Hyponatremia: What to Worry About in the Hospital

MIAMI BEACH – When you get a call in the hospital to evaluate a patient with postoperative hyponatremia, you need to worry primarily about three causes, according to an expert.

Increased free water intake, sodium loss that exceeds free water loss, and – "what we see all the time" – an inability to excrete free water will be your main concerns with these inpatients, Dr. Rachel E. Thompson said.

Initially rule out the most serious potential consequences of hyponatremia. "Assess mental status first to rule out increased intracranial pressure," said Dr. Thompson, founder and director of the Medicine Consult Service at Harborview Medical Center in Seattle. She spoke at a meeting on perioperative medicine sponsored by the University of Miami. "We have rigid skulls. There is very little space for tissue expansion." Left unchecked, intracranial hypertension can lead to brain damage, herniation, and respiratory arrest. "You can die from this."

It’s also important to distinguish neurology patients from others, Dr. Thompson said. Neurologic surgeons often want patients to have sodium levels above 140 mEq/L. "However, in other populations, if there is not brain damage that is going to be worsened by this, we are a lot more laissez faire. We might allow it to go lower, and people don’t get too worried about it until you’re in the mid to low 120s."

Dr. Thompson cited a neurosurgery patient as a case example. You get a call about a 66-year-old woman currently in the rehabilitation unit following endovascular coiling for aneurysmal subarachnoid hemorrhage repair two weeks earlier. The rehabilitation specialist reports her sodium is low at 126 mEq/L (it was 142 mEq/L when she left the neurosurgery unit 7 days earlier).

Dr. Thompson electronically polled meeting attendees regarding the next appropriate step. Of the total 91 responses, 33% would evaluate the patient’s volume status, 29% would evaluate mental status, 24% would check serum osmolality, and the remaining 14% would recheck the sodium level.

"I like that you want to see the volume status, and another third of you want to check the mental status. That means you are going to go see the patient. That is great," Dr. Thompson said.

Early assessment of mental status is key in Dr. Thompson’s four-step practical model for perioperative providers caring for hyponatremia patients:

• Step 1. Go to the bedside to assess mental status. Does it reflect what you expect for that sodium level? Assess acuity and severity, check which fluids are running, determine if the patient is hypovolemic, and find out if the patient had any recent vomiting or diarrhea that could facilitate volume loss.

• Step 2. Review medications. Did the patient take any diuretics or medications known to cause syndrome of inappropriate antidiuretic hormone (SIADH)? For more information on this syndrome, see (Nephron. Clin. Pract. 2011;119:c62-73).

• Step 3. Order appropriate studies. You might repeat the sodium level and check serum osmolality; also measure urine osmolality and sodium. Which brings us to the final step ...

• Step 4. "The urine is going to be where your answers are," Dr. Thompson said. If the urine is dilute, think primary polydipsia or "tea and toast diet syndrome." If the urine is concentrated, causes include chronic kidney disease, thiazides, hypothyroidism, or glucocorticoid deficiency.

It is important to be thorough and closely monitor hyponatremia patients either way, Dr. Thompson said.

Hyponatremia comes with risks. In one retrospective cohort study, hospital-acquired hyponatremia was associated with increased in-hospital mortality (adjusted odds ratio, 1.66); a 64% adjusted increase in length of stay; and a greater likelihood of discharge to a short- or long-term care facility (OR, 1.64) compared to unaffected patients (Arch. Intern. Med. 2010;8:294-302). The researchers found 38% of more than 55,000 inpatients at a single center over 7 years had hospital-acquired hyponatremia, defined as a decrease in serum sodium to below 138 mEq/L following normal levels at admission.

Although management of inpatients with hyponatremia might appear complex, there are two main treatment choices. "You either give fluids or you restrict fluids," Dr. Thompson said.

Give fluids to patients who are hypovolemic, have cerebral salt wasting, or display acute mental status changes. Go slow with treatment, she added, with a goal correction of no more than 0.5 mEq/L per hour or 12 mEq/L every 24 hours. Some clinicians recommend a more conservative increase of 6 mEq/L per 24 hours, she added.

Restrict fluids to patients with SIADH or primary polydipsia. Restriction to 1L to 2L free water is generally appropriate, Dr. Thompson said.

Sodium chloride tablets and vasopressin antagonists are two additional treatment options. Consider administration of sodium chloride tablets to patients with cerebral salt wasting, Dr. Thompson said. Some clinicians are reluctant to treat with salt tablets. "I was one of the people who used to think this was a terrible thing, but it actually works in cerebral salt wasting." The tablets also are indicated as a treatment for chronic SIADH, she said.

Vasopressin antagonists can be given I.V. or oral and are considered a treatment of last resort, she added. "Save them for the severely symptomatic patient. Yes, the sodium comes up, but there are no data on better outcomes in the acute setting." At an estimated daily cost of $260-$550, "they are extremely expensive." She cautioned that patients need to be watched for rapid overcorrection with these agents.

