Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and Diabetes insipidus (DI) can be challenging to distinguish from each other at first glance. However, several key differences between them will help you, as a nurse, make an accurate diagnosis and care plan.
SIADH vs DI NCLEX Review Practice Questions
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SIADH is a condition where there’s an overabundance of the hormone vasopressin (also called antidiuretic hormone), which regulates the amount of water in the body. This causes the client to become dehydrated and retain excess water in their body tissues, which results in hyponatremia (low sodium levels) and hypovolemia (low blood volume).
DI is a disease that causes too much urine production because the body doesn’t produce enough ADH (antidiuretic hormone). This results in polyuria (increased urination), which can result in dehydration if left untreated.
Both conditions involve the kidneys, but there are some key differences. In SIADH, excess water is retained by the body, while in DI, insufficient water is produced to keep up with what’s being excreted.
DI and SIADH Pathophysiology
One of the main differences between these two conditions is that SIADH is caused by increased antidiuretic hormone (ADH) in the kidneys. In contrast, DI is caused by a decrease in the amount of ADH.
In SIADH, there is too much ADH, which causes the body to produce too much urine and not conserve enough water. This results in dehydration, low blood pressure, and low sodium levels.
In DI, there isn’t enough ADH, so the body doesn’t produce enough urine, resulting in dehydration, high blood pressure, and high sodium levels. DI occurs when there is a lack of ADH, so the kidneys cannot reabsorb water from the urine. This causes increased urination, as well as dehydration, which can lead to serious health problems if not treated.
With DI clients, their kidneys aren’t making enough ADH. This leads to a loss of fluids, which can result in excessive urination and dehydration.
SIADH occurs when the body produces too much antidiuretic hormone (ADH), which causes the body to retain water. This leads to low blood sodium levels and high blood potassium levels. In SIADH clients, their kidneys are producing too much antidiuretic hormone (ADH), which helps retain water. This can lead to dehydration, especially if they’re not drinking enough fluids.
Causes of SIADH and DI
The most common cause of SIADH is a brain tumor in the pituitary gland. Other causes include certain cancers, head injuries, infections, and some medications.
SIADH is caused by the kidneys not filtering the fluid properly. This results in the body producing too much urine, which dilutes the blood. As a result, this can cause swelling in the brain and lungs.
DI is caused by an imbalance of two hormones: vasopressin and AVP (vasopressin precursor). Vasopressin controls how much water leaves the body through urine, and AVP helps regulate blood pressure and blood volume.
When these hormones are out of balance, the body loses too much water through urine or does not retain enough water to stabilize blood pressure.
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Labs for SIADH and DI
Remember these lab values for SIADH and DI:
SIADH
- Urine osmolarity >300 mOsm/kg (with a low serum sodium level)
- Urine sodium level <20 mEq/L (with a high serum osmolarity)
- Urine Na+ >20 mEq/L, with urine osmolality >300 mOsm/kg (with a low serum sodium level)
- Hyponatremia with increased plasma tonicity
- Hypernatremia with decreased plasma tonicity
- Hypernatremia with decreased plasma tonicity in the absence of DI or SIADH
- Serum sodium < 135 mmol/L, serum chloride < 96 mmol/L, urine osmolality > 300 mosm/kg (or urine specific gravity > 1.020)
Memory tricks:
- SOAKED Inside “Low & Liquidy” Labs
- HYPO osmolality (LOW)
- HYPOnatremia below 135 Na+ (LOW)
- STICKY thick urine” Outside -> LOW urine output (STOPS urine)
- HIGH specific Gravity 1.030+
DI
- Serum sodium < 125 mmol/L, serum chloride < 95 mmol/L, urine osmolality < 300 mosm/kg (or urine specific gravity < 1.010)
- Urine osmolarity >300 mOsm/L in the presence of normal serum electrolytes and normal body weight (>45 kg)
Memory tricks:
- Dry Inside “High & Dry” Labs
- HYPER osmolality (HIGH)
- HYPERnatremia over 145 Na+ (HIGH)
- DIluted OUTSIDE ‘’High urine output (Drains urine)
- LOW specific Gravity 1.005
- D • Desmopressin/Vasopressin (synthetic ADH)
- D • Decreases Urine Output “Pressin” the BP Up!
