ESPE Abstracts

A 17-year-old girl comes to our attention for a second opinion due to reduced bone mineralization. She has a family history of osteogenesis imperfecta: her mother and younger sister have a COL1A1 mutation. The girl never had any fractures, but considering the familiarity it was carried out a DEXA, showing a Z-score of -1.9 SDS at the femoral level and -2 SDS at the lumbar level; no fractures visible in the spine X-ray. The genetic analysis of COL1A1 was carried out, which came out negative. Prophylaxis with calcium 500 mg/day and vitamin D 440 IU/day was started. On the day of our first evaluation, the girl shows us her blood tests of calcium-phosphorus metabolism carried out a few months earlier. The results are within the normal limits except for PTH exceeding the normal values (9.4 pmol/L with normal values 1.6-6.9) and calcium, which is at the upper limits (11 mg/dL), with 25OH-vitamin D 29.7 ng/mL. We therefore suggest to stop the prophylaxis with calcium and vitamin D and to repeat the tests after 15 days: serum calcium remains unchanged and PTH tends to the upper normal limits (carried out in a different laboratory, 73.2 pg/mL with normal values 15-88), with calcium to creatinine ratio 0.14 mg/mg. An ultrasound of the thyroid and parathyroids is then performed, showing an 11x6 mm nodule with poor intrinsic vascular signal at the lower pole of the left thyroid lobe, compatible with a parathyroid adenoma. We decide to carry out a Tc99/sestaMIBI parathyroid scan, which shows a focal radiopharmaceutical uptake consistent with the hyperactivity of the left inferior parathyroid. Also, all the tests to rule out MEN1, MEN2A and MEN4 result negative: blood pressure monitoring, urinary catecholamine dosage, calcitonin, chromogranin, prolactin, fasting glucose, insulin, abdomen ultrasound and MEN1, RET and CDKN1B gene analysis. The patient is currently a candidate for elective parathyroidectomy. In pediatric patients, primary hyperparathyroidism must be taken into account as a rare cause of reduced bone mineralization: an excess of PTH leads to an increased bone resorption. In these cases it is essential to perform an ultrasound of the thyroid and parathyroids and Tc99/sestaMIBI parathyroid scan for early identification and treatment of parathyroid adenomas.