From the Guidelines
Tea and toast syndrome leads to euvolemic hyponatremia primarily through inadequate protein and solute intake, resulting in decreased urea generation and reduced solute excretion by the kidneys, which in turn causes water retention relative to sodium. This condition is characterized by a state of hyponatremia where the body's total water increases proportionally more than sodium, diluting serum sodium levels while maintaining normal extracellular fluid volume. The pathophysiology involves the kidneys' inability to effectively excrete free water due to insufficient solutes to maintain proper osmotic gradients, despite normal volume status 1.
Key Factors Contributing to Euvolemic Hyponatremia
- Inadequate protein intake leading to decreased urea generation
- Reduced solute excretion by the kidneys
- Continued water intake without sufficient solutes
- Impaired ability of the kidneys to dilute urine, resulting in water retention
Diagnostic Considerations
Euvolemic hyponatremia, as seen in tea and toast syndrome, must be distinguished from other causes of hyponatremia, such as the syndrome of inappropriate antidiuretic hormone (SIADH), which is characterized by inappropriately high urine osmolality and high urinary sodium concentration in the absence of diuretic treatment, adrenal insufficiency, heart failure, cirrhosis, and hypothyroidism 1.
Management Approach
Treatment of euvolemic hyponatremia in the context of tea and toast syndrome involves dietary improvement with adequate protein and salt intake, along with careful fluid restriction until sodium levels normalize. This approach addresses the underlying nutritional deficiencies and helps restore the body's ability to maintain proper osmotic gradients and excrete excess water. In more severe cases or when associated with other conditions like SIADH, management may include pharmacological interventions such as vasopressin 2 receptor antagonists or hypertonic saline, as recommended by expert opinion 1.
From the Research
Tea and Toast Syndrome Leading to Euvolemic Hyponatremia
- Tea and toast syndrome is a condition where patients, often elderly, consume a diet consisting mainly of tea and toast, leading to hyponatremia due to excessive water intake and low solute intake 2.
- This condition can lead to euvolemic hyponatremia, which is characterized by a normal fluid volume status, but low serum sodium levels 3.
- Euvolemic hyponatremia is often caused by the syndrome of inappropriate antidiuretic hormone secretion (SIADH), which can be treated with vasopressin receptor antagonists such as tolvaptan or urea 4, 5, 6.
- The treatment approach for euvolemic hyponatremia involves correcting the underlying cause, and medications such as urea and vaptans can be effective in managing the condition 2, 4, 6.
Mechanism of Euvolemic Hyponatremia in Tea and Toast Syndrome
- The exact mechanism of euvolemic hyponatremia in tea and toast syndrome is not fully understood, but it is thought to be related to the low solute intake and excessive water consumption, leading to a dilutional effect on serum sodium levels 2.
- The syndrome of inappropriate antidiuretic hormone secretion (SIADH) may also play a role in the development of euvolemic hyponatremia in these patients, as it can lead to excessive water retention and dilutional hyponatremia 3.
Treatment Options for Euvolemic Hyponatremia
- Treatment options for euvolemic hyponatremia include urea, vaptans, and fluid restriction, with the goal of correcting the underlying cause and normalizing serum sodium levels 2, 4, 6.
- Urea and vaptans have been shown to be effective in managing euvolemic hyponatremia, with urea having a lower risk of overcorrection compared to vaptans 4, 5, 6.