Diabetes insipidus

The story of a young woman who was suffering from chronic thirst (polydipsia) reminds us that the most obvious symptoms can sometimes be overlooked, resulting in the delayed diagnosis and treatment of a medical disorder.

A 38-year-old woman who had just delivered her baby by C-section in the morning, asked a nurse to bring her a glass of water because she was extremely thirsty. The nurse obliged and brought her a pitcher of water before bedtime. The next morning, an alarmed OB-GYN intern wakes up her patient - she had drunk well over three gallons of water overnight! And her urine output had been just as spectacular. The intern was worried and wanted to find out what was happening to her patient. Excessive thirst, also called polydipsia, is one of the telltale signs of diabetes mellitus. And because she had suffered from polydipsia most of her life, the young woman had already been tested for diabetes several times before. She had also had her blood glucose levels checked and undergone glucose tolerance tests, but the results never revealed any abnormalities. The intern suspected her patient could be suffering from a rare type of diabetes called: diabetes insipidus.

In the case of diabetes insipidus, a patient’s body produces and uses insulin correctly, but is unable to produce vasopressin. Vasopressin is a hormone secreted by the pituitary gland located in the brain. The role of vasopressin is to let the kidneys know they need to conserve water from the urine when the body needs more water. Individuals who suffer from diabetes insipidus cannot produce any vasopressin. Consequently, the kidneys eliminate every ounce of water that passes through them. The result? The patients’ urine is diluted, abundant and very light in colour, even if they drink large quantities of liquid. In fact, patients who suffer from diabetes insipidus are incessantly thirsty because their body must consistently compensate for the great quantities of water lost through frequent and abundant urination.

A simple blood test confirmed that the young woman did not produce any vasopressin and therefore suffered from diabetes insipidus. But why was her pituitary gland not producing vasopressin? To find an answer to this dilemma, the woman underwent a magnetic resonance imaging (MRI) scan which ruled out the presence of a tumour on the pituitary gland. During their investigation, physicians ascertained that the young woman had never suffered any trauma or surgery to the brain, which could have inadvertently damaged the gland and prevented it from producing vasopressin. Having ruled out all possible causes, a diagnosis of idiopathic diabetes insipidus was rendered. Idiopathic simply means that the cause is unknown.

Unfortunately, diabetes insipidus cannot be cured. However, it can be controlled with the use of a synthetic vasopressin nose spray administered once daily. Although this course of treatment is simple and efficient, it is one that must be followed an entire lifetime.

The story of this young mother reminds us never to ignore symptoms that seem, at first glance, without explanation. Sometimes, further testing and investigating are required to really get to the bottom of things. So, take charge of your health! You are, after all, the very best person to determine if you are feeling well…or not.