What Labs Are Elevated After a Seizure?

A convulsive seizure is a short burst of intense work for the muscles, heart, and stress hormones, and the blood carries the traces of it afterward. Many abnormal results drawn in the ER shortly after a seizure are the body’s expected reaction, not a new illness. Those traces fade on different timetables, from under two hours to several days, so the timing of the blood draw matters as much as the number itself.

The Labs That Most Often Rise

The biggest lab changes follow generalized tonic-clonic seizures, the kind with stiffening, rhythmic jerking of the whole body, and loss of consciousness. From here on, these are called convulsive seizures. Seizures that stay in one part of the brain, without full-body jerking, often change these labs only a little or not at all.1PubMed. Serum prolactin, cortisol and growth hormone concentrations after various epileptic seizures One event touches so many values because violent muscle work uses oxygen faster than the blood can deliver it, and the brain triggers a surge of stress hormones such as adrenaline and cortisol.

Shortly after a convulsive seizure, these values are commonly high:

A normal panel doesn’t mean nothing happened. Smaller or focal seizures often leave almost no signature, and a blood draw hours after the event may find lactate and prolactin already back to normal.

Much of the blood work after a first seizure is meant to find a trigger, not to confirm the seizure. Sodium, calcium, magnesium, and glucose are checked because very low levels can themselves provoke a seizure. Kidney and liver tests, and sometimes a toxicology screen, look for other causes or for organ strain. That’s why a report can list many tests even though only some of them rise from the seizure itself.

Lactate and Blood Acid Levels

Lactate is a byproduct muscles make when they work harder than their oxygen supply allows. Right after a convulsive seizure, it rises on average almost 9-fold.7PubMed Central. Acute metabolic effects of tonic‐clonic seizures The longer the stiffening-and-jerking phase lasts, the higher it tends to climb.8PubMed Central. Acute metabolic effects of tonic‐clonic seizures

Extra lactate makes the blood acidic for a while. Right after grand-mal seizures, blood pH has averaged about 7.14, well below the normal 7.35 to 7.45. Bicarbonate, the blood’s buffer, often reads low, around 17 versus a typical 23 to 24.9PubMed. The Denver Seizure Score: anion gap metabolic acidosis predicts generalized seizure The report may then flag a high “anion gap,” a calculated sign of extra acid in the blood that your report may list.10PubMed. The Denver Seizure Score: anion gap metabolic acidosis predicts generalized seizure The gap comes from sodium, chloride, and bicarbonate, so it isn’t a separate measurement. After a convulsive seizure it usually reflects the lactic acid and shrinks as lactate clears. A gap that stays high beyond the first hours is a reason to look for other acids, such as from poisoning or diabetic ketoacidosis.

Lactate, and with it the acidity, usually returns to baseline within about 2 hours.11PubMed Central. Acute metabolic effects of tonic‐clonic seizures Doctors often just repeat the test. A repeat showing a fall is consistent with a seizure as the cause. A level that stays high makes them look for something else, such as infection or ongoing seizures.

Treatment is rarely needed because the lungs and kidneys start clearing acid as soon as the jerking stops. Breathing often becomes fast after a seizure, which blows off carbon dioxide and helps correct the acidity. Bicarbonate or other acid-correcting drugs are generally kept for severe or persistent cases.

Prolactin and Stress Hormones

Prolactin is a hormone from the pituitary gland at the base of the brain, best known for milk production. After convulsive seizures it rises sharply and peaks about 30 minutes after the seizure starts.12PubMed. Serum prolactin, cortisol and growth hormone concentrations after various epileptic seizures The rise fades within about 2 hours, so a late blood draw can miss it.13PubMed Central. Acute metabolic effects of tonic‐clonic seizures

Because the window is short, prolactin is drawn quickly, roughly within 30 minutes to 2 hours. Doctors sometimes take a second sample hours later as a baseline for comparison. In hospital monitoring units, blood may be drawn right after a recorded event. The lab’s normal range differs between men and women, so the result is read against the right one. Certain medicines, pregnancy, and breastfeeding also raise prolactin, so the doctor needs to know about them.

