Relationship of Conjunctival and Corneal Calcification with Secondary Hyperpara-thyroidism in Hemodialysis Patients

Background/Objective: Hyperphosphatemia is the consequence of end stage renal failure. Inadequate control of serum phosphorus results in elevated Ca×P product with subsequent soft tissue deposition in the form of conjunctival and corneal calcification.  In this study, we evaluated the relationship of conjunctival and corneal calcification with secondary hyperparathyroidism in hemodialysis patients.  Patients and methods: This is a descriptive–analytic study performed on 24 hemodialysis patients.  We measured serum calcium, phosphorus, alkaline phosphatase, iPTH and conjunctival and corneal calcification using slit–lamp microscope according to a modification of Porter's criteria. The duration of hemodialysis was 30.7 ± 21.7 months. Results: 24 patients participated in this study.  The biochemical values were: Ca: 9.1 ± 0.8 mg/dl, P: 6.5 ± 2.2 mg/dl, ipTH: 488 ± 326 pg/ml, Ca×P : 51.5 ± 16.6 The mean of conjunctival and corneal calcification score was 7.1±4.There was a positive correlation between conjunctival and corneal calcification with a duration of hemodialysis (p=0.033, r=0.436), Ca×P product (p=0.007, r=0.538).  P (p=0.006, r=548) and iPTH (p= 0.028 , r=0.449). There was no correlation between conjunctival and corneal calcification with the age of the patients, serum calcium and alkaline phosphatase.  Conclusion: There is a positive correlation of serum phosphorus, Ca×P product and iPTH with conjunctival and corneal calcification and no significant correlation with serum calcium implying that there is a central role for phosphorus in calcium-phosphorus deposition in soft tissues like cornea and conjunctiva, underscoring further attention to phosphorus control in hemodialysis patients.