The available literature is still controversial and shows that surgical (parathyroidectomy, PTX) or medical (calcitriol) treatment actually improved or even corrected the rhEPO-resistant anemia of ESRD patients with severe SHP. The aims of this study were to 1) assess the influence of SHP on hematological parameters in ESRD patients, 2) evaluate whether or not calcitriol could improve anemia and reduce the need of erythropoietin in dialysis patients, and 3) investigate the longitudinal effect of a parathyroidectomy for 6 months on regarding any improvements in calcitriol-refractory ESRD patients. 37 chronic hemodialysis patients in Chang Gung Memorial Hospital Dialysis Unit were divided into two groups: patients with SHP (iPTH>300 pg/mL) and patients without SHP (ipTH<300 pg/mL) before calcitriol therapy was applied. Sixteen patients remain with a status of hyperparathyroidism and were considered candidates for calcitriol therapy. Furthermore, we divided the patients according to the response of HPT to calcitriol into responding patients and nonresponding patients. Among nonresponder groups, three patients agreed to accept surgical intervention to treat their hyperparathyroidism status. The phosphate levels and serum alkaline phosphatase levels in patients with SHP were significantly higher when compared with those without SHP (P<0.05). As for the hematological data, hematocrit for patients with SHP was significantly higher than those without SHP (10.5 +/- 0.6 vs. 8.9 +/- 0.8, p<0.05). Other hematological parameters such as transferrin saturation and serum ferritin were not significantly different. We found a significant difference in alkaline phosphate levels in responding and nonresponding patients at 6 months on calcitriol therapy. Concomitantly, the hematocrit level is significantly higher in responding group when compared to those in nonresponding group (10.63 +/- 0.72 vs. 8.96 +/- 1.21, p<0.01). As for the dose of EPO requirement, significant difference between groups was also found after 6-month treatment (3617 +/- 2011 vs. 5416 +/- 1947, p<0.05). As for rhEPO dose requirement, positive effects of PTX were significantly found. The rhEPO doses needed to maintain patients in the hematocrit target range of 30-33% decreased gradually by 29% from 5323 +/- 1326 micro to 3774 +/- 2145 micro per week. The hematocrit level showed a significant increase at 3 months after PTX (p<0.05). This effect lasted until 6 months after PTX. The serum ferritin level was constantly around 350 to 400 pg/mL. While the transferrin saturation decreased 3 months after PTX (p<0.05) and recovered at 6 months. ESRD patients with SHP, usually associated with more severe anemia show resistance to rhEPO. In this case, investigation of SHP is strongly recommended with measurement of serum PTH, phosphate and alkaline phosphatase level. Treatment of calcitriol has a beneficial effect on renal anemia in ESRD patients with SHP. In addition, PTX could also provide another choosing therapy in improving renal anemia when medical treatment fails.