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Zaradi odvečne količine rastnega hormona otroci z gigantizmom dosežejo nenormalne telesne višine, ki precej presegajo povprečne vrednost.<ref>{{Cite journal|last1=Eugster|first1=Erica A.|last2=Pescovitz|first2=Ora H.|date=1999-12-01|title=Gigantism|journal=The Journal of Clinical Endocrinology & Metabolism|volume=84|issue=12|pages=4379–4384|doi=10.1210/jcem.84.12.6222|pmid=10599691|issn=0021-972X|doi-access=free}}</ref> Starost, pri kateri se začnejo kazati jasni znaki gigantizma, je pogosto variabilna, velikokrat pa se to zgodi ob starosti 13 let.<ref name=":0" /> Za obolele so značilna tudi druge bolezenske težave, kot je denimo [[zvišan krvni tlak]] (hipertenzija). Značilnosti, ki so bolj pogoste za bolnike z akromegalijo, se lahko pojavijo pri pacientih blizu [[Adolescenca|adolescence]] (mladostniškega obdobja), ki so bližje zlitju rastnega hrustanca.<ref>{{Cite book|chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK278971/|title=Endotext|last1=Murray|first1=P. G.|last2=Clayton|first2=P. E.|date=2000|publisher=MDText.com, Inc.|editor-last=De Groot|editor-first=Leslie J.|location=South Dartmouth (MA)|pmid=25905205|editor-last2=Chrousos|editor-first2=George|editor-last3=Dungan|editor-first3=Kathleen|editor-last4=Feingold|editor-first4=Kenneth R.|editor-last5=Grossman|editor-first5=Ashley|editor-last6=Hershman|editor-first6=Jerome M.|editor-last7=Koch|editor-first7=Christian|editor-last8=Korbonits|editor-first8=Márta|editor-last9=McLachlan|editor-first9=Robert|chapter=Disorders of Growth Hormone in Childhood}}</ref>
=== HormonalHormonski causevzrok ===
[[GrowthRastni hormone]]hormon (GH) andin [[insulin-likeinzulinu growthpodobni factorrastni faktor 1|insulin-like growth factor-I]] ([[Igf1|IGF-I1]]) aresta twodve substancessnovi, thatza havekateri beenje identifiedbilo asspoznano, influencingda growthvplivata platena formationnastajanje andrastnega bonehrustanca growthin and,rast thereforekosti, gigantismter posledično tudi na gigantizem. TheirVsi specificmehanizmi mechanismsnjunega aredelovanja stillše notniso wellpopolnoma understoodrazumljeni.<ref name=":0" /><ref>{{Cite journal|last=Shim|first=Kye Shik|date=March 2015|title=Pubertal growth and epiphyseal fusion|journal=Annals of Pediatric Endocrinology & Metabolism|volume=20|issue=1|pages=8–12|doi=10.6065/apem.2015.20.1.8|issn=2287-1012|pmc=4397276|pmid=25883921}}</ref> Tako za GH kot tudi IGF je bilo pokazano, da se vključujeta v večino faz rasti: embrionalno, prenatalno in postnatalno.<ref name=":3">{{Cite journal|last=Laron|first=Z|date=October 2001|title=Insulin-like growth factor 1 (IGF-1): a growth hormone|journal=Molecular Pathology|volume=54|issue=5|pages=311–316|issn=1366-8714|pmc=1187088|pmid=11577173|doi=10.1136/mp.54.5.311}}</ref><ref name=":4">{{Cite journal|last1=Lupu|first1=Floria|last2=Terwilliger|first2=Joseph D.|last3=Lee|first3=Kaechoong|last4=Segre|first4=Gino V.|last5=Efstratiadis|first5=Argiris|title=Roles of growth hormone and insulin-like growth factor 1 in mouse postnatal growth|journal=Developmental Biology|volume=229|issue=1|pages=141–162|doi=10.1006/dbio.2000.9975|pmid=11133160|year=2001}}</ref>
Rastni hormon je prekurzor IGF-1, vsaka od dveh snovi pa ima svojo neodvisno vlogo v hormonalnih poteh. Vseeno se zdi, da je učinek obeh snovi na rast skupen.<ref name=":4" />
