| Underwood's disease (sclerema neonatorum) 778.1 | 
  | Undescended - see also Malposition, congenital | 
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  | Undetermined diagnosis or cause 799.9 | 
  | Undeveloped, undevelopment - see also Hypoplasia | 
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  | Undiagnosed (disease) 799.9 | 
  | Undulant fever (see also Brucellosis) 023.9 | 
  | Unemployment, anxiety concerning V62.0 | 
  | Unequal leg (acquired) (length) 736.81 | 
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  | Unerupted teeth, tooth 520.6 | 
  | Unextracted dental root 525.3 | 
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  | Unicorporeus uterus 752.3 | 
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  | Unilateral - see also condition | 
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  | Unilateralis uterus 752.3 | 
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  | Union, abnormal - see also Fusion | 
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  | Universal | 
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  | Unknown | 
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  | Unna's disease (seborrheic dermatitis) 690.10 | 
  | Unresponsiveness, adrenocorticotropin (ACTH) 255.41 | 
  | Unsatisfactory | 
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  | Unsoundness of mind (see also Psychosis) 298.9 | 
  | Unspecified cause of death 799.9 | 
  | Unstable | 
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  | Untruthfulness, child problem (see also Disturbance, conduct) 312.0 | 
  | Unverricht (-Lundborg) disease, syndrome, or epilepsy 333.2 | 
  | Unverricht-Wagner syndrome (dermatomyositis) 710.3 | 
  | Upper respiratory - see condition | 
  | Upset | 
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  | Urachus - see also condition | 
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  | Urbach's lipoid proteinosis 272.8 | 
  | Urbach-Oppenheim disease or syndrome (necrobiosis lipoidica diabeticorum) 250.8  [709.3] | 
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  | Urbach-Wiethe disease or syndrome (lipoid proteinosis) 272.8 | 
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  | Urea, blood, high - see Uremia | 
  | Uremia, uremic (absorption) (amaurosis) (amblyopia) (aphasia) (apoplexy) (coma) (delirium) (dementia) (dropsy) (dyspnea) (fever) (intoxication) (mania) (paralysis) (poisoning) (toxemia) (vomiting) 586 | 
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  | Ureter, ureteral - see condition | 
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  | Ureterostomy status V44.6 | 
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  | Urethra, urethral - see condition | 
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