Acción de la vitamina K sobre la salud ósea / Action of vitamin K on bone health

Objetivos: Se admite hoy en día que la vitamina K tiene un papel importante en la salud ósea. Es necesaria para la gamma-carboxilación de la osteocalcina (la proteína no colágena más importante en el hueso), consiguiendo que la osteocalcina funcione. Hay dos formas importantes de la vitamina K (vitamina K1 y vitamina K2), que provienen de diferentes fuentes y tienen diferentes actividades biológicas. Estudios epidemiológicos sugieren que una dieta con niveles altos de vitamina K se asocia con un menor riesgo de fracturas de cadera en hombres ancianos y mujeres. Sin embargo, ensayos clínicos controlados y aleatorizados, realizados con suplementos de vitamina K1 o K2 en la población blanca, no muestran un aumento en la densidad mineral ósea (DMO) en la mayoría de las diferentes partes del esqueleto. Los suplementos con vitamina K1 y K2 pueden reducir el riesgo de fractura, pero los ensayos clínicos que incluyen las fracturas como resultado final tienen limitaciones metodológicas, por lo que se necesitarían ensayos clínicos con mayor número de pacientes y mejor diseñados para comprobar la eficacia de la vitamina K1 y K2 en las fracturas. Como conclusión, podríamos decir que actualmente no existe una evidencia suficiente para recomendar el uso rutinario de suplementos de vitamina K para la prevención de la osteoporosis y las fracturas en mujeres postmenopáusicas (AU)

Objetives: Nowadays it is recognised that vitamin K plays an important role in bone health. It is necessary for the gamma-carboxylation of osteocalcin (the most important non-collagen protein in the bone), making the osteocalcin function. There are two important forms of vitamin K (vitamin K1 and vitamin K2), which come from different sources and have different biological activity. Epidemiological studies suggest that a diet with high levels of vitamin K is associated with a lower risk of hip fractures in older men and in women. However, controlled randomised clinical trials, carried out with supplements of vitamin K1 or K2 in the white population do not show an increase in bone mineral density (BMD) in most of the different areas of the skeleton. Supplementation with vitamin K1 and K2 may reduce the risk of fracture, but the clinical trials which include fractures as a final result have methodological limitations, so clinical trials with greater numbers of patients, and which are better designed, would be needed in order to prove the efficacy of vitamin K1 and K2 in relation to fractures. In conclusion, we may say that there is currently insufficient evidence to recommend the routine use of vitamin K for the prevention of osteoporosis and fractures in postmenopausal women (AU)

[Guide for the prevention and treatment of glucocorticoid-induced osteoporosis of the Spanish Society of Internal Medicine]. / Guía de prevención y tratamiento de la osteoporosis inducida por glucocorticoides de la Sociedad Española de Medicina Interna.

Our objective has been to elaborate an updated Clinical Guide of the Spanish Society of Internal Medicine (SEMI) for the prevention and treatment of glucocorticoids-induced osteoporosis (GIO), identifying and measuring the grade of evidence that supports the given recommendations. For this, we reviewed studies performed on pathophysiology, diagnosis, prevention and treatment of GIO and after analyzing them we elaborated the present recommendations. This was done after a pre-specified and reproducible process that included an accepted model for the evaluation, and the reference of the evidence that supported it. Once the Scientific Committee elaborated the draft of the Clinical Guide, it was reviewed by all the members of the Working Group on Osteoporosis of the SEMI, and by an External Committee who included experts of many different specialities. Pathophysiology of GIO is complex and yet unknown. Bone effects of glucocorticoids are determined by multiple factors although accumulated doses seems to be the most important one. The best method to diagnose GIO is Dual X-Ray Absorptiometry (DXA), although WHO criteria defined for the diagnosis of postmenopausal osteoporosis are not applicable in GIO. The presence of a T-score lower than -1.5 Tscore indicates the necessity of treatment in any patient who receives or is going to receive more than 3 months treatment with glucocorticoids at a dose higher than 2.5 mg/day (in postmenopausal women) and 5 mg/day (in premenopausal women and men). DXA is also useful to follow up the patients, who can be done annually. Treatment must be prescribed to any patient who is receiving glucocorticoids or is going to receive them at doses higher than 7.5 mg/day for more than 3 months and 5 mg/day if the patient is a postmenopausal woman or has suffered from previous fragility fractures. Risedronate and alendronate are the drugs of election, always together with calcium and vitamin D supplements and general measurements usually prescribed in the treatment of osteoporosis. In very ill patients, parathyroid hormone can be used. The treatment for GIO should be maintained while glucocorticoid therapy is used.