Dr. Thompson did not have any relevant disclosures.

MIAMI BEACH – When you get a call in the hospital to evaluate a patient with postoperative hyponatremia, you need to worry primarily about three causes, according to an expert.

Increased free water intake, sodium loss that exceeds free water loss, and – "what we see all the time" – an inability to excrete free water will be your main concerns with these inpatients, Dr. Rachel E. Thompson said.

Initially rule out the most serious potential consequences of hyponatremia. "Assess mental status first to rule out increased intracranial pressure," said Dr. Thompson, founder and director of the Medicine Consult Service at Harborview Medical Center in Seattle. She spoke at a meeting on perioperative medicine sponsored by the University of Miami. "We have rigid skulls. There is very little space for tissue expansion." Left unchecked, intracranial hypertension can lead to brain damage, herniation, and respiratory arrest. "You can die from this."

It’s also important to distinguish neurology patients from others, Dr. Thompson said. Neurologic surgeons often want patients to have sodium levels above 140 mEq/L. "However, in other populations, if there is not brain damage that is going to be worsened by this, we are a lot more laissez faire. We might allow it to go lower, and people don’t get too worried about it until you’re in the mid to low 120s."

Dr. Thompson cited a neurosurgery patient as a case example. You get a call about a 66-year-old woman currently in the rehabilitation unit following endovascular coiling for aneurysmal subarachnoid hemorrhage repair two weeks earlier. The rehabilitation specialist reports her sodium is low at 126 mEq/L (it was 142 mEq/L when she left the neurosurgery unit 7 days earlier).

Dr. Thompson electronically polled meeting attendees regarding the next appropriate step. Of the total 91 responses, 33% would evaluate the patient’s volume status, 29% would evaluate mental status, 24% would check serum osmolality, and the remaining 14% would recheck the sodium level.

"I like that you want to see the volume status, and another third of you want to check the mental status. That means you are going to go see the patient. That is great," Dr. Thompson said.

Early assessment of mental status is key in Dr. Thompson’s four-step practical model for perioperative providers caring for hyponatremia patients:

• Step 1. Go to the bedside to assess mental status. Does it reflect what you expect for that sodium level? Assess acuity and severity, check which fluids are running, determine if the patient is hypovolemic, and find out if the patient had any recent vomiting or diarrhea that could facilitate volume loss.

• Step 2. Review medications. Did the patient take any diuretics or medications known to cause syndrome of inappropriate antidiuretic hormone (SIADH)? For more information on this syndrome, see (Nephron. Clin. Pract. 2011;119:c62-73).

• Step 3. Order appropriate studies. You might repeat the sodium level and check serum osmolality; also measure urine osmolality and sodium. Which brings us to the final step ...

• Step 4. "The urine is going to be where your answers are," Dr. Thompson said. If the urine is dilute, think primary polydipsia or "tea and toast diet syndrome." If the urine is concentrated, causes include chronic kidney disease, thiazides, hypothyroidism, or glucocorticoid deficiency.

It is important to be thorough and closely monitor hyponatremia patients either way, Dr. Thompson said.

Hyponatremia comes with risks. In one retrospective cohort study, hospital-acquired hyponatremia was associated with increased in-hospital mortality (adjusted odds ratio, 1.66); a 64% adjusted increase in length of stay; and a greater likelihood of discharge to a short- or long-term care facility (OR, 1.64) compared to unaffected patients (Arch. Intern. Med. 2010;8:294-302). The researchers found 38% of more than 55,000 inpatients at a single center over 7 years had hospital-acquired hyponatremia, defined as a decrease in serum sodium to below 138 mEq/L following normal levels at admission.

Although management of inpatients with hyponatremia might appear complex, there are two main treatment choices. "You either give fluids or you restrict fluids," Dr. Thompson said.

Give fluids to patients who are hypovolemic, have cerebral salt wasting, or display acute mental status changes. Go slow with treatment, she added, with a goal correction of no more than 0.5 mEq/L per hour or 12 mEq/L every 24 hours. Some clinicians recommend a more conservative increase of 6 mEq/L per 24 hours, she added.

Restrict fluids to patients with SIADH or primary polydipsia. Restriction to 1L to 2L free water is generally appropriate, Dr. Thompson said.

Sodium chloride tablets and vasopressin antagonists are two additional treatment options. Consider administration of sodium chloride tablets to patients with cerebral salt wasting, Dr. Thompson said. Some clinicians are reluctant to treat with salt tablets. "I was one of the people who used to think this was a terrible thing, but it actually works in cerebral salt wasting." The tablets also are indicated as a treatment for chronic SIADH, she said.

Vasopressin antagonists can be given I.V. or oral and are considered a treatment of last resort, she added. "Save them for the severely symptomatic patient. Yes, the sodium comes up, but there are no data on better outcomes in the acute setting." At an estimated daily cost of $260-$550, "they are extremely expensive." She cautioned that patients need to be watched for rapid overcorrection with these agents.

Dr. Thompson did not have any relevant disclosures.

