GHD can be present at birth or develop later in life.[1] Causes may include genetics, trauma, infections, tumors, or radiation therapy.[2] Genes that may be involved include GH1, GHRHR, or BTK.[3] In a third of cases no cause is apparent.[2] The underlying mechanism generally involves problems with the pituitary gland.[2] Some cases are associated with a lack of other pituitary hormones, in which case it is known as combined pituitary hormone deficiency.[4] Diagnosis involves blood tests to measure growth hormone levels.[2]