Page 180 - Registrar Orientation Manual 2016

Reference:
Effective date:
2015
Expiry date:
2018
Page:
6 of 28
Title: Laboratory Testing Guidelines (DRAFT)
Type:
Clinical Guideline
Version:
01
Authorising initials:
ESR ($8)
The Choosing Wisely recommendations include the following:
Don’t order an ESR to look for inflammation in patients with undiagnosed conditions. The DHB Shared Services Laboratory Test Referral Guidelines note:
The ESR should not be used to screen for plasma cell dyscrasias; if these conditions are suspected, protein electrophoresis and/or serum free light chains should be used.
The CRP is the preferred test for the assessment of possible inflammatory or infective disorders. It is seldom appropriate for both an ESR and CRP to be performed on the same sample.
However, the CRP and ESR are driven by different inflammatory processes and can be useful together in selected patients but only requests from SMOs will be processed.
The ESR may have some advantages in the assessment of the following conditions:
 Systemic lupus erythematosis;
 Rheumatoid arthritis;
 Kawasaki disease;
 Rheumatic fever;
 Hodgkin’s lymphoma.
Group and Save ($44 and an additional $80 if an antibody is found)
Many patients who have a ‘Group and Save’ never get transfused. We recommend:
Do not do a ‘Group and Save’ unless the patient is likely to require an urgent blood transfusion (major surgery or actively bleeding).
Do not do a ‘Group and Save’ in stable patients with a chronic anaemia or ‘just in case’.
Haemachromatosis studies ($100)
Haemachromatosis testing costs over $100,000 a year. Many tests are not indicated.
The commonest cause of hereditary haemochromatosis is mutations in the HFE genes.
Most patients (90%) with hypeferritinaemia will not have iron overload.
Testing is appropriate for investigation of hyperferritinaemia but only if there is one or more of:
 persistent hyperferritinaemia that is not explained by the more common causes such as alcohol intake, fatty liver, liver pathology or inflammation, or
 severe hyperferritinaemia (persistently >1000 without severe inflammation), or
 hyperferritinaemia with fasting iron saturation >0.50.
Testing is also indicated in screening of relatives a patient with confirmed haemachromatosis. Do not do HFE genotype testing for hyperferritinaemia without these indications. Genetic testing will only be performed once in a patient’s life time.
JAK2 V617F Mutation ($190)
JAK2 tests cost over $60,000 a year. Testing should always be discussed with a haematologist.
JAK2 mutations are associated with the myeloproliferative disorders polycythaemia vera (PV), essential thrombocythaemia (ET) and myelofibrosis.
Testing is usually indicated in the presence of sustained erythrocytosis (Hb > upper normal limit) and/or thrombocytosis (platelets >600) if this is not clearly explained by other causes (for example chronic hypoxia and inflammation, respectively). Venous thrombosis (particularly mesenteric) is occasionally associated with these conditions.