New York, Dec 6: Biomedical engineers have developed a novel smartphone application that could non-invasively detect anaemia without the need for a blood test.

The app uses photos of a person's fingernails taken on a smartphone to accurately measure how much haemoglobin is in their blood.

Fingernail beds are ideal for detection of anaemia because they do not contain melanin -- pigment that gives human skin, hair, and eyes their colour -- indicating that the test can be valid for people with a variety of skin tones.

"All other 'point-of-care' anaemia detection tools require external equipment, and represent trade-offs between invasiveness, cost, and accuracy," said principal investigator Wilbur Lam, Associate Professor from Emory University in the US.

"This is a standalone app whose accuracy is on par with currently available point-of-care tests without the need to draw blood," said Lam.

The app is particularly helpful for pregnant women, women with abnormal menstrual bleeding, runners/athletes, and patients with chronic anaemia as they can monitor their disease and identify the times when they need to adjust their therapies or receive transfusions, the researchers said.

The app, detailed in the journal Nature Communications, is part of the doctoral work of former biomedical engineering graduate student Rob Mannino, who was motivated to conduct the research by his own experience living with beta-thalassemia -- an inherited blood disorder that reduces the production of haemoglobin.

Maninno first took pictures of himself before and after transfusions as his haemoglobin levels were changing.

Later, the researchers studied fingernail photos and correlated the colour of the fingernail beds with haemoglobin levels measured by complete blood count (CBC) in 337 people.

The results showed some healthy and others with a variety of anaemia diagnoses.

However, additional research is needed to eventually achieve the accuracy to replace blood-based anaemia testing for clinical diagnosis, according to the team.

The smartphone anaemia app is projected to be commercially available for public download in 2019.

Novel smartphone app can detect anaemia without blood test