From the Guidelines
Thyroid disease is associated with several electrolyte imbalances, including hypokalemia, hypophosphatemia, and hypermagnesemia, as well as hypokalaemic thyrotoxic periodic paralysis in hyperthyroidism, and hypocalcemia, hyponatremia, and hyperkalemia in hypothyroidism.
Electrolyte Imbalances in Thyroid Disease
The most recent and highest quality study, 1, highlights the electrolyte disorders associated with thyroid disease, including hypokalaemia or hypokalaemic thyrotoxic periodic paralysis, hypophosphataemia, and hypermagnesaemia.
- Hypokalemia is a common electrolyte imbalance in hyperthyroidism, resulting from increased Na-K-ATPase activity.
- Hypophosphatemia can also occur in hyperthyroidism due to increased renal excretion of phosphate.
- Hypermagnesemia is another possible electrolyte imbalance in thyroid disease, although it is less common.
- In contrast, hypothyroidism is often associated with hypocalcemia, hyponatremia, and sometimes hyperkalemia, as noted in 1.
Clinical Implications
Patients with thyroid disorders should have their electrolyte levels regularly monitored, especially calcium, sodium, and potassium.
- Treatment focuses on correcting the underlying thyroid dysfunction with medications like methimazole or levothyroxine.
- Severe electrolyte abnormalities may require specific interventions, such as calcium supplementation for hypocalcemia or fluid restriction for hyponatremia.
- The severity of these imbalances generally correlates with the degree of thyroid dysfunction, and most electrolyte abnormalities resolve with proper treatment of the thyroid condition, as supported by 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Electrolyte Imbalances in Thyroid Disease
The following electrolyte imbalances are seen in thyroid disease:
- Hyponatremia: a condition where the concentration of sodium in the blood is lower than normal, which can occur in patients with hypothyroidism, particularly those with severe hypothyroidism and myxedema 2, 3, 4
- Hypokalaemia: a condition where the concentration of potassium in the blood is lower than normal, which can be more common in patients with elevated TSH levels 3
- Hyperkalaemia: a condition where the concentration of potassium in the blood is higher than normal, which can be more common in patients with high TSH levels 3
- Phosphate level abnormalities: phosphate levels can be higher in patients with elevated TSH levels 3
- Calcium and magnesium abnormalities: serum calcium and magnesium can correlate significantly with TSH levels 3
Mechanisms and Associations
The mechanisms and associations between thyroid function and electrolyte disorders are not fully understood, but it is thought that:
- Impaired free water excretion and changes in sodium handling in the kidney can contribute to hyponatremia in patients with hypothyroidism 2, 4
- Thyroid hormone can have a central regulatory effect on body functions, including electrolyte balance 3
- The association between thyroid function and electrolyte disorders may only be relevant in marked hypo-/hyperthyroidism 3