PB0580 - Laboratory diagnosis of Prekallikrein deficiency: importance of suspicion and laboratory method

Monday, June 26, 2023

18:30 – 19:30 ET

Room: Exhibition

Co-Author(s)

TS

Teresa Sevivas

MD
Department of Blood and Transfusion Medicine, Coimbra Hospital and Universitary Centre, Portugal
Coimbra, Coimbra, Portugal

Co-Author(s)

EG

Elsa Gonçalves

Lab
Department of Laboratory Medicine, Coimbra Hospital and Universitary Centre, Portugal
Coimbra, Coimbra, Portugal
CF

Celeste Freire

Lab
Department of Laboratory Medicine, Coimbra Hospital and Universitary Centre, Portugal
Coimbra, Coimbra, Portugal
TM

Telma Marques

Lab
Department of Laboratory Medicine, Coimbra Hospital and Universitary Centre, Portugal
Coimbra, Coimbra, Portugal
TF

Teresa Ferreira

Lab
Department of Laboratory Medicine, Coimbra Hospital and Universitary Centre, Portugal
Coimbra, Coimbra, Portugal
AC

Ana Lúcia Correia

Lab
Department of Laboratory Medicine, Coimbra Hospital and Universitary Centre, Portugal
Coimbra, Coimbra, Portugal
GR

Guiomar Rasteiro

Lab
Department of Laboratory Medicine, Coimbra Hospital and Universitary Centre, Portugal
Coimbra, Coimbra, Portugal
Jose Mª Bastida, PhD, MD

Hematology Department
Complejo Asistencial Universitario de Salamanca-IBSAL-USAL (Salamanca)
Salamanca, Castilla y Leon, Spain

Presenting Author(s)

João Mariano Pego, Medical Doctor

MD
Department of Clinical Pathology, Coimbra Hospital and Universitary Centre, Portugal
Coimbra, Coimbra, Portugal

Background: PK deficiency (DefPK) is a rare autosomic recessive transmission disease. Patients are generally asymptomatic or present very mild bleeding symptoms. It is underdiagnosed because the significant prolongation of activated partial thromboplastin time (aPTT) associated with it is ultimately very little investigated.

Aims: Illustrate the importance of the Haemostasis´ Laboratory (LabH) in the diagnosis of DefPK.

Methods: Boy, 5 years, fever and petechiae. Platelets 271x 109/L, PT 12.4/11, aPTT 40.3/31. Pediatric consultation 2 days later: aPTT 178.2/31. No bleeding symptoms, new sample for confirmation and investigation of aPTT.
Samples: sodium citrate 3.2%, centrifuged at 2500rpm 12 min. Tests: Prothrombin Time (PT) with RecombiPlastin2G®; aPTT with SynthAsil® (silica activator) and SynthAFax® (activator- alagic acid) and two incubations (3 min, 15 min); Fibrinogen by Clauss method; Factors VIII, IX, XI and XII, coagulating method with SynthAsil® and IL deficient plasmas; Lupus anticoagulant (LAC) with dRVVT and Silica Cloting Time; Activity of PK and High Molecular Weight Quininogen, coagulant method and deficient plasmas of Technoclone®. Equipment: ACL TOP 550 (Werfen®) and Sysmex CS-2500 System (Siemens Healthineers®). Family studies have been done. Molecular studies were carried out by massive sequencing of the KLKB1 gene with a Custom capture panel.

Results: Table

Conclusion(s): Investigation of rare diseases in LabH should be based on a critical evaluation of results and a high degree of suspicion. In a sample with very prolonged aPTT, in which the patient did not have bleeding symptoms and in which the first stages of the investigation were normal, there was a suspicion of a DefPK. This could be confirmed by: 1. normalization of aPTT after increasing the pre-incubation time of the sample; 2. normalization of aPTT with a reagent with elagic acid; 3. dosing of PK activity. This methodology allowed the diagnosis of severe deficiency in the propositus and brother 2, mild deficiency in brother 1.