Syndrome of inappropriate antidiuretic hormone (SIADH): Nursing process (ADPIE)

Definitions & Key takeaways

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by excessive release of antidiuretic hormone from the posterior pituitary gland or another source. The increase in fluid retention often results in dilutional hyponatremia in which the plasma sodium levels are lowered. SIADH may present with euvolemic hyponatremia with continued urinary sodium excretion. Urine osmolality is usually higher than serum osmolality. Very low serum sodium levels can lead to cerebral edema or seizures. Other symptoms of SIADH include fatigue, confusion, muscle weakness, nausea, vomiting, lack of appetite, and weight loss. Treatment usually involves fluid restriction, salt tablets, IV hypertonic saline, diuretics, and drugs like conivaptan, tolvaptan, or demeclocycline.

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Client Report0:00–0:49

Jamal Hashem is a 68-year-old male client who presents to his primary care provider's office along with his wife Admira.
Jamal was recently diagnosed with depression and has been taking the selective serotonin reuptake inhibitor or SSRI sertraline for the past 3 weeks.
Today, Jamal reports that he's been experiencing intermittent forgetfulness, headache, lethargy, muscle weakness, and decreased urine output.
Laboratory results showed a serum sodium level of 124 milliequivalents per liter. His SSRI is discontinued, and Jamal is admitted to the medical unit for continued monitoring and treatment of syndrome of inappropriate anti-diuretic hormone.
A syndrome of inappropriate anti-diuretic hormone secretion, or SIADH for short, is a condition where the body produces too much of the hormone ADH, also called vasopressin, leading to decreased blood osmoality, which refers to the concentration of dissolved particles like sodium or other electrolytes.

Pathology0:49–5:15

The normal blood osmolarity value is between 285 and 295 milliosmos per kilogram. Now, ADH is the primary hormone that regulates fluid balance in the body and is normally produced by the hypothalamus and stored in the posterior pituitary, which are both located within the brain.
To do this, the hypothalamus contains osmo receptors which are able to sense the osmolarity of the blood. When a person is dehydrated, for example, osmolarity increases, so osmo receptors sense this and in response stimulate the pituitary to release the stored ADH into the blood.
ADH then travels to the kidneys to decrease water excretion in urine and increase water reabsorption back into the blood to help restore normal blood osmolarity.
In addition, osmo receptors trigger the sensation of thirst. After the person drinks water, the osmolarity returns to normal and ADH secretion stops.
OK, now SIADH can have several important causes. The first one is paraneoplastic syndrome, where a tumor outside the brain secretes ADH.
This is especially common in clients with small cell lung carcinoma. Other pulmonary diseases such as pneumonia and chronic obstructive pulmonary disease or COPD can also temporarily lead to SIADH, but the exact mechanism is unknown.
Other causes include surgeries of the central nervous system or head trauma that may damage the pituitary, which can cause stored ADH to be released.
Finally, SIADH can be caused by certain medications, including seizure medications like carbamazepine, antidepressants like selective serotonin reuptake inhibitors or SSRIs, certain anti-diabetic medications, as well as anti-hypertensive medications like thiazide diuretics, chemotherapeutics like cyclophosphamide, and analgesic medications like NSAIDs.
Also, several risk factors can increase the risk of SIADH, and the most important ones are advanced age and having chronic conditions such as epilepsy, heart failure, or diabetes mellitus.
Now with SIADH, the increased ADH leads to increased water reabsorption in the kidneys. This results in dilutional hyponatremia, where the total amount of body water increases, which then lowers the plasma concentration of sodium by dilution.
Hyponatremia typically presents with gastrointestinal symptoms including abdominal cramps, nausea, and vomiting. Additionally, hyponatremia can lead to muscle weakness as well as altered mental status, such as restlessness, irritability, and confusion.
SIADH can also cause some severe complications. The most dangerous one is cerebral edema, which occurs due to excessive accumulation of fluid in the brain, leading to increased intracranial pressure and can cause seizures, coma, and even brain stem herniation and death.
Diagnosis of SIADH generally involves blood tests showing decreased blood osmolarity and hyponatremia, which is when sodium goes below 136 millimoles per liter.
Diagnosis is supported by a urine test showing increased urine osmolarity. Treatment of SIADH is based on fluid restriction.
Additionally, to excrete the extra water, clients may take medications such as loop diuretics like furosemide or vasopressin receptor antagonists such as Tovaptan.
Finally, salt tablets and intravenous administration of hypertonic saline can help correct the hyponatremia. It's important to note that hyponatremia should be corrected slowly in order to prevent osmotic demyelination syndrome, which is associated with severe neurological consequences.
Finally, whenever possible, the underlying cause should be treated. Jamal and Amira have just been admitted to the medical unit, and you begin your assessment by noting Jamal is oriented to his surroundings, is able to answer all your questions appropriately, but he occasionally repeats questions that he already answered.

