Height, Weight, BMI & MUST

Height

Measuring height in most people is relatively straightforward however there are times when the gold standard technique cannot be achieved. In certain situations a patient may be unable to tolerate the testing, be unable to weight bear or unable to stand with a straight back for medical reasons e.g. scoliosis/kyphosis. In this case height may be estimated from either ulna length or height of the knee. The method used for estimating height may depend on the trust in which you are working and if in any doubt seek senior advice or specialist referral. Where height is estimated it should be documented in the patient’s notes that this is an estimated height and the rationale for doing this.

The process for measuring height and estimating height by either ulna length or knee height can be found here

Weight

It is important to know how much a person weighs as this can influence certain treatments or the safe dosage of a medication a person may be prescribed, give an indicator to their nutritional status and give a baseline to monitor trends in changing weight. There are times where treatment's may be based on ideal weight which is calculated from height but actually weight should also be taken and recorded in the notes.

For medical documentation weight is generally recorded in Kilograms (Kg) but many people will give their weight in Stones and Pounds. There are multiple free tools online or apps on many smart phones which will convert between the two systems for you.

There are  times where there may be confounding factors which might affect the recording of a patient's weight such as an individual with a partial or total limb amputation or a person who has a plaster cast on. In situations such as these there are specific means of calculating a corrected body weight which takes these into account. It may be that in these situations senior guidance or guidance from colleagues in other professions such as dietetics, orthopaedics or physiotherapy may be required.

Weight can be recorded by having the patient stand on calibrated scales, sat in a special chair with an inbuilt scales or specialist equipment for immobile patients to use on a bed.

Body Mass Index (BMI)

Completing a Body Mass Index (BMI) for patients is an important part of identifying an individual's nutrition status and is required for the purpose of completing tools such as the Malnutrition Universal Screening Tool (MUST). To calculate an individual’s BMI correctly requires an accurate measurement of their height and weight. Once a height and weight are recorded the BMI is calculated by the following formula

Weight (in Kg) ÷ Height (in Metres) Squared also written as Kg/M²

As an example a 185cm tall individual who weighs 80Kg would be calculated as

80(Kg)/1.85²(M) = 23.4(BMI)

Equally the NHS provides and online calculator which will work out the BMI for you and can be found here:

Malnutrition Universal Screening Tool (MUST)

The MUST is a tool which looks to identify patient's at risk of malnutrition. I comprises of a BMI score, if the patient has unintentionally lost weight recently and if so how much and finally the likely impact of their illness.

Read the illustrated guide to nutrition screenings on ClinicalSkills.net here: 

You will need to be logged into ClinicalSkills.net to use these pages: Go to ClinicalSkills.net, click login at the top, enter your user name and password. You must have set up your account to do this. For further information on how to login to your ClinicalSkills.net account please click here: How to Login to ClinicalSkills.net

Click on the button below to navigate to the 'Take a Test' area of ClinicalSkills.net. Please make sure you're logged into ClinicalSkills.net already, otherwise you may not be able to open and take the test. Once you have reached the 'Take a Test' area, select 'Local Tests' and then click on the test called 'Height, Weight, BMI & MUST' to begin. You will need to score 80% or more to pass. Make sure you've read the ClinicalSkills.net procedure thoroughly before taking the test as many of the answers will be found within there!

Watch this space quiz coming soon...........

Royal Marsden Manual of Clinical Procedures (9th Edition): Nutritional Status- Page 134- 140

ProQuest Ebook Central - Reader 

Date reviewed: 

Next review: August 2023