title: Effects on calcium homeostasis of changing PTH replacement therapy of postoperative hypoparathyroidism from intact PTH to teriparatide: a case series.
abstract: The objective of this study was to assess the effect on calcium homeostasis of changing PTH replacement therapy (PTH-RT) from intact PTH (PTH(1-84)) to teriparatide (PTH(1-34)). This study is a consecutive case series. All patients with postoperative hypoparathyroidism who changed medication from PTH(1-84) (100 µg) to PTH(1-34) (20 µg) were included. Plasma ionized calcium, daily dose of 1α-hydroxylated-vitamin D metabolites alfacalcidol, calcium, TSH and PTH was collected. Eight patients (women = 88%) with a mean age of 54 ± 12 years and a duration of hypoPT of 13 ± 6 years were included. Before initiation of PTH(1-84), the mean daily dose of alfacalcidol was 1.9 ± 1.1 µg/d and calcium supplements were 1,550 ± 705 mg. Alfacalcidol dose was reduced with 88 ± 29% (p < 0.01) after 6 months of PTH(1-84) treatment and terminated in six patients. Calcium levels were reduced with 78 ± 36% (p = 0.02) to 273 ± 353 mg/d and stopped in five patients. Six patients received 100 µg PTH(1-84) daily, the seventh 2 out of 3 days and the last every second day. When changing from PTH(1-84) to PTH(1-34), plasma ionized calcium initially dropped and the demand for supplements increased. Alfacalcidol was resumed in five patients; mean daily dose increased to 1.50 ± 1.56 µg/d, (p = 0.02) and calcium increased to 329 ± 368 mg/d, (p = 0.72). Five patients received 20 µg PTH(1-34) a day, two patients twice-a-day and one 20/40 µg/d alternately. Compared with PTH(1-34), PTH(1-84) has a longer plasma half-life and a higher calcemic response. We have shown a need for higher doses of alfacalcidol and calcium supplements to maintain normal serum calcium when treated with PTH(1-34) compared to PTH(1-84) and in some a need for more than one daily PTH(1-34) dose.
authors.affiliation: Department of Internal Medicine and Endocrinology, MEA, Aarhus University Hospital, Tage-Hansensgade 2, 8000, Aarhus, Denmark, lisesofieandersen@gmail.com.
authors.forename: Lise Sofie
authors.initials: LS
authors.lastname: Bislev
authors.forename: Tanja
authors.initials: T
authors.lastname: Sikjaer
authors.forename: Lars
authors.initials: L
authors.lastname: Rejnmark
mesh_terms: D000328:Adult; D000368:Aged; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000008:administration & dosage / Q000097:blood*; D005260:Female; D006706:Homeostasis; D020249:Hormone Replacement Therapy; D006801:Humans; D006887:Hydroxycholecalciferols / Q000008:administration & dosage; D007011:Hypoparathyroidism / Q000188:drug therapy / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000008:administration & dosage* / Q000627:therapeutic use; D019379:Teriparatide / Q000008:administration & dosage / Q000627:therapeutic use*; D013997:Time Factors; D055815:Young Adult
chemical_list: D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D019379:Teriparatide; D002117:Calcitriol; D002118:Calcium; C008088:alfacalcidol