Diagnostic Criteria for HHT

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For a diagnosis of HHT, physicians should use ICD-10 Code i78.0 (previously ICD-9 Code 448.0)

HHT is under-diagnosed: Only 10% of affected individuals have the diagnosis of HHT

 

Quick diagnosis of HHT allows the individual with HHT and their family members receive screening and treatment before complications happen. Diagnosis is typically confirmed with clinical features in people with symptoms, OR with genetic testing in family members who do not have symptoms (Faughnan et al.,2020).

The Curaçao Diagnostic Criteria for HHT

  • If a doctor determines that at least three of these criteria are met, it is considered to be definite HHT.
  • If two of the criteria are met, it is considered possible HHT.
  • If less than two of these criteria apply, it is unlikely to be HHT.
  1. Recurrent and spontaneous nosebleeds (epistaxis), which may be mild to severe.
  2. Multiple telangiectases on the skin of the hands, lips, face, or inside of the nose or mouth. Telangiectases are small red spots that disappear when pushed on.
  3. Arteriovenous malformations (AVMs) or telangiectases in one or more of the internal organs, including the lungs, brain, liver, intestines, stomach, and spinal cord.
  4. A family history of HHT (i.e. first-degree relative such as brother, sister, parent or child who meets these same criteria for definite HHT or has been genetically diagnosed).

A few features of the diagnostic criteria:

  • The criteria spell out in detail what is required for each manifestation for it to be considered HHT. For example, since there is no agreement among doctors about the precise number of episodes or severity of nosebleeds needed to satisfy a diagnosis of HHT, the criteria merely highlight that to be considered a symptom of HHT, nosebleeds should occur spontaneously on more than one occasion, with night-time bleeds being particularly suspicious.
  • The criteria stresses the importance of taking a detailed and targeted family history in order to establish the diagnosis of this disorder in an individual. When someone has the HHT genetic mutation it is very likely that they will experience symptoms, but the symptoms of HHT can vary a lot between individuals, even within the same family. These criteria also allow doctors to distinguish between individuals who definitely have HHT, and those in whom it is suspected, ensuring appropriate follow-up and medical management.
  • The criteria emphasizes that all children of an individual with HHT are at risk of having the disease. It is recommended that if there is any concern regarding the presence or absence of physical signs, a physician experienced with HHT should be consulted. Since establishing the diagnosis of HHT based on clinical criteria is less reliable in children than in adults, genetic testing is important in this age group.

Sometimes a physician is not able to make a definitive clinical diagnosis based on the above criteria alone.

In these cases, a genetic test might help determine if they have HHT:

  • A positive genetic test would confirm that someone does have HHT.
  • A negative test does not rule out HHT. 15% of people with HHT have mutations in genes that are not yet identified HHT genes. Repeat testing in the future would be beneficial in these cases because new HHT causing genes can be discovered.

 

Reference: Faughnan, M. E. et al.(2020). Second International Guidelines for the Diagnosis and Management of Hereditary Hemorrhagic Telangiectasia. Annals of internal medicine, 173(12), 989–1001. https://doi.org/10.7326/M20-1443