Telehealth systems in underserved countries leverage various low-cost portable medical sensors to transmit patients’ vital information to remote doctors, facilitating timely diagnoses and interventions. However, the potential risks associated with inaccurate data pose considerable threats to the health of individuals. This study focuses on identifying high-quality portable hemoglobin sensors, employing the Japanese clinical pathology laboratory as a gold standard. Out of the eight sensors evaluated in this study, four were found to be highly erroneous.