Gigantism and Acromegaly are due to:

1. Hypersecretion of Growth hormone
2. Hypersecretion of Thyroxine
3. Hyposecretion of Growth hormone
4. Hyposecretion of Thyroxine

Hypersecretion of Growth hormone

Reason — Acromegaly and Gigantism are disorder in adults in which the pituitary gland produces too much of Growth hormone.