- CAUTION: “Headaches” Priority!
- Low Na+ (135 or less) > Seizures > DEATH!
DI and SIADH Treatment
SIADH and DI are treated with a combination of fluids and medication.
For SIADH, the primary treatment is to restrict fluids and replace sodium as prescribed by the health care provider (HCP). Monitor for fluid volume excess. If the patient has too much fluid volume overload, that can lead to pulmonary edema (which is life-threatening), so it’s important to monitor labs along with intake and output.
For DI, the primary treatment is to maintain adequate fluid intake and administer medications as prescribed by the HCP. As a nurse, you should monitor for signs of dehydration, such as intake and output, skin turgor, and dry mucous membranes.
Another important nursing assessment is obtaining vital signs and monitoring neurologic and cardiovascular status. Maintain safety if there is a change in the level of consciousness (LOC).
DI and SIADH Medications
The most common medications that clients with SIADH and DI receive are Vasopressin and Desmopressin (DDAVP).
Vasopressin is a medication used for managing DI that helps to regulate the amount of water in the body. DDAVP is a synthetic version of vasopressin that helps to increase urine output and supplement low vasopressin levels.
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The kidneys are involved in both SIADH and DI – however there are some significant distinctions. In SIADH, the body holds onto extra water, but in DI, not enough water is created to match the amount being expelled.
The fact that SIADH is brought on by elevated antidiuretic hormone (ADH) in the kidneys is one of the primary distinctions between these two diseases. DI, on the other hand, is brought on by a reduction in ADH levels.
Fluids and medications are used in conjunction to treat SIADH and DI. In addition to all of this, nurses also look for dehydration.
Patients with SIADH and DI are most frequently prescribed vasopressin and desmopressin (DDAVP).
https://www.ncbi.nlm.nih.gov/books/NBK470458/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6466927/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3474650/
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FAQs
What is the difference between DI and SIADH treatment? ›
SIADH vs DI Conclusion
The fact that SIADH is brought on by elevated antidiuretic hormone (ADH) in the kidneys is one of the primary distinctions between these two diseases. DI, on the other hand, is brought on by a reduction in ADH levels. Fluids and medications are used in conjunction to treat SIADH and DI.
Since SIADH results in the retention of water, remember “SI” for “soaked inside.” For DI, excess fluid leaves the body, therefore think “dry inside.” Here's a table outlining the main differences between SIADH and DI. Too much ADH prevents the production of urine and leads to the retention of excess water in the body.
What is the pathophysiology of SIADH? ›The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a disorder of impaired water excretion caused by the inability to suppress the secretion of antidiuretic hormone (ADH) [1]. If water intake exceeds the reduced urine output, the ensuing water retention leads to the development of hyponatremia.
What is the priority nursing intervention for SIADH? ›Fluid restriction is a priority in the management of SIADH, as the main issue with this disease is fluid excess and hyponatremia.
What is the treatment solution for SIADH? ›Oral salt tablets in patients with SIADH — Patients with syndrome of inappropriate antidiuretic hormone (SIADH) secretion who have very mild or absent symptoms and a serum sodium above 120 mEq/L can be treated with oral salt tablets in addition to fluid restriction.
What are common medications for SIADH? ›Conivaptan and tolvaptan are currently the only vasopressin receptor antagonists that are commercially available in the United States and FDA-approved for the treatment of euvolemic hyponatremia in hospitalized patients.
What is the simple explanation of SIADH? ›Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a condition in which the body makes too much antidiuretic hormone (ADH). This hormone helps the kidneys control the amount of water your body loses through the urine. SIADH causes the body to retain too much water.
