Parathyroid changes after high dose radioactive iodine in patients with thyroid cancer.

OBJECTIVE: The study aimed to investigate the effect of high dose radioactive iodine (RAI) on parathyroid function in patients with differentiated thyroid cancer. METHODS: Nineteen patients (8 men/11 women, age 46.5 +/- 13.2 years) undergoing RAI for thyroid remnant ablation were enrolled in the study. The biochemical parameters related to parathyroid function [serum calcium (Ca), phosphate (P), creatinine (Cr), alkaline phosphatase (ALP), intact parathyroid hormone (iPTH), urinary Ca, cAMP concentrations and the maximum tubular capacity for phosphate per unit volume of glomerular filtrate (TmP/GFR)] were evaluated at baseline and at the 1st, 3rd, 6th and 12th months of RAI administration. SPSS 15.0 was used for statistical analysis. RESULTS: For all patients, thyroid-stimulating hormone levels were >30 U/ml at baseline and <0.1 U/ml at the following visits. Serum iPTH levels were decreased significantly at the 6th month and reached basal levels at the 12th month (baseline vs. 6th p = 0.027, 1st vs. 6th p = 0.011, 3rd vs. 6th p = 0.047, 3rd vs. 12th p = 0.014, 6th vs. 12th p = 0.001). At the 6th month, P and TmP/GFR levels were higher (p = 0.036, 0.017, respectively), and urinary cAMP measurements were lower (p = 0.020) compared to those of the 1st month. No difference was detected concerning the other parameters. Serum Ca levels decreased below 2.1 mmol/l in several patients (n = 5 at 1st month, n = 4 at 3rd month, n = 8 at 6th month and n = 3 at 12th month) without clinical symptoms. CONCLUSIONS: The study indicated a transient decline in PTH levels at the 6th month following RAI therapy. Although this decrease did not cause symptoms in any of the present cases, this pattern might be important especially in individuals with diminished parathyroid background.

Clodronic acid in the treatment of postmenopausal osteoporosis.

BACKGROUND: Clodronic acid, a first-generation bisphosphonate, has been successfully used in the treatment of high bone turnover states, Paget's disease and osteolytic bone metastases. However, controversies remain over its optimal dosage and method of administration in the treatment of postmenopausal osteoporosis. In this study we aimed to evaluate the effect of clodronic acid treatment for 3 years on bone mineral density (BMD) in women with postmenopausal osteoporosis. METHODS: This was a prospective, open-label, randomised, controlled study that was conducted in an outpatient clinic at the Bone Metabolism Unit of a tertiary referral centre university hospital. Thirty postmenopausal women (age range 48-73 years) with osteoporosis and a control group of 49 osteoporotic women (age range 47-74 years) received randomised therapy. The clodronic acid group of participants received oral doses of clodronic acid 800 mg plus elemental calcium 500 mg and 400 IU of vitamin D daily, while the control group was treated with calcium and vitamin D only. BMD was measured by dual energy x-ray absorptiometry at yearly intervals. Biochemical markers of bone turnover were also measured. RESULTS: In this clinical study of postmenopausal women with osteoporosis, 36 months of clodronic acid treatment significantly increased average femoral neck BMD by 3.2 +/- 2.9%, trochanter BMD by 2.2 +/- 2.9% and lumbar spine BMD by 3.1 +/- 3%. In the control group, femoral neck, trochanter and lumbar spine BMD decreased by -6 +/- 2.7%, -7.3 +/- 2.5% and -5.4 +/- 2%, respectively (p<0.01, p<0.05 and p<0.05 for clodronic acid vs control, respectively). There was a significant decrease in urinary hydroxyproline (-38.3%) over 3 years in the clodronic acid group compared with baseline (p<0.05), while no significant change occurred in the control group. Clodronic acid was well tolerated and compliance was good. There were no clinically meaningful differences in the incidence of individual adverse events between the groups. CONCLUSION: These results indicate that daily oral administration of clodronic acid 800 mg provides benefits to skeletal bone density in osteoporotic postmenopausal women. Calcium and vitamin D supplementation alone did not prevent further bone loss.