What is the neurohypophysis?
The neurohypophysis is the posterior part of the pituitary gland and is also known as the posterior lobe of the pituitary or posterior pituitary. This part of the pituitary gland is intended to store various hormones secreted by the hypothalamus, including antidiuretic hormone (ADH) or vasopressin (AVP), which is responsible for enhancing water reabsorption at the renal level and regulating the concentration of various substances in the blood. When a patient suffers from the syndrome of inadequate ADH secretion, the kidney does not recover the water it should, there is an absence of glucose loss in the urine and what is known as diabetes insipidus occurs. This pathology has nothing to do with diabetes due to lack of insulin, but is so named because it shares certain symptoms, such as diuresis and increased thirst, which causes the need to drink water constantly.
Function of the neurohypophysis
The neurohypophysis is responsible for storing and releasing the two hormones related to the organ: oxytocin and vasopressin. It is often mistakenly thought that this gland produces hormones.
- Oxytocin: plays a key role in social bonding, sexual reproduction and is vital during and after childbirth.
- Vasopressin: main functions include increasing the amount of solute-free water reabsorbed into the circulation, which allows an increase in peripheral vascular resistance and increases blood pressure. It could also play an important role in social behavior, sexual motivation or bonding between people, due to the release of vasopressin in certain areas of the brain.
Diabetes insipidus produces intense thirst.
Pathologies that can affect the neurohypophysis
The diseases that can affect include those secondary to the defect or excess of the production of the antidiuretic hormone. An injury, degeneration or alteration in the function can cause a deregulation of the secretion of the two hormones mentioned above (oxytocin and vasopressin).
- Diabetes insipidus: deficit in the production or action of antidiuretic hormone, by renal resistance to the action of antidiuretic hormone, by increased water intake or by increased water catabolism. The body loses the ability to concentrate and store urine and the patient may excrete up to 20 liters of dilute urine daily.
- Syndrome of inappropriate secretion of antidiuretic hormone: excess of antidiuretic hormone action. It is mainly caused by drugs and generates various gastrointestinal, respiratory, neuromuscular and neurological symptoms.
Treatments for neurohypophysis pathologies
Treatment of diabetes insipidus is usually performed with a synthetic hormone called desmopressin, as it is caused by a lack of antidiuretic hormone. It can be administered orally, by injection or as a nasal spray. This hormone will eliminate the increased urination but it is important to regulate it with a specialist, since in most cases the deficiency of antidiuretic hormone is not complete and the amount produced may vary. In the case of mild diabetes insipidus it may only be necessary to increase water consumption.
Inappropriate antidiuretic hormone secretion syndrome should be treated early, especially in severe cases, as it can lead to cerebral edema. Fluid intake should be limited and, if possible, the cause treated. Sometimes intravenous fluids are administered, including those with high sodium concentrations, always with the guidance of a specialist. In the event that the treatment is not effective, the specialist physician may administer certain drugs to the patient.
Specialist treating pathologies of the neurohypophysis
The physician in charge of treating pathologies related to the neurohypophysis is a specialist in Endocrinology.