Weight loss and fatigue

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Quick Overview

Weight loss (>5% in 3-6 months or >10% in 6 months) and fatigue are common undifferentiated presentations requiring systematic evaluation. NICE NG12 emphasizes urgent cancer pathway referral for unexplained weight loss with specific features. Distinguish physiological fatigue (self-limiting, exercise-responsive) from pathological (persistent >4 weeks, associated symptoms).

Core Facts & Concepts

📊 Significant Weight Loss Thresholds:

  • >5% body weight in 3-6 months OR >10% in 6 months = pathological
  • Unintentional weight loss warrants investigation regardless of BMI

🚩 NICE NG12 Two-Week Wait Criteria (Suspected Cancer):

  • Age ≥40 with unexplained weight loss PLUS upper abdominal mass
  • Age ≥55 with weight loss PLUS upper abdominal symptoms (reflux, dyspepsia)
  • Age ≥60 with weight loss PLUS anaemia OR raised inflammatory markers
  • Weight loss + jaundice = immediate specialist referral

Key Causes by Category:

CategoryCommon CausesDiscriminating Features
MalignancyLung, GI, pancreatic, lymphomaConstitutional symptoms, night sweats, lymphadenopathy
EndocrineHyperthyroidism, diabetes, Addison'sHeat intolerance/polyuria/pigmentation respectively
GICoeliac, IBD, malabsorptionDiarrhoea, steatorrhoea, abdominal pain
Chronic DiseaseCOPD, CCF, CKD, TBOrgan-specific symptoms, known disease
PsychiatricDepression, anorexiaMood changes, eating behaviours
MedicationsMetformin, SSRIs, chemotherapyTemporal relationship to drug initiation

Figure 1: Blood film showing hypersegmented neutrophils in megaloblastic anaemia

Fatigue Classifications:

  • Acute (<1 month): Usually physiological or viral
  • Subacute (1-6 months): Requires investigation
  • Chronic (>6 months): Consider CFS/ME criteria

Problem-Solving Approach

Step 1: Quantify Weight Loss

  1. Calculate percentage: (usual weight - current weight) ÷ usual weight × 100
  2. Verify with objective measurements (clothing size, witness accounts)
  3. Document timeframe precisely

Step 2: Rapid Assessment Algorithm

  1. History: Appetite, diet, swallowing, GI symptoms, systemic features
  2. Examination: BMI, lymph nodes, abdominal masses, thyroid, skin changes
  3. Bedside: Urinalysis (glucose, protein), temperature

Step 3: First-Line Investigations (Within 48 hours)

  • FBC (anaemia, infection, haematological malignancy)
  • U&E, LFTs, bone profile (organ dysfunction)
  • TFTs (hyperthyroidism)
  • HbA1c (diabetes)
  • ESR/CRP (inflammation, malignancy)
  • Coeliac serology (tissue transglutaminase IgA)
  • Chest X-ray (lung pathology, TB)

Figure 2: Chest X-ray showing apical consolidation in pulmonary tuberculosis

🚩 Red Flags Requiring Urgent Action:

  • Persistent fever + weight loss + night sweats (lymphoma)
  • Progressive dysphagia (oesophageal cancer)
  • New-onset jaundice (pancreatic/biliary malignancy)
  • Palpable mass (any site)
  • Age >60 + unexplained weight loss alone

Step 4: Safety-Netting

  • Review within 2 weeks if investigations negative but symptoms persist
  • Provide written information on alarm symptoms
  • Document weight trajectory for monitoring

Analysis Framework

Fatigue Differentiation:

Discriminating Physiological vs Pathological Fatigue:

FeaturePhysiologicalPathological
OnsetIdentifiable triggerInsidious/unexplained
Duration<4 weeks>4 weeks
Exercise responseImproves with activityWorsens (post-exertional malaise)
SleepRefreshingNon-restorative
Associated symptomsNoneWeight loss, fever, pain

Investigations Priority Matrix:

  • High yield: FBC, TFTs, HbA1c, CRP, coeliac serology
  • Targeted: Based on clinical suspicion (cortisol for Addison's, HIV test if risk factors)
  • Low yield in isolation: Vitamin D, ferritin (unless specific indication)

Key Points Summary

Significant weight loss = >5% in 3-6 months - always investigate unintentional loss

NICE NG12: Age ≥60 + weight loss + anaemia/raised inflammatory markers = 2-week wait referral

Essential first-line tests: FBC, U&E, LFTs, TFTs, HbA1c, ESR/CRP, coeliac serology, CXR

Red flags: Persistent fever + night sweats + weight loss (think lymphoma/TB)

Pathological fatigue: >4 weeks duration, worsens with exercise, non-restorative sleep

Safety-net: Review within 2 weeks if investigations negative but symptoms persist - document weight trajectory

Common pitfall: Attributing weight loss to "stress" or "ageing" without objective investigation in older adults

Practice Questions: Weight loss and fatigue

Test your understanding with these related questions

Understanding the concept of 'diagnostic uncertainty' in managing undifferentiated symptoms in primary care involves recognizing that certain presentations cannot be immediately diagnosed. Which of the following statements best describes the evidence-based approach to managing diagnostic uncertainty?

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Flashcards: Weight loss and fatigue

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