BACKGROUND AND AIMS: Parathyroid hormone (PTH) measurements in hemodialysis (HD) patients are routinely performed every 3 to 6 months of therapy, which are adjusted in accordance with PTH. However, recent evidences show very high PTH biological variability. The aim of our study was to evaluate the role of serum ß-crosslap (CTX), a validated marker of bone resorption, as indicator of PTH maintenance at different time intervals. METHODS: Forty-six HD patients fulfilled the inclusion criteria (HD age of more than 21 months and 7 PTH measurements for the last 21 months) for this retrospective cohort study and were enrolled. Data of the backward quarter PTH values for the last 21 months were collected from clinical records, and a single CTX was measured.To evaluate the relationship between CTX value and the maintenance of PTH in the short-term and long-term, 7 time intervals (3, 6, 9, 12, 15, 18, and 21 months) were stated and the mean value of PTH was measured within each interval and calculated for every patient. RESULTS: We found the following: (1) positive correlation between mean PTH in each time interval and ß-crosslaps with a progressive increase of the correlation coefficient (highest value for the 12- and 21-month intervals); (2) significant differences between tertiles of ß-crosslaps at 6-, 9-, 12-, 15-, 18-, and 21-month intervals, with a progressively growing value of the test coefficient; and (3) after the computation of receiver operating characteristic curves, ß-crosslaps showed to significantly estimate threshold PTH values with the highest areas under the curves (AUCs; AUC, 0.763; 95% confidence interval, 0.625-0.901 for <150 pg/mL of PTH; AUC, 0.774; 95% confidence interval, 0.614-0.934 for >300 pg/mL of PTH) and best value of both sensitivity and specificity at the 12-month time interval (82% and 72% for <150 pg/mL of PTH; 78% and 79% for >300 pg/mL of PTH). CONCLUSIONS: In HD patients, ß-crosslaps have a potential ability to best estimate backward PTH into 12 months of interval.