Hematology Case Study: A 12 Year Old Female with Thrombocytopenia.

Case History

A 12 year old female presented with thrombocytopenia. Previous platelet count performed at a different facility showed a platelet count of <100K.  Patient signs show history of bruising, no history of trauma, intermittent epistaxis.

Family history shows no history of anemia or hypothyroidism from either parent. Incidental finding of hypothyroidism was revealed for this patient when laboratory testing was performed.

gray-platelet-small
Light staining, “gray” platelets.

Laboratory results

DAT: Negative

PT 11.7/INR 1.1

PTT 38.3

Platelet aggregation studies: Decreased response to ADP-Collagen-Epinephrine and Arachidonic Acid. Results of which are consistent with platelet dysfunction due to storage pool defect.

vonWillberand panel shows within range results for Factor 8, vW antigen and vW Ristocetin.

Peripheral blood smear shows light staining (gray) appearance of platelets.

Diagnosis: Gray Platelet Syndrome

 

Discussion

Gray platelet syndrome (GPS) is an inherited platelet disorder that presents with thrombocytopenia and characteristic pale/gray appearance of platelets under light microscopy. This gray appearance of platelets is due to the absence of alpha granules and their constituents.

According to Gunay-Aygun et al., the diagnosis of GPS requires demonstration of the absence or marked reduction of α-granules in platelets observed by electron microscopy (EM). Megakaryocytes also show decreased α-granules. Platelet dense bodies and lysosomes are unaffected. Alpha granules, the most abundant vesicles in platelets, store proteins that promote platelet adhesiveness and wound healing when secreted during platelet activation. Some α-granule proteins (eg, platelet factor 4 and β-thromboglobulin) are synthesized in megakaryocytes and packed into the vesicles, whereas others are either passively (eg, immunoglobulins and albumin) or actively (eg, fibrinogen) taken up from the plasma by receptor-mediated endocytosis. Proteins synthesized in megakaryocytes are markedly reduced in GPS, whereas other α-granule constituents are less affected. Studies of granule membrane-specific proteins have shown that platelets and megakaryocytes of GPS patients have rudimentary α-granule precursors. Therefore, the basic defect in GPS is thought to be the inability of megakaryocytes to pack endogeneously synthesized secretory proteins into developing α-granules. (Gunay-Aygun et al, 2010).

Most patients who present with GPS are characteristically macrothrombocytopenic and the number of megakaryocytes in the bone marrow appears normal. However platelet survival is reduced. This inability of megakaryocytes to survive is due to the alpha granule deficiency of this disorder therefore leading to thrombocytopenia. Myelofibrosis and splenomegaly is also apparent on patients with GPS but severe hemorrhage is unlikely, bleeding tendencies tend to be mild to moderate for GPS.

Most patients had bleeding symptoms from infancy with the average onset of 2 years of age. Average age of diagnosis is 10-14 years of age; some patients who have Gray Platelet Syndrome have presented with initial diagnosis of ITP (idiopathic thrombocytopenic purpura).

Reference

Gunay-Aygun, M., Zivony-Elboum, Y., Gumruk, F., Geiger, D., Cetin, M., Khayat, M., . . . Falik-Zaccai, T. (2010). Gray platelet syndrome: natural history of a large patient cohort and locus assignment to chromosome 3p. Blood, 116(23), 4990-5001. doi:10.1182/blood-2010-05-286534

 

-Written in collaboration with Stephanie Foster, BS MLS

ledesma_small

-Carlo Ledesma, MS, SH(ASCP)CM MT(ASCPi) MT(AMT) is the program director for the Medical Laboratory Technology and Phlebotomy at Rose State College in Midwest City, Oklahoma as well as a technical consultant for Royal Laboratory Services. Carlo has worked in several areas of the laboratory including microbiology and hematology before becoming a laboratory manager and program director.

A Brief Overview of 7-day Platelets

The transfusion community has targeted platelets as the primary culprit in transfusion-associated clinical sepsis and fatal microbial infection. Platelets (PLTs) are associated with a higher risk of sepsis and related fatality than any other transfusable blood component. Concerns over bacterial contamination in PLT concentrates prompted the US Food and Drug Administration (FDA) in 1986 to issue a memorandum limiting the storage time of platelet products to 5 days. Only recently did the FDA issue draft guidance describing bacterial testing to improve the safety and availability of PLTs, and outlined the steps necessary for transfusion services to extend apheresis PLTs to 7 days.

Microbial infections were the 4th leading cause of transfusion-related mortality, accounting for 8% of them between 2010 and 2014. PLT storage at ambient room temperature supports high titer bacterial proliferation. Skin flora are the most common source of contamination, occurring at the time of collection. Despite the introduction of improved pre-collection arm preparation and analytically sensitive culture-based bacterial detection methods, the risk of fatal and non-fatal clinical sepsis has persisted.

