Resum

Introduction: The osteoporosis was defined in the year 1993 as a systemic squeleton disease caraterized by a reduced bonemass and a bone tissue microarquitecture deterioration.

The reduced bone mass is a typical anomaly of osteoporosis. The other anomaly observed is the derangement of normal microarchitecture

petter. There is a less number of bone trabeculae in the osteoporotic bone and the trabecules are thiner than regular ones; there are as well horizontal backups that are not linked with other structures and therefore they do not give any structural support.The doble source energy radiologic densitometry (DEXA) is the gold standard for the bone mass measurement. The transdermic hormonal replacement therapy prevents bonemass loss.

Objectives: Main: Estimation of the needed interval between two densitometries so real differences show up between two consecutive densitometries.

Secondary: Evaluation of recognizable risk factors for bone mass loss between two consecutive densitometries, stablish differences when progesterone is added and economic cost assesement.

Pacients and Methods: Prospective cohort study in which 3826 postmenopausal patients where included and entered the inclusion criteria, to whom a densitometry was made within the period of January 1994 and December1995. A control group of 2393 patients, a group which received transdermical strogens of 807 patients and a group which received Strogens and progesterone of 626 patients. All where folowed up for a maximun period of 5 years being made an annul DEXA.

Results: Lumbar bone L1-L4. Treatment with strogens OR: 0.472 IC95% (0.389-0.572); Age > 55 years OR: 0.618 IC95% (0.534-0.715); Body Mass Index OR: 0.604 IC95% (0.525-0.694) Menopause>45 años OR: 1.300 IC95% (1.118-1.511). Osteopenia in basal DEXA OR: 1.879 IC95% (1.575-2.242); normal in DEXA OR: 2.553 IC95% (2.100-3.105). 1-2 years period from basal DEXA No significative. 2-3 years period from basal DEXA No significative. 3-4 years period OR 1.869 IC95% (1.420-2460). 4-5 years period OR: 2.164 IC95% (1.492-3.138).

Conclusions: DEXA can be done to patients who are under hormonal replacement therapy in periods no shorter than 3 years. Except for the high risk patients, body mass index < 25 or age below 55 years.

La difusió d'aquesta tesi per mitjà del servei TDX ha estat autoritzada pels titulars dels drets de propietat intel.lectual únicament per a usos privats emmarcats en activitats d'investigació i docència. No s'autoritza la seva reproducció amb finalitats de lucre ni la seva difusió i posada a disposició des d'un lloc aliè al servei TDX. No s'autoritza la presentació del seu contingut en una finestra o marc aliè a TDX (framing).

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