{"id":5978,"date":"2026-10-19T09:48:17","date_gmt":"2026-10-19T09:48:17","guid":{"rendered":"https:\/\/phd.hi.is\/doktorsvorn\/doktorsvorn-i-laeknavisindum-holmfridur-helgadottir\/"},"modified":"2026-10-19T09:48:17","modified_gmt":"2026-10-19T09:48:17","slug":"doktorsvorn-i-laeknavisindum-holmfridur-helgadottir","status":"publish","type":"phd_defence","link":"https:\/\/phd.hi.is\/en\/doktorsvorn\/doktorsvorn-i-laeknavisindum-holmfridur-helgadottir\/","title":{"rendered":"Doktorsv\u00f6rn \u00ed l\u00e6knav\u00edsindum – H\u00f3lmfr\u00ed\u00f0ur Helgad\u00f3ttir"},"content":{"rendered":"
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F\u00f6studaginn 27. september ver H\u00f3lmfr\u00ed\u00f0ur Helgad\u00f3ttir doktorsritger\u00f0 s\u00edna \u00ed l\u00e6knav\u00edsindum vi\u00f0 L\u00e6knadeild H\u00e1sk\u00f3la \u00cdslands. Ritger\u00f0in ber heiti\u00f0: Pr\u00f3t\u00f3nupumpu-hemlar: \u00der\u00f3un og forsp\u00e1rgildi fyrir offramlei\u00f0slu \u00e1 gastr\u00edni og kynjabundin sk\u00f6mmtun. Proton pump inhibitors: Acid rebound, development and predictors of gastrin elevation and dosage based on gender.<\/strong><\/p>\n

Andm\u00e6lendur eru dr. Peter Bytzer, pr\u00f3fessor vi\u00f0 Kaupmannahafnarh\u00e1sk\u00f3la, og dr. Gunnar Gu\u00f0mundsson, pr\u00f3fessor vi\u00f0 L\u00e6knadeild.<\/p>\n

Umsj\u00f3narkennari og lei\u00f0beinandi var dr. Einar S. Bj\u00f6rnsson, pr\u00f3fessor vi\u00f0 L\u00e6knadeild.<\/p>\n

Auk hans s\u00e1tu \u00ed doktorsnefnd dr. David C. Metz, pr\u00f3fessor vi\u00f0 l\u00e6knadeild H\u00e1sk\u00f3lans \u00ed Pennsylvan\u00edu \u00ed Bandar\u00edkjunum, El\u00edn I. Jacobsen, kl\u00edn\u00edskur lyfjafr\u00e6\u00f0ingur \u00e1 Landsp\u00edtala, dr. Helge Waldum, pr\u00f3fessor vi\u00f0 H\u00e1sk\u00f3lann \u00ed \u00der\u00e1ndheimi \u00ed Noregi og Sveinbj\u00f6rn Gizurarson, pr\u00f3fessor vi\u00f0 Lyfjafr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands.<\/p>\n

Ingibj\u00f6rg Har\u00f0ard\u00f3ttir, pr\u00f3fessor og varaforseti L\u00e6knadeildar, stj\u00f3rnar ath\u00f6fninni sem fer fram \u00ed H\u00e1t\u00ed\u00f0asal H\u00e1sk\u00f3la \u00cdslands og hefst kl. 13:00.<\/p>\n

\u00c1grip af ranns\u00f3kn <\/strong><\/p>\n

Pr\u00f3t\u00f3nu-pumpuhemlar (PPI) hindra seytingu \u00e1 magas\u00fdru og eru me\u00f0al mest notu\u00f0u lyfja \u00ed heiminum \u00ed dag m.a. vi\u00f0 brj\u00f3stsvi\u00f0a og v\u00e9lindab\u00f3lgu. Gastr\u00ednh\u00e6kkun er \u00feekkt aflei\u00f0ing me\u00f0fer\u00f0ar me\u00f0 PPI-lyfjum. Gastr\u00edn er horm\u00f3n sem leikur lykilhlutverk \u00ed stj\u00f3rnun \u00e1 s\u00fdruframlei\u00f0slu magans. Gastr\u00ednh\u00e6kkun er \u00e1hyggjuefni \u00fear sem h\u00fan er talin geta valdi\u00f0 aukinni s\u00fdruframlei\u00f0slu \u00feegar lyfjat\u00f6ku er h\u00e6tt. \u00dea\u00f0 er einnig hugsanleg \u00e1st\u00e6\u00f0a vaxandi t\u00ed\u00f0ni langt\u00edma PPI-lyfjame\u00f0fer\u00f0ar.<\/p>\n

Markmi\u00f0 ranns\u00f3knarverkefnisins var a\u00f0 kanna mikilv\u00e6gi kl\u00edn\u00edskra \u00fe\u00e1tta er var\u00f0a notkun PPI-lyfja hj\u00e1 sj\u00faklingum me\u00f0 v\u00e9lindabakfl\u00e6\u00f0i \u00e1 langt\u00edma PPI-lyfjame\u00f0fer\u00f0. S\u00e9rst\u00f6k \u00e1hersla var l\u00f6g\u00f0 \u00e1 tengsl gastr\u00edns vi\u00f0 kyn \u00fear sem fyrsta ranns\u00f3knin s\u00fdndi a\u00f0 konur \u00e1 PPI-lyfjum h\u00f6f\u00f0u markt\u00e6kt h\u00e6rra gastr\u00edngildi en karlar (Ranns\u00f3kn I). \u00deessar mikilv\u00e6gu ni\u00f0urst\u00f6\u00f0ur ur\u00f0u kveikjan a\u00f0 framkv\u00e6md tv\u00edblindrar slembiranns\u00f3knar til a\u00f0 \u00e1kvar\u00f0a hlutfall sj\u00faklinga sem getur minnka\u00f0 PPI skammtinn sinn um helming (Ranns\u00f3kn II). A\u00f0 auki var ger\u00f0 \u00feversni\u00f0sranns\u00f3kn (Ranns\u00f3kn III) til a\u00f0 \u00e1kvar\u00f0a mikilv\u00e6ga \u00fe\u00e6tti sem sp\u00e1 fyrir um gastr\u00ednh\u00e6kkun. Ennfremur voru borin saman lyfjahv\u00f6rf PPI-lyfs hj\u00e1 heilbrig\u00f0um einstaklingum (Ranns\u00f3kn IV) og ger\u00f0 ranns\u00f3kn \u00e1 \u00f6rvun \u00e1 \u00a0gastr\u00edni eftir einungis fj\u00f6gra daga PPI-lyfjame\u00f0fer\u00f0.<\/p>\n