MIAMI BEACH – When you get a call in the hospital to evaluate a patient with postoperative hyponatremia, you need to worry primarily about three causes, according to an expert.

Increased free water intake, sodium loss that exceeds free water loss, and – "what we see all the time" – an inability to excrete free water will be your main concerns with these inpatients, Dr. Rachel E. Thompson said.

Initially rule out the most serious potential consequences of hyponatremia. "Assess mental status first to rule out increased intracranial pressure," said Dr. Thompson, founder and director of the Medicine Consult Service at Harborview Medical Center in Seattle. She spoke at a meeting on perioperative medicine sponsored by the University of Miami. "We have rigid skulls. There is very little space for tissue expansion." Left unchecked, intracranial hypertension can lead to brain damage, herniation, and respiratory arrest. "You can die from this."

It’s also important to distinguish neurology patients from others, Dr. Thompson said. Neurologic surgeons often want patients to have sodium levels above 140 mEq/L. "However, in other populations, if there is not brain damage that is going to be worsened by this, we are a lot more laissez faire. We might allow it to go lower, and people don’t get too worried about it until you’re in the mid to low 120s."

Dr. Thompson cited a neurosurgery patient as a case example. You get a call about a 66-year-old woman currently in the rehabilitation unit following endovascular coiling for aneurysmal subarachnoid hemorrhage repair two weeks earlier. The rehabilitation specialist reports her sodium is low at 126 mEq/L (it was 142 mEq/L when she left the neurosurgery unit 7 days earlier).

Dr. Thompson electronically polled meeting attendees regarding the next appropriate step. Of the total 91 responses, 33% would evaluate the patient’s volume status, 29% would evaluate mental status, 24% would check serum osmolality, and the remaining 14% would recheck the sodium level.

"I like that you want to see the volume status, and another third of you want to check the mental status. That means you are going to go see the patient. That is great," Dr. Thompson said.

Early assessment of mental status is key in Dr. Thompson’s four-step practical model for perioperative providers caring for hyponatremia patients:

• Step 1. Go to the bedside to assess mental status. Does it reflect what you expect for that sodium level? Assess acuity and severity, check which fluids are running, determine if the patient is hypovolemic, and find out if the patient had any recent vomiting or diarrhea that could facilitate volume loss.

• Step 2. Review medications. Did the patient take any diuretics or medications known to cause syndrome of inappropriate antidiuretic hormone (SIADH)? For more information on this syndrome, see (Nephron. Clin. Pract. 2011;119:c62-73).

• Step 3. Order appropriate studies. You might repeat the sodium level and check serum osmolality; also measure urine osmolality and sodium. Which brings us to the final step ...

• Step 4. "The urine is going to be where your answers are," Dr. Thompson said. If the urine is dilute, think primary polydipsia or "tea and toast diet syndrome." If the urine is concentrated, causes include chronic kidney disease, thiazides, hypothyroidism, or glucocorticoid deficiency.

It is important to be thorough and closely monitor hyponatremia patients either way, Dr. Thompson said.

Hyponatremia comes with risks. In one retrospective cohort study, hospital-acquired hyponatremia was associated with increased in-hospital mortality (adjusted odds ratio, 1.66); a 64% adjusted increase in length of stay; and a greater likelihood of discharge to a short- or long-term care facility (OR, 1.64) compared to unaffected patients (Arch. Intern. Med. 2010;8:294-302). The researchers found 38% of more than 55,000 inpatients at a single center over 7 years had hospital-acquired hyponatremia, defined as a decrease in serum sodium to below 138 mEq/L following normal levels at admission.

Although management of inpatients with hyponatremia might appear complex, there are two main treatment choices. "You either give fluids or you restrict fluids," Dr. Thompson said.

Give fluids to patients who are hypovolemic, have cerebral salt wasting, or display acute mental status changes. Go slow with treatment, she added, with a goal correction of no more than 0.5 mEq/L per hour or 12 mEq/L every 24 hours. Some clinicians recommend a more conservative increase of 6 mEq/L per 24 hours, she added.

Restrict fluids to patients with SIADH or primary polydipsia. Restriction to 1L to 2L free water is generally appropriate, Dr. Thompson said.

Sodium chloride tablets and vasopressin antagonists are two additional treatment options. Consider administration of sodium chloride tablets to patients with cerebral salt wasting, Dr. Thompson said. Some clinicians are reluctant to treat with salt tablets. "I was one of the people who used to think this was a terrible thing, but it actually works in cerebral salt wasting." The tablets also are indicated as a treatment for chronic SIADH, she said.

Vasopressin antagonists can be given I.V. or oral and are considered a treatment of last resort, she added. "Save them for the severely symptomatic patient. Yes, the sodium comes up, but there are no data on better outcomes in the acute setting." At an estimated daily cost of $260-$550, "they are extremely expensive." She cautioned that patients need to be watched for rapid overcorrection with these agents.

Dr. Thompson did not have any relevant disclosures.