Screening guide for APDs
MUST vs MST: which screen, and why
Two validated malnutrition screens, built in different countries for different settings. Here is what each one measures, what it asks of you, and how to choose when your service has not chosen for you.
The short answer
Use the screen your health service mandates. If nothing is mandated and you cannot rely on a measured height and weight, use MST: it asks two questions, needs no measurements, and was developed and validated in Australian adult acute hospital inpatients. If height and weight are already recorded as routine and you want a risk category with management guidance attached to it, MUST is the tool built for that, and BAPEN publishes it.
Looking for a MUST score calculator?
It is not here, on purpose
MUST is the Malnutrition Universal Screening Tool, and it belongs to BAPEN. Its scoring steps, its cut-offs and the management guidance attached to each risk category are BAPEN's work, and BAPEN sets the terms on which they may be reproduced, including asking to be approached before MUST is built into an electronic system.
So we describe MUST on this page and we do not reproduce it. We removed the MUST calculator we used to host in August 2026 for that reason, and we are not putting one back.
If you need to score a patient with MUST, use BAPEN's own MUST calculator and the Explanatory Booklet that goes with it. That is the current, authoritative version, and it is the one your audit trail should point at rather than somebody's copy of it.
What you can score here
MST, free and with no account. Two questions, the working shown, and the same scoring the AI Dietitians app uses, running entirely in your browser.
Open the free MST calculator, which also sets out how MST, MUST, MNA-SF and NRS-2002 differ and what each one is best suited to.
Screening identifies risk. It is not a diagnosis, and it is not clinical advice. Follow your local policy.
Side by side
The honest difference between the two is what they need from the setting, not how well they work. Both are validated screens and both are designed to be sensitive rather than precise, so both will flag people who turn out to be adequately nourished. That is the design working.
MST is the Malnutrition Screening Tool; MUST is the Malnutrition Universal Screening Tool. The names are one letter apart and the instruments are not interchangeable, which is worth saying out loud in a policy document.
How to choose
- Check the policy first. Almost every Australian health service names a screening tool, the interval for re-screening and the referral pathway that follows a positive result. That decision is above your pay grade in the useful sense: consistency across a ward matters more than the margin between two validated tools.
- Then ask what you can measure. If a current height and weight are not reliably available, an instrument built around BMI will be completed from estimates, and an estimated input produces a score nobody should defend. MST avoids the problem by not asking.
- Match the tool to the population. MST was validated in adult acute inpatients. MNA-SF was designed for older adults and STAMP for children. A screen used outside the population it was validated in is a judgement call you should be able to explain.
- Write down which one you used. Two tools whose names differ by one letter end up transcribed interchangeably in notes. Name the instrument, the score and the date, not just "screened".
Where screening ends and diagnosis begins
A screen sorts, it does not diagnose
Both MST and MUST answer one question: does this person need a full nutrition assessment? Neither answers whether the person is malnourished. Recording a screening score as a diagnosis is the single most common documentation error in this part of the process.
Malnutrition is diagnosed on assessment, against criteria such as GLIM, by a dietitian.
GLIM starts from a positive screen
GLIM is explicitly two-step. Step one is a positive result from a validated screen such as MST, MUST or NRS-2002. Step two needs at least one phenotypic criterion and at least one aetiological criterion, with severity staged on the phenotypic criteria.
The step most often skipped is the first one. GLIM applied without a screen is not GLIM, and a completed GLIM diagnosis is what carries the work into the coded record.
References: Ferguson M, Capra S, Bauer J, Banks M. Development of a valid and reliable malnutrition screening tool for adult acute hospital patients. Nutrition 1999;15(6):458-464. Cederholm T, Jensen GL, Correia MITD, et al. GLIM criteria for the diagnosis of malnutrition. Clinical Nutrition 2019;38(1):1-9. BAPEN, Introducing MUST. Instruments named on this page remain their authors' work; see our Attributions and Data Sources.
From the screen to the note
Screening is one step. The rest of it is the work.
MST, NRS-2002, SGA, STAMP and GLIM sit in the same place as the assessment, the PES statement and the note that comes out the other end. Fourteen-day free trial.
FAQ
MUST and MST, asked and answered.
Is there a MUST calculator on this site?
No, and there is not going to be one. MUST is copyright BAPEN, and reproducing its scoring steps and thresholds as a working instrument is what their terms reserve. We describe MUST here and link to BAPEN's own online calculator and Explanatory Booklet, which is the authoritative and current version and the one your audit trail should point at. The calculator we do provide is MST.
Is MUST better than MST?
Neither is better in the abstract. They are both validated screens that sort people into "needs a full nutrition assessment" and "does not, for now", and they differ mainly in what they need from you. MST asks two questions and needs no measurements. MUST uses a measured BMI and an acute disease effect as well as weight loss, so it asks more of the setting and gives you more back. If your health service mandates one, use that one: screening consistently across a service is worth more than the margin between two validated tools.
Which malnutrition screening tool is used in Australian hospitals?
MST is the one developed and validated here. It was built for Australian adult acute hospital inpatients by Ferguson and colleagues in 1999, which is why it appears throughout Australian acute screening policy and why this site provides it. MUST is used in Australia too, particularly where height and weight are already recorded as routine. Your local screening policy is the answer for your ward, not a general preference.
Can I use MST outside hospital?
MST was validated in adult acute inpatients, so that is where its published performance comes from. It is widely used beyond that because it needs no measurements, which suits community, telehealth and private practice. Be honest in your documentation about the setting you used it in, and if your service has validated a different screen for aged care or paediatrics, use theirs: MNA-SF was designed for older adults and STAMP for children.
Does a positive screen mean the patient is malnourished?
No. A screen identifies risk and nothing else. Malnutrition is diagnosed on a full nutrition assessment against criteria such as GLIM, which is explicitly a two-step process: a validated screen must be positive first, and the diagnosis then needs at least one phenotypic and one aetiological criterion. Recording a screening score as a diagnosis is the error that leaves malnutrition screened, treated and never coded.
What should I do after a positive screen?
Refer to a dietitian or start your local nutrition pathway, set explicit energy and protein goals rather than "encourage oral intake", name the interval at which you will review them, and document both the screen and the action taken. An unactioned positive screen is a documented risk rather than a managed one.
General information only, for clinicians. Screening tools identify risk and are not diagnostic. Work from your own service's screening policy and the current published criteria, and apply your clinical judgement to the patient in front of you.
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