How to diagnose and manage muscle wasting?

How to Check for Muscle Wasting

Muscle wasting should be assessed through a systematic physical examination focusing on specific anatomical sites combined with functional assessment and patient history, using a standardized approach that can be performed by any trained healthcare professional.

Physical Examination Sites

The physical examination for muscle wasting involves visual inspection and palpation of specific muscle groups, scored systematically:

Key Anatomical Sites to Examine

• Temporalis muscle - assess for temporal hollowing 1
• Clavicles - evaluate prominence (more prominent indicates wasting) 1
• Shoulder contour - rounded shoulders indicate well-nourished state; squared shoulders indicate malnutrition and muscle loss 1
• Scapula - assess visibility and prominence (winging or increased visibility suggests wasting) 1
• Ribs - evaluate visibility through the chest wall 1
• Interosseous muscles - examine the muscle mass between thumb and forefinger 1
• Quadriceps muscle mass - assess bulk and tone of thigh muscles 1

Subcutaneous Fat Assessment

While assessing muscle, also evaluate subcutaneous fat to differentiate fat loss from muscle wasting:

• Infraorbital fat pads - should appear as slight bulge in well-nourished individuals; appear "hollow" in malnourished patients 1
• Triceps and biceps - gently pinch skin above these muscles; the thickness of the fold indicates nutritional status 1

Historical Assessment

Combine physical findings with key historical elements:

• Weight loss over past 6 months - loss of >10% is severe, 5-10% is moderate, <5% is mild 1
• Dietary intake changes - assess for decreased appetite, nausea, vomiting 1
• Unintentional weight loss combined with decreased physical performance before presentation 1

Functional Assessment

Muscle function should be assessed alongside muscle mass, as wasting affects both structure and function:

• Gait assessment - identify abnormal gait patterns, particularly waddling gait which suggests proximal muscle weakness 1, 2
• Gowers' sign - observe how patient rises from floor or seated position (using hands to "climb up" their legs indicates proximal weakness) 2, 3
• Handgrip dynamometry - quantifies muscle strength in conscious, cooperative patients 1
• Timed function tests - assess activities of daily living and functional capacity 2

Standardized Scoring System

Use a 7-point scale for each assessment component (recommended by the National Kidney Foundation K/DOQI guidelines):

• Scores of 1-2 indicate severe malnutrition/wasting 1
• Scores of 3-5 indicate moderate to mild malnutrition/wasting 1
• Scores of 6-7 indicate mild malnutrition to normal nutritional status 1

The global assessment is not a simple arithmetic average but allows the examiner to weight physical findings more heavily when they clearly indicate severe wasting, even if historical factors suggest otherwise 1.

Advanced Assessment Tools (When Available)

For more detailed evaluation in specific clinical settings:

• Ultrasound - can evaluate lean body mass 1
• CT scan - useful for assessing muscle mass, particularly in patients undergoing abdominal imaging 1
• Bioelectrical impedance - measures body composition and lean body mass in stable patients without fluid shifts 1
• Serum creatine kinase (CK) - elevated levels may indicate muscle disease rather than simple wasting 2

Important Clinical Caveats

Edema can obscure weight loss and muscle wasting, requiring careful interpretation of weight changes in patients with fluid retention 1. Physical examination findings should be weighted more heavily in these cases.

Training is essential - any healthcare professional performing these assessments should undergo training to increase precision and standardization of measurements 1. The assessment technique is operator-dependent and requires practice for reliable results.

Context matters - intentional weight loss should be given less weight in the overall assessment compared to unintentional loss 1.