Most recently, the 2016 AABB standards stated that PLTs may be stored for 7 days only if: 1) storage containers are cleared or approved by FDA for 7-day PLT storage and 2) labeled with the requirement to test every product stored beyond 5 days with a bacteria detection device cleared by FDA and labeled as a “safety measure.” The Verax PGD test is a rapid, single use, lateral flow immunoassay, and the only rapid, day of transfusion test the FDA has cleared as a “safety measure.” The proprietary test detects surface bacterial antigens, namely lipotechoic acid found on gram positive organisms and lipopolysaccharide found on gram negatives. The PGD test as a “safety measure” is to be used in concert with culture, not replace it.

Verax PGD test

Approximately 2.2 million PLT transfusions are administered yearly in the United States, of which more than 90% consist of apheresis PLTs. If the available data were generalized to the entire US apheresis PLT supply, approximately 650 contaminated apheresis PLTs would be caught with the PGD test, preventing septic transfusion reactions and potential fatalities each year. The FDA approval of this test allows non-culture based testing to extend dating from 5 to 7 days and further closes the safety gap that exists in apheresis PLTs.

 

Rogers

-Thomas S. Rogers, DO is a third-year resident at the University of Vermont Medical Center, a clinical instructor at the University of Vermont College of Medicine, and the assistant medical director of the Blood Bank and Transfusion Medicine service.

The author declares that he has no disclosures.

Platelet-Rich Plasma: My View from the Transfusion Service

Platelets play a significant role in primary hemostasis, however they also serve as a reservoir of a number of important growth factors, including but not limited to platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF). Thus, autologous platelets applied topically or injected into areas of recent surgical reconstruction or to wounds are thought to stimulate angiogenesis and aid in tissue repair/regeneration. Several instruments are available to harvest platelets, (re-suspended in plasma a.k.a. platelet-rich plasma, PRP), and this provides a vehicle for delivery as a topical or injectable product.

There is no doubt that basic science and in vitro studies substantiate the release of platelet-derived growth factors and their potential role in healing, however robust trials and in vivo studies are lacking and often show conflicting results. The lack of strong clinical evidence is due to the marked heterogeneity of PRP preparations, platelet counts, and growth factor yields or activity. Differences in the site of use, type of injury and tissue, and patient comorbidities likewise contribute to the broad range of study results. Dosing regimens for optimal use are also unknown. There are no evidence-based studies of head-to-head comparisons of these products or their relative efficacies on patient outcomes.  Current literature maintains that there is insufficient evidence to support the routine use of PRP in clinical practice. In spite of this, there continues to be extensive utilization of this product.

And I purposefully highlight the word product.

In my view, when allowing the use of instruments to acquire PRP, this represents manufacture of a blood product and constitutes a transfusion activity for which the Transfusion Service and specifically, the Transfusion Service Medical Director are ultimately responsible. All relevant transfusion activities fall under the auspice of the Transfusion Service and applicable standards would demand oversight of policies, processes and procedures. The AABB Standards for Blood Banks and Transfusion Services(1) clearly identify elements to be included such as equipment, suppliers, informed consent, document and record control, along with relevant quality and patient safety activities.

There are limited standards applicable to PRP specifically, such as storage temperature, expiration and conditions of use listed in the AABB Standards for Perioperative Autologous Blood Collection and Administration.(2) To this end, the International Cellular Medical Society(3), in 2011, noted a serious lack of guidelines surrounding the use of PRP and submitted a draft document which outlined elements for training, indications/contra-indications, informed consent processes, preparation, injection/application, safety issues and patient follow-up. A 2014 Cochrane Review called for standardization of PRP methods.(4)

Overall, I would venture to say that few hospital Transfusion Services are aware of the scope of use of PRP within their facility(ies). Regardless of one’s opinion of the current literature, I would urge all of us involved in transfusion practice to be informed of the use of PRP and to be vigilant in oversight of this activity. It is not merely a regulatory and accreditation issue, but our duty as laboratory physicians and clinical scientists to provide quality, safe and effective transfusion therapies to all patients. Often this requires educating our clinical colleagues and enabling them to understand our role in this critical process.

REFERENCES AND SUGGESTED READING:

  1. AABB Standards for Blood Banks and Transfusion Services, 29th edition, 2014
  2. AABB Standards for Perioperative Autologous Blood Collection and Administration, 5th edition, 2013
  3. cellmedicinesociety.org
  4. Morae VY et al. Platelet-rich therapies for musculoskeletal soft tissue injuries. The Cochrane Library 2014
  5. Griffin XL et al. Platelet-rich therapies for long bone healing in adults. The Cochrane Library 2012
  6. Leitner GC et al. Platelet content and growth factor release in platelet-rich plasma: A comparison of four different systems. Vox Sang 2006; 91: 135-138
  7. Everts PA et al. Platelet-rich plasma and platelet gel: A review. J Extra Corpor Technol 2006; 38: 174-187

Burns

-Dr. Burns was a private practice pathologist, and Medical Director for the Jewish Hospital Healthcare System in Louisville, KY. for 20 years. She has practiced both surgical and clinical pathology and has been an Assistant Clinical Professor at the University of Louisville. She is currently available for consulting in Patient Blood Management and Transfusion Medicine. You can reach her at cburnspbm@gmail.com.