What is St Mark’s solution?

St Mark’s solution is a glucose-electrolyte solution, also known as an oral rehydration solution (ORS) and is used for some people with conditions causing intestinal failure such as short bowel syndrome and enterocutaneous fistula. This usually means they have a high stoma/fistula output.

As a result of these conditions, the small intestine’s ability to maintain fluid and electrolyte (e.g., sodium, potassium, magnesium) balance is reduced and this can lead to dehydration and electrolyte imbalance.

Many people with intestinal failure will require intravenous nutrition (parenteral nutrition) and/or fluids to maintain their health but ORSs, such as St Mark’s solution, are also important in helping maintain fluid balance and can reduce the need for intravenous treatment.

How does St Mark’s solution work?

For people with intestinal failure, low-sodium fluids (also known as hypotonic fluids) such as tea, coffee, water, alcohol, carbonated drinks, and fruit juices lead to sodium and fluid moving from the body into the bowel and then passing out of the body. This can lead to high fluid and sodium losses, making you feel very thirsty and dehydrated.

To help counteract this, you may be put on a fluid restriction to limit the amount of hypotonic fluid you consume. We will then recommend using an ORS such as St Mark’s solution to help maintain hydration.

The St Mark’s solution helps to boost the absorption of both sodium and water and the shift in this balance helps reduces the amount of sodium and water that is moved to the bowel and lost from your body.

If you experience dehydration

If you experience any signs of dehydration, do not drink hypotonic fluids. Follow guidance from your medical or nutrition team or contact them for advice.

Signs of dehydration:

  • feeling thirsty
  • dark yellow, strong-smelling urine
  • urinating less often than usual
  • feeling dizzy, lightheaded, or tired
  • dry mouth, lips, or tongue

How do I prepare St Mark’s solution?

The solution must be prepared freshly every day using the recipe below (figure 1).
Measuring spoons will be provided with your medication and should be used. All ingredients can be bought from supermarkets or pharmacies for less than a single prescription charge.

Preparation of St Mark's solution
Ingredients for a one litre batch Amount
Glucose Powder 20g or six level 5ml spoonful
Sodium Bicarbonate (baking soda) 2.5g or one full 2.5ml spoonful
Sodium Chloride (table salt) 3.5g or one level 5ml spoonful

Measure out all the ingredients and dissolve them in one litre of cold tap water. Drink the prescribed volume throughout the day. This is usually between 1-2 litres but check with your clinical team if you are unsure.

The solution will taste salty but can be improved by:

  • Being stored in the fridge before you drink it, so it is chilled.
  • Being frozen and taken as slush or used to make ice cubes.
  • Being sipped through a straw.
  • Adding a small amount of squash, fruit juice or cordial.
  • If the solution is still very bitter then the sodium bicarbonate can be replaced by the same quantity of sodium citrate.

These adjustments are best added to the whole solution rather than adding to each glass, to ensure the salt content remains high.

How should I store my St Mark’s solution?

St Mark’s solution can be stored at room temperature, in a vacuum bottle or in the fridge. Any remaining solution must be thrown away after 24 hours and a fresh batch prepared the next day.