[What is the opinion of Spanish internists on osteoporosis?]. / 'Qué opinan los internistas españoles de la osteoporosis?

OBJECTIVE: To conduct an opinion survey on osteoporosis in Spanish internists. METHOD: Survey sent by mail and by personal visit to members of the Spanish Internists Society. Collection of data on opinion on the disease, diagnostic and therapeutic attitude and means available (general laboratory analyses, conventional radiology, biochemical markers of bone remodeling, densitometry and ultrasounds) and preference when choosing a certain treatment. RESULTS: A total of 538 internists answered. More than 90% of those surveyed consider that osteoporosis is a disease that should be treated by internists. A total of 93% consider that osteoporosis is a prevalent disease. More than 80% have access to densitometry. CONCLUSIONS: The majority of Spanish internists consider that osteoporosis is a disease that should be treated by internists and that it is a disease that enters into their action scope. In general, they have the means necessary for its study and treatment. Bisphosphonates constitute the drug of choice and calcium and vitamin D supplements are indicated in almost all the cases.

¿Qué opinan los internistas españoles de la osteoporosis? / What is the opinion of Spanish internists on osteoporosis?

Objetivo. Realizar una encuesta de opinión sobre osteoporosis en internistas españoles. Método. Encuesta remitida por correo y por visita personal a miembros de la Sociedad Española de Medicina Interna. Recogida de datos sobre opinión acerca de la enfermedad, actitud diagnóstica y terapéutica y medios disponibles (analítica general, radiología convencional, marcadores bioquímicos de remodelamiento óseo, densitometría y ultrasonidos) y preferencias a la hora de elegir un determinado tratamiento. Resultados. Contestaron un total de 538 internistas. Más del 90% de los encuestados opina que la osteoporosis es una enfermedad que deben tratar los internistas. El 93% considera que la osteoporosis es una patología prevalente. Más del 80% tiene acceso a una densitometría. Conclusiones. Los internistas españoles opinan mayoritariamente que la osteoporosis es una enfermedad que deben tratar los internistas y que entra en su ámbito de actuación. Por lo general disponen de los medios que necesitan para su estudio y tratamiento. Los bifosfonatos constituyen el fármaco de elección y en la práctica totalidad de los casos indican un suplemento de calcio y vitamina D

Objective. To conduct an opinion survey on osteoporosis in Spanish internists. Method. Survey sent by mail and by personal visit to member of the Spanish Internists Society. Collection of data on opinion on the disease, diagnostic and therapeutic attitude and means available (general laboratory analyses, conventional radiology, biochemical markers of bone remodeling, densitometry and ultrasounds) and preference when choosing a certain treatment. Results. A total of 538 internists answered. More than 90% of those surveyed consider that osteoporosis is a disease that should be treated by internists. A total of 93% consider that osteoporosis is a prevalent disease. More than 80% have access to a densitometry. Conclusions. The majority of Spanish internists consider that osteoporosis is a disease that should be treated by internists and that it is a disease that enters into their action scope. In general, they have the means necessary for its study and treatment. Bisphosphonates constitute the drug of choice and calcium and vitamin D supplements are indicated in almost all the cases

Nutrición y osteoporosis / No disponible

No disponible

Short- and long-term effects of calcium and exercise on bone mineral density in ovariectomized rats.

