Endocrine Abstracts

Objective: In chronic hypoparathyroidism, conventional therapy consists of oral calcium supplements and active vitamin D analogs but some patients cannot achieve treatment goals despite the high dose of oral calcium supplementation. Therefore, parathyroid gland transplantation and recombinant human PTH have been investigating as new therapeutic options. Calcium absorption from intestinal cells occurs by transcellular path and paracellular path. Transcellular absorption occurs through transient receptor potential vanilloid type6 (TRPV6) receptors and is saturable due to oral calcium intake. Paracellular absorption is non-saturable but very slow and limited. Alternate-day oral calcium intake may upregulate TRPV6 receptors. The objective of this study was to investigate the effectiveness of alternate-day oral calcium intake in patients with challenging chronic hypoparathyroidism.

Methods: In this retrospective study, we evaluated 66 patients with chronic hypoparathyroidism admitted to our hospital within the last 2 years. 14 patients (who received ≥2000 mg/day daily calcium carbonate or who admitted to the emergency department at least once in the last 3 months for hypocalcemia) were switched to the alternate-day dosing regimen (ADR) (patients used oral calcium carbonate every other day), and data of these patients were analyzed retrospectively.

Results: All of the patients were female. Median age was 41.5 (19–63) years and median duration of disease was 70 (6–228) months. Two patients were using teriparatide. Before ADR; oral calcium intake was 3750 (2000–8000) mg/day, oral calcitriol intake was 0.88 (0.5–3)mcg/day, serum calcium level was 7.71 (7.1–8.7) mg/dL, serum phosphate level was 5.35 (3–6.5) mg/dL and 24-hour urine calcium level was 165 (22.5–331) mg/day. After ADR; oral calcium intake was 1500 (1000–2500) mg/day, oral calcitriol intake was 0.88 (0.5–2) mcg/day, serum calcium level was 8.25 (7.7–9.3) mg/dL, serum phosphate level was 5 (4–5.9) mg/dL, and 24-hour urine calcium level was 210.5 (21–564) mg/day. After ADR, oral calcium intake was decreased and serum calcium level was increased significantly (P=0.001 and P=0.001 respectively). Two patients did not need teriparatide after ADR and teriparatide treatment was stopped. Three patients were in parathyroid gland transplantation queue and all of them came out from the waitlist with their own request. The number of the emergency department visits in 3-month-period before ADR was 21 and it was decreased to 2, in 3-month-period after ADR (P=0.02).

Conclusion: Patients with challenging hypoparathyroidism can be controlled in a cheaper, more comfortable and more effective manner with ADR.