From the Guidelines
In a grand mal seizure, ordering calcium, phosphate, and magnesium levels is not routinely recommended as part of the initial workup for otherwise healthy adults, as there is no strong evidence to support their use in this context, as noted in the study by 1. However, in certain situations, such as patients with known medical disorders like renal insufficiency or malnutrition, or those taking diuretics, these electrolyte levels may be relevant, as suggested by 1. The importance of monitoring electrolytes, including phosphate, potassium, and magnesium, is stressed in critically ill patients, particularly when initiating feeding, as highlighted in the guideline by 1 and 1. Additionally, periodic monitoring of calcium, phosphorus, magnesium, and other nutrients is recommended in patients with short bowel syndrome, as outlined in the clinical practice update by 1. In the context of a grand mal seizure, the focus should be on identifying and addressing the underlying cause of the seizure, rather than routinely ordering these electrolyte levels, unless there are specific clinical indications, such as symptoms or history suggestive of electrolyte imbalances, as implied by 1 and 1. Key points to consider when evaluating a patient with a grand mal seizure include:
- Identifying the underlying cause of the seizure
- Assessing for potential metabolic causes, such as hypoglycemia or hyponatremia
- Evaluating the patient's medical history and current medications
- Considering the potential for electrolyte imbalances in certain patient populations, such as those with renal insufficiency or malnutrition
- Ordering laboratory tests, including glucose, sodium, and drug levels, as necessary to comprehensively evaluate the patient, as suggested by 1 and 1.
From the Research
Gran Mal Seizure: Laboratory Orders
When a patient presents with a gran mal seizure, it is essential to order certain laboratory tests to identify potential underlying causes. The following tests are commonly ordered:
- Calcium levels: to check for hypocalcemia or hypercalcemia, which can be associated with seizures 2
- Phosphate levels: to check for hypophosphatemia, which has been linked to generalized tonic-clonic (GTC) seizures 3
- Magnesium levels: to check for hypomagnesemia, which can cause neurological symptoms, including seizures 4
Rationale for Ordering These Tests
The rationale for ordering these tests is based on the potential relationship between electrolyte disturbances and seizures. For example:
- Hypomagnesemia can cause seizures, and magnesium levels should be obtained in patients presenting with encephalopathy or atypical neurological symptoms 4
- Hypophosphatemia is common after GTC seizures and could represent an additional biological marker to help differentiate GTC seizures from other transient loss of consciousness (TLOC) 3
- Calcium, magnesium, and phosphate abnormalities are associated with increased morbidity and mortality, and derangements of these minerals can have vital roles in the cellular physiology of the neuromuscular and cardiovascular systems 5
Interrelationship Between Electrolytes
It is also important to note that there is an interrelationship between calcium, magnesium, and phosphate metabolism. For example: