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Diabetes Insipidus
Posterior pituitary disorders
| Question | Answer |
|---|---|
| What does diabetes insipidus result from? | Diabetes insipidus results from a deficiency of ADH, which is secreted by the posterior lobe of the pituitary gland (neurohypophysis). |
| What does decreased ADH cause and what are the signs and symptoms? | Decreased ADH reduces the ability of collecting and distal renal tubules in the kidneys to concentrate urine, resulting in excessive diluted urination, excessive thirst, and excessive fluid intake. |
| What are the 3 types of diabetes insipidus? | Neurogenic, nephrogenic, and drug-induced |
| Neurogenic diabetes insipidus is caused by... | Caused by damage to the hypothalamus or pituitary gland from trauma, irradiation, or cranial surgery. |
| Nephrogenic diabetes insipidus is caused by... | It is inherited; renal tubules do not react to ADH |
| Drug-induced diabetes insipidus is caused by... | Lithium carbonate or demeclocycline which may alter the way the kidneys respond to ADH. |
| What are the risk factors associated with diabetes insipidus? | Head injury, tumor or lesion, surgery near the pituitary gland, infection, taking lithium or demeclocycline, and older adults. |
| What are the physical assessment findings regarding diabetes insipidus? | Sunken eyes, tachycardia, hypotension, loss or absence of skin turgor, and dry mucous membranes. |
| The urine specific gravity will be? | decreased (less than 1.005) |
| The urine osmolality will be? | Decreased (less than 300 mOsm/L). As the urine volume increases the osmolality decreases. |
| The urine pH will be? | Decreased |
| The urine sodium will be? | Decreased |
| The urine potassium will be? | Decreased |
| Urine chemistry will be? | Dilute |
| Serum chemistry will be? | Concentrated |
| The serum osmolality will be? | Increased (greater than 300 mOsm/L). As serum volume decreases the serum osmolality will increase. |
| The serum sodium will be? | Increased. |
| The serum potassium will be? | Increased |
| The radioimmunoassay will show what lab value? | Decreased ADH |
| What is an easy and reliable diagnostic test for diabetes insipidus? | The water deprivation test. Dehydration is induced by withholding fluids. The urine out is measured and tested hourly. The kidneys will be unable to concentrate urine despite dehydration. |
| What is a complication of the water deprivation test and what is the nursing action if a complication occurs? | Severe dehydration. The nurse should monitor for postural hypotension, tachycardia, and dizziness. Stop the test if this occurs. |
| What is the vasopressin test? | A SQ injection of vasopressin. This produces urine output with an increased specific gravity if the pt has neurogenic DI. This differentiates neurogenic from nephrogenic. |
| What is the deciding factor for how much IV fluids are given? | Output. The intake and output must be matched to prevent dehydration. |
| True or false. The pt may drink fluids in response to thirst. | True |
| Name two ADH replacement medications | desmopressin acetate (DDAVP) and aqueous vasopressin (Pitressins). |
| How can ADH replacements be administered? | Intranasally, orally, or parentally. |
| While taking ADH replacements should the client restrict their fluids? | Yes and they should be instructed to notify their provider if they develop a headache or confusion. |
| Name an ADH stimulant. | Carbamazepine (Tegretol)- an anticonvulsant which stimulates the release of ADH. |
| Does the patient have to take Tegretol with regards to meals? | Yes. The pt should take Tegretol with meals to reduce gastric distress. |
| What are the nursing consideration for Tegretol? | Take with meals, monitor vitals, I&O, CVP, specific gravity, monitor labs, monitor for dizziness or drowsiness, and monitor for thrombocytopenia (sore throat, bruising, and fever). |
| What effect does vasopressin (Pitressin) have on the kidneys and urinary output? | Vasopressin is a posterior pituitary hormone (ADH replacement) that causes an increase in water absorption from kidneys and a decrease in urine output. |
| What are the complication of DI? | Hypovolemia, hyperosmolarity, hypernatremia, circulatory collapse, unconsciousness, CNS damage, and seizures. |