Diabetes Insipidus is an uncommon endocrine disorder characterized by excessive thirst and excretion of large volumes of urine. The condition usually occurs due to insufficient production of anti-diuretic hormone (ADH) that regulates the water conservation mechanism of the kidneys.
The cause of diabetes insipidus is insufficient production of anti-diuretic hormone (ADH) or vasopressin by the posterior pituitary. The hormone maintains the water levels of the body by regulating the amount of water excreted through urine. A drop in the water levels of the body stimulates the pituitary gland to secrete ADH to conserve water by decreasing the volume of water lost through urine. Any impairment in this mechanism may lead to diabetes insipidus. Diabetes insipidus can be categorized into four broad categories — central diabetes insipidus, nephrogenic diabetes insipidus, gestational diabetes insipidus and dipsogenic diabetes insipidus.
The causes of central diabetes insipidus include any damage to the pituitary gland or hypothalamus due to surgery or tumour, illness such as meningitis and inflammation or head injury. In few cases certain unknown factors may disrupt the normal functioning of ADH. In nephrogenic diabetes insipidus, a defect of the tubules or other part of the kidneys may be responsible for improper response of the kidneys to ADH. The defect usually arises secondary to a genetic disorder or chronic kidney disorder. Sometimes intake of certain drugs such as lithium or tetracycline may also cause nephrogenic diabetes insipidus. During pregnancy some women may experience gestational diabetes insipidus where an enzyme secreted by the placenta destroys the ADH in the mother. Dipsogenic diabetes insipidus otherwise known as primary polydipsia or psychogenic polydipsia leads to excessive fluid intake that may suppress the function of ADH. Some diseases such as sarcoidosis or mental illness may also lead to dipsogenic diabetes insipidus.
The most common signs and symptoms of diabetes insipidus includes intense thirst and frequent excretion of excessive amounts of urine. Some patients may experience disruption of sleep due to a tendency to urinate at night or may have bed-wetting episodes. Diabetes insipidus affected infants or young children may present with symptoms such as excessive crying or unexplainable irritability, fever, vomiting or diarrhoea, delayed growth or weight loss and dry skin with cool extremities.
The diagnosis of the condition includes detailed medical history and physical examination of the patient to identify the condition. Other lab tests such as water deprivation test or urinalysis may be conducted to confirm the condition. MRI imaging may be performed to detect any related abnormalities in the brain tissues. Genetic screening may also be used to identify any underlying hereditary factor responsible for the disorder.
The treatment of the condition includes treatment of the underlying cause. Other modalities of treatment include plenty of fluid intake, low salt diet or some medications such as non-steroidal anti-inflammatory drugs and hydrochlorothiazide
The possible complications of diabetes insipidus, in case of undiagnosed or poorly controlled patients, include chronic dehydration, low body temperature, weight loss, rapid heart rate, fatigue and low blood pressure.