What is the difference between DI and SIADH osmolality? ›The typical patient with SIADH has a plasma osmolality of less than 270 mOsm/kg and a urine osmolality that is higher than the plasma. In contrast, a patient with diabetes insipidus has a plasma osmolality greater than 320 mOsm/kg and a urine osmolality less than 100 mOsm/kg.
What is the difference between diabetes insipidus and ADH? ›Diabetes insipidus is caused by a lack of antidiuretic hormone (ADH), also called vasopressin, which prevents dehydration, or the kidney's inability to respond to ADH. ADH enables the kidneys to retain water in the body. The hormone is produced in a region of the brain called the hypothalamus.
What is the differential diagnosis of SIADH? ›SIADH must be differentiated from cerebral salt wasting, adrenal insufficiency, hypopituitarism, hypothyroidism, and psychogenic polydipsia. Excessive release of antidiuretic hormone (ADH or vasopressin) from the posterior pituitary gland or another source.
Why does SIADH restrict fluid? ›
Fluid restriction that causes a negative fluid balance will increase the serum sodium concentration. To this end daily water intake (oral, intravenous, and metabolic production) must be lowered beyond daily water losses (skin, respiratory tract, stool, urine).
What is the first step in managing a patient with SIADH? ›Management and Treatment
In all cases of SIADH, the first step is to limit your fluid intake. This helps prevent excess fluid from building up in your body. Your provider will tell you what your total daily fluid intake should be, including water, coffee, tea, soda, etc.
Nursing Interventions
Monitor intake and output, weight, and specific gravity of urine. Maintain the intake of adequate fluids, and monitor for signs of dehydration. Instruct the client to avoid foods or liquids that produce diuresis. Administer chlorpropamide (Diabinese) if prescribed for mild diabetes insipidus.
Creating a safe environment, promoting good health practices, and listening closely to patients are daily nursing interventions you will perform and perfect throughout your career as a nurse.
What is the fluid of choice in SIADH? ›0.9% NaCl has a limited role in correction of the hyponatremia in SIADH and 3% NaCl is the fluid of choice.
How do medications cause SIADH? ›The differential diagnosis includes hyponatraemia caused by excessive sodium loss, such as with diuretic therapy, diarrhoea, vomiting or Addison's disease. Drugs are thought to cause SIADH by direct or indirect stimulation of vasopressin release from the posterior pituitary gland, although the mechanism is not known.
What are the 4 types of SIADH? ›There are four types of SIADH: type A, B, C, and D. Type A occurs independently of plasma osmolality. There are high levels of ADH and urine osmolality. Type B is characterized by a constant release of ADH.
How do you treat hyponatremia in SIADH? ›In the acute setting (ie, < 48 h since onset) with moderate symptoms such as confusion, delirium, disorientation, nausea, and vomiting, the treatment options for the hyponatremia include 3% hypertonic saline (513 mEq/L), loop diuretics with saline, vasopressin-2 receptor antagonists (aquaretics), and water restriction.
Why does SIADH cause low sodium? ›With SIADH, the urine is very concentrated. Not enough water is excreted and there is too much water in the blood. This dilutes many substances in the blood such as sodium. A low blood sodium level is the most common cause of symptoms of too much ADH.
Does DI cause high or low sodium? ›How is diabetes insipidus diagnosed? Certain blood and urine tests can point to a diagnosis of diabetes insipidus such as a high sodium level (hypernatraemia) and high concentration of the blood (serum or plasma osmolality), along with a low urine concentration (urine osmolality).
Is urine output high or low in SIADH? ›
SIADH consists of hyponatremia, inappropriately elevated urine osmolality (>100 mOsm/kg), and decreased serum osmolality in a euvolemic patient.
Is urine sodium high or low in SIADH? ›Urine sodium levels in SIADH have been described to average 70–80 mmol/L (31, 32). Levels exceeding 100–150 mmol/L are typically seen in CSW, where Arieff et al. described urine sodium levels of 153 ± 50 mmol/L in CSW vs. 75 ± 41 mmol/L in post-operative patients with SIADH (31).
