Predicting the effect of intravenous calcitriol on parathyroid gland activity using double-phase technetium Tc 99m-sestamibi scintigraphy.
BACKGROUND
Although intravenous calcitriol is useful for decreasing intact parathyroid hormone (iPTH) blood levels in patients with secondary hyperparathyroidism (SHP) undergoing hemodialysis, approximately half these patients remain refractory to this treatment. The current study measures the diagnostic utility of double-phase technetium Tc 99m-sestamibi (MIBI) scintigraphy in predicting the response to calcitriol treatment.


METHODS
Sixty hemodialysis patients with SHP with iPTH blood levels between 240 and 600 pg/mL (ng/L) were selected. Initial intravenous calcitriol pulse therapy was 6 microg/wk (for iPTH levels of 400 to 600 pg/mL [ng/L]) or 3 microg/wk (for iPTH levels of 240 to 400 pg/mL [ng/L]). MIBI scintigraphy was performed before the onset of calcitriol therapy and repeated 1 year later. Patients were injected intravenously with 740 MBq of MIBI. Images were obtained at 15 minutes (thyroid phase) and 2 hours (parathyroid phase) after radiotracer administration. Focal areas of increased MIBI uptake were considered pathological parathyroid glands.


RESULTS
Forty-eight patients completed the study. After 1 year, iPTH levels had decreased significantly in 95.2% (47 patients), whereas good control (iPTH < 240 pg/mL [ng/L]) was reached in 70.8% (34 patients) and only 4 patients had iPTH levels greater than 400 pg/mL (ng/L; all were patients with 3 MIBI-positive areas at baseline determination). At baseline, there were 30 patients (62.5%) with MIBI positive areas (1, 2, or 3 areas), which decreased to 14 patients (29%) at the end of the study period. No patient showed 4 positive areas at any time. The 18 patients (37.5%) with no MIBI-positive area at baseline remained unchanged.


CONCLUSIONS
MIBI scintigraphy is a reliable exploratory tool in predicting the response to treatment with intravenous calcitriol in hemodialysis patients with SHP.
Renal Transplant Unit, Hospital Clínic Barcelona, Barcelona, Spain. vtorre@clinic.ub.es
Jose-Vicente
JV
Torregrosa
David
D
Fuster
Juan
J
Ybarra
Jaime
J
Ortín
Agustín
A
Moreno
Neus
N
Valveny
D000328:Adult; D000368:Aged; D002117:Calcitriol / Q000008:administration & dosage / Q000627:therapeutic use*; D002120:Calcium Channel Agonists; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000188:drug therapy*; D007676:Kidney Failure, Chronic / Q000150:complications / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000000981:diagnostic imaging* / Q000187:drug effects*; D010281:Parathyroid Hormone / Q000097:blood; D020551:Pulse Therapy, Drug; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D006435:Renal Dialysis; D017256:Technetium Tc 99m Sestamibi
D002120:Calcium Channel Agonists; D010281:Parathyroid Hormone; D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi; D002117:Calcitriol