2025 – PAGE 291 – HEMATOLOGY & ONCOLOGY

PLATELET DISORDERS

(DOUBLE TAKE) CELL LIFE SPANS

The red blood cell (RBC) has a life span of about 120 days (about 4 months). Platelets live for about 10 days.

MNEMONIC: Imagine an EGG carton (12) that has RBCs in it. Alternatively, if you are worried that will make you think of 12 days instead of 120 days, imagine a CAR (4) with FOUR balloon-like RED BLOOD CELLS on the car instead of four wheels to remind you that RBCs live for 4 months.

MNEMONIC: Imagine going BOWLING (10) at a place that uses 10 PLATES instead of pins.

MNEMONIC: Bigger cell (RBC) = Bigger lifespan!

THROMBOCYTOPENIA

Thrombocytopenia is defined in children as < 250 x 10⁹/l, and in adolescents/adults as < 150.

MATERNAL IMMUNE (OR IDIOPATHIC) THROMBOCYTOPENIC PURPURA

In Maternal Immune Thrombocytopenic Purpura, the mother CARRIES antibodies that affect her own platelet count as well as the platelet count of the neonate. The neonatal thrombocytopenia can last for weeks and can cause severe, and even fatal, bleeds. The key to finding the diagnosis is the presence of the thrombocytopenia in the baby and the mother.

NEONATAL ALLOIMMUNE THROMBOCYTOPENIA (NAIT)

In Neonatal Alloimmune Thrombocytopenia (NAIT), the mother FORMS antibodies against fetal platelet antigens. These antigens are often inherited from the father and are absent in the mother in much the same way as in Rh disease. Thrombocytopenia is present in the neonate and is a leading cause of intracranial hemorrhage in full-term infants. There is a high risk of NAIT recurring in subsequent pregnancies.

NEONATAL SEPSIS-INDUCED THROMBOCYTOPENIA

Neonatal sepsis may result in thrombocytopenia, or platelet dysfunction, which can cause mucosal or GI bleeding, bruising, nosebleeds, and petechiae.

PEARLS: In general, epistaxis is commonly due to dry air and does not usually require a workup if the patient is otherwise healthy. If you see a deep muscle bleed, that’s more likely to be due to a coagulopathy issue rather than a platelet problem.

THROMBOCYTOPENIA AND ABSENT RADIUS (AKA TAR SYNDROME)

In Thrombocytopenia and Absent Radius syndrome (AKA TAR syndrome), patients have thrombocytopenia and absent RADII. You may also see hand or shoulder anomalies. The thrombocytopenia is AMEGA­KARYOCYTIC (low or absent number of megakaryocytes on bone marrow biopsy).

• • IMAGE: www.pbrlinks.com/TARSYNDROME1
  • IMAGE: www.pbrlinks.com/TARSYNDROME2

PEARL: This is usually a BILATERAL problem with both RADII missing. The thumbs are PRESENT.

IMMUNE THROMBOCYTOPENIC PURPURA (AKA ITP, AKA IDIOPATHIC THROMBOCYTOPENIA PURPURA)

Look for LARGE platelets with a high Mean Platelet Volume (MPV) to indicate immune thrombocytopenia (ITP). ITP often occurs after a viral syndrome. Most kids can be managed with watchful waiting. For moderate or severe bleeding, treat with steroids and/or IVIG. If both options are present and a rapid rise of platelet counts is needed, choose IVIG over steroids. Rhogam (WinRho) can also be used if the patient is Rh+ to induce a mild hemolysis that then “distracts” the immune system. For kids under 10, it usually resolves after a few months. Transfuse if there are signs of bleeding. If given a platelet count of < 20 x 10⁹/l, transfuse if BLEEDING.

PEARLS: Look for a low platelet count (thrombocytopenia), but BIG platelets (high MPV). If there are any signs or symptoms that suggest leukemia, don’t give steroids until LEUKEMIA HAS BEEN RULED OUT. Steroids given to a leukemic patient can induce a short remission resulting in delayed diagnosis and treatment.