Diabetes Insipidus
Definition
Diabetes insipidusis an endocrine disorder characterized by the inability of the kidney to conserve water. This leads to excessive urination and thirst of the person affected. The word diabetes comes from the Greek word diabainein, which means to stand with legs apart (as in urination) or to go through. Insipidus is originated from a Latin word meaning without taste. The urine excreted in diabetes insipidus is tasteless (because it has relatively low sodium content) whilst in Diabetes Miletus a sweet urine (glucose content) is excreted.
Types
There are different types of Diabetes Insipidus, each has a different cause. The most common types are the following:
- Central Diabetes Insipidus – caused by the deficiency of antidiuretic hormone (ADH). This type of diabetes insipidus is also called pituitary diabetes insipid or neurogenic diabetes insipidus.
- Nephrogenic Diabetes Insipidus – caused an insensitivity of the kidneys to the ADH.
Review of Related Anatomy and Physiology
The antidiuretic hormone (ADH) or vasopressin is secreted by the posterior pituitary or neurohypophysis. It targets the kidney to conserve or retain water in the body. This hormone is very helpful in regulating the fluid volume and urine output by decreasing the amount of urine excreted and increasing water reabsorption. Through the said mechanism, the extracellular fluid volume rises resulting in a vasoconstrictor effect (increased BP). In cases where the vascular volume drops more ADH is released.
Anxiety, trauma and pain all contributes to the release of ADH from the neurohypophysis. When a person changes position (from lying to standing) and when the body is exposed to high temperatures, ADH secretion is also augmented. When the level of ADH falls, minimal or no water reabsorption will occur thereby, increasing the urine output and might lead to dehydration.
Pathophysiology
Causes
Pituitary or Neurogenic or Central Diabetes Insipidus
- Head trauma
- Brain tumor
- Surgical ablation of the pituitary gland
- Irradiation of the pituitary gland
- Infection to the CNS (meningitis, encephalitis)
- Tumors (metastatic disease)
Nephrogenic Diabetes Insipidus
- Hypokalemia
- hypercalcemia
- Medications (lithium, demecleocyclin, amphotericin B)
Clinical Manifestations
- Polyuria
- Polydipsia
- Diluted urine with a specific gravity of 1.001-1.005
- Signs of dehydration
Diagnostic Evaluation
- Radiography, CT scan or ultrasound of the skull
- Urinalysis
Treatment
Pituitary or Neurogenic or Central Diabetes Insipidus
The goals of the treatment are focused on the following:
- Fluid replacement
- Vasopressin replacement with Desmopressin (DDVAP), which is a synthetic vasopressin without the vascular effects of the natural ADH.
- Correct the underlying disease process
Nephrogenic Diabetes Insipidus
- Fluid replacement
- Thiazide diuretics
- Prostaglandin inhibitors (indomethacin, ibuprofen)
- Stopping the medication (if the drugs given are causing the disease)
Daisy Jane Antipuesto RN MN
Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.
