Diabetes Insipidus is the inability to control excess excretion of water via urination. The balance in the amount of H20 that circulates in our bodies is carried out by a multi-organ system of communication that when compromised, leads to an uncomfortable and permanent condition. As we all know, the brain is the control room of our bodies and communicates with other areas via electrical stimuli and chemical signals like hormones. Different structures in the brain produce different hormones for different functions all across our bodies. A very special cerebral structure called the pituitary gland is small in size but carries several gargantuan tasks.
The pituitary gland is a pea-sized endocrine gland that rests on top of the pituitary fossa, a cup shaped bone structure that is located at the central rear of the nasal bridge. The pituitary gland is made of 2 lobes called anterior and posterior lobes. The posterior portion produces and excretes a crucial hormone called vasopressin or ADH (Anti-Diuretic Hormone). As its name indicates, the function of this hormone is to hinder the kidneys from expelling more urine and thus encourages retention of fluids. This is achieved by the presence of ‘detectors’ in the brain that are responsible for monitoring blood dilution (concentrations of H20 in the blood), whether too high or too low.
When H20 levels are insufficient, the posterior pituitary gland sends a signal to the kidney in the form of the aforementioned vasopressin hormone. When vasopressin reaches the kidney, water is reabsorbed back into the body instead of being expelled via urine. In contrast, when H20 levels are high, the production and secretion of vasopressin diminishes so as to return proper fluid balance by allowing the renal system to continue to expel fluid waste.
As it is, this cooperative system can be disrupted in several fashions. Excessive loss of water through urination as a result of pituitary or hypothalamic trauma is called Central Diabetes Insipidus.
How does this happen and what are the symptoms of Diabetes Insipidus?
An injury to the hypothalamus (a larger brain structure that contains the pituitary gland), a tumor, sarcoidosis, Diabetes Mellitus (due to the diuretic effects of high glucose levels), meningitis, polycystic kidneys and Langerhans cell histiocytosis (an overproduction of immature types of immune cells that may result in tumor formation) are all known causes of Diabetes Insipidus. However, spontaneous occurrence of Diabetes Insipidus can happen at random with no warning. In this instance, the cause is unknown and referred to as idiopathic. Other metabolism related causes are hypokalemia and hyperkalemia.
In the case of a renal condition preventing proper reception of vasopressin (such as sarcoidosis) by the kidney, it is called Nephrogenic Diabetes Insipidus.
Due to persistent loss of water through urination, two of the main symptoms of Diabetes Insipidus is polyuria and polydipsia; abnormally high frequency of urination and a higher need for liquid consumption due to persistent thirsty sensations, respectively. Dehydration therefore is quite common and must be addressed immediately. Oftentimes the sensation of thirst is so overwhelming for some children that drinking out of a vase or out of other unsanitary vessels is also seen.
Treating Diabetes Insipidus
Because the stomach pH ruins orally ingested vasopressin, a synthetic form of the hormone is injected. Similar synthetic compounds can be sprayed nasally or through oral absorption. In terms of effectiveness, a drug called Desmopressin is highly touted and is available in spray, via injection and in tablet form. The tablet form has been shown to be the most widely used because of its ease and efficacy. The usual dosage for the Desmotabs is between 5 – 200 µg every 8 or 12 hours.
Unfortunately, there is no cure for this condition. Nevertheless, the Central form of Diabetes Insipidus can be easily reversed and proper fluid balance achieved with Desmopressin.