Thesis (MScMedSc) -- Stellenbosch University, 2001. / ENGLISH ABSTRACT: Osteopenia is a well documented complication of anorexia nervosa (AN). The pathogenesis of this bone loss is presently poorly defined in the literature. Pathogenetic mechanisms that have been implicated include certain nutritional factors, exercise abuse, hypogonadism, hypercortisolism and/or vitamin 0 deficiency. We studied, 59 Caucasian eating disorder patients aged 15-45yr. The eating disorder was classified by a single, qualified psychiatrist according to OSM IV R criteria as either anorexia nervosa (AN: n =25), bulimia nervosa (BN: n = 17) or eating disorder not otherwise specified (EONOS: n = 17). All patients were subjected to a detailed dietary and general history. We assessed the prevalence and severity (OEXA), the nature (osteocalcin, deoxypyridinoline) and site (vertebral versus hip) of osteopenla in these patients. he role of nutritional factors (energy intake, weight, height, BMI, plasma albumin, lipids), physical activity, hypercortisolemia (plasma and urinary free cortisol), vitamin 0 deficiency (plasma 250HD) and hypogonadism (amenorrhoea, E2, LH, FSH) in the pathogenesis of bone loss were also evaluated. Mild osteopenia (BMO decreased by more than 1SO below age-matched controls) was documented in 46% of the total study population, with more marked osteopenia (Z-Score < -2 SO) present in 15%. Both vertebral and hip osteopenia were documented. In the study population those patients with AN (Lumbar BMO (q/cm") = 0.869 ± 0.121) were most likely to develop osteoporosis, although a significant percentage of patients with BN (Lumbar BMO (q/crn") = 0.975 ± 0.16) and EONOS (Lumbar BMO (g/cm2) = 0.936 ± 0.10) were also osteopenic (29% and 35% respectively). Twenty four percent (24%) of the total patient population had a history of fragility fractures. These fractures were reported more commonly amongst patients with AN and EONOS (28% and29.4%). Fracture prevalence was however similar in patients with normal and low bone mass. Conventional risk factors were similar in patients with normal and low bone mass, except for a significantly longer duration of amenorrhoea (p = 0.009), a lower BMI (p = 0.0001) and greater alcohol consumption (p = 0.05) in the osteopenic patients. Nutritional parameters (S-albumin, protein, Ca, and P04 intakes), physical activity, as well as 25(OH) vitamin D levels were similar in AN and BN subjects, as well as in patients with a low versus normal BMD. Plasma and urine cortisol levels were also similar in these subgroups. With the exception of two patients with borderline osteopenia, significant bone loss was only documented in those patients with a past or current history of amenorrhoea. In the total patient population the duration of amenorrhoea was significantly (p<0.009) longer in patients with osteopenia versus those with a normal bone mass. A significant negative correlation between BMD (Z-Score) and duration of amenorrhoea was also documented in the total patient population (r = -0.4, P = 0.001) as well as in all three eating disorder groups (AN r - -0.4, P = 0.03; BN r = - 0.6, P = 0.008; EDNOS r = -0.6, P = 0.005). In the total patient population, those patients with amenorrhoea, had lower BMD and BMI values and lower estrogen levels compared to those with a normal menstrual cycle. We conclude that osteopenia commonly attends AN, as well as BN and EDNOS. Nutritional (with the exception of alcohol consumption) and mechanical factors as well as hypercortisolemia did not appear to contribute significantly to bone loss in this study population. Hypogonadism appeared to be the main cause of the bone loss observed in these patients. / AFRIKAANSE OPSOMMING: Osteopenie is In welbekende komplikasie van anorexia nervosa (AN). Die patogenese van hierdie beenverlies is swak in die huidige literatuur omskryf en nutrisiele faktore, 'n vita mien 0 gebrek, oormatige oefening, hiperkortisolemie en hipogonadisme word onder andere qeimpliseer. Vir die doel van die studie is In totaal van 59 Kaukasier eetsteurnis pasiente patients volledig ondersoek. Die tipe eetsteurnis is deur In enkel gekwalifiseerde psigiater volgens die DSM IV R kriteria geklassifiseer as anorexia nervosa (AN: n =25) of bulimia nervosa (BN: n = 17) of eetsteurnis nie anders gespesifiseer (EDNOS: n = 17). Elke pasient is ook aan In gedetailleerde dieet en algemene risikofaktor vraelys vir osteoporose onderwerp. Die voorkoms en graad (DEXA), die aard (osteokalsien, deoksipiridinolien) asook die tipe (werwelkolom/heup) osteopenie is ondersoek. Die rol van nutrisiele faktore (totale kalorie-inmame, gewig ,Iente LMI, plasma albumien, lipiede) en vitamien 0 gebrek, oefening, hiperkortisolemie (plasma en urinere kortisol) en hipogonadisme (amenoree, plasma E2, LH,FSH) in die patogenese van die beenverlies is ook evalueer. Matige osteopenie (BMD meer as 1 SO onder die van ouderdomskontrole) is in 46% van die totale pasientpopulasie gedokumenteer, met erge osteopenie (Z-Telling < -2) in 15%. Aantasting van beide werwelkolom en heup is aangetoon. In hierdie studiepopulasie kom osteopenie meer algemeen voor in die AN (Lumbaal BMD (g/cm2) = 0.869 ± 0.121) groep (64%) in vergelyking met BN (Lumbaal BMD (g/cm2) = 0.975 ± 0.16) (29%) en (EDNOS) (Lumbaal BMD (g/cm2) = 0.936 ± 0.10) (32%). Vier-en-twintig persent van die totale pasientpopulasie het In geskiedenis van frakture gehad. Frakture het meer algemeen in AN en EDNOS pasiente voorgekom (28% en 29%). Pasiente met 'n lae beenmassa was gekenmerk deur In betekenisvolle laer LMI (p = 0.0001), hoer alkolholverbruik (p = 0.05) en langer duurte van amenoree(p = 0.009). Nutrisiele parameters (s-albumien, protetene, Ca, P04 inname) oefening, asook 25(OH) vitamien 0 vlakke was soortgelyk in AN en BN pasiente. Hierdie parameters het ook nie verskil tussen pasiente met osteopenie en die met In normale BMD nie. Plasma en urinere vry kortisolvlakke was ook soortgelyk in hierdie twee groepe. Betekenisvolle beenverlies (met die uitsondering van twee pasiente met grenslyn osteopenie) het slegs voorgekom in pasiete met 'n huidige of In vorige geskiedenis van amenoree. In die totale pasientpopulasie was die duurte van amenoree (p< 0.009) betekenisvollanger in die pasiente met osteopenie. In Betekenisvolle negatiewe korrelasie tussen BMD (Z-Telling) en die duurte van amenoree in die toale pasient populasie (r = -0.4; P = 0.001) asook in al drie eetsteurnis groepe (AN: r = -0.4; P = 0.03; BN: r = -0.06; P = 0.008; EDNOS: r = - 0.6, P = 0.005) is aangetoon. In die groep as 'n geheel, het die amenoree pasiente In laer LMI, E2vlakke en BMD gehad in vergelyking met die pasiente met normale menses. Opsommend dus, kom osteopenie algemeen in pasiente met AN, asook BN en EDNOS voor. In Betekenisvolle bydrae van nutrisiele (met die uitsondering van alkoholinname) en meganiese faktore asook hiperkortisolemie tot been verlies, kon nie in hierdie tudie populasie gedemonstreer word nie. Hipogonadisme is as die hoofoorsaak van osteopenie in die pasiente qefdentifiseer.