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Approach to Unintentional Weight Loss - UK Teaching Guide

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1. DEFINITIONS AND SIGNIFICANCE

• Loss >10% is associated with protein-energy malnutrition and impaired physiological function
• Loss >20% is associated with nutritional deficiencies and multi-organ dysfunction
• IWL affects 15-20% of people over 65, and 50-60% of nursing home residents
• Carries a 22-39% excess mortality, reflecting underlying pathology

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2. CAUSES - THE BIG PICTURE

• M - Malignancy
• A - Addison's/Adrenal insufficiency
• L - Liver disease / Loss of appetite (depression)
• N - Neurological (dementia, Parkinson's, dysphagia)
• O - Oral/dental problems
• U - Uraemia (CKD)
• R - Respiratory (COPD, cardiac cachexia)
• I - Infection (TB, HIV, endocarditis)
• S - Social (poverty, isolation, alcohol)
• H - Hyperthyroidism / Hyperglycaemia (DM)
• E - Eating disorders / Enteropathy (IBD, coeliac)
• D - Drugs (metformin, SSRIs, opioids, digoxin)

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3. GP APPROACH IN THE UK

First Consultation - Key Questions

1. Quantify the weight loss - how much, over what period? Do clothes or jewellery fit differently? Can a family member corroborate?
2. Confirm it is unintentional - not dieting, GLP-1 agonist use, or increased exercise
3. Appetite - decreased (think cancer, depression, systemic disease) vs. increased (think hyperthyroidism, diabetes)
4. Dietary history - what is the patient eating? Any dysphagia, odynophagia, early satiety, nausea, vomiting?
5. Full systematic review - bowel habit changes (colorectal), haemoptysis/cough (lung), abdominal pain/jaundice (pancreas/liver), night sweats/fevers (lymphoma, TB, infection), urinary symptoms (renal/prostate), fatigue
6. Mood screen - low mood, anhedonia, sleep, PHQ-2 (depression is the most common non-malignant cause)
7. Social history - living alone, poverty, alcohol, smoking (strongest independent predictor of IWL), support network
8. Medication review - drugs that reduce appetite or cause GI side effects
9. Family history - malignancy, coeliac, IBD

Examination

• General: cachexia, pallor, jaundice, lymphadenopathy (cervical, axillary, inguinal, supraclavicular - Virchow's node)
• Oral/dental: dentition, ulcers, candidiasis, fit of dentures
• Cardiovascular and respiratory: signs of cardiac failure, COPD
• Abdomen: organomegaly, masses, ascites, rectal examination
• Neurological: cognition, signs of Parkinson's, dysphagia
• Thyroid: goitre, signs of thyrotoxicosis (tremor, tachycardia, lid lag)
• Skin: rashes (IBD-related), acanthosis nigricans (DM/malignancy)

GP First-Line Investigations (UK Standard - NICE NG12 informed)

• Full blood count (anaemia, leucocytosis, lymphocytosis)
• U&E, LFTs, bone profile (renal disease, liver disease, hypercalcaemia)
• Glucose / HbA1c
• TFTs (thyroid disease)
• ESR / CRP (inflammatory / infective / malignant process)
• Urinalysis
• Chest X-ray (lung cancer, cardiac failure, TB)
• FIT (Faecal Immunochemical Test) - now a core part of the UK pathway for colorectal cancer risk
• PHQ-9 (depression screen)

• HIV serology (risk factors or unexplained weight loss + constitutional symptoms)
• Coeliac serology (TTG-IgA + IgA level)
• Serum protein electrophoresis (myeloma)
• PSA (men with urinary symptoms)
• Calcium (malignancy, sarcoidosis, hyperparathyroidism)
• LDH / urate (lymphoma)
• Upper GI endoscopy / colonoscopy (GI symptoms, iron-deficiency anaemia, positive FIT)
• Abdominal USS (upper abdominal pain, abnormal LFTs, jaundice)
• CT abdomen/pelvis (if USS inconclusive or strong clinical suspicion of malignancy)

UK-Specific Referral Thresholds (NICE NG12 + NHS England 2025)

1. Urgent Suspected Cancer (2-week wait / USC) referral - when specific cancer symptoms are present alongside weight loss (e.g. dysphagia → upper GI, rectal bleeding + weight loss, haemoptysis + smoking history)
2. Non-Specific Symptom (NSS) Pathway / Rapid Diagnostic Centre (RDC/ADOC) referral:

• New unexplained unintentional weight loss: >5% in 3 months (documented or strong clinical suspicion)
• Constitutional symptoms (fatigue, anorexia, malaise) lasting 4+ weeks
• GP "gut feeling" of possible cancer
• Pre-referral tests required: CXR + FIT + blood panel
• Referred to Acute Diagnostic Oncology Clinic (ADOC) - part of the National Rapid Diagnostic Centre programme

1. If no cause found: Follow-up in 4-6 weeks. Repeat investigation if weight loss continues. Revisit the algorithm at each review.