What are the 3 P's of diabetes insipidus? ›The bottom line. The three P's of diabetes are polydipsia, polyuria, and polyphagia. These terms correspond to increases in thirst, urination, and appetite, respectively.
What are the 3 causes of diabetes insipidus? ›- a brain tumour that damages the hypothalamus or pituitary gland.
- a severe head injury that damages the hypothalamus or pituitary gland.
- complications that occur during brain or pituitary surgery.
Diabetes insipidus happens when your body doesn't make enough antidiuretic hormone (ADH) or your kidneys don't use it properly. Your body needs ADH to retain appropriate amounts of water. Without ADH, your body loses water through urine. Diabetes mellitus is much more common than diabetes insipidus.
What is the hallmark of SIADH? ›Hyponatremia (ie, serum Na+< 135 mmol/L) with concomitant hypo-osmolality (serum osmolality < 280 mOsm/kg) and high urine osmolality are the hallmark of SIADH.
What are the lab indicators for SIADH? ›Diagnosis of SIADH
decreased serum osmolality (<275 mOsm/kg) increased urine osmolality (>100 mOsm/kg) euvolaemia. increased urine sodium (>20 mmol/L)
Symptoms and Signs of SIADH
Symptoms can be subtle and consist mainly of changes in mental status, including altered personality, lethargy, and confusion. As the serum sodium falls to < 115 mEq/L (< 115 mmol/L), stupor, neuromuscular hyperexcitability, hyperreflexia, seizures, coma, and death can result.
The principal drawback is that patients find it extremely difficult to maintain fluid restriction, as thirst in SIADH is inappropriately normal due to a downward resetting of the osmotic thirst threshold (15).
What electrolyte disorder is associated with SIADH? ›Results: Hyponatremia is recognized as the most common electrolyte disorder encountered in the clinical setting and is associated with a variety of conditions including dilutional disorders, such as congestive heart failure and the syndrome of inappropriate antidiuretic hormone secretion, and depletional disorders, ...
Why does a patient have decreased urine output with SIADH? ›
ADH secretion also plays a role in the sensation of thirst. In SIADH, the body is unable to suppress the secretion of ADH, leading to impaired water excretion and reduced urine output.
What is the most serious complication of SIADH? ›A low sodium level or hyponatremia is a major complication of SIADH and is responsible for many of its symptoms. Early symptoms may be mild and include cramping, nausea, and vomiting. In severe cases, SIADH can cause confusion, seizures, and coma.
Which interventions would the nurse implement when caring for a client with SIADH? ›Nursing care for SIADH
You will restrict fluids and replace sodium as ordered by the provider. Monitor for fluid volume excess. If the patient has too much fluid volume overload, that can lead to pulmonary edema which is life threatening, so it's important to monitor for that.
Your GP or endocrinologist (a specialist in hormone conditions) may advise you to drink a certain amount of water every day, usually at least 2.5 litres. But if you have more severe cranial diabetes insipidus, drinking water may not be enough to control your symptoms.
How are diuretics used to treat diabetes insipidus? ›Thiazide diuretics are a form of medication that is commonly used to treat water retention and increase the passage of water in urine. However, in patients with diabetes insipidus, the drug raises the concentration of urine and reduces the amount of urine passed from the body.
What are the 5 nursing priorities? ›- The common thread uniting different types of nurses who work in varied areas is the nursing process—the essential core of practice for the registered nurse to deliver holistic, patient-focused care. Assessment. ...
- Diagnosis. ...
- Outcomes / Planning. ...
- Implementation. ...
- Evaluation.
The first-level priority problems are health issues that are life-threatening and require immediate attention. These are health problems associated with ABCs; airway, breathing, and circulation, such as establishing an airway, supporting breathing, and addressing sudden perfusion and cardiac issues.
