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Test ID: PTEM Platelet Transmission Electron Microscopic Study, Whole Blood

Useful For

Diagnosing platelet disorders

Method Name

Transmission Electron Microscopy

Reporting Name

Platelet TEM, B

Specimen Type

Whole Blood ACD

Shipping Instructions

Ship specimen overnight in an Ambient Shipping Box-Critical Specimens Only (T668) following the instructions in the mailer.


Send specimen Monday through Wednesday

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

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 transfer blood to other containers.

Specimen Minimum Volume

3 mL

Specimen Stability Information

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

Clinical Information

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-Trousseus-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 mutation

-Jacobson/Paris Trousseau syndrome


Alpha and delta granules:

-Alpha-delta storage pool deficiency

Reference Values

Mean dense granules/platelet ≥1.2


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.

Clinical Reference

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

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

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

Day(s) and Time(s) Performed

Monday through Friday; 7 a.m.-3 p.m.

Analytic Time

10 days

Test Classification

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 U.S. Food and Drug Administration.

CPT Code Information



LOINC Code Information

Test ID Test Order Name Order LOINC Value
PTEM Platelet TEM, B 79768-8


Result ID Test Result Name Result LOINC Value
CK109 Platelet TEM 79768-8
CK110 Interpretation 59466-3


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.

Mayo Clinic Laboratories | Hematology Catalog Additional Information: