Gafni RI, et al. - Researchers sought for the efficacy of subcutaneous human parathyroid hormone (hPTH) therapy in decreasing the renal comorbidities of hypoparathyroidism: nephrocalcinosis (NC), nephrolithiasis (NL), and renal insufficiency. Treatment with subcutaneous hPTH 1-34 may lead hypocitraturia and high urinary calcium (Uca)/urinary citrate (Ucit) ratio that may increase renal morbidity. They recommend close monitoring and exploration for treatment of hypocitraturia with increasing PTH therapy use in hypoparathyroidism.

Methods

• In 31 hypoparathyroid subjects receiving hPTH 1-34 therapy for up to 5 years, researchers determined 24-h UCa, Ucit, and UCa/Ucit.

Results

• The geometric least squares mean UCa was 346mg/day (normal <250) and Ucit was 500mg/day (normal 250–1190) before hPTH 1-34; UCa/Ucit was 0.67 mg/mg.
• UCa decreased (238, p < 0.001) after 6 months of hPTH 1-34, but with a greater decrease in Ucit (268, p < 0.001), increasing UCa/Ucit, which became significant over time (p < 0.001).
• Compared to the last measures on hPTH 1-34, Ucit rose to 626 (p < 0.001), reducing UCa/Ucit to 0.44, (p < 0.05) after stopping hPTH 1-34 and resuming conventional therapy (follow-up; FU); UCa also rose (273), but was still lower than baseline (p < 0.05).
• No correlation of daily hPTH 1-34 dose with UCa was observed, but it was observed to be inversely related to Ucit, and directly related to UCa/Ucit (p < 0.01).
• Significantly decreased mean blood bicarbonate on hPTH 1-34 was noted and it remained lower than baseline at FU (p < 0.01).
• On hPTH 1-34, mean eGFR increased (86 to 96 mL/min/1.73 m², p < 0.001); it returned to baseline at FU.
• In this study, 6 subjects displayed no NC/NL on renal imaging, 8 displayed NC/NL prior to hPTH 1-34 that remained unchanged, and 16 developed new-onset (n = 10) or progressive (n = 6) NC/NL while on hPTH 1-34.