Peripheral endocrine organ functions are controlled to varying degrees by pituitary hormones. Some functions (eg, secretion of insulin by the pancreas, primarily controlled by the blood glucose level) are controlled to a minimal extent or are independent of pituitary control (eg, secretion of parathyroid hormone Overview of Parathyroid Function by the parathyroid glands, primarily in response to blood calcium levels), whereas many (eg, secretion of thyroid or gonadal hormones) are controlled to a great extent. Secretion of pituitary hormones is controlled by the hypothalamus.