UK Stoma Care · Electrolyte & Output Calculator + 7-Day Chart

UK Stoma Hydration, St Mark’s Electrolyte Solution & 24h Output Calculator

Estimate your daily fluid and isotonic electrolyte balance by stoma type, weight, and weather, see how NHS stoma teams manage watery ileostomy output, and print a 1-page 7-day fluid chart.

Written by María G. · hola@siilostomy.com · Last updated: 14 November 20269 min read

Sipping isotonic rehydration fluid across the day keeps salt and energy steady when the large bowel is no longer present.

Quick answer

With an ileostomy, the colon is no longer there to reabsorb 1.0 to 1.5 litres of water and salt each day. Drinking pints of plain tap water, tea, or fizzy drinks can actually flush more sodium into your stoma bag. NHS intestinal failure and stoma care teams advise steady sipping (around 2.0–2.5 L/day unless restricted) with isotonic oral rehydration solutions (60–90 mmol/L sodium, such as double-strength rehydration sachets or St Mark’s Electrolyte Mix when prescribed) and contacting your stoma nurse or NHS 111 if output tops 1,200–1,500 ml in 24 hours.

600–1,000 mltypical settled 24h ileostomy output
>1,500 ml/24hNHS high-output stoma alert threshold
90 mmol/L Na+classic St Mark's isotonic sodium target
7-day A4 chartfree printable fluid & bag output diary

Check your daily fluid target, isotonic balance & output band

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UK Stoma Care · Electrolyte & Output Calculator + 7-Day Chart

Your stoma type

Your approximate body weight (kg — e.g., 70 kg ≈ 11 st)

Weather & activity level today

Bag emptyings over the past 24 hours (at ~half to two-thirds full)

Estimated 24-hour fluid target

2,250 ml / day

~76 fl oz · ORS: 1,100 ml

Ileostomy guidance: sip isotonic electrolyte fluids (oral rehydration sachets or savoury Bovril/stock drinks) steadily through the day rather than gulping large mugs of plain water or tea.

Settled bag rhythm: passing pale straw-coloured urine 4–6 times a day shows your hydration is nicely on track.

Comparing St Mark's Solution, pharmacy ORS sachets & everyday UK drinks

Named after St Mark’s Hospital (London’s national bowel hospital), St Mark’s Electrolyte Mix uses exact proportions of glucose, sodium chloride (table salt), and sodium bicarbonate (or sodium citrate) in 1 litre of water so the upper small bowel actively absorbs both salt and fluid via SGLT1 co-transport. Combine steady isotonic sips with natural meal thickeners from our UK interactive 24-food stoma diet checker.

Comparing St Mark's Solution, pharmacy ORS sachets & everyday UK drinks
Drink / Solution	Tonicity in Small Bowel	Sodium Content	NHS Stoma Care Guidance
St Mark's Electrolyte Mix (1 L daily batch)	Isotonic high-sodium	~90 mmol/L	NHS benchmark for high-output ileostomies when guided by your stoma nurse or dietitian; chill and add a tiny splash of sugar-free squash for taste.
Pharmacy Oral Rehydration Sachets (WHO / Dioralyte)	Isotonic (~240–245 mOsm/L)	60–75 mmol/L	Convenient for travel and mild loose output (dietitians sometimes advise specific double-strength mixing—check with your team).
Warm Savoury Stock, Miso or Broth Drinks	Mildly isotonic	50–70 mmol/L	Easy savoury way to top up sodium alongside crisp salty snacks.
Standard Isotonic Sports Drinks (shop-bought)	Often high-sugar	18–24 mmol/L	Too low in sodium for high-output stomas unless diluted 50:50 with water plus a pinch of salt.
Pure Fruit Juice, Sugary Fizzy Drinks & Alcohol	Hypertonic	<5 mmol/L	Pulls fluid into the bowel and speeds up watery bag filling.
Plain Tap Water, Mug of Tea or Coffee	Hypotonic	0–5 mmol/L	Fine in moderation for settled stomas, but restricted when managing high-output ileostomy.

Four practical habits to avoid salt depletion and tiredness

Check urine colour every afternoon
Aim for pale straw-coloured urine. Dark apple-juice-coloured urine or passing very little urine means your kidneys are conserving fluid.
Sip little and often—chill with ice or lemon
Keeping a chilled flask of electrolyte mix with fresh lemon juice or a dash of no-added-sugar cordial makes daily sipping effortless.
Recognise low-salt & low-magnesium signs
Night-time leg cramps, sudden fatigue, pins and needles, or feeling woozy standing up merit a blood test (U&Es + magnesium) via your GP or stoma clinic.
Pack rehydration sachets alongside your GHIC
Mediterranean holidays double sweat losses—keep ORS sachets in your hand luggage from day one.

UK stoma hydration & St Mark's Solution FAQs

What counts as a high-output stoma in NHS guidelines?

An ileostomy or jejunostomy producing more than 1,200 to 1,500 ml of watery output in 24 hours (or needing emptying 8–10+ times daily) is classed as high output and carries a high risk of dehydration, low sodium, and acute kidney strain if untreated.

Why do NHS dietitians restrict plain water when stoma output is high?

Plain water, tea, and coffee contain almost zero sodium. In a shortened small bowel, sodium leaks from your blood into that plain water and flushes straight into your stoma bag—leaving you more dehydrated than before you drank.

Should I start St Mark's Solution on my own?

Always confirm the exact recipe and daily volume with your NHS stoma care nurse, pharmacist, or dietitian first—especially if you have high blood pressure, kidney problems, heart conditions, or diabetes, as it delivers significant sodium and glucose.

How can I improve the taste of oral rehydration solutions?

Make the solution fresh each morning, chill it thoroughly in the fridge, sip through the day (avoid straws if prone to wind), or add a squeeze of fresh lemon/lime or a small dash of sugar-free squash as approved by your dietitian.

More free SIIL interactive tools for UK ostomates

UK clinical reference sources: Informed by high-output stoma protocols from St Mark’s Hospital Academic Institute, ASCN UK Clinical Guidelines, Ileostomy & Internal Pouch Association (IA), and NHS Trust Dietetic Leaflets. Educational guide; confirm sodium/fluid targets with your NHS team.

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