Anemia

Is paleness always reliable? Unfortunately NO !!

  • Patient’s natural skin pigment
    – Cyanosis can mask the paleness
  • Diameter of subepidermal vessels
    – Vasoconstriction from cold may cause pallor without anemia
    – Vasodilation due to inflammation can cause redness

The best location to look for anemia

  • Conjunctival rim
    – Conjunctival rim pallor  if present has a +LR of 16.7. If examination of anterior rim of inferior conjunctiva reveals the same pale fleshy colour as the posterior aspect of conjunctiva, it is present. Normally, anterior rim has bright red colour.
  • Conjunctival pallor also has good +LR = 4.7
  • The next best location to find pallor is palm
    – palmar crease pallor has +LR of 7.9
    – palmar pallor has +LR of 5.6

Nail bed pallor has no diagnostic value

NO physical sign argues against diagnosis of anemia.

  • Most have -LR of >0.4, conjunctival and palmar pallor have -LR of 0,6 and 0.4 respectively.
  • This means presence of pallor is good for dx of anemia, but absence of it does not exclude anemia.

Learning points

  • Conjunctiva and palm are the 2 best locations to find anemia in a dark skinned patient.
  • Diagnosis of anemia could not be excluded just by physical examination alone. It could be present but not obvious. NO PHSICAL SIGN argues against the diagnosis of anemia.

Reference: Evidence-based physical diagnosis, Steven McGee – 2nd ed

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