Methods and Results: In order to clarify the predialytic factors influencing the onset of secondary hyperparathyroidism (SHPT) in patients on chronic maintenance haemodialysis, the time-course changes of serum levels of intact-PTH (i-PTH) during haemodialysis for 5 years were investigated. The subjects were 69 non-diabetic patients who had a serum aluminium level of less than 1.85 nmol/L at the end of observation. Patients were divided into two groups based on i-PTH levels obtained at the start of dialysis; the high group (H group) consisted of patients whose i-PTH levels were more than 22.00 pmol/L, the low group (L group) had levels less than 22.00 pmol/L. In the H group, i-PTH was 41.46 ± 2.87 pmol/L at the start of dialysis (vs L group, P < 0.0001) and 15.82 ± 2.85 pmol/L after haemodialysis initiation. In the L group, i-PTH levels did not significantly change and was 11.69 ± 2.50 pmol/L 12 months after the start of dialysis (at the 12th month). However, at the 60th month, the i-PTH level was 33.24 ± 5.30 pmol/L in the H group, and 9.85 ± 2.13 pmol/L in the L group (P < 0.005).
Conclusion: It is suggested that control of i-PTH levels in the predialytic period may be important to suppress SHPT throughout haemodialysis.