Assessment5:15–6:49

Jamal tells you that lately it's been hard to concentrate. You measure his level of consciousness at 14 using the Glasgow Coma Scale, or GCS.
His vital signs are tympanic temperature 98.4 °F or 36.8 °C, apical heart rate 78 BPM and regular, respiratory rate 16 breaths per minute, BP 164/80 millimeters of mercury, and SPO 2 94% on room air.
His current weight is 187 lbs or 84.8 kg. He reports weighing 182 lbs or 82.5 kg two weeks ago.
A neurologic examination reveals fine hand tremors bilaterally and decreased strength to both his lower extremities. Admira tells you Jamal doesn't like to ask for help and has almost fallen at home several times.
You take note of the following lab results serum sodium 122 milliequivalents per liter, serum osmolarity 270 milliosmoles per kilogram, urine osmolarity 530 milliosmoles per kilogram, and urine sodium 47 millequivalents per liter.
Then you document your findings and begin developing Jamal's plan of care. With the assessment data you collected, you are ready to identify these priority nursing diagnoses excess fluid volume related to fluid retention, acute confusion related to sodium imbalance, and risk for falls related to muscle weakness and possible seizure activity.

Diagnosis6:49–7:08

Next, you collaborate with Jamal, Admira, and the multidisciplinary health team to create a plan of care for Jamal. After 24 hours of treatment, Jamal's fluid and sodium levels will begin returning to normal parameters, and at the time of discharge, Jamal will be fully alert and oriented, and he will not have experienced a fall or a seizure during his hospitalization.

Planning7:08–7:34

It's now time to implement Jamal's plan of care. After reviewing the physician's orders, you start a slow IV infusion of 3% hypertonic saline, and you let Jamal know you will be checking the sodium level in his blood frequently to ensure it's not increasing too quickly.

Implementation7:34–8:55

Next, you administer the loop diuretic furosemide and teach Jamal and Amira that Jamal's oral fluids will be temporarily restricted to 800 mL for 24 hours.
You explain the importance of following the fluid restriction to prevent further fluid and electrolyte imbalance, and you also help Jamal plan how to pace his oral fluid intake throughout the day.
At this time, you also ensure that the nursing assistant is aware of the fluid restriction as well as the need for strict uptake and output and daily weights.
You reorient Jamal as needed, and you write updates on the communication board in his room throughout your shift to help Jamal keep track of his plan of care.
Next, you initiate seizure and fall precautions. You ensure the call light is within reach and remind Jamal to call staff for assistance with his needs.
You encourage Edmira to remain present at his bedside as she is able, and you perform hourly bedside rounding. Finally, you remind Jamal that his physician has discontinued the SSRI sertraline and you assure him that his physician will prescribe an alternate antidepressant.
Your shift is almost complete, so let's check back in with Jamal and Amira to evaluate how he's doing. His latest laboratory results show that Jamal's serum sodium levels are now 128 milliequivalents per liter.

Evaluation8:55–10:07

The nursing assistant confirms that Jamal has been following the oral fluid restriction and that he has had 700 mL of urine output during the last 8 hours.
His vital signs are tympanic temperature of 98.6 °F or 37 °C, apical heart rate 70 BPM, respiratory rate 14 breaths per minute, BP 142/75 millimeters of mercury, oxygen saturation of 98% on room air, and GCS 15.
Jamal shares with you that it's easier for him to concentrate now. A neurologic check reveals that the tremors to Jamal's hands have currently subsided, but his lower extremities remain weak.
You are glad that Jamal has not experienced a fall or seizure on your shift and that he is currently meeting his care goals.
The health care team will continue to monitor Jamal for any acute changes in mental status or laboratory results throughout his hospitalization.

Summary10:07–10:55

All right, as a quick recap, Jamal Hashem was diagnosed with SIADH, which is a condition where the body produces too much of the hormone ADH, leading to decreased blood osmolarity.
Your assessment revealed confusion, fluid and sodium imbalance, and muscle weakness. Your priority nursing diagnoses you established were excess fluid volume, acute confusion, and risk for falls.
Careful planning allowed you to create goals that focused on alleviating Jamal's symptoms and ensuring his physical safety.
Implementation of the plan of care involved normalizing his serum sodium levels and instituting safety measures. Finally, you evaluated that Jamal's plan of care was effective in promoting his well-being.