Cortisol, the main stress hormone, also rises and peaks around 30 minutes after a convulsive seizure.14PubMed. Serum prolactin, cortisol and growth hormone concentrations after various epileptic seizures In the first hour it has been more than twice as high after epileptic seizures as after non-epileptic events.15PubMed Central. Dissimilar Changes in Serum Cortisol after Epileptic and Psychogenic Non-Epileptic Seizures: A Promising Biomarker in the Differential Diagnosis of Paroxysmal Events? Cortisol and adrenaline also signal the liver to release sugar, so blood glucose rises.16PubMed Central. Seizing the Connection: Exploring the Interplay Between Epilepsy and Glycemic Control in Diabetes Management

A one-time high glucose right after a seizure is usually this stress response. People with diabetes may see a temporary spike in home readings afterward. A reading that stays high days later is a separate question for their doctor.

Ammonia and White Blood Cells

Ammonia is normally something doctors associate with liver trouble. Yet after a convulsive seizure, about half of people show raised ammonia, using a cutoff of 50 µg/dL.17PubMed. Hyperammonaemia and associated factors in unprovoked convulsive seizures: A cross-sectional study Higher readings are linked to higher lactate, more acidic blood, and longer convulsions.18PubMed. Hyperammonaemia and associated factors in unprovoked convulsive seizures: A cross-sectional study Levels have fallen from a median of about 250 to 54 µg/dL within roughly 8 hours, without treatment.19PubMed. Transient hyperammonemia in seizures: a prospective study A high ammonia that clears within hours usually points to the seizure rather than liver failure.20Spartan Medical Research Journal. Transient Hyperammonemia Seen in Post Seizure Activity: A Series of Six Case Reports

The reason is that muscles produce ammonia in large amounts during intense work, and a sudden burst can outpace the body’s clearing for a short time. In liver disease, the liver can’t convert ammonia to urea, so levels stay high for days rather than hours. That difference in timing lets doctors separate the two.

Ammonia is a real concern in some cases: people taking the epilepsy drug valproate can have high ammonia from the medicine. A rise from the drug or the liver usually doesn’t clear in a few hours, so it’s worth asking whether a repeat test was done before worrying about liver damage.

White blood cells jump without infection too. Many of them normally sit parked along the walls of small blood vessels in the lungs.21PubMed Central. The Magnitude of Postconvulsive Leukocytosis Mirrors the Severity of Periconvulsive Respiratory Compromise: A Single Center Retrospective Study The adrenaline surge speeds blood flow and flushes them into circulation, raising the count.22PubMed Central. Hiding in plain sight? A review of post-convulsive leukocyte elevations So a high white count soon after a convulsion is often not a sign of infection. Still, fever, a stiff neck, or confusion that doesn’t clear can mean an infection caused the seizure.

CK and Muscle Breakdown

CK, short for creatine kinase, is an enzyme that leaks out of skeletal muscle when it is strained or damaged.23PubMed. Postictal elevation of serum creatine kinase level It can climb sharply after a seizure, in step with how intense the muscle activity was.24PubMed. Postictal elevation of serum creatine kinase level Still, only about 1 in 10 convulsive seizures pushes CK above normal, and the peak comes around 48 hours later.25PubMed Central. Acute metabolic effects of tonic‐clonic seizures

That delay explains why CK may be normal in the ER and high later. It takes many hours to leak out of muscle and reach the blood, so an early draw can miss it. A doctor worried about muscle injury may repeat the test a day or two later, and a normal early value doesn’t mean the muscles were spared.

Falls and injuries add to CK. A fall during a seizure bruises muscle on top of the strain, and lying in one position for a long time afterward can also raise it. When CK is very high, doctors may check other causes.

The number is also read against a baseline. Normal CK varies with sex, muscle mass, and ethnicity, so a heavily muscled person may start higher. Hard exercise in the days before a seizure can already raise CK.

Very high CK can mean rhabdomyolysis, a serious breakdown of muscle that can hurt the kidneys.26PubMed Central. The role of creatine kinase in distinguishing generalized tonic–clonic seizures from psychogenic non-epileptic seizures (PNES) and syncope: a retrospective study and meta-analysis of 1300 patients Levels above 5,000 U/L, and especially above 15,000 U/L, predict more serious kidney injury.27PubMed Central. When a Seizure Is Not Just a Seizure: Rhabdomyolysis and Acute Kidney Injury as a Reminder to Check Creatine Kinase Even extremely high levels can recover with fluids and supportive care when caught early.28PubMed Central. When a Seizure Is Not Just a Seizure: Rhabdomyolysis and Acute Kidney Injury as a Reminder to Check Creatine Kinase

In the days after a seizure, watch for dark, tea- or cola-colored urine, severe muscle pain or weakness beyond ordinary soreness, or passing much less urine than usual. Any of these warrants calling a doctor or returning for a CK and kidney test.

