Pituitary Hormones

Diabetes Insipidus

Caused by either a deficiency of ADH or an inability to recognize ADH in the blood. It leads to an inability to concentrate urine.

Morning

Cortisol and ACTH levels are highest at this time of the day.

Testosterone

Created by the testes, in response to LH, this hormone negatively feeds back on GnRH secretion by the hypothalamus. Thus, if testosterone is injected in increased ammounts, the GnRH secretion will stop, which will stop production of both FSH and LH. This will lead to a decrease in both testosterone production (LH) and spem (FSH).

Follicle Stimulating Hormone

FSH. In males, this hormone stimulates production of spermatozoa by the testes. In females, this hormone stimulates ovulation.

Leutinizing Hormone

LH. In males, this hormone stimulates production of testosterone by the testes. In females, this hormone stimulates oestradiol production by the ovaries.

Cushing's Syndrome

This disorder is caused by an excess of cortisol. Symptoms include hyperglycaemia, obesity, muscle weakness, osteoporosis, hypertension, irregular periods, hirsutism (female hairyness) and psychosis. Diagnosis involves admistration of steroids which normlly will switch off CRF/ACTH. They are administrated at 11pm, and cortisol levels are checked at 9am the next morning. If cortisol levels are higher than 50nmol/L, a diagnosis of this disease is made.

ADH

This hormoe is released by the posterior lobe of the pituitary and is responsible for reducing water loss through the kidneys. It is produced in response to dehydration.

Cortisol

This hormone, produced by the adrenal cortex has a negative feedback loop on both CRF and ACTH production. It is produced in response to ACTH released by the pituitary. Its actions include increasing blood glucose, gluconeogenesis, hepatic glycogenolysis, lypolysis, proteolysis, and inhibit GH secretion. It can cause osteoporosis if its levels are constantly high. It increases cardiac output, increases response to catecholamines, increases renal blood flow and GFR, can cause mood lability, psychosis, euphoria, is implicated in cataracts and modulates white blood cell function.

Corticotropic releasing factor (CRF or CRH)

This hormone, produced by the hypothalamus stimulates the production of ACTH by the anterior lobe of the pituitary.

Insulin-like growth factor 1 (IGF-1)

This hormone, produced by the liver in response to GH, negatively feeds back on to both GH and GHRH production.

Prolactin

This hormone, released by the anterior lobe of the pituitary gland, is responsible for milk production by the breasts. Dopamine secretion from the hypothalamus inhibits this hormone's secretion. It inhibits FSH/LH production and thus can cause anovulation and low libido. Combination of this along with oestrogen and HCG cause development of the breast during pregnancy. It's production is promoted by suckling.

Growth Hormone

This hormone, released by the anterior lobe of the pituitary gland, is responsible for regular growth in children. Its actions are almost all mediated by IGF-1. It causes linear growth, hyperglycaemia, lipolysis, protein synthesis, renal salt/water reabsorption. Deficiency of this in kids leads to short stature, and in adults can lead to fatigue, poor muscle function/bulk, fat excess, osteoporosis, cardiac disease and poor quality of life.

Adrenocorticotropic Hormone (ACTH)

This hormone, released by the anterior lobe of the pituitary gland, is responsible for stimulating the production/secretion of corticosteroids such as cortisol from the adrenal cortex. It is produced in response to stress.

Thyroid Stimulating Hormone (TSH)

This hormone, released by the anterior lobe of the pituitary gland, is responsible for stimulating the release of thyroid hormones from the thyroid. Thus, it helps regulate metabolism. It's release is stimulated by TRH, which is released by the hypothalamus.

Gonadotropin Releasing Hormone (GnRH)

This hormone, released by the hypothalamus, stimulates release of FSH and LH from the anterior lobe of the pituitary.

Pro-opiomelanocortin

This is a prehormone that is enzymatically cleaved prior to secretion into ACTH, beta-endorphin and melanocyte stimulating hormone.

Dexamethasone suppression test

This is a test for the diagnosis of Cushing's syndrome. Steroids are administered at 11pm, and cortisol levels are checked at 9am the next morning. If cortisol levels are higher than 50nmol/L, a diagnosis of this disease is made.

Acromegaly

This is caused by an excess of GH. It causes gigantism in kids and enlargemet of tissues in adults. It can lead to diabetes, hypertension, cardiac enlargement, early death, arthralgia, and nerve entrapment.

V2 receptor

This receptor found on the basolateral (blood) side of the tubule cells in kidneys, responds to ADH and causes a cAMP/PKA mediated process of sending more aquaporins to the luminal side, bringing more water back from the lumin of the tubule.

ADH/Oxytocin

These are the only two hormones that are released from the posterior lobe of the pituitary gland.

FSH/LH

These two hormones are released by the anterior lobe of the pituitary land and are involved in sexual function.

Hyperprolactinaemia

Possibly caused by a prolactin secreting tumour of the pituitary, this can cause ammenorrhoea, low libido, infertility and osteoporosis. It can be treated with dopamine agonists which act to inhibit prolactin secretion.

Growth Hormone Releasing Hormone

Produced in the hypothalamus, this hormone stimulates production of GH by the pituitary gland. It is produced in response to hypoglycaemia, glucagon, arginine, stress and sleep.

Pulsatile

Produced mainly in the sleep, GH secretion is described as...