25th July 2023

Malnutrition

Overview

Malnutrition is a multi-system disorder and one of the most common nutritional challenges among the UK geriatric population. Common symptoms include low energy, unintentional weight loss, and perioral and nail lesions. Consider a biopsychosocial approach for the causes of malnutrition. These include conditions such as Alzheimer’s Disease, dysphagia, poor oral health, severe learning disabilities or mental health problems, frailty, immobility, and catabolic states. Social factors include poor diet, isolation and the inability to do their own food shopping. Complications include frequent falls, chest infections secondary to muscle weakness, low mood and anxiety, heart failure, worsening underlying chronic conditions and immunosuppression. This can lead to loss of independence, prolonged hospital stays, and in severe cases, death.

Assessment

• BMI is a key measure (weight in kg divided by height in metres squared) and classifies malnutrition as mild (17-18.5), moderate (16-17) and severe (<16)
• The Malnutrition Universal Screening Tool (MUST)
• The Mini Nutritional Assessment Short Form (MNA®-SF)

Consider offering nutritional support to the following:

• BMI <18.5
• Unintentional weight loss of more than 10% in the past 3-6 months
• Little or no food intake for >5 days and who are unlikely for the next >=5 days
• BMI <20 and unintentional weight loss of more than 5% in the past 3-6 months
• Poor absorption/high nutrient losses/increased nutritional needs

Micronutrient Deficiencies

Table 1: Micronutrient deficiencies – causes, manifestations, and management

Acute Management

Patients at high risk of malnutrition must be identified early to prevent and monitor for refeeding syndrome. High risk patients include those who are frail, have existing comorbidities, low physiological reserve, chronic malnutrition, chronic alcoholism, postoperative and have long term use of antacids and antibiotics.

Refeeding syndrome is a potentially fatal condition that develops due to the shift of electrolytes and fluids in a malnourished patient post commencement of enteral or parenteral nutrition. Biochemically it can present as electrolyte deficiencies, namely hypophosphatemia, hypomagnesemia, and hypokalemia. Fluid balance abnormalities, abnormal glucose metabolism and thiamine deficiency, can also occur. Hence, patients should be assessed for dehydration, hypoglycaemia, anaemia, and infection alongside malnutrition.

To prevent refeeding syndrome:

• Check and correct electrolyte levels prior to commencement of nutrition, with subsequent daily checks for a week and at least three times the following week.
• Electrolyte supplementation, either orally, enterally or intravenously, should be given unless levels are high prior to commencement of nutrition.
• Refeeding started at no more than 50% of normal energy requirements in high-risk patients, i.e. in those who have eaten little or nothing for more than five days, with the aim to increase the rate if tolerated.
• For high-risk patients, nutritional energy repletion started slowly with a maximum of 10kcal/kg/24hrs, and the rate increased to meet full needs over 4-7 days.
• For Patients who are severely malnourished, i.e., BMI of 14 or less, or have had a negligible intake for two weeks or more, refeeding should start at a maximum of 5kcal/kg/24hrs with cardiac monitoring.