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.

Cribado de parto prematuro con progesterona salival / Screening of premature labor with salivary progesterone

Preterm birth is the most frequent cause of perinatal morbidity and mortality, especially before 34 weeks. Current screening methods include medical history of preterm delivery and ultrasound assessment of cervix length during the second trimester of pregnancy, which give a detection rate of approximately 65 percent with a false positive rate of 10 percent. Vaginal progesterone therapy has proved to reduce the risk of early preterm delivery by 50 percent in patient under risk. This might suggest that preterm pregnancies have lower levels of progesterone compared to term pregnancies. Although, the prediction of prematurity using biomarkers, including plasma progesterone, has been researched for several years, none of them have proved to be associated with preterm delivery. However, measuring salivary progesterone has already been suggested to be a potential biomarker associated with prematurity in pregnancies at high risk of preterm delivery. Saliva is a fluid that reflects only the free fraction of the biologically active steroidal hormone, and thus is more representative measure than the total plasma progesterone, which is the one usually measured in laboratories. For these reasons, the aim of our study is to evaluate whether the assessment of salivary progesterone can be used as a screening test for prediction of preterm delivery less than 34 weeks in pregnant women who attended at our Fetal Medicine Unit at 11-14 and 20-25 weeks of gestation.

Detección de cortisol salival nocturno en una muestra de sujetos de Santiago de Chile, mediante la técnica deelectroquimioluminicencia / Night salivary cortisol measurement in a sample of volunteers from Santiago using an electroquimioluminicence technique

Cortisol is a glucocorticoid hormone with circadian cycle, it shows high levels in the morning and lower in the night. The salivary cortisol is the biologically active fraction and night measurement has been very useful for improving the diagnosis of Cushing’s syndrome, an endocrine disorder characterized by high levels of cortisol and loss of their circadian cycle. A disadvantage of this measurement is the establishment of reference ranges, which depends on the population and technique. Therefore the night salivary cortisol values were determined in a sample of 75 healthy volunteers, aged 18-75 years old. Each volunteer collects two samples in consecutive days and these samples were analyzed by electrochemiluminescence. The average of night salivary cortisol of volunteers was 0.165 +/- 0.059 ug/dL with a range from 0.082 to 0.352 ug/dL and no significant differences were found between two samples of cortisol in day 1 and 2. Our results suggest that the proposed cut-off limit 0.32 ug/dL between patients with and without Cushing Syndrome would be suitable for this technique and in our population.