Ranns\u00f3knirnar leiddu \u00ed lj\u00f3s a\u00f0 konur \u00e1 langt\u00edma PPI-lyfjame\u00f0fer\u00f0 h\u00f6f\u00f0u markt\u00e6kt h\u00e6rri \u00f6rvun \u00e1 gastr\u00edni samanbori\u00f0 vi\u00f0 karla og voru l\u00edklegri en karlar til a\u00f0 \u00feola skammtal\u00e6kkun um helming. PPI-lyfjaskammtur og kvenkyn vir\u00f0ast gegna lykilhlutverki \u00ed \u00fer\u00f3un offramlei\u00f0slu \u00e1 gastr\u00edni. \u00deessar ni\u00f0urst\u00f6\u00f0ur benda til aukins n\u00e6ms kvenna fyrir PPI-lyfjum. Ni\u00f0urst\u00f6\u00f0urnar eru mikilv\u00e6gar \u00fear sem konur me\u00f0 v\u00e9lindabakfl\u00e6\u00f0i g\u00e6tu n\u00e1\u00f0 \u00e1rangursr\u00edkri einkennastj\u00f3rnun me\u00f0 l\u00e6gri sk\u00f6mmtum en karlar.<\/p>\n

Abstract <\/strong><\/p>\n

In this research project the aim was to investigate important clinical aspects of the use of proton pump inhibitors (PPIs) in patients with gastroesophageal reflux disease. The study had a particular focus on the association of gastrin levels and gender since the first study, a cross-sectional study found significantly higher gastrin values among female PPI users than males (Study I). This novel observation led to a double blind randomized trial to determine the proportion of patients who could reduce their prior dosage by half with the hypothesis that females might be more sensitive to PPIs and therefore more likely to have a successful step down (Study II). As only a proportion of PPI users develops hypergastrinemia, we also wanted to determine the most important predictors of hypergastrinemia in long-term users of PPIs (Study III). Furthermore, we aimed to compare serum concentration of the PPI drug esomeprazole in males and females (Study IV).<\/p>\n

Um doktorsefni\u00f0 <\/strong><\/p>\n

H\u00f3lmfr\u00ed\u00f0ur Helgad\u00f3ttir er f\u00e6dd \u00ed Reykjav\u00edk \u00e1ri\u00f0 1989. H\u00fan lauk st\u00fadentspr\u00f3fi af n\u00e1tt\u00farufr\u00e6\u00f0ibraut Menntask\u00f3lans vi\u00f0 Sund 2009. H\u00fan lauk BS-pr\u00f3fi \u00ed l\u00e6knisfr\u00e6\u00f0i fr\u00e1 H\u00e1sk\u00f3la \u00cdslands \u00e1ri\u00f0 2012 og emb\u00e6ttispr\u00f3fi \u00ed l\u00e6knisfr\u00e6\u00f0i fr\u00e1 sama sk\u00f3la \u00feremur \u00e1rum s\u00ed\u00f0ar. A\u00f0 loknu kand\u00eddats\u00e1ri h\u00f3f h\u00fan s\u00e9rn\u00e1m \u00ed almennum lyfl\u00e6kningum vi\u00f0 Landsp\u00edtala \u00fear sem h\u00fan starfar enn. H\u00f3lmfr\u00ed\u00f0ur hefur stunda\u00f0 ranns\u00f3knarvinnu samhli\u00f0a l\u00e6knan\u00e1mi og starfi undir handlei\u00f0slu Einars Stef\u00e1ns Bj\u00f6rnssonar pr\u00f3fessors. Foreldrar H\u00f3lmfr\u00ed\u00f0ar eru Helgi J\u00f3hannesson og Gunnlaug Einarsd\u00f3ttir. D\u00e6tur H\u00f3lmfr\u00ed\u00f0ar eru Sigurborg Krist\u00f3fersd\u00f3tir 3 \u00e1ra og \u00c1lfhildur Krist\u00f3fersd\u00f3ttir 1 \u00e1rs.<\/p>\n<\/div><\/div>","protected":false},"featured_media":1162,"template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_phd_date_start":"2019-09-27T13:00:00+00:00","_phd_date_end":"2019-09-27T16:00:00+00:00","_phd_location":"A\u00f0albygging H\u00e1t\u00ed\u00f0asalur","_phd_admission":"A\u00f0gangur \u00f3keypis","_phd_thesis_title":"Pr\u00f3t\u00f3nupumpu-hemlar: \u00der\u00f3un og forsp\u00e1rgildi fyrir offramlei\u00f0slu \u00e1 gastr\u00edni og kynjabundin sk\u00f6mmtun. 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