Continuous rhPTH (1-34) treatment in chronic hypoparathyroidism

[Experience in using teriparatide for the treatment of postoperative hypoparathyroidism in hemodialysis patients]

The frequency of chronic postoperative hypoparathyroidism after total parathyroidectomy for secondary and tertiary hyperparathyroidism in patients with end-stage renal failure, according to various authors, can reach 20% or more. Prescribing active metabolites of vitamin D and calcium it is not always sufficient for achievement of target goals. This dictates the need for replacement therapy with recombinant parathyroid hormone. Teriparatide is the only drug of this series approved by the American Food and Drug Administration (FDA) and registered in the Russian Federation. However, it is registered as an anabolic anti-osteoporotic drug and is not indicated for the treatment of chronic hypoparathyroidism. The use of teriparatide in postoperative hypoparathyroidism in patients receiving renal replacement therapy with programmed hemodialysis in the Russian Federation has not been previously studied. Data on this issue is also limited in foreign literature. However, it is a potential treatment option for hemodialysis patients with chronic hypoparathyroidism and severe bone disorders. In this article, we present 2 clinical cases of substitution and anabolic therapy with teriparatide in this cohort of patients.

Discovery of a Long-Acting Parathyroid Hormone 1-34 Analogue to Treat Hypoparathyroidism

Hypoparathyroidism (HP) is a rare disease with clinical manifestations of hypocalcemia and hyperphosphatemia, resulting from deficient or absent parathyroid hormone (PTH) secretion. Conventional treatment for patients with HP involves extensive calcium and vitamin D supplementation. In 2015, PTH1-84 was approved by the United States Food and Drug Administration as an adjunct for HP patients who cannot be well-controlled on conventional treatment. However, PTH1-84 therapy requires a daily injection, leading to poor patient compliance. The purpose of this study was to develop a long-acting PTH1-34 analogue by increasing its affinity to albumin. Three PTH1-34 variants were generated by substituting two of the three lysine (Lys) residues with arginine, reserving a single Lys as the modification site in each sequence. A series of side chains, containing fatty acid, deoxycholic acid, or biotin groups, were synthesized to modify these PTH1-34 variants by using a solid-liquid phase synthesis approach. In vitro bioactivity and albumin affinity tests were used to screen these new PTH1-34 analogues. Finally, Lys27-AAPC was selected from 69 synthesized analogues as a candidate therapeutic compound because it retained potency and exhibited a high albumin-binding capacity. In pharmacodynamic experiments, Lys27-AAPC demonstrated enhanced and prolonged efficacy in serum calcium elevating relative to PTH1-84. Moreover, a lyophilized powder for injection containing Lys27-AAPC was developed for further testing and represented a potential long-acting HP treatment.

Continuous Teriparatide Treatment in Chronic Hypoparathyroidism: A Case Report

Patient: Female, 29-year-old

Final Diagnosis: Chronic hypoparathyroidism

Symptoms: Muscle cramps • numbness • tingling in fingers

Medication: —

Clinical Procedure: —

Specialty: Endocrinology and Metabolic

The challenges of post-bariatric surgery hypocalcaemia in pre-existing hypoparathyroidism

SUMMARY

Conventional treatment of hypoparathyroidism relies on oral calcium and calcitriol. Challenges in managing post-parathyroid- and post-thyroidectomy hypocalcaemia in patients with a history of bariatric surgery and malabsorption have been described, but postoperative management of bariatric surgery in patients with established hypoparathyroidism has not. We report the case of a 46-year-old woman who underwent elective sleeve gastrectomy on a background of post-surgical hypoparathyroidism and hypothyroidism. Multiple gastric perforations necessitated an emergency Roux-en-Y gastric bypass. She was transferred to a tertiary ICU and remained nil orally for 4 days, whereupon her ionised calcium level was 0.78 mmol/L (1.11-1.28 mmol/L). Continuous intravenous calcium infusion was required. She remained nil orally for 6 months due to abdominal sepsis and the need for multiple debridements. Intravenous calcium gluconate 4.4 mmol 8 hourly was continued and intravenous calcitriol twice weekly was added. Euthyroidism was achieved with intravenous levothyroxine. Maintaining normocalcaemia was fraught with difficulties in a patient with pre-existing surgical hypoparathyroidism, where oral replacement was impossible. The challenges in managing hypoparathyroidism in the setting of impaired enteral absorption are discussed with analysis of the cost and availability of parenteral treatments.

LEARNING POINTS

Management of hypoparathyroidism is complicated when gastrointestinal absorption is impaired. Careful consideration should be given before bariatric surgery in patients with pre-existing hypoparathyroidism, due to potential difficulty in managing hypocalcaemia, which is exacerbated when complications occur. While oral treatment of hypoparathyroidism is cheap and relatively simple, available parenteral options can carry significant cost and necessitate a more complicated dosing schedule. International guidelines for the management of hypoparathyroidism recommend the use of PTH analogues where large doses of calcium and calcitriol are required, including in gastrointestinal disorders with malabsorption. Approval of subcutaneous recombinant PTH for hypoparathyroidism in Australia will alter future management.