Recomendaciones para el uso correcto de densitometría ósea en la práctica clínica. Consenso de la Sociedad Chilena de Endocrinología y Diabetes / Guidelines of the Chilean Endocrinology Society for the correct clinical use of bone densitometry

Osteoporosis is a silent and frequent disease, which increases fracture risk. Approximately half of women and one of five men over 50 years old will suffer an osteoporotic fracture throughout their lives. Dual-energy x-ray absorptiometry (DXA) allows a real bone mineral density (BMD) measurement in different parts of the skeleton and is considered the "gold standard" for quantifying osteoporosis with high accuracy and precision. The Board of the Chilean Society of Endocrinology and Diabetes (SOCHED) required from the Bone Disease Study Group to develop a consensus about the "Correct use of bone densitometry in clinical practice in Chilean population". Therefore, we elaborated 25 questions which addressed key aspects about the indications for a DXA scan, and the details of how to perform and report this test. Since some of the evidence obtained was of low quality or inconclusive, we decided to create a multidisciplinary group of national experts in osteoporosis to develop a consensus in this subject. The group consisted of 22 physicians including endocrinologists, gynecologists, geriatricians, radiologists, rheumatologists and nuclear medicine specialists. Using the Delphi methodology to analyze previously agreed questions, we elaborated statements that were evaluated by the experts who expressed their degree of agreement. The final report of this consensus was approved by the SOCHED board.

Marcadores de recambio óseo en mujeres postmenopáusicas: utilidad clínica / Bone remodelling markers in postmenopausal women: clinical utility

Bone metabolism is a dynamic process, which includes formation and resorption. Osteoblast and osteoclast are responsible of replacing 20 percent of bone each year. Bone Markers are fragments of bone matrix; these peptides are released in the process of formation and resorption, later accumulated in body compartments (bone and blood) and finally excreted in the urine, reflecting bone dynamic. The international Federation of Osteoporosis and the International Federation of Laboratory and Clinical Chemistry recommend the use of these two markers (one representing bone formation and the other bone resorption) to evaluate bone turnover, especially in high-risk groups such as postmenopausal women. The collagen C-terminal telopeptide or carboxi-terminal collagen crosslinking (CTX) is one of the most used, among different bone markers. This is a blood biomarker that can be measured to assess bone turnover; this marker increases when the bone resorption is accelerated. On the other hand, osteocalcin (a non-collagen protein) is a bone formation marker, which has been widely studied and can be measured in venous blood during bone formation. Both markers are important for monitoring anti-resorptive therapy, and they have been validated to predict fracture risk complementing densitometry in osteoporosis diagnosis. Main disadvantages are variability of the laboratory techniques and lack of information about normal reference values in different populations. Therefore it is necessary to establish normal reference values for each population before its incorporation as a clinical tool.

Déficit de vitamina D. Revisión epidemiológica actual / Vitamin D deficiency. Current epidemiological review

Vitamin D is a liposoluble hormone that exists in two molecular forms. Ergocalciferol (vitamin D-2) and colecalciferol (vitamin D-3). Vitamin D-3 is produced in the skin by the action of UV-B radiation. Both forms are metabolized by the liver to 25-hydroxy-Vit D (25OHD) and later in the kidney to the active form 1,25-dihydroxy-Vit D. This form promotes bone mineralization by intestinal absorption of calcium and phosphate. Normal levels of 25OHD are associated with less fracture, normal neuromuscular and immune function and possibly have a preventive effect on certain types of cancer. The Endocrine Society's Clinical Practice Guidelines recommends that optimal plasma levels of 25OHD are above 30 ng/ml, insufficiency between 21 and 29 ng/ml and deficiency below 20 ng/ml. The prevalence rate of 25OHD deficit is about 2 to 90% in different populations. Risk factors of Vitamin D deficit like year season, skin pigmentation, sunlight exposition, use of sunblock and inadecuate Vitamin D ingestion, together with different measurement techniques explain the variability of results between epidemiological studies. An important risk group is the health professionals that are not exposed to sunlight. There are no studies that describe the prevalence in this population in Chile. (AU)

Enfermedad de graves en asociación con miastenia gravis: presentación de un caso y revisión de la literatura / Myasthenia gravis with concomitant hyperthyroidism: report of one case

Myasthenia gravis and Graves disease are autoimmune diseases that can coexist in the same patient. We report a 18 years old female with a history of myasthenia gravis diagnosed at the age of six, treated with neostigmine and prednisone. She starts with palpitations, dyspnea, proximal muscle weakness and exophthalmos appearing seven months after the onset of symptoms. She was admitted to the hospital due to her decompensated hyperthyroidism. After admission, she develops a myasthenic crisis, that requires mechanical ventilation. Afterwards, the patient is subjected to a thymectomy and thyroidectomy with a good postoperative evolution.

Prolactinoma gigante de inicio en la adolescencia: a propósito de 2 casos clínicos / Report of two adolecents with giant prolactinomas

The prevalence of pituitary among adolescents is 0.1 per million and the most common type is prolactinoma. We report two adolescents with pituitary adenomas. A 15 years old female presenting with a progressive reduction of visual acuity, headache and galactorrhea. Magnetic resonanceshowed a sellar tumor with suprasellar expansion. She was subjected to transcraneal surgery and the pathological study of the piece disclosed a prolactinoma. A 23 years old male presenting with weight gain, headache and decreased visual acuity of the left eye. Magnetic resonance demonstrateda tumor with sellar and suprasellar involvement. He was subjected to transsphenoidal surgery and the pathological study of the surgical piece disclosed a prolactinoma.