Whose TPMT activity is it anyway?

Ford, Loretta; Prout, Catherine; Gaffney, Dairena; Berg, Jonathan
November 2004
Annals of Clinical Biochemistry;Nov2004, Vol. 41 Issue 6, p498
Academic Journal
Determination of thiopurine S-methyltransferase (TPMT) activity prior to starting azathioprine therapy is used to identify individuals with low or deficient TPMT activities who are at risk of severe complications and even death This case describes a patient treated with azathioprine without prior knowledge of TPMT status. Pancytopaenia developed over several months and at this point TPMT activity was determined and found to be low at 16 nmol 6-methyl thioguanine (6-MTG)/g Hb/h, which is within the reference interval associated with heterozygosity for TPMT mutant alleles. On repeating the TPMT measurement 3 months later, the TPMT activity was 2 nmol 6-MTG/g Hb/h, consistent with deficient TPMT activity (homozygosity for TPMT mutant alleles), suggesting the patient is at high risk of myelosuppression if treated with thiopurine drugs. Retrospectively, it was found that the patient had received transfusions of red blood cell and platelets 6 days before TPMT activity was first measured. This case underlines the importance of determining TPMT activity status prior to azathioprine treatment, rather than taking a dose incrementation approach. It also highlights the caution that must be taken in interpreting TPMT activity in patients who have recently been transfused.


Related Articles

  • THE SKEWNESS OF VOLUME DISTRIBUTION CURVES OF ERYTHROCYTES. Winter, H.; Sheard, R. P. // Australian Journal of Experimental Biology & Medical Science;Dec1965, Vol. 43 Issue 6, p687 

    The article presents a discussion on the skewness of volume distribution curves of erythrocytes. Volume distribution curves of erythrocytes, obtained by automatic cell counting, are skew, the right side being flatter than the left one, indicating a greater than normal population of larger cells....

  • CLOT RETRACTION  // Davis's Comprehensive Handbook of Laboratory & Diagnostic Tests ;Jan2006, p386 

    The clot retraction test measures the adequacy of platelet function by measuring the speed and extent of clot retraction. Normally, when blood clots in a test tube, it retracts away from the sidewalls of the tube. Platelets play a major role in the clot retraction process. When platelets are...

  • Effects of a Pneumatic Tube System on Routine and Novel Hematology and Coagulation Parameters in Healthy Volunteers. Kratz, Alexander; Salem, Raneem O.; van Cott, Elizabeth M. // Archives of Pathology & Laboratory Medicine;Feb2007, Vol. 131 Issue 2, p293 

    Context.—Technologic advances affecting analyzers used in clinical laboratories have changed the methods used to obtain many laboratory measurements, and many novel parameters are now available. The effects of specimen transport through a pneumatic tube system on laboratory results...

  • Comparison of the ProCyte Dx analyzer with the ADVIA 2120 and the manual differential for validation of equine and bovine hemograms. Goldmann, Fee; Bauer, Natali; Moritz, Andreas // Comparative Clinical Pathology;Sep2013, Vol. 22 Issue 5, p855 

    The aim of this study was to evaluate the laser-based in-house hematology analyzer ProCyte Dx performing a complete hemogram for bovine and equine blood samples. This is a prospective study of clinically healthy or ill horses ( n = 175) and cattle ( n = 115). EDTA-anticoagulated blood samples...

  • Response to Letter: Mean Platelet Volume in Patients With Dilated Cardiomyopathy and Left Ventricular Thrombus. Tekin, Gulacan; Tekin, Yusuf Kenan; Sivri, Nasır; Yetkin, Ertan // Angiology;Dec2012, Vol. 63 Issue 7, p557 

    A response from the authors of the article "Mean platelet volume in patients with dilated cardiomyopathy: does it have a role on left ventricular thrombus formation?" in the October 2012 issue, is presented.

  • How to Decipher Your Blood Work And Know Which Tests You Need.  // Heart Advisor;Oct2015, Vol. 18 Issue 10, p3 

    The article explains how individuals should look at their annual blood test report and determine key information about their heart, blood and kidneys. It cites the complete blood count (CBC) where tests for levels of red and white blood cells, hemoglobin, hematocrit, and platelets are included,...

  • The importance of a complete hemogram. Meman, A. Rick // DVM: The Newsmagazine of Veterinary Medicine;May2005, Vol. 36 Issue 5, p60 

    This article focuses on the importance of a complete hemogram or blood cell count. Of all the diagnostic tests available, blood evaluation is one of the most valuable in assessing the general health of the body. The complete blood count (CBC) is the best and most convenient mechanism to detect...

  • blood count. Peters, Michael // BMA A-Z Family Medical Encyclopedia;2004, p110 

    An encyclopedia entry for "blood count" is presented. Also called full blood count, this test measures the haemoglobin concentration and the numbers of red blood cells, white blood cells and platelets in 1 cubic millimeter of blood. It cites the importance of this test for the diagnosis of...

  • Thrombocytopenia in Neonatal Infection. Modanlou, Houchang D.; Ortiz, Oscar B. // Clinical Pediatrics;Jun1981, Vol. 20 Issue 6, p402 

    Serial platelet counts by phase microscopy were done for three groups of neonates who were admitted to the Special Care Unit of the Miller Children's Hospital. Group 1 (78 neonates) was evaluated for septicemia. Group 2 (28 neonates) was randomly selected sick neonates whose working diagnosis...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics