Preheating of urine improves the specificity of urinary cryptococcal antigen testing using the lateral flow assay

Abstract

A delay in laboratory diagnosis is related to sequelae and death. Thus, early diagnosis is the key to decrease the high lethality rate due to cryptococcosis. The cryptococcal antigen lateral flow assay (CrAg LFA) Immy test is standardized for a fast screening point-of-care test for cryptococcosis, detecting cryptococcal antigen in serum and cerebrospinal fluid (CSF). Urine screening would be ideal as a noninvasive approach, but previous studies have shown that fresh urine present false positive results. For this reason, we introduced just one simple physical procedure (i.e, heating of fresh urine prior to CrAg LFA Immy testing) to increase the specificity without compromising test sensitivity.