At the level of prevention of bone mineral loss produced by ovariectomy, the aim of the present study was to determine the effect produced by supplementation of Ca in the diet and a moderate exercise programme (treadmill), simultaneously or separately, in ovariectomized rats, an experimental model of postmenopausal bone loss. Female Wistar rats (n 110, 15 weeks old) were divided into five groups: (1) OVX, rats ovariectomized at 15 weeks of age, fed a standard diet; (2) SHAM, rats sham operated at 15 weeks of age, fed a standard diet; (3) OVX-EX, ovariectomized rats, fed a standard diet and performing the established exercise programme; (4) OVX-Ca, ovariectomized rats fed a diet supplemented with Ca; (5) OVX-EXCa, ovariectomized rats with the exercise programme and diet supplemented with Ca. The different treatments were initiated 1 week after ovariectomy and were continued for 13 weeks for subgroup 1 and 28 weeks for subgroup 2, to look at the interaction of age and time passed from ovariectomy on the treatments. Bone mineral density (BMD) was determined, at the end of the study, in the lumbar spine (L2, L3 and L4) and in the left femur using a densitometer. Bone turnover was also estimated at the end of the study, measuring the serum formation marker total alkaline phosphatase (AP) and the resorption marker serum tartrate-resistant acid phosphatase (TRAP). As expected, OVX rats showed a significant decrease (P<0.05) in BMD, more pronounced in subgroup 2, and a significant increase in AP and TRAP with regard to their respective SHAM group. The simultaneous treatment with Ca and exercise produced the best effects on lumbar and femoral BMD of ovariectomized rats, partially avoiding bone loss produced by ovariectomy, although it was not able to fully maintain BMD levels of intact animals. This combined treatment produced a significant increase in AP, both in subgroups 1 and 2, and a decrease in TRAP in subgroup 1, with regard to OVX group. The exercise treatment alone was able to produce an increase in BMD with regard to OVX group only in subgroup 1 of rats (younger animals and less time from ovariectomy), but not in subgroup 2. In agreement with this, there was an increase of AP in both subgroups, lower than that observed in animals submitted to exercise plus Ca supplement, and a decrease of TRAP in subgroup 1, without significant changes in this marker in the older rats. Ca treatment did not produce any significant effect on BMD in OVX rats in both subgroups of animals, showing a decrease of AP and TRAP levels in the younger animals with no significant variations in markers of bone remodelling in the older female rats compared with their respective OVX group.

Bone mass assessment in rats by dual energy X-ray absorptiometry.

At present there are many techniques available for determining bone mass, measurement of which is essential for monitoring osteopenia. Rats are preferred to other laboratory species when designing animal studies on osteoporosis. The precision and accuracy of dual energy X-ray absorptiometry (DXA) for the assessment of bone mineral density (BMD) and bone mineral content (BMC) in laboratory animals were assessed. Precision, expressed as a coefficient of variation (CV), was measured, making five determinations (Hologic QDR-1000) on lumbar spine (in vivo) and femur (in vitro), both with and without repositioning. The correlation (r) between densitometric parameters and mineral content of bone ashes was calculated both in lumbar spine (in vivo) and in femur (in vitro). In our study, DXA had good precision, better in femur (CV 0.53%) than in lumbar spine (L2-L4) (CV 1.0%). Repositioning did not increase significantly the coefficients of variation (CV 0.61% and 1.2%, respectively). The linear regression between BMD and ash weight, calcium and phosphorous content showed high correlation coefficients (r = 0.64-0.85, p < 0.05). Although we found an overestimate of values of BMC with respect to ash weight (21% in lumbar spine and 31% in femur), the correlation between BMC and mineral content was high (r = 0.96-0.99, p < 0.05). The results suggest that the DXA technique has the precision necessary when used to assess BMD and BMC in small laboratory animals.