Test Catalog

Test Id : PTEM

Platelet Transmission Electron Microscopic Study, Whole Blood

Useful For
Suggests clinical disorders or settings where the test may be helpful

Diagnosing platelet disorders

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

This test is indicated for assessing platelet ultra-structural abnormalities in congenital and acquired platelet disorders.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Transmission Electron Microscopy

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.


Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Platelet TEM, B

Specimen Type
Describes the specimen type validated for testing

Whole Blood ACD

Shipping Instructions

Send specimen Monday through Wednesday.


Specimens must be received in testing laboratory within 72 hours of collection. Ship specimen overnight in an Ambient Shipping Box-Critical Specimens Only (T668) following the instructions in the mailer.

Necessary Information

Platelet Esoteric Testing Patient Information is required, see Special Instructions. Testing may proceed without the patient information, however, the information aids in providing a more thorough interpretation. Ordering providers are strongly encouraged to fill out the form and send with the specimen.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Patient Preparation: Fasting is preferred but not required. 

Supplies: Ambient Shipping Box-Critical Specimens Only (T668)

Collection Container/Tube:

Preferred: Yellow top (ACD, solution B)

Acceptable: Yellow top (ACD, solution A)

Specimen Volume: 6 mL

Collection Instructions: Send specimen in original tube. Do not aliquot.

Special Instructions
Library of PDFs including pertinent information and forms related to the test


1. Platelet Esoteric Testing Patient Information is required. See Special Instructions.

2. If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.

3 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Gross lipemia OK

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Whole Blood ACD Ambient 72 hours

Useful For
Suggests clinical disorders or settings where the test may be helpful

Diagnosing platelet disorders

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

This test is indicated for assessing platelet ultra-structural abnormalities in congenital and acquired platelet disorders.

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Patients with either hereditary or acquired platelet disorders usually have bleeding diathesis, which can potentially be life threatening. A reliable laboratory diagnosis of a platelet disorder can significantly impact patients' and, potentially, their family members' clinical management and outcome.


Platelet (P) transmission electron microscopy (TEM) has been an essential tool for laboratory diagnosis of various hereditary platelet disorders since it was first used to visualize fibrin-platelet clot formation in 1955. PTEM employs 2 main methods to visualize platelet ultrastructure, whole mount (WM) TEM and thin section (TS) TEM.


WM-TEM is considered the gold standard test for diagnosing dense granule deficiencies in Hermansky-Pudlak syndrome, alpha-delta platelet storage pool deficiency, Paris-Trousseau-Jacobsen syndrome, Wiskott-Aldrich syndrome, TAR (thrombocytopenia, absent radii) syndrome, Chediak-Higashi syndrome, and more.


TS-TEM is a preferred method to visualize platelet alpha granules, other organelles, and abnormal inclusions.


Platelet disorders that can be detected by PTEM include (but are not limited to):

Delta granules (dense bodies):

-Hermansky Pudlak syndrome

-Wiskott-Aldrich syndrome

-Chediak Higashi syndrome

-Jacobson/Paris-Trousseau syndrome

-York platelet syndrome

-Storage pool deficiency, not otherwise specified


Alpha granules:

-Gray platelet syndrome

-White platelet syndrome

-X-linked GATA-1 variant

-Jacobson/Paris-Trousseau syndrome


Alpha and delta granules:

-Alpha-delta storage pool deficiency

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Mean dense granules/platelet: > or =1.2

Provides information to assist in interpretation of the test results

Ultrastructural abnormalities identified by platelet transmission electron microscopy (TEM) are evaluated by a Mayo hematopathologist.


Platelet size, alpha granules, Golgi complex, and abnormal inclusions will be assessed as part of the morphologic examination under TEM.


Distinct and sometimes pathognomonic ultrastructural abnormalities are found in Hermansky Pudlak syndrome, gray platelet syndrome with virtually absent alpha granules, white platelet syndrome, Medich giant platelet disorder, X-linked GATA-1 macrothrombocytopenia, and, recently described, York platelet syndrome.

Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Yellow top (ACD) whole blood specimens must be stored and transported at ambient temperature to be received within 72 hours of collection. Suboptimal transportation may cause falsely low dense granule counts.

Supportive Data

Extensive validation studies with normal donors and known patient samples were performed. A total 111 normal donor platelet samples were assessed to establish the baseline. Of the 10 known patient samples, 6 were from patients with Hermansky-Pudlak syndrome, 2 patients had gray platelet syndrome, 1 had MYH9 variant-associated platelet disorder, and 1 had Paris-Trousseau/Jacobson syndrome.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. White JG: Electron-dense chains and clusters in platelets from patients with storage pool-deficiency disorders. J Thromb Haemost. 2003 Jan;1(1):74-79. doi: 10.1046/j.1538-7836.2003.00032.x

2. White JG: Use of the electron microscope for diagnosis of platelet disorders. Semin Thromb Hemost. 1998;24(2):163-168. doi: 10.1055/s-2007-995836

3. Chen D, Uhl CB, Bryant SC, et al: Diagnostic laboratory standardization and validation of platelet transmission electron microscopy. Platelets. 2018 Sep;29(6):574-582. doi: 10.1080/09537104.2018.1476682

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

This test identifies dense granule deficiency by semiquantitative counting of dense granules on whole mount grids by technologists and verified by a hematopathologist/hematologist.


Whole mount-transmission electron microscopy is a quick and simple way to examine platelet electron opaque or dense granule (DG) by laying platelet-rich plasma on an electron microscopy grid. The high content of calcium in DG blocks electron beam of transmission electron microscopy (TEM) and creates a sharp dark shadow.(White JG: The dense bodies of human platelets: inherent electron opacity of the serotonin storage particles. Blood. 1969 Apr;33[4]:598-606; Winey M, Meehl JB, O'Toole ET, Giddings TH Jr: Conventional transmission electron microscopy. Mol Biol Cell. 2014 Feb;25[3]:319-323. doi: 10.1091/mbc.E12-12-0863)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Friday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

10 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Not retained

Performing Laboratory Location
Indicates the location of the laboratory that performs the test


Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.



LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
PTEM Platelet TEM, B 79768-8
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
CK109 Platelet TEM 79768-8
CK110 Interpretation 59466-3

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports