Excess antidiuretic hormone can cause low sodium levels, seizures | Dr. Erika Kube
Diane was brought to the emergency department via ambulance from home where her husband called 911 because she was acting strangely. According to Diane’s husband, she was intermittently acting differently that day, but things worsened in the evening when he finally called for help. He wondered if she had a urinary tract infection because she got them frequently and was urinating more often the past few days. Diane’s husband drove separately to the ED, and the paramedics said he would be in the ED shortly.
Diane appeared uncomfortable when I entered the room. She had her hands on her lower abdomen. I asked if she was in pain, and she said, "yes," but when I asked where, she couldn’t tell me. She could tell me her name but did not know where she was, and she didn’t know the day of the week or the year. I was worried that maybe she was having a stroke, so I quickly did an exam and noted she was not displaying any signs of a stroke. I examined her head, neck and back to make sure there wasn’t any bruising or sign of injury, since she really couldn’t tell me what was going on.
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At this point, Diane did not show signs of stroke or injury that could explain her symptoms. I had the nurse check her blood sugar, get an EKG and put an IV into Diane’s arm. We also got a urine sample to check for an infection, as I figured this was likely the explanation for Diane’s symptoms. I asked the nurse to let me know when Diane’s husband arrived.
The lab technician called me just a few minutes later with a critical result: She told me Diane’s sodium level was very low. The technician said she was already in the process of rerunning the sample to make sure the result was accurate. I reviewed Diane’s chart in the computer, checking to see if she ever had electrolyte abnormalities. I was surprised to see that Diane only had one previous ED visit for a laceration that needed sutures.
Diane’s husband arrived in the ED about 20 minutes later and was able to give me more history about Diane and what was going on. He said Diane had surgery on her gums the week prior and went several days without eating or drinking very much because she had a lot of pain in her mouth, and the pain medications made her feel nauseated. She also recently started a new medication for her bladder spasms and pain that she just started taking. He was certain she had not been drinking alcohol or using any drugs.
I got a call from the lab, while I was talking to Diane’s husband, that her sodium level was indeed critically low. Meanwhile the remainder of her evaluation was coming back normal. I consulted with our ED pharmacist to give Diane a special concentrated saline infusion we use for this very scenario and called the intensive care unit physician to admit Diane to the ICU.
Low sodium can lead to swelling of the brain tissues and seizures and needs to be corrected, however, the sodium level cannot be corrected too quickly due to potential for permanent damage to the nerve cells and myelin, which is a material that insulates and protects nerve fibers. Diane received the concentrated sodium solution in her IV very slowly and had her sodium levels rechecked frequently to ensure her sodium level was slowly increasing.
Once in the ICU and receiving the appropriate treatment to increase her sodium levels, Diane underwent additional testing to determine the cause of her low sodium level. After reviewing results of her blood and urine tests, it was determined that Diane was suffering from a condition called syndrome of inappropriate antidiuretic hormone. Antidiuretic hormone is a natural hormone in the body that helps blood vessels constrict and helps the kidneys to control the amount of salt and water in the body. SIADH is a condition in which there is excessive production of antidiuretic hormone, which then causes the body to retain water instead of excreting normally in urine. This excess water can then cause electrolytes like sodium to drop.
Symptoms of hyponatremia generally depend on how rapidly the condition develops. Many of the symptoms are vague: nausea, vomiting, headache, fatigue, confusion, low blood pressure, muscle weakness, twitching or cramps. In severe cases, hyponatremia can lead to seizures and coma.
There are numerous causes for SIADH including infection or inflammation of the brain and the tissues that surround the brain, head trauma, certain types of cancer, lung disease, as a side effect of certain medications, and it can also be hereditary. Treatment is focused on treating the underlying condition, restricting fluid intake and possibly using medications to adjust electrolyte balance in the body.
In Diane’s case, it was determined the new medications she was taking led to her hyponatremia. She didn’t feel that medication improved her symptoms, so she stopped taking it. After slowly correcting her sodium level in the ICU, Diane was able to be discharged home with a plan to drink no more than one liter of water each day. As her sodium level normalized, her mental status improved, and she was back to herself at the time of discharge. She had an appointment scheduled to see her family physician a few days later so they could recheck her sodium levels and ensure she did not have recurrence of her symptoms.
Dr. Erika Kube is an emergency physician who works for Mid-Ohio Emergency Services and OhioHealth.
drerikakubemd@gmail.com
This article originally appeared on The Columbus Dispatch: Dr. Erika Kube: Excess antidiuretic hormone can cause seizures