More broadly, GH and IGF have both been identified to be involved in most stages of growth: embryonic, prenatal, and postnatal.<ref name=":3">{{Cite journal|last=Laron|first=Z|date=October 2001|title=Insulin-like growth factor 1 (IGF-1): a growth hormone|journal=Molecular Pathology|volume=54|issue=5|pages=311–316|issn=1366-8714|pmc=1187088|pmid=11577173|doi=10.1136/mp.54.5.311}}</ref><ref name=":4">{{Cite journal|last1=Lupu|first1=Floria|last2=Terwilliger|first2=Joseph D.|last3=Lee|first3=Kaechoong|last4=Segre|first4=Gino V.|last5=Efstratiadis|first5=Argiris|title=Roles of growth hormone and insulin-like growth factor 1 in mouse postnatal growth|journal=Developmental Biology|volume=229|issue=1|pages=141–162|doi=10.1006/dbio.2000.9975|pmid=11133160|year=2001}}</ref> Moreover, the receptor gene for IGF has been shown to be particularly influential throughout various stages of development, especially prenatally. This is the same for GH receptor genes which have been known to drive overall growth throughout various pathways.<ref name=":3" /><ref name=":5">{{Cite journal|last1=Sanders|first1=Esmond J.|last2=Harvey|first2=Steve|title=Growth hormone as an early embryonic growth and differentiation factor|journal=Anatomy and Embryology|volume=209|issue=1|pages=1–9|doi=10.1007/s00429-004-0422-1|pmid=15480774|year=2004|s2cid=19528310}}</ref>
=== Diagnostično testiranje ===
Growth hormone is a precursor ([[Upstream and downstream (DNA)|upstream]]) of IGF-I, but each has its independent role in hormonal pathways. Yet both seem to ultimately come together to have a joint effect on growth.<ref name=":4" />
Pri diagnostičnem testiranju gigantizma en sam vzorec z normalnimi vrednostmi rastnega hormona ni dovolj za potrditev odsotnosti gigantizma, ker je sekrecija rastnega hormona ob različnih delih dneva lahko raznolika. Po drugi strani je naključen vzorec krvi z zvišano ravnjo rastnega hormona dovoljšen pokazatelj gigantizma in s tem povezane hipersekrecije rastnega hormona.<ref name=":6">De Mais, Daniel. ASCP Quick Compendium of Clinical Pathology, 2nd Ed. ASCP Press, Chicago, 2009.</ref>
Za dokazovanje hipersekrecije rastnega hormona je dober pokazatelj tudi inzulinu podobni rastni faktor 1 (IGF-1), ki se izloča enakomerno in bo njegova raven pri bolnikih z gigantizmov vselej zvišana. Normalna vrednost IGF-1 kaže, da ni hipersekrecije rastnega hormona.<ref name=":6" />
=== Diagnostic testing ===
Evaluation of growth hormone hyper-secretion cannot be excluded with a single normal GH level due to [[diurnal variation]]. However, a random blood sample showing markedly elevated GH is adequate for diagnosis of GH hyper-secretion. Additionally, a high-normal GH level that fails to suppress with administration of glucose is also sufficient for a diagnosis of GH hyper-secretion.<ref name=":6">De Mais, Daniel. ASCP Quick Compendium of Clinical Pathology, 2nd Ed. ASCP Press, Chicago, 2009.</ref>
Insulin-like growth factor-1 (IGF-1) is an excellent test for evaluation of GH hyper-secretion. It does not undergo diurnal variation and will thus be consistently elevated in GH hyper-secretion and therefore patients with gigantism. A single normal IGF-1 value will reliably exclude GH hyper-secretion.<ref name=":6" />
== Genetic ==
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