Association between Hypothyroidism and Hyponatremia: An Evidence-Based Literature Review

Area of Science:

• Endocrinology
• Nephrology
• Internal Medicine

Background:

• Hypothyroidism has been traditionally linked to euvolemic hyponatremia.
• Coexisting conditions in hypothyroid patients can complicate the determination of hyponatremia's cause.

Purpose of the Study:

• To critically evaluate the evidence supporting a causal relationship between hypothyroidism and hyponatremia.
• To clarify the association between different severities of hypothyroidism and hyponatremia.

Main Methods:

• A narrative review of 13 retrospective and prospective clinical studies.
• Studies were identified through a comprehensive PubMed search.

Main Results:

• Most studies failed to demonstrate a direct causal link between hypothyroidism and hyponatremia.
• Hyponatremia was primarily observed in severe hypothyroidism (e.g., myxedema), not uncomplicated cases.
• Hypothyroidism accounted for a small percentage of patients presenting with hyponatremia.

Conclusions:

• The available clinical evidence does not consistently support hypothyroidism as a direct cause of uncomplicated hyponatremia.
• Clinicians should not assume hypothyroidism is the cause of hyponatremia and must consider alternative etiologies.
• Further research with caution is advised due to the retrospective nature of most studies.