by Iris Frances Forster Benzie. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 170-184.

M.Med. (Medical Genetics)--University of the Witwatersrand, Faculty of Health Sciences, School of Pathology, 2012 / Down syndrome (DS) (OMIM #190685), the most common viable chromosome abnormality, is associated with an increased risk of medical complications. The most frequent endocrine abnormalities observed in children with DS involve the thyroid gland, and the risk of thyroid dysfunction increases with age. Global studies have documented a wide spectrum of thyroid dysfunction in children with DS. Due to the paucity of data from sub-Saharan Africa regarding thyroid function in African children with DS, this study was conceived. The main aim of the study was to document the range of thyroid function in a cohort of 391 South African children with DS, seen at the Genetic Clinics from 2003 to 2008. Referral and treatment practices at two tertiary hospitals in Johannesburg were also documented. The majority (84%) of children had at least one thyroid function test (TFT) performed, and the most common form of thyroid dysfunction encountered was subclinical hypothyroidism (25.3%). Notably, up to one third of patients with abnormal TFT results were not referred to the Endocrine Clinics for evaluation, and were thus not receiving the necessary treatment. There were 13 neonates with congenital hypothyroidism; at least two of them were not referred, and thus not treated during the sensitive neonatal period. A significant difference was noted between the results from Chris Hani Baragwanath Hospital and those from the other two hospitals. The difficulties in interpretation of results obtained from different biochemical machines and different populations, as compared to those used to derive the reference ranges, were raised. Problems with regular follow-up of patients and annual thyroid surveillance were also highlighted. The clinical features of hypothyroidism may be difficult to distinguish from the phenotypic features of DS. Thus, regular biochemical screening, even in the absence of physical signs and symptoms, is warranted in this group of children to ensure that hypothyroidism is treated, and further, irreversible neurological and physical impairment prevented.

A dissertation submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, in part fulfilment of the requirements for the degree Master of Medicine in Internal Medicine. 1993. / Normal thyroid physiology and pathophysiOlogy with reference to non-thyroidal illness is reviwed, including infections, specific disease states and drugs and their effects on thyroid function tests. A review of the literature reveals that following almost any infection the serum T4 and T3 decrease as a result of diminished secretion of TSH and thyroxine, accelerated T4 disappearance, inhibition of hormone binding to transport proteins and decreased peripheral T4 to T3 conversion. [Abbreviated Abstract. Open document to view full version] / AC2017

<p>Uvod: Poslednjih godina u fokusu istraživača je efekat sintetskih jednjenja na endokrini sistem. Estri ftalne kiseline se koriste u procesu plastifikacije, kao industrijski rastvarači, lubrikanti, aditivi u tekstilnoj industriji, u pesticidima, kozmetičkim proizvodima. Raste broj dokaza da je tiroidna žlezda podložna dejstvu endokrinih disruptora. Tiroidni hormoni imaju važnu ulogu u regulaciji rasta, tkivne diferencijacije, energetskog metabolizma, reprodukcije i formiranja centralnog nervnog sistema. Brojna istraživanja ukazala su da ftalati deluju kao EDs. Ciljevi istraživanja: 1. Procena izloženosti populacije mono-etilheksil-ftalatu (MEHP) i mono-etil-ftalatu (MEP). 2. Evaluacija razlika u nivou pokazatelja tirodine funkcije između ftalat pozitivnih i ftalat negativnih ispitanika i između gojaznih i normalno uhranjenih ftalat pozitivnih ispitanika. 3.Utvrđivanje razlika u serumskom nivou leptina gojaznih ispitanika sa i bez pozitivnih ftalatnih metabolita i procena povezanosti leptina sa MEP i MEHP i pokazateljima tiroidne funkcije. Izbor ispitanika i metod rada: Istraživanje je sprovedeno kao studija preseka, obuhvatilo je 201 ispitanika. Ispitanici su podeljeni u grupu MEP/MEHP pozitivnih i negativnih i na podgupe normalno uhranjenih i gojaznih. Od antropometrijskih mera određena je telesna visina, telesna masa, obim struka i indeks telesne mase. Laboratorijske analize: jutarnji uzorak urina za određivanje MEP i MEHP; na&scaron;te uzet uzorka venske krvi za FT4, FT3, TSH i leptin. Statististička analiza sprovedena je na softverskom paketu SPSS. Rezultati: Polovina stanovni&scaron;tva je izložena ftalatima. MEP dovodi do povi&scaron;enja FT4 samo u subpopulaciji gojaznih. Nije utvrđen statistički značajan uticaj MEP na FT3. Kod gojaznih MEP pozitivnih osoba ženskog pola povi&scaron;en je TSH. MEHP uzrokuje sniženje FT4 kod normalno uhranjenih ispitanika, a kod normalno uhranjenih mu&scaron;karaca snižava FT3. Nije utvrđen uticaj MEHP na tirotropin. U gojaznih nije ustanovljen uticaj DEHP i DEP na leptinsku sekreciju.Uočena je tendencija negativne korelacije leptina i FT4 kod gojaznih, dok uticaja na FT3 i TSH nema. Zaključak: Na&scaron;a populacija je u velikoj meri izložena ftalatima. Potvrđeno je da MEP i MEHP imaju uticaj na pojedine indikatore tiroidne funkcije. Ftalati u na&scaron;em istraživanju ne uzrokuju poremećaj leptinske skrecije, a leptin ima blag uticaj jedino na FT4.</p> / <p>Introduction: Effects of synthesized chemicals on endocrine system has been in the focus in the last years. Phthalates are used in plasticization, as industrial solvents, lubricants, textile industry additives, in pesticides and cosmetic products. Evidence for thyroid disruption is growing. Thyroid hormones (TH) have an important role in regulation of growth, tissue differentiation, energy metabolism, reproduction and central nervous system formation. Studies show phthalates can cause endocrine disruption. Aims: 1. Estimation of burden of mono-ethyl phthalate (MEP) and di-2-ethylheksyl phthalate(MEHP) in the population. 2. Evaluation of differences in TH and TSH in MEP/MEHP positive and negative participants, as in obese and lean MEP/MEHP positive participants. 3. Evaluation of differences in leptin in obese MEP/MEHP positive and negative subjects and evaluation of the connection between leptin, MEP, MEHP and thyroid indicators. Patients and methods: This was a cross-sectional study that comprised 201 subjects divided into MEP/MEHP positive and negative group, further subdivided in obese and lean. Anthropometric parameters done: body height, body weight, waist and body mass index. Laboratory tests done: morning urine sample analysis for MEP/MEHP and venous sample analysis for free thyroxine (FT4), free tri-iodothyronine (FT3), thyroid stimulating hormone (TSH) and leptin. Statistical analysis was done in SPSS. Results: Half of subjects were exposed to phthalates. MEP induced an increase in FT4 in obese participants and had no influence on FT3. TSH was increased in obese MEP positive female subjects. MEHP induced a decrease in FT4 in lean participants and a decrease of FT3 in lean males. There was no correlation between MEHP and TSH. Influence of MEP/MEHP on leptin secretion. A tendency for negative correlation between leptin and FT4 was seen. There was no influence of leptin on FT3 and TSH. Conclusion: Our population is greatly exposed to phthalates. MEP and MEHP influence certain thyroid indicators i.e. cause thyroid disruption. Phthalates do not influence leptin secretion in our study. There is a mild effect of leptin on FT4.</p>