key predictors of ocular calcification in this population.
Main Methods:
- Cross-sectional study involving 44 male hemodialysis patients.
- Assessment of conjunctival and corneal calcification severity.
- Measurement of serum calcium, phosphorus, intact parathyroid hormone (iPTH), alkaline phosphatase (ALP), osteocalcin, and bone mineral density (BMD).
Main Results:
- Severity of calcification significantly correlated with duration of hemodialysis, serum phosphorus, calcium x phosphorus product, iPTH, ALP, and osteocalcin.
- A negative correlation was found between calcification severity and radial BMD.
- No significant correlation was observed with age, serum calcium levels, or lumbar BMD.
Conclusions:
- Conjunctival and corneal calcification in hemodialysis patients is linked to prolonged treatment and abnormal mineral metabolism, specifically elevated serum calcium and phosphorus.
- Increased bone turnover and decreased bone mineral density, particularly in the radial bone, are associated with this condition.
- These findings highlight the importance of monitoring and managing mineral and bone disorders in hemodialysis patients to prevent ocular complications.
Abstract:
Conjunctival and corneal calcification is well recognized as a metastatic calcification in patients undergoing hemodialysis. In 44 male hemodialysis patients, we examined the relationship between the severity of conjunctival and corneal calcification and age; duration of hemodialysis; serum levels of calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH), alkaline phosphatase (ALP), and osteocalcin; and bone mineral density (BMD). The mean age was 58.3 years (range, 33-79 yr), and the mean duration of hemodialysis was 94.3 months (range, 25-258 mo). The serum level of Ca was 9.6 +/- 0.1 mg/dL, P was 5.9 +/- 0.1 mg/dL, Ca x P was 57.5 +/- 1.2, iPTH was 204.0 +/- 34.6 pg/mL, ALP was 173.8 +/- 11.8 U/L, and osteocalcin was 62.8 +/- 9.5 ng/mL. Lumbar BMD was 0.997 +/- 0.022 g/cm2 and radial BMD was 0.642 +/- 0.015 g/cm2. There was a significant positive correlation between the severity of conjunctival and corneal calcification and the duration of hemodialysis (P < 0.0001), the serum levels of P (P = 0.0035), the Ca x P (P = 0.0034), the iPTH (P = 0.0154), the ALP (P < 0.0001), and the osteocalcin (P = 0.0010), and was negatively correlated with radial BMD (P = 0.0008). However, the severity of conjunctival and corneal calcification was not significantly correlated with age (P = 0.986), serum Ca levels (P = 0.138), or lumbar BMD (P = 0.449). Based on these findings, we suggest that the conjunctival and corneal calcification developed by excessive serum levels of Ca and P associated with abnormal bone and mineral metabolism. This resulted in an increased bone turnover and decreased BDM after prolonged hemodialysis even though efforts were made to maintain the homeostasis of Ca and P metabolism in hemodialysis patients by using various therapeutic approaches.