Overview of the Hypoparathyroidism Treatment Landscape

Dr. Khosravi begins with conventional therapy, noting that first-line treatment requires careful balance: at baseline, serum calcium is low, phosphate is high, and urinary calcium is high, meaning calcium and active vitamin D will increase calcium but can also raise phosphate and urinary calcium. When hypercalciuria persists despite this regimen, thiazide diuretics can be added—chlorthalidone is preferred for its longer duration of action, started at a low dose. Caution is warranted in very young and very old patients, in those with ADH1 who have hypomagnesemia, and in APS1 patients with adrenal insufficiency who may not tolerate thiazides due to hypertension, orthostasis, or hyponatremia—making monitoring of sodium, potassium, and blood pressure important. Magnesium supplementation can also help symptomatically.

Since 2024, palopegteriparatide has been available as PTH replacement. Unlike earlier short-acting formulations requiring multiple daily injections that inadequately addressed hypercalciuria, palopegteriparatide uses a TransCon linker that cleaves slowly, yielding a 60-hour half-life and stable once-daily dosing. Starting at 18 micrograms and titrated in 3-microgram increments with calcium checks at seven to ten days, it maintains calcium in the full normal range—not just the low-normal range—lowers phosphorus, and reduces urinary calcium over time. Most patients achieve independence from active vitamin D and pharmacologic calcium supplementation. Dr. Khosravi cautions that supply disruption can precipitate hypocalcemia due to increased bone turnover, so patients should keep calcium and calcitriol on hand even if they have fully weaned off conventional therapy.

Dr. Cusano notes that the kidneys and brain appear to need more constant PTH exposure to reduce renal and neuropsychiatric symptoms, making longer-acting preparations especially important. Asked how the management approach has evolved, Dr. Khosravi reflects that clinicians once focused simply on keeping calcium from crashing, but now have the ability to truly address two hormonal deficiencies—PTH and active vitamin D—enabling better control of a disease affecting multiple organ systems beyond just symptomatic relief of hypocalcemia.

In the next episode, "Limitations of Conventional Therapy and Transitioning to PTH Replacement in Hypoparathyroidism," Dr. Ferenczi discusses monitoring cadence for conventional therapy and identifies the clinical triggers—biochemical, symptomatic, and comorbidity-based—that should prompt a transition to PTH replacement therapy.