Heart, Brain, and Kidney Markers

Troponin is a blood test for heart muscle stress, often ordered in the ER. After convulsive seizures, stress hormones more than double, heart rate climbs, and troponin rises in about 1 in 10 to 1 in 4 people.29PubMed. Blood markers of cardiac stress after generalized convulsive seizures In people with hard-to-treat epilepsy, about 1 in 4 had a significant troponin rise after a seizure.30PubMed. cTnI, BNP and CRP profiling after seizures in patients with drug-resistant epilepsy

The heart is affected because the adrenaline surge raises heart rate and blood pressure, making it work harder, and low oxygen during the seizure adds strain. Troponin leaks when heart cells are stressed, even without a blocked artery. A small rise may be strain, but doctors still check the heart. They may repeat the test to see whether it rises or falls, and an ECG and heart history help separate seizure strain from a heart attack. A heart attack usually comes with chest pain, characteristic ECG changes, or risk factors such as older age, smoking, or diabetes. Seizure-related rises are often small and fall on repeat testing. A heart rhythm problem can also cause fainting that looks like a seizure, so when unsure, doctors lean toward further heart testing.

A brain-cell protein can rise after single seizures in some people, more after convulsive ones.31PubMed. Neuron-specific enolase is increased after single seizures during inpatient video/EEG monitoring It is higher after status epilepticus, prolonged seizures that don’t stop.32PubMed. Serum neuron-specific enolase in the major subtypes of status epilepticus

Long seizures change the picture. A seizure lasting more than 5 minutes is a medical emergency, and prolonged seizures multiply muscle, acid, and kidney stress. After prolonged or back-to-back grand-mal seizures, very high uric acid has caused kidney failure, sometimes needing dialysis, which recovered.33PubMed. Hyperuricaemic acute renal failure after epileptic seizures Kidney tests are especially important after clusters of seizures.

Can Labs Prove It Was a Seizure

A high prolactin strongly favors an epileptic seizure over a psychogenic non-epileptic seizure, an event that looks like a seizure but isn’t caused by abnormal brain electricity.34PubMed. Use of serum prolactin in diagnosing epileptic seizures: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology But prolactin is high after only about 6 in 10 convulsive seizures and fewer than half of focal seizures with impaired awareness, so a normal prolactin does not exclude a seizure.35PubMed. Use of serum prolactin in diagnosing epileptic seizures: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology36PubMed. Serum prolactin levels after epileptic seizures It can also rise after fainting, so it doesn’t separate a seizure from a faint.37PubMed. Serum prolactin levels after seizure and syncopal attacks Recovery after a faint is usually quick, while a convulsive seizure is followed by minutes of confusion, so doctors lean on lactate timing and the history.

A lactate drawn within 2 hours helps separate convulsive seizures from fainting and non-epileptic events.38PubMed. Clinical utility of serum lactate levels for differential diagnosis of generalized tonic-clonic seizures from psychogenic nonepileptic seizures and syncope CK can help in hindsight, but its late peak and low rate limit it. No lab test replaces the account of what happened, EEG, and examination.39PubMed. Clinical utility of serum lactate levels for differential diagnosis of generalized tonic-clonic seizures from psychogenic nonepileptic seizures and syncope

Treatment for psychogenic events differs from epilepsy drugs, so telling the two apart prevents years of unneeded medicine. Lab clues help, but video EEG monitoring is the most reliable way to settle it.

A witness can add a lot: how long the jerking lasted, whether the body stiffened first, whether the eyes were open or closed, and how long confusion lasted afterward. A phone video can be more useful than any lab value.

When asking about your own results, find out what time the blood was drawn relative to the event and whether a baseline sample was taken for comparison. Ask too which tests were checked to find a cause, such as electrolytes, kidney, and liver tests.