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4. HOSPITAL DOCTOR APPROACH

Admissions Assessment

• Weigh the patient on admission (this must be documented as baseline)
• Review GP records, previous weights in SystmOne/EMIS
• Compare with patient/family-reported pre-illness weight

• 0 (Low risk): Routine care, repeat weekly in hospital
• 1 (Medium risk): 3-day food diary, dietitian referral if not improving, repeat weekly
• ≥2 (High risk): Urgent dietitian referral, nutritional support, weekly monitoring

• CT chest/abdomen/pelvis (if not already done) - high yield for occult malignancy
• Upper GI endoscopy if not done (yield of 12-44% in IWL)
• Bone marrow biopsy if haematological malignancy suspected
• PET scan if CT inconclusive and malignancy still suspected
• Further directed tests based on clinical picture

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5. WARD MANAGEMENT OF A PATIENT WITH WEIGHT LOSS

Nutritional Support - Step-by-Step

• Involve the ward dietitian early (day 1 if MUST ≥2)
• Calculate estimated energy needs: typically 25-35 kcal/kg/day + 0.8-1.5 g protein/kg/day (higher if malnourished or post-surgical)

• Offer high-calorie, high-protein meals; liaise with catering
• Allow patients to eat at their own pace; avoid interruptions during meals
• Protected mealtimes policy - enforce on ward rounds
• Fortified foods: full-fat milk, cream, cheese, enriched products
• High-calorie drinks between meals (Complan, Build-Up, Ensure)

• Prescribe if dietary modifications insufficient (Ensure Plus, Fortisip, Fresubin)
• Two bottles/day of standard ONS = approximately 600 kcal additional intake

• Consider if oral intake remains inadequate despite ONS
• NG feeding: short-term (<4 weeks)
• PEG/RIG: longer-term (chronic dysphagia, neurological causes)
• Check NG position with pH test paper and CXR (first placement)

• Reserved for patients with non-functional GI tract (bowel obstruction, short bowel, paralytic ileus, post-surgical)
• Central PN via PICC or Hickman line; peripheral PN for short-term use
• Requires specialist nutrition team involvement
• Monitor daily: electrolytes (especially phosphate - refeeding risk), glucose, LFTs

• Check Mg, phosphate, K, Ca before starting feeding
• Start feeds slowly (50% of target on day 1, increase over 3 days)
• Replace thiamine (Pabrinex IV for 3 days before and after starting feeds)
• Monitor phosphate, Mg, K, glucose twice daily for 72 hours
• Target phosphate >0.6 mmol/L (supplement aggressively if low)

Treating the Underlying Cause

MDT Team on the Ward

• Dietitian - nutritional assessment and support plan
• Speech and Language Therapy (SALT) - if dysphagia
• Occupational Therapy - functional assessment (ability to cook, eat independently)
• Physiotherapy - sarcopenia/deconditioning management
• Social Worker - housing, finances, safeguarding
• Liaison Psychiatry - depression, eating disorders, dementia
• Palliative Care - when weight loss is part of end-stage disease
• Specialist Referral - oncology, gastroenterology, endocrinology as appropriate

Monitoring in the Ward

• Weigh twice weekly and document in notes
• Daily food charts (in/out documentation)
• Repeat bloods as clinically indicated (FBC, U&E, LFTs, CRP, albumin/pre-albumin)
• MUST score reassessment weekly
• Review feeding plan response at 72 hours; escalate if no improvement

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6. WHEN NO CAUSE IS FOUND

• Approximately 16-28% of IWL cases remain unexplained after full investigation
• These patients have a much lower rate of cancer (~2% at 2 years if initial workup negative)
• Management: close follow-up every 1-4 months, depending on clinical concern
• Revisit history, re-examine, repeat bloods at each review
• If further weight loss occurs, repeat the full diagnostic algorithm
• Consider PET-CT if no cause found and clinical suspicion remains high
• Refer to RDC/ADOC if not already done

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7. QUICK REFERENCE SUMMARY CARD

UNINTENTIONAL WEIGHT LOSS - UK CLINICAL PATHWAY

DEFINE: >5% body weight over 6-12 months (unintentional)

FIRST-LINE BLOODS: FBC | U&E | LFTs | Bone profile | Glucose/HbA1c
                   TFTs | ESR/CRP | Urinalysis

IMAGING: Chest X-ray (all patients) + FIT (UK colorectal screening)

REFER TO RDC/ADOC: >5% weight loss in 3 months
                    + constitutional symptoms ≥4 weeks
                    + pre-referral: CXR + FIT + bloods done

WARD: MUST score on admission → Dietitian if score ≥2
      Treat underlying cause + nutritional support
      Refeeding precautions if prolonged starvation
      MDT: Dietitian, SALT, OT, Social Work, Psychiatry

IF NO CAUSE: Follow up every 1-4 months. Repeat algorithm if loss continues.

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• NICE NG12 Suspected Cancer: Recognition and Referral (updated 2025/26, evidence review April 2026)
• NHS England NSS/RDC Referral Criteria (2024)
• Symptom to Diagnosis: An Evidence-Based Guide, 4th Ed - Weight Loss chapter
• Yamada's Textbook of Gastroenterology, 7th Ed - Unintentional Weight Loss chapter
• BAPEN MUST Tool (2023 update)
• Approach to weight loss in adults - PMC11182459