Free tool for APDs
Score the MST below, then see how MST, MUST, MNA-SF and NRS-2002 differ and what to do with a positive result.
The short answer
An MST total of 2 or more means the person is at risk of malnutrition and should be referred to a dietitian for a comprehensive nutrition assessment. The total is an appetite score (1 if the person has been eating poorly because of a decreased appetite, otherwise 0) plus an unintentional weight loss score out of 4.
Those are the weight loss scores. Add 1 more if appetite has decreased, for a maximum of 5. MST is a screening tool, not a diagnostic one: a positive screen identifies risk, and malnutrition is diagnosed on a full nutrition assessment against criteria such as GLIM.
Screening only, not diagnostic or clinical advice.
A screening result is not a diagnosis. Confirm any positive screen with a full nutrition assessment and follow your local policy. This tool runs entirely in your browser and no data is sent anywhere.
MST — Ferguson M, Capra S, Bauer J, Banks M, Nutrition 1999;15(6):458–464. 'MUST' is © BAPEN; we describe it here but do not reproduce it — use BAPEN's own calculator. Instruments named on this page remain their authors' work. See our Attributions and Data Sources.
MST is a two-question screen. It adds an appetite score and an unintentional weight loss score.
MST result
Enter the details to see the risk category and guidance.
These are all validated screens, and the differences between them are mostly about what you can measure rather than how well they work. If your health service mandates one, use that one — consistency across a service is worth more than the margin between validated tools.
MST
Malnutrition Screening Tool
MUST
Malnutrition Universal Screening Tool
MNA-SF
Mini Nutritional Assessment – Short Form
NRS-2002
Nutritional Risk Screening 2002
We reproduce MST above because we can attribute it precisely. For the others, use the publisher's own version — it is the current, correct scoring, and it is what your audit trail should point at.
Screening exists to divide a caseload into "needs a full nutrition assessment" and "does not, for now". It is built to be sensitive rather than precise, so it will flag people who turn out to be adequately nourished. That is the design working, not the tool failing.
Malnutrition itself is diagnosed on assessment, against criteria such as GLIM, by a dietitian. A screening score is never the diagnosis and should not be recorded as one.
Nutritional risk moves. A screen taken on admission says nothing about the same patient after a week of poor intake, a new acute illness, or a change in swallowing or appetite. Most policies set re-screening at a fixed interval for exactly this reason.
Re-screen sooner when the clinical picture changes rather than waiting for the interval to come round.
After the score
A positive MST is only worth the assessment that follows it, and the assessment is only worth the record it lands in. AI Dietitians runs the screening tools against a saved patient record, so the score, the assessment it triggered and the review that followed sit in one place instead of three.
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FAQ
MST is two questions and the scores are added. Question 1, appetite: 1 if the person has been eating poorly because of a decreased appetite, otherwise 0. Question 2, unintentional weight loss: 0 for none, 1 for 1 to 5 kg, 2 for 6 to 10 kg, 3 for 11 to 15 kg, 4 for more than 15 kg, and 2 if weight loss is likely but the amount is unsure. The maximum total is 5. A total of 2 or more means the person is at risk of malnutrition and should be referred to a dietitian for a comprehensive nutrition assessment. MST is a screen, not a diagnosis, and you should follow your local policy.
A total of 2 or more. At 2 or above the person is at risk of malnutrition and should be referred to a dietitian for a comprehensive nutrition assessment. Below 2 is low risk, which means routine care and re-screening at your local interval. A positive screen identifies risk; it does not diagnose malnutrition. Screening only, follow your local policy.
Screening is a short, standardised check that sorts people into "needs a full nutrition assessment" and "does not, for now". It is deliberately quick and deliberately blunt: a screen is designed to be sensitive rather than precise, so it will flag people who turn out to be well nourished, and that is the correct trade-off. A screen never diagnoses malnutrition. Diagnosis needs a full nutrition assessment against criteria such as GLIM, carried out by a dietitian.
It depends on what you can measure and who you are screening. MST asks two questions about appetite and unintentional weight loss, needs no measurements, and is widely used in Australian acute care. MUST adds measured BMI and an acute disease effect, so it suits settings where height and weight are already recorded. MNA-SF is designed for older adults. NRS-2002 is common in European hospital practice. Your health service almost certainly mandates one of them, and consistency across a service matters more than the choice between validated tools.
BAPEN publishes MUST, the MUST Explanatory Booklet and an official online calculator on its own site, and that is the authoritative source. We do not reproduce the MUST instrument here. BAPEN sets the terms on which MUST may be reproduced and asks to be approached about incorporating it into electronic systems, so using their published version means you are working from the current, correct scoring.
Act rather than observe. Refer to a dietitian or nutrition support team, or start your local nutrition pathway, agree explicit intake goals, and review progress against them at a stated interval. The screen has done its job at that point; what changes outcomes is the assessment and the plan that follow it. Record the screening result and the action taken, since an unactioned positive screen is a documented risk rather than a managed one.
Follow your local policy, which usually sets screening on admission and then at a fixed interval, commonly weekly for inpatients and at each review in the community. Nutritional risk is not static, and a negative screen only describes the day it was taken. Re-screen sooner if the clinical picture changes, particularly after a period of poor intake, a new acute illness, or a change in swallowing or appetite.
Every answer is general information only. MUST and MST are screening tools, not diagnostic tools. Confirm a positive screen with a full nutrition assessment and follow your local policy.