Bone Abstracts

Conventional treatment of hypoparathyroidism with calcium and active vitamin D analogues causes a high renal calcium excretion and over-mineralized bone.

We studied 62 patients with hypoPT randomized to 6 months of treatment with either parathyroid hormone (PTH(1-84)) 100 μg/d s.c. or similar placebo, administered as an add-on therapy. Forty-two of the patients had follow-up test performed after 2.5 years; 9 patients had continued daily PTH treatment (group 1), 15 had PTH for 6 months followed by 2 years of conventional treatment (group 2) and 18 had only received conventional treatment (controls).

PTH for 2.5 years kept p-calcium within the physiological range. We found no change in renal calcium excretion in group 1 or group 2 after 2.5 years. We have previously reported a decrease in BMD z-score at the hip, lumbar spine and whole body after 6 months of PTH treatment. Interestingly we found a significant increase in z-score at the hip, spine and a tendency towards an increase at the whole body, but not the forearm in group 2, resulting in a higher increase in z score values after 2.5 years in group 2 compared to controls.

Continuous treatment for 2.5 years compared to controls resulted in a decrease at the forearm and borderline increase at the spine.

A total of 2.5 years of treatment with PTH substitution therapy is capable of maintaining normal p-calcium levels, but not capable of reducing urinary calcium excretion.

Long-term PTH therapy is safe regarding BMD, the previously shown initial in BMD reverses.