False-seronegative HCV infection motivated by interference with cryoglobulins.

Objectives: Cryoglobulins (CGs) are serum proteins that undergo a reverse cold-induced precipitation in vitro. The CGs are a well-known cause of analytical interferences in several laboratory tests, leading to spurious results. With this in view, we present a case of a patient initially misdiagnosed due to CGs interference in Hepatitis C Virus (HCV) serology. Case presentation: We report a case of a woman of advanced age affected by acute renal failure that required urgent haemodialysis. In the absence of infections and other causes of CGs production, a diagnosis of acute renal failure secondary to essential cryoglobulinemia was established. However, an unexpected positive HCV viral load was encountered. At this point, a false-seronegative HCV infection conditioned to CGs interference in vitro was suspected, confirmed by repeating serology in pre-warmed serum. Finally, the patient was correctly diagnosed with HCV-secondary cryoglobulinemia. Conclusions: As shown in the case, the presence of CGs in blood may represent a challenge for the correct interpretation of several laboratory tests. The identification of CGs and the pre-treatment of serum are decisive to avoid spurious results and reach a genuine diagnosis.

Use of predictive tools in the management of COVID-19 patients: a key role of clinical laboratories.

Objectives: Coronavirus disease 2019 (COVID-19) is widely spreading and represents a critical threat to global health. In the fight against this pandemic, provincial hospitals urgently need rapid diagnostic of COVID-19 infected patients to avoid collapsing of emergency units. However, the high demand of patients with severe acute respiratory symptoms limits the fast delivery of results by the gold standard method reverse transcription-polymerase chain reaction real time (rRT-PCR) for the identification of COVID-19 positive pneumonia. The principal aim is to find other useful laboratory indicators to assist rRT-PCR tests and to help controlling of this outbreak. Methods: Blood, coagulation and inflammatory parameters were collected from a total of 309 patients classified as negative (128) and positive (181) rRT-PCR test groups. Patients were classified as positive by molecular diagnostic test. Results: Leukocyte count (WBC), neutrophils count, lymphocytes count and lactate dehydrogenase (LDH) were statistically different between both groups of patients. The use of LDH/WBC ratio increases the diagnostic performance with the best area under the curve (0.783), sensibility (82%) and the best percentage (80.5%) of correctly identified COVID-19 positive patients. Conclusions: The combination of predictive LDH/WBC ratio with clinical illness features could help in medical management of patients and improve the technical resources of hospitals, especially in a critical scenario with a large shortage of medical equipment and lack of reagents for performing rRT-PCR.