Switch from calcitriol to paricalcitol in secondary hyperparathyroidism of hemodialysis patients: Responsiveness is related to parathyroid gland size

Abstract

Paricalcitol is more effective than calcitriol in hemodialysis patients (HD) with secondary hyperparathyroidism (SHPT), but it is not effective in some of them. We have investigated the relationship between paricalcitol responsiveness and parathyroid gland (PTG) size. Thirty HD with SHPT treated previously with calcitriol for at least 6 months were switched to paricalcitol (1:4 conversion ratio). Parathyroid gland number and size (maximum longitudinal diameter [MLD] of largest PTG) was measured by ultrasonography. Patients were divided into 2 groups: group A (MLD ≤9.0 mm [17 HD]); and group B (MLD >9.0 mm [13 HD]). They were defined responder if both the last 2 monthly determinations of inhibit parathyroid hormone (iPTH) were within the target (<300 pg/mL) according to National Kidney Foundation Kidney Disease Outcomes Quality Initiative recommendations. Twenty-six and 20 HD completed 6-month and 12-month paricalcitol therapy, respectively. After 6 months of paricalcitol treatment, 23.5% HD of group A and 7.7% of group B were responders. At 12 months, 41.2 % of group A and 7.7% of group B were responders. Throughout paricalcitol therapy, serum calcium and phosphorus concentrations slightly increased in all HD but more significantly in group B. The baseline iPTH and MLD of the largest PTG were significantly correlated with final iPTH levels. Paricalcitol is more effective than calcitriol in SHPT, but the responsiveness to paricalcitol and hypercalcemia are related to PTG size. The measurement of MLD by ultrasonography may be useful for predicting responsiveness to paricalcitol, avoiding an unnecessary and expensive therapy.

Efficacy and Tolerability of Intravenous Paricalcitol in Calcitriol-Resistant Hemodialysis Patients with Secondary Hyperparathyroidism: 12-Month Prospective Study

“…However, they did not provide the ratio of patients with parathyroid adenoma. In a recent study, Vulpio et al 24 switched 30 hemodialysis patients with SHPT treated previously with calcitriol for at least 6 months to paricalcitol with a 1:4 conversion ratio. They divided the patients into two groups according to sonographically determined parathyroid gland sizes.…”

Efecto de paricalcitol sobre el metabolismo mineralóseo en pacientes trasplantados renales con hiperparatiroidismo secundario

“…El paricalcitol consigue reducciones en los niveles séricos de la parathormona (PTH) en hemodiálisis de más del 30% en el 68-91% de los casos y de más del 50% en el 45-60% de los pacientes 2,4,6 , logrando alcanzar las cifras recomendadas en las guías en el 30-50% de ellos, con una eficacia similar o incluso superior a cinacalcet en algunos estudios 6 . Cuando se compara con el uso de calcitriol en casos con hiperparatiroidismo resistente en hemodiálisis, se observan reducciones de PTH, aunque no fueran respondedores a calcitriol [5][6][7] . Debido a su menor efecto sobre las proteínas transportadoras de calcio y fósforo a nivel intestinal, induce menores incrementos en sus niveles séri-cos que calcitriol 8,9 , lo que permite un manejo más seguro en casos con hiperparatiroidismo más severo.…”

Treatment Failure of Active Vitamin D Therapy in Chronic Kidney Disease: Predictive Factors

“…Tonbul et al [46] described treatment resistance as elevated serum iPTH (>300 pg/ml) despite treatment with calcitriol at a dosage of up to 9 μg/week for 6 months. In a study by Vulpio et al [47] , this phenomenon was defined as iPTH >300 pg/ml after patients received IV calcitriol therapy for at least 6 months. Kazama et al [48] defined it as iPTH 300 pg/ml despite treatment with doses of up to 4.5 μg of IV calcitriol per week for 24 weeks, whereas Capuano et al [49] described treatment resistance as patients with iPTH >300 pg/ml who had received pulse IV calcitriol for at least 1 year.…”

“…At 6 months, iPTH levels were significantly lower (p = 0.03), as were calcium levels (p = 0.05) and the calcium × phosphorus product (p = 0.01) [51] . Vulpio et al [47] conducted a switch study (described earlier) in 30 HD patients with iPTH levels >300 pg/ml, calcium levels from 8.0 to 10.5 mg/dl, and calcium × phosphorus product <70 mg 2 /dl 2 (5.6 mmol 2 /l 2 ) after ≥ 6 months of treatment with calcitriol. Patients were divided into 2 groups, depending on the MLD of the largest parathyroid gland ( ≤ 9 vs. >9 mm).…”

“…Identification of these characteristics in conjunction with individual laboratory parameters for serum calcium, phosphorus, and PTH may help predict poor patient response to active vitamin D treatment. In a 12-month prospective, open-label study, the number and size of the parathyroid glands of patients with a subclinical response to calcitriol were assessed before patients were switched to paricalcitol treatment [47] . A higher rate of treatment response (defined as iPTH <300 pg/ml) was observed at 6 (23.5%) and 12 months (41.2%) in patients with a smaller gland size (maximum longitudinal diameter [MLD] ≤ 9 mm) compared with responses at 6 and 12 months (7% at both time points) in patients with larger gland sizes (MLD >9 mm) [47] .…”