Posterior pituitary insufficiency is characterized by an isolated failure of posterior pituitary hormone secretion, or at least by reduced secretion of the hormones oxytocin and ADH (antidiuretic hormone) produced in the hypothalamus. Oxytocin plays a special role in birth processes in women and generally has a positive effect on social relationships. ADH is an antidiuretic peptide hormone that is also synthesized in the hypothalamus and released into the bloodstream by the posterior pituitary lobe.
What is posterior pituitary insufficiency?
The posterior pituitary lobe (HHL), more appropriately called the neurohypophysis, is an integral part of the pituitary gland but evolutionarily represents a development of the brain. Unlike the anterior pituitary lobe (HVL), the HHL does not synthesize the secreted hormones itself; instead, the HHL serves as a storehouse and activator of the hormones oxytocin and ADH produced in the hypothalamus. Decreased hormone secretion or complete failure of hormone secretion by the HHL is referred to as posterior pituitary insufficiency (HHL insufficiency). The term insufficiency simply expresses that hormone secretion of oxytocin and the antidiuretic hormone ADH is impaired or completely absent. The mere fact that the hormone secretion of HHL is disturbed says nothing about the causes of the disturbed hormone secretion. For example, no conclusions can be drawn as to whether the causes lie in a dysfunction of the HHL or in the hypothalamus or in the transmission pathway of the “raw hormones” from the hypothalamus to the HHL. The transmission pathway consists of unmyelinated axons.
Causes
Posterior pituitary insufficiency isolated from the anterior pituitary lobe (HVL) may be due to a wide variety of causes. One of the possible causes is inflammation of the tissues of the HHL itself, so that it cannot respond adequately to control hormones from the hypothalamus to activate and release oxytocin and ADH. Similar symptomatology occurs when the pituitary gland is invaded by a tumor or tumors or hemorrhages in surrounding tissues interfere with the function of the HHL due to spatial stress. The reason for a malfunction or for a complete loss of function of the HHL may also lie in the transmission pathway of the non-activated hormones from the hypothalamus to the HHL. For example, the unmyelinated axons are very sensitive to possible compression. They run within the pituitary stalk (infundibulum), which is an integral part of the HHL and provides the connection to the hypothalamus. In very rare cases, hypothalamic dysfunction results in decreased synthesis of both hormones, which is symptomatically expressed as HHL insufficiency. Of course, radiation therapy or traumatic brain injury (SHT) can also lead to HHL insufficiency.
Symptoms, complaints, and signs
The symptoms and complaints of HHL insufficiency usually correspond to those typically seen with an undersupply of the hormones ADH and oxytocin. Oxytocin plays a major role in the birth process, inducing labor and causing milk to shoot into the nipples. In addition, oxytocin, sometimes called the cuddle hormone, has a positive systemic effect on the psyche in both men and women. It promotes the bond between two partners – comparable to the mother-child relationship, which is also controlled by oxytocin. The hormone facilitates and strengthens social bonds and counteracts social phobias. An undersupply of oxytocin makes births more difficult and women cannot breastfeed without it. The psychological effects of an oxytocin deficiency are diverse and vary from individual to individual. Deficiency of the antidiuretic hormone ADH, also called vasopressin, prevents the necessary reabsorption of primary urine, resulting in severe water loss. The condition is called diabetes insipidus, which can hardly be compensated even by increased drinking – in extreme cases up to 20 liters per day. If HHL insufficiency is caused by tumors or by hemorrhage or other spatial stress, primary disease symptoms such as headaches and, in extreme cases, visual disturbances also occur beyond the hormone deficiency symptoms.
Diagnosis and course of the disease
In cases where no primary symptoms and complaints are noticed, a suspicion of the presence of HHL insufficiency can only be triggered by the corresponding hormone deficiency symptoms. Imaging techniques such as X-ray, computed tomography (CT), magnetic resonance imaging (MRI), or somatostatin receptor scintigraphy are used to confirm or reject the suspected diagnosis. Since imaging procedures do not always allow clear findings or can also lead to misinterpretations, an endocrinological examination with regard to hormone levels in the serum is helpful in many cases to confirm the diagnosis. The course of the disease depends on the primary disease. If left untreated, HHL insufficiency may either persist or may progress to a more severe course – for example, due to tumors of the pituitary gland.
