At det er en "primær" mangel, vil sige, at der ikke er fundet nogen anden årsag til det lave indhold af IGF- 1, f. eks. fejlernæring, lavt indhold af skjoldbruskkirtelhormon eller brug af medicin, der kaldes steroider, til at afhjælpe eller forhindre inflammation.
It is a ‘ primary’ deficiency, meaning that there is no other identified cause for the low levels of IGF-1, such as malnutrition, low levels of thyroid hormone or the use of medicines called steroids to reduce or prevent inflammation.