Elevations in Serum and Urinary Calcium with Parathyroid Hormone (1-84) with and without Alendronate for Osteoporosis

Context: The effect of PTH therapy on serum and urinary calcium levels and the risk of hypercalcemia or hypercalciuria has not been formally evaluated. Objective: The objective was to examine changes in serum and urinary calcium associated with PTH(1-84) therapy in the PaTH trial and the extent to which a defined algorithm resolved the elevated values. Design, Setting, Participants, and Intervention: A total of 178 postmenopausal women were randomized to PTH(1-84) either alone or in combination with alendronate during the first year of the PaTH study. Main Outcome Measure(s): The main outcome measures were fasting serum calcium at baseline and 1, 3, and 12 months and 24-h urinary calcium at baseline and 3 months. Results: In 14% of participants, serum calcium more than 10.5 mg/dl (>2.6 mmol/liter) developed. Following the defined algorithm, 58% of elevated measurements were normal on repeat testing; 38% required discontinuation of calcium and vitamin D supplementation, and one necessitated a decrease in P...