Complications
Pituitary posterior lobe insufficiency usually results in various complaints that can negatively affect both the patient’s mental and physical state. In most cases, the disease negatively affects the birth process. Even after birth, in most cases the mother is unable to breastfeed the child. As a rule, the child must then be fed artificially, although this results in psychological discomfort for the mother. Likewise, social ties are weakened and no longer properly respected, which can lead to problems with friends or with the partner. It is not uncommon for visual disturbances or headaches to occur as a result of posterior pituitary insufficiency. The quality of life of the patient decreases extremely due to the disease and it is not uncommon that various psychological upsets of the patient occur. The treatment of posterior pituitary insufficiency is carried out with the help of hormones, but there are no further complications. If the mother is unable to breastfeed the child, the child can be cared for in other ways. In this case, there are usually no developmental delays in the child.
When should you go to the doctor?
Symptoms such as visual disturbances, headaches in the back of the skull, or a general feeling of illness indicate posterior pituitary insufficiency. A visit to the doctor is necessary if the signs mentioned persist for more than a week or rapidly increase in intensity as they progress. Affected persons should then immediately consult their family doctor and arrange for an examination. It is possible that the symptoms are due to a harmless cause that can be treated directly. If the cause is actually posterior pituitary insufficiency, the patient must be treated in a specialist clinic. Therefore, with clear signs such as the characteristic headache and visual disturbances, medical advice should be sought in any case. Tumor patients are particularly susceptible to posterior pituitary insufficiency. Individuals who have suffered a traumatic brain injury or have undergone radiation therapy are also at increased risk for developing HHL. In any case, anyone who considers himself or herself to be in these risk groups must inform the appropriate physician. In addition to the primary care physician, a neurologist or an internist may also be consulted.
Treatment and therapy
Treatment of HHL insufficiency may be aimed at curing the primary disease or at treating the symptoms, which generally involves administration of replacement hormones. If primary diseases of the pituitary gland and especially of the posterior pituitary lobe can be treated causally, the insufficiency of the hormones ADH and oxytocin may resolve itself. In all other cases, where restoration of the secreting action of the HHL is no longer possible, treatment consists of lifelong hormone replacement or hormone balancing therapy. Hormone therapy always involves direct hormone administration. This is true even in cases in which the pituitary gland normally regulates hormone concentrations by secreting control hormones, i.e., it merely induces a specific target organ to increase the secretion of the actual hormone into the metabolism.
Prevention
Direct preventive measures that might prevent the development of HHL insufficiency are not known. The best protection is early detection of oxytocin and ADH deficiency.While a gradual onset of oxytocin deficiency is not readily recognizable as such, insufficient ADH levels in the blood serum are noticeable by severe feelings of thirst, which should be clarified.
Follow-up
In most cases of posterior pituitary insufficiency, measures of immediate follow-up are severely limited. In general, patients with this condition rely on prompt and early diagnosis to prevent further complications and worsening of symptoms. In posterior pituitary insufficiency, there is no independent cure. Therefore, the affected person should see a doctor at the first symptoms and signs of the disease, so that early treatment can be initiated. Those affected by this disease are usually dependent on taking various medications that can permanently alleviate the symptoms. It is always important to ensure that the medication is taken correctly and in the correct dosage. In the case of children, parents in particular should monitor and check that the medication is taken correctly. Since posterior pituitary insufficiency can also have a negative effect on other organs of the body, the affected person should undergo regular examinations by a physician in order to detect possible damage at an early stage. In this regard, it cannot be universally predicted whether the disease will result in a reduced life expectancy for the patient.
Here’s what you can do yourself
Patients with posterior pituitary insufficiency often need to take hormones for the rest of their lives. Until these hormones are perfectly adjusted, they should have a lot of patience, especially if the hormones were prescribed in the form of nasal sprays or injections rather than tablets. After that, the hormone replacement or hormone balancing therapy should be reliably integrated into the daily routine. It should go without saying that hormone levels are checked regularly. To ensure the necessary adherence to therapy, it is advisable to keep a record of the blood tests and the hormone status determined. This is particularly helpful when patients go on vacation for a longer period of time or change their place of residence. In this way, new doctors can always get an accurate picture of the course of the disease. Patients with posterior pituitary insufficiency may suffer from the fact that their bodies no longer produce oxytocin at the level needed for well-functioning social bonds. This can negatively affect relationships with friends, family, and partners, and in the worst cases, make them impossible. If medication alone is not enough, accompanying psychotherapeutic treatment is recommended in this case. Mothers with posterior pituitary insufficiency are often unable to breastfeed their child, which can be just as difficult psychologically. Here, too, psychotherapeutic treatment is recommended and in most cases is paid for by the statutory health insurers without any objections.