What are nursing considerations for medications? ›The nurse should be aware of the patient's allergies, as well as any history of any drug interactions. Additionally, nurses collect appropriate assessment data regarding the patient's history, current status, and recent lab results to identify any contraindications for the patients to receive the prescribed medication.
What is the best treatment for DI? ›Treatment for gestational diabetes insipidus involves taking the manufactured hormone desmopressin. Primary polydipsia. There is no specific treatment for this form of diabetes insipidus other than lowering the amount of fluids you drink. If the condition is related to a mental illness, treating that may ease symptoms.
What drug is preferred for DI treatment? ›Desmopressin and other drugs
In patients with central DI, desmopressin is the drug of choice. A synthetic analogue of antidiuretic hormone (ADH), desmopressin is available in subcutaneous, IV, intranasal, and oral preparations.
Which antibiotic is used in the treatment of SIADH? ›
Nitrofurantoin and cephalexin are commonly used antibiotics for treating urinary tract infections.
What is the difference between desmopressin and vasopressin? ›Desmopressin (1-deamino-8-O-arginine-vasopressin, DDAVP) is a synthetic analogue of arginine vasopressin. It has 10 times the antidiuretic action of vasopressin, but 1500 times less vasoconstrictor action. These modifications make metabolism slower (half-life of 158 min).
What is the main treatment for diabetes insipidus? ›Health care professionals most often treat central diabetes insipidus with a man-made hormone called desmopressin link, which replaces the vasopressin your body is not making. You can take this medicine as a nasal spray, a pill, or a shot.
What is the best medication for diabetes insipidus? ›Desmopressin is the first-line treatment for central diabetes insipidus. It's a medication that works like an antidiuretic hormone (ADH, or vasopressin). You can take desmopressin as an injection (shot), a pill or in a nasal spray.
What are 3 symptoms of DI? ›- Severe thirst.
- Peeing more than 3 liters a day (your doctor might call this polyuria)
- Getting up to go a lot at night.
- Peeing during sleep (bed-wetting)
- Pale, colorless urine.
- Low measured concentration of urine.
- Preference for cold drinks.
- Dehydration.
Thiazide diuretics can reduce the rate the kidneys filter blood, which reduces the amount of urine passed from the body over time.
Why are diuretics used in diabetes insipidus? ›Thiazides have been used in patients with nephrogenic diabetes insipidus (NDI) to decrease urine volume, but the mechanism by which it produces the paradoxic antidiuretic effect remains unclear.
Why do you give vasopressin for diabetes insipidus? ›Diabetes insipidus is caused by a lack of antidiuretic hormone (ADH), also called vasopressin, which prevents dehydration, or the kidney's inability to respond to ADH. ADH enables the kidneys to retain water in the body.
Why give diuretics for SIADH? ›In order to increase free water excretion rates, loop diuretics have proven effective in the treatment of SIADH. This may be related to an inhibition of the ability of the kidney to maintain a medullary concentration gradient [22].
Do you give furosemide for SIADH? ›Introduction: Furosemide can be used in the treatment of SIADH. However, to be effective, renal medulla osmolality (OsmRM) as reflected in urinary osmolality (UOSM) must be high.
Why do you give desmopressin for SIADH? ›
Desmopressin can be given to increase the urine concentration and reduce free-water loss, thereby limiting autocorrection of serum sodium level. It is vital that this be done carefully, and the patient must have strict fluid restrictions or have no enteral intake.
Is DDAVP or vasopressin for diabetes insipidus? ›Treatments. The medication used to treat this disorder is called desmopressin acetate (DDAVP), which is similar to the antidiuretic hormone (ADH), also called vasopressin, produced by your body. DDAVP comes in several forms.
Is vasopressin a diuretic or antidiuretic? ›Antidiuretic hormone (ADH), also known as vasopressin, is a hormone that regulates water and electrolytes (e.g. sodium) balance. It does so by increasing water reabsorption into the bloodstream by acting